Insect Declines in the Anthropocene

Promoting equity between the Global North and Global South in entomological research

International collaborations in entomological research are crucial for addressing global biodiversity challenges, particularly in the Global South, where much of the world's insect diversity is concentrated. These partnerships enable the sharing of knowledge, resources, and expertise across borders, leading to more comprehensive and impactful research outcomes. For the Global South, equitable collaborations are essential to ensure that local researchers are contributors and equal partners in the research process. Hallmarks of mutual partnerships include co-developing research questions, sharing the benefits of research outcomes, and receiving fair compensation and support. Emphasizing equity in these collaborations helps to address historical imbalances, strengthens local research capacities, and ensures that the perspectives and needs of Global South researchers are fully integrated into the global scientific community. Equitable international collaborations enhance the quality and relevance of entomological research, contributing to better research, monitoring, and conservation worldwide.

Protected area coverage of the full annual cycle of migratory butterflies

Effective conservation of migratory species relies on habitat protection throughout their annual cycle. Although protected areas (PAs) play a central role in conservation, their effectiveness at conserving habitats across the annual cycle of migratory species has rarely been assessed. We developed seasonal ecological niche models for 418 migratory butterfly species across their global distribution to assess whether they were adequately represented in the PAs across their full annual cycle. PA coverage was inadequate in at least one season for 84% of migratory butterflies, adequate for only 17% of species in one season, and inadequate for 45% of species in all seasons. There was marked geographic variation in PA coverage: 77% of species met representation targets in Sri Lanka, for example, but only 32% met targets in Italy. Our results suggest that coordinated efforts across multiple countries will be needed to develop international networks of PAs that cover the full annual cycle of migratory insects and that conservation measures, in addition to the establishment and maintenance of PAs, are likely to be needed to effectively conserve these species.

Flower power: Modeling floral resources of wild cherry (Prunus avium L.) for bee pollinators based on 3D data

Pollinator declines pose a threat to ecosystems and food production. Agriculture contributes to, but also suffers from, the erosion of pollination services. Our study explores the potential of trees in agricultural landscapes to support pollinators by providing floral resources. Our overarching objective is the quantification of floral resources produced by wild cherry (Prunus avium L.) that can be used by flower-visiting and pollinating insects such as bees. Using an innovative approach, we combine pollen measurements with manual counts of flowers on branches and 3D data derived from terrestrial laser scanning. This approach allows us to scale up flower numbers from branches to entire trees. The derived models for estimating the probability of flower occurrence (R2 c = 0.52, R2 m = 0.50) and the number of flowers per branch (R2 c = 0.88, R2 m = 0.84), as well as the number of flowers per tree (R2 = 0.83), show good model fits with only a small set of predictors. The model fits indicate that, at the branch level, predicting flowering probability is more challenging than predicting flower abundance. We found differences in the number of flowers per branch in different crown sections, suggesting that floral resources are heterogeneously distributed. Furthermore, we demonstrate that the number of flowers per tree increases exponentially with tree dimension (stem diameter, crown volume). Therefore, large trees provide disproportionately more floral resources than small trees and are particularly worthy of conservation efforts. For example, our models estimate that a single tree with a stem diameter of 25 cm carries 195,535 flowers (95% CI: 159,991-237,318), thus providing about 57 cm3 (95% CI: 32-88 cm3) of pollen and producing 170 g (95% CI: 48-345 g) nectar sugar per 24 h. This amount of pollen is sufficient to rear, for example, 5202 larvae (95% CI: 2886-8022) of Lasioglossum laticeps, a common and generalist sweat bee of cherry trees. In contrast, a smaller tree with a stem diameter of 10 cm provides only 8% of these resources. In conclusion, we demonstrate how our results contribute to the broader single-large-or-several-small debate in nature conservation by highlighting the value of large trees. Additionally, we show how information gathered at the branch level may be nondestructively upscaled to entire trees.

Functional redundancy compensates for decline of dominant ant species

Evidence is accumulating of declines in widespread, abundant insect species. The consequences of these losses for ecosystem functioning are predicted to be severe but remain poorly tested in real-world ecosystems. Here we tested the relative importance of functional redundancy versus complementarity in conferring stability of multifunctional performance in the face of dominant insect species decline. We conducted an experimental manipulation of functional trait-space occupancy within naturally occurring ant communities in Australia. Experimental suppression of dominant ant species in multiple trait groupings caused a counterintuitive increase in multifunctional performance, which was associated with an increase in species richness. The resident ant community had high functional redundancy, contributing to rapid compensatory dynamics following suppression. However, colonization by new species with increased trait complementarity drove higher multifunctional performance. This increased multifunctionality probably occurred via reduced interspecific competition but at the cost of increased sensitivity of ecosystem multifunctionality to further species loss. Our findings show that functional redundancy can buffer multifunctional performance of a community against decline of dominant insect species but suggest that future stability of ecosystem multifunctionality depends more on functional complementarity and altered competitive interactions.

Warmer temperatures reinforce negative land-use impacts on bees, but not on higher insect trophic levels

Climate and land-use change are major drivers of insect decline, yet their interactive effects on insect richness and abundance, especially across trophic levels, remain poorly understood. Here, we investigate how temperature and land use shape insect communities across spatial scales and trophic levels, from flowering plants and cavity-nesting bees to hunting wasps, their antagonists and parasitism rates. Using trap nests and a space-for-time approach, we surveyed 179 plots spanning four habitat types (forest, grassland, arable land and settlements) across 60 study regions in Germany covering semi-natural, agricultural and urban landscapes. Bee richness and abundance responded to climate-land-use interactions across spatial scales, being higher with warmer local daytime temperatures and overall warmer climates, but only in less intensive land uses. In contrast, elevated night-time temperatures negatively affected bees. Higher trophic levels benefited more consistently from warmer climates than lower trophic levels and were less affected by high local daytime and night-time temperatures. Parasitism rates were lowest in arable land but similar across habitats within semi-natural regions, suggesting that landscape-scale processes buffer local effects. Our findings underscore the importance of considering night-time temperatures for diurnal insects and suggest that rising temperatures may exacerbate the negative impacts of land use on pollinators.

Alpha diversity with increasing altitude and Rapoport's rule adherence: Elevational trends in Noctuoidea (Lepidoptera) of Mizoram, India

An assessment of the alpha diversity across the altitudinal range sizes for the moths of Noctuoidea (Lepidoptera) collected from 25 locations in Mizoram, a biodiversity hotspot in India, was undertaken. A total of 164 moth specimens were examined. based on morphological and genitalia characteristics for their identity. Identified specimens belonged to 42 species and 34 genera of three families Erebidae, Noctuidae and Nolidae. The results showed that the alpha diversity of Noctuoidea moths was the highest at the lower middle altitude range (400-800 m), while the least was at the lower elevation range (0-400 m). In contrast, the species' ranges increased with rising altitude. Steven's (R = 0.903, p < 0.001), Pagel's (R² = 0.873, p < 0.06), Rohde's (R² = 0.961, p < 0.001) and cross-species (R² = 0.013, p < 0.6) methods were used to test Rapoport's rule. They yielded three positive results with the cross-species method being negative due to outliers in the species distribution. Rapoport's rule applicability for moths in the Indo-Myanmar biodiversity hotspot was evaluated for the first time. These findings are vital in explaining the elevational diversity patterns of noctuoid moths in northeast India and Indo-Myanmar, leading to a better understanding of the region's biogeography.

Where the wild bees are: Birds improve indicators of bee richness

Widespread declines in wild bee populations necessitate urgent action, but insufficient data exist to guide conservation efforts. Addressing this data deficit, we investigated the relative performance of environmental and/or taxon-based indicators to predict wild bee richness in the eastern and central U.S. Our methodology leveraged publicly available data on bees (SCAN and GBIF data repositories), birds (eBird participatory science project) and land cover data (USDA Cropland Data Layer). We used a Bayesian variable selection algorithm to select variables that best predicted species richness of bees using two datasets: a semi-structured dataset covering a wide geographical and temporal range and a structured dataset covering a focused extent with a standardized protocol. We demonstrate that birds add value to land cover data as indicators of wild bee species richness across broad geographies, particularly when using semi-structured data. These improvements likely stem from the demonstrated sensitivity of birds to conditions thought to impact bees but that are missed by remotely sensed environmental data. Importantly, this enables estimation of bee richness in places that don't have direct observations of bees. In the case of wild bees specifically, we suggest that bird and land cover data, when combined, serve as useful indicators to guide monitoring and conservation priorities until the quality and quantity of bee data improve.

Explosive Growth of the Jorō Spider (Trichonephila clavata (L. Koch): Araneae: Araneidae) and Concurrent Decline of Native Orbweaving Spiders in Atlanta, Georgia Forests at the Forefront of the Jorō Spider's Invasive Spread

The Jorō spider (Trichonephila clavata (L. Koch): Araneae: Araneidae), an invasive species from Asia, and native orbweaving spiders were censused at 25 forest sites in the Atlanta, Georgia, region at the forefront of the Jorō spider's spread from 2022 through 2024. The Jorō spider was found in all 25 sites in all three years, doubling in abundance each year. In 2022, the number of Jorō spiders found was 444 or 16.34 per hour of census. This doubled in 2023 to 859 or 30.54 per hour. The Jorō numbers doubled again in 2024 to 1713 or 59.14 per hour. This contrasts markedly with the seven species of native orbweavers found during the censuses, which declined by ca. 40% each year. In 2022, 52 or 1.72 individuals per hour of six native orbweaver species were found at 18 sites. In 2023, the number dropped to 32 or 1.06 individuals per hour of six species found at 11 sites. In 2024, the number further declined to 18 or 0.55 individuals of six species found at eight sites. The Jorō spider's spread and rapid increase in abundance may disrupt trophic networks and negatively influence the abundance of both native orbweavers and flying insect species.

Polystyrene microplastics reduce honeybee survival by disrupting gut microbiota and metabolism

Polystyrene microplastics (PS-MPs) pose significant risks to honeybee health. However, how microplastics (MPs) adversely influence honeybee survival through the gut pathway, especially the metabolic processes, remains poorly understood. To conduct the experiment, the honeybees (Apis mellifera L.) were exposed to PS-MPs (0.5 μm and 5 μm) at environmental concentrations of 25 mg/L and 50 mg/L for 21 days. Results revealed that PS-MPs reduced honeybee survival rates and food consumption. The accumulation of PS-MPs in honeybee guts caused structural damage to gut walls and elevated oxidative stress levels. Additionally, PS-MPs altered gut microbial communities, with a decrease in Lactobacillus and an increase in Bartonella. Gut metabolomics analysis indicated that PS-MPs disrupted metabolic pathways, upregulated amino acid and carbohydrate metabolism, and downregulated alpha-linolenic acid and lipid metabolism. Our study offers important insights into the physiological effects of accumulated MPs on honeybees, highlighting the critical need for effective strategies to manage environmental pollutants.

Investigating the effects of the main agronomic interventions on carabids and spiders in European arable fields: A systematic review protocol

BACKGROUND

Designing agroecological cropping systems enhancing functional biodiversity and natural pest regulations requires understanding the ecological processes involved, specifically regarding the response of generalist predators. A more precise knowledge of the changes in ground-dwelling communities implied by individual agronomic interventions is needed to make enlightened and consistent choices in the design of such innovative cropping systems. A recent systematic map showed that fertilization, tillage, pesticides use, grazing and mowing are the most studied agronomic interventions regarding their effects on arthropods. The direct and indirect effects of disturbances induced by agronomic interventions on ground-dwelling arthropods in arable fields have been widely investigated, especially for carabids and spiders. However, there is not always a clear pattern outstanding, probably due to antagonistic responses of species with different functional traits. Here, we propose a quantified synthesis on this topic. We will show the impact of the main agronomic interventions in arable fields on the two most studied ground-dwelling predator groups, carabids and spiders, and compare their response (abundance, species richness, taxonomic and functional diversity) in different contexts (crop types and production methods). We will investigate contrasting responses at different taxonomic levels depending on functional traits.

METHODS

The evidence will be identified from the recent systematic map on the impacts of agricultural management practices on biodiversity indicator species groups published in 2024. We will select all studies reporting the effect of the most studied agronomic interventions (fertilization, tillage, pesticide application, mowing and grazing) in arable fields (arable crops and temporary grasslands) on carabids and spiders in the map database. A search update will be performed using the search strings used for the systematic map for carabids and spiders, and extracted references will be sorted at title, abstract and full text levels according to the topic of the present work. All selected studies will be critically appraised and a low, medium, or high risk of bias will be assigned to each study. The synthesis of the data extracted from the studies will be first narrative (using qualitative data), and then quantitative for those with adequate data for a meta-analysis.

Characterization of two cellular superoxide dismutases in Protohermes xanthodes (Megaloptera: Corydalidae) in response to sublethal chlorpyrifos stress

Pesticides released into the environment are increasingly recognized as a global threat to freshwater ecosystems because of their adverse effects on non-target organisms, particularly aquatic insects and other arthropods. Superoxide dismutases (SODs) are important antioxidant enzymes that play a crucial role in protecting organisms from oxidative stress induced by harmful materials. In this study, we identified 2 cellular SODs (PxSOD1 and PxSOD2) in Protohermes xanthodes Navás (Megaloptera: Corydalidae), an freshwater predatory insect, and determined the oxidative stress induced in P. xanthodes larvae by sublethal exposure to chlorpyrifos (CPF). PxSOD1 and PxSOD2 are members of the cytoplasmic Cu/ZnSODs and mitochondrial MnSODs, respectively, and differ substantially in protein structure. Both PxSOD1 and PxSOD2 recombinant proteins demonstrated catalytic activity toward O2•- in the activity assays. After exposure to sublethal concentrations of CPF, malondialdehyde (MDA) content and SOD activities were increased in P. xanthodes larvae in a dose-dependent manner. PxSOD1 expression was decreased in the 0.42 and 4.2 μg/L CPF groups and increased in the 4.2 μg/L CPF group. PxSOD2 was upregulated by 0.42, 4.2, and 8.4 μg/L CPF treatments and the expression levels in the 4.2 and 8.4 μg/L CPF groups were significantly higher than that in the no CPF control. Our results suggest that sublethal concentrations of CPF can induce oxidative stress in P. xanthodes larvae, and the cellular SODs in P. xanthodes larvae may contribute to the protection against CPF-induced oxidative stress.

Elevated extinction risk in over one-fifth of native North American pollinators

Pollinators are critical for food production and ecosystem function. Although native pollinators are thought to be declining, the evidence is limited. This first, taxonomically diverse assessment for mainland North America north of Mexico reveals that 22.6% (20.6 to 29.6%) of the 1,579 species in the best-studied vertebrate and insect pollinator groups have elevated risk of extinction. All three pollinating bat species are at risk and bees are the insect group most at risk (best estimate, 34.7% of 472 species assessed, range 30.3 to 43.0%). Substantial numbers of butterflies (19.5% of 632 species, range 19.1 to 21.0%) and moths (16.1% of 142 species, range 15.5 to 19.0%) are also at risk, with flower flies (14.7% of 295 species, range 11.5 to 32.9%), beetles (12.5% of 18 species, range 11.1 to 22.2%), and hummingbirds (0% of 17 species) more secure. At-risk pollinators are concentrated where diversity is highest, in the southwestern United States. Threats to pollinators vary geographically: climate change in the West and North, agriculture in the Great Plains, and pollution, agriculture, and urban development in the East. Woodland, shrubland/chaparral, and grassland habitats support the greatest numbers of at-risk pollinators. Strategies for improving pollinator habitat are increasingly available, and this study identifies species, habitats, and threats most in need of conservation actions at state, provincial, territorial, national, and continental levels.

Integrating multiple evidence streams to understand insect biodiversity change

Insects dominate animal species diversity yet face many threats from anthropogenic drivers of change. Many features of insect ecology make them a challenging group, and the fragmented state of knowledge compromises our ability to make general statements about their status. In this Review, we discuss the challenges of assessing insect biodiversity change. We describe how multiple lines of evidence-time series, spatial comparisons, experiments, and expert opinion-can be integrated to provide a synthesis overview of how insect biodiversity responds to drivers. Applying this approach will generate testable predictions of insect biodiversity across space, time, and changing drivers. Given the urgency of accelerating human impacts across the environment, this approach could yield a much-needed rapid assessment of insect biodiversity change.

Insect immunity in the Anthropocene

Anthropogenic activities result in global change, including climate change, landscape degradation and pollution, that can alter insect physiology and immune defences. These changes may have contributed to global insect decline and the dynamics of insect-transmitted diseases. The ability of insects to mount immune responses upon infection is crucial for defence against pathogens and parasites. Suppressed immune defences reduce fitness by causing disease-driven mortality and elevated immune responses reduce energy available to invest in other fitness traits such as reproduction. Understanding the impact of anthropogenic factors on insect-pathogen interactions is therefore key to determining the contribution of anthropogenic global change to pathogen-driven global insect decline and the emergence and transmission of insect-borne diseases. Here, we synthesise evidence of the impact of anthropogenic factors on insect immunity. We found evidence that anthropogenic factors, such as insecticides and heavy metals, directly impacting insect immune responses by inhibiting immune activation pathways. Alternatively, factors such as global warming, heatwaves, elevated CO2 and landscape degradation can indirectly reduce insect immune responses via reducing the energy available for immune function. We further review how anthropogenic factors impact pathogen clearance and contribute to an increase in vector-borne diseases. We discuss the fitness cost of anthropogenic factors via pathogen-driven mortality and reduced reproductive output and how this can contribute to species extinction. We found that most research has determined the impact of a single anthropogenic factor on insect immune responses or pathogen resistance. We recommend studying the combined impact of multiple stressors on immune response and pathogen resistance to understand better how anthropogenic factors affect insect immunity. We conclude by highlighting the importance of initiatives to mitigate the impact of anthropogenic factors on insect immunity, to reduce the spread of vector-borne diseases, and to protect vulnerable ecosystems from emerging diseases.

Using AI to prevent the insect apocalypse: toward new environmental risk assessment procedures

Insect populations are declining globally, with multiple potential drivers identified. However, experimental data are needed to understand their relative contributions. We highlight the sublethal effects of pesticides at field-relevant concentrations, often overlooked in standard environmental risk assessments (ERA), as significant contributors to these declines. Behavior, as an easily monitored high-level phenotype, reflects alterations at various phenotypic levels. We propose incorporating behavioral assays with AI-based analytical methods into ERA protocols to better assess the safety of molecules intended for large-scale field use. This approach aims to safeguard food supplies and protect vital ecosystems in the future.

A Dark Future of Endangered Mountain Species, Parnassius bremeri, Under Climate Change

Climate and land-use changes are key factors in the habitat loss and population declines of climate change-sensitive endangered species. We assessed the climate change effects on the distribution of Parnassius bremeri, a critically endangered wildlife species in the Republic of Korea, in association with food availability (Sedum kamtschaticum and Sedum aizoon), land-use change, and dispersal limitation. We first predicted the current and future distributions of P. bremeri, S. kamtschaticum, and S. aizoon using the presence/absence data and current (2000) and future climate data (2050, 2100) with BioMod2, an ensemble platform for species distribution model projections. Then, the dispersal capacity of P. bremeri and land-use change were coupled with SDMs using MigClim. We used future climate and land-use changes predicted according to the SSP scenarios (SSP1-2.6, SSP2-4.5, and SSP3-7.0) and the dispersal model estimated from previous studies. The current distributional areas of P. bremeri were predicted to be about 10,956 km2 without land-cover coupling and 8.861 km2 with coupling, showing land-cover decreased by about 19% of the suitable habitat. The future predictions under climate change only showed the distribution reduced by 56% and 50% in 2050 and 2100 under SSP1-2.6, respectively, 55% and 48% under SSP2-4.5, and 44% and 14% under SSP3-7.0. Applying land-use change and dispersal capacity further decreased the future distribution of P. bremeri but trivially (about 0.42% on average). The strict conservation policies and measures for P. bremeri's habitats explain the trivial additional decrease, delaying its habitat loss. However, our results suggest that such efforts cannot halt the climate change-driven habitat loss trend of P. bremeri. Strong climate mitigation efforts and promoting the species' adaptive capacity are the only ways to reverse the tragic decline of climate-sensitive species.

Winter and summer conditions affect the mountain population of Carabus variolosus, a ground beetle of European conservation concern

The changing climate has a significant impact on insect populations. Numerous species are challenged by increasing temperatures, changes in precipitation regimes, and reduction of snow cover, which alters soil moisture patterns in their habitats. Among them is Carabus variolosus Fabricius, 1787, a strongly hygrophilous, stenotopic species. The aim of our research was to analyze intra-seasonal changes in the first capture and activity of C. variolosus and to assess the potential impact of climatic factors on its abundance by analyzing climatic conditions during the summer of species activity, the preceding summer, and the winter before its emergence. Additionally, we aimed to determine whether different climatic conditions affect its spring and autumn activity. Our 4-year study revealed significant inter-seasonal variations in the first capture and activity patterns. We confirmed that C. variolosus is a spring breeder with adult summer diapause, and low activity of young beetles in autumn. Over 90 % of beetles were captured for the first time during the breeding season. The highest activity occurred in May, which seems to be male-driven, as the capture rate for females gradually decreased over time. Different climatic conditions influenced captures during the spring and autumn activity. Spring activity is correlated with conditions from the previous summer and winter, while autumn activity is related only to the summer conditions of the same year.

Understanding and counteracting the denial of insect biodiversity loss

Biodiversity loss is occurring globally with negative impacts on ecosystem function and human well-being. There is a scientific consensus that diverse environmental and anthropogenic factors are altering different components of insect biodiversity, with changes occurring at all levels of biological organisation. Here, we describe how uncertainty around specific trends and the semantics of 'decline' in relation to insect biodiversity have been leveraged by denialist campaigns to manufacture doubt around the insect biodiversity crisis. Disinformation is one of the biggest threats to social cohesion and environmental integrity globally. We argue that scientists, academic institutions, policymakers, and journalists must combat denialism by relying on robust research, supporting efforts to communicate scientific uncertainty more effectively, and build consensus on the global impacts of insect biodiversity loss.

"WhatsBarb" Citizen Surveillance: Survey of Insects Mistaken for Triatomines

BACKGROUND

Triatomine recognition by the public is an important factor in Chagas disease (CD) prevention campaigns. Citizen surveillance has been demonstrated as an effective alternative strategy, increasing the possibility of monitoring vector populations on a broad geographic scale. Thus, our study aimed to explore a database built from pictorial/video records and specimens sent through citizen participation, identify the main groups confused with triatomines, and systematize the data on insect diversity.

METHODS

Due to demand from the local community, the "WhatsBarb" project was established using a digital platform application, to receive photos of suspected insects, or triatomines, and provide digital campaigns, with instructions for collecting insects and delivery to Entomological Surveillance Services.

RESULTS

In total, 465 insect records were obtained between 2019 and 2024. We identified taxonomic orders and families in 464 and 454 records, respectively, and estimated at least 68 genera, 42 species, and 101 distinct taxa. Triatomines represented 32.3% of the volunteer contacts. Records showed a predominance of true bugs (Hemiptera: Heteroptera), including phytophagous species and predator reduviids (54.6%; n=254). Contacts were received from 20 of the 26 states in Brazil, in addition to the Federal District.

CONCLUSIONS

Our findings demonstrate the power of digital tools in public health, which could aid in describing, preventing, and controlling CD vectors, and could be applied to other neglected diseases.

Temperature Effects on the Survival and Oviposition of an Invasive Blow Fly Chrysomya rufifacies Macquart (Diptera: Calliphoridae)

The globally increased severity and frequency of elevated temperatures are altering native species' geographic distributions and local abundances while also increasing the invasion of new areas by exotic species. These distributional shifts have affected native species. Through two experiments, we investigated the effects of temperature on the survival and oviposition of the hairy maggot blow fly Chrysomya rufifacies (Macquart), a highly competitive and predatory invasive blow fly of ecological, economic, and forensic importance. In our first experiment, we exposed mixed-sex colonies of C. rufifacies to a given temperature (10-45.0 °C) for 24 h. High survival (≥90%) was observed from 10 to 40 °C, with moderate mortality at 42.5 °C (29.2%) and high mortality at 43.5 °C (75.4%). All flies died when exposed to 44.5 or 45.0 °C for 24 h. Oviposition occurred from 22.5 to 42.5 °C, with the greatest occurrences (100%) at 30 and 35 °C and the greatest number of eggs (2035) occurring at 30 °C. Although oviposition occurred from 22.5 to 42.5 °C, egg viability was only observed from 22.5 to 37.5 °C. Thus, C. rufifacies has distinct thermal limits for survival, and oviposition may exhibit a bet-hedging strategy in response to temperature exposure. In our second experiment, we assessed the effects of an acute heat shock on C. rufifacies oviposition performance. Adult virgins (males and females) were exposed to 25.0 °C, 42.0 °C, or 44.0 °C for 1 h, and then maintained at ~25 °C in mixed-sex colonies for 14 d. Pre-breeding heat exposure had no effect on male or female reproductive success, except for females exposed to 44.0 °C. Females exposed to this temperature before breeding oviposited sooner (2.5 ± 0.0 d, 37.5% decrease), more frequently (0.5 ± 0.4, 33.3% increase), and produced more eggs (10,772.9 ± 2258.6 eggs, 73.3% increase) than female flies exposed to 25 °C. The combined results show that C. rufifacies survives exposures up to 43.5 °C, successfully oviposits up to 37.5 °C, and accelerates both oviposition timing and intensity following brief exposure to near upper lethal temperatures (44.0 °C), potentially provides C. rufifacies a competitive advantage over native calliphorids in warming environments.

Effects of short-term heat stress on the thermal tolerance of western corn rootworm (Coleoptera: Chrysomelidae)

Insect responses to warming temperatures are determined partly by their physiology, which is influenced by genetic factors and plasticity induced by past temperature exposure. The effect that prior high temperature exposure has on insect thermal tolerance is complex and depends on the degree of heat stress experienced; high heat exposure may allow for individuals to tolerate higher temperatures through hardening or may reduce an individual's capacity to withstand higher temperatures through accumulated heat stress. In this study, we assessed how short exposures to high temperatures and a laboratory colony's geographical origin affected the critical thermal maximum (CTmax) of western corn rootworm (Diabrotica virgifera virgifera LeConte), an economically important pest. Despite a wide latitudinal range of source populations, western corn rootworm colonies did not differ in their CTmax. Regardless of colony origin, we found that exposing western corn rootworm to higher temperatures resulted in lower CTmax, which suggests that heat stress accumulated. This study highlights how western corn rootworm experiences heat stress at temperatures near the temperatures they experience in the field, which may have important and currently unknown implications for its behavior.

Negative effects of nitrogen fertilization on herbivore fitness are exaggerated at warmer temperatures and in high-altitude populations

Biodiversity is currently under strong pressure due to anthropogenic global change. Different drivers of global change may exert direct and indirect effects on biodiversity, and may furthermore interact with one another, but our respective knowledge is still very limited. We investigated indirect and interactive effects of two important drivers of global change, eutrophication and climate change, in replicated low- and high-altitude populations of an insect herbivore, the butterfly Lycaena tityrus, in a laboratory setting. We found local adaptation in developmental traits, with low-altitude populations being adapted to warmer temperatures and longer seasons. Lycaena tityrus responded negatively to agriculturally relevant levels of fertilization of its host plant, showing reduced body mass and prolonged development time. Negative effects were particularly pronounced at warmer temperatures and in high-altitude populations. Our study adds to the increasing knowledge that different drivers of global change may interact and thereby increase the overall level of threat to biodiversity. We suggest that populations inhabiting naturally nutrient-poor environments might be even more vulnerable to agricultural intensification than others, potentially applicable to many species. These findings may have important implications for protecting numerous vulnerable species in the face of rapid environmental change.

An in-depth dataset of northwestern European arthropod life histories and ecological traits

Background

In response to the ongoing biodiversity crisis amongst arthropods, it is essential to implement efficient conservation strategies to safeguard both species diversity and the vital ecosystem services they provide. Developing such strategies requires reliable predictive models that can identify the species that are the most vulnerable to current and future threats, including those posed by climate and land-use change. Species life histories are central to these models, as they influence both population dynamics and spread rates.

New information

To support this effort, we compiled a dataset with key traits for arthropods based on several literature sources and expert knowledge. The dataset contains data on body size, life history, thermal niche and ecology for 4874 northwestern European species across 10 different orders. By gathering these essential trait data, we aim to create a robust foundation for predicting species vulnerability and anticipating shifts in arthropod communities in response to global change.

Family-Level Diversity of Hymenopteran Parasitoid Communities in Agricultural Drainage Ditches and Implications for Biological Control

Agricultural drainage ditches contain a variety of non-crop vegetation, including potential sources of alternate hosts and food for hymenopteran parasitoids that provide conservation biological control on adjacent farm fields. To assess the patterns of family-level diversity of hymenopteran parasitoids, we surveyed ditch and adjacent crop habitats during June, July, and August 2021-2023, using yellow sticky traps over one week. We sampled two agricultural drainage ditches on each of five farms on the Delmarva Peninsula, eastern USA. We collected 36,725 specimens and identified 29 families across 738 sticky traps. Parasitoid diversity was greater in agricultural ditches than in adjacent fields. While parasitoid family diversity and abundance varied across the farms, ditches within a farm were similar. Within crop fields, diversity was greater at 1.5 m from agricultural ditches than at 9.1 m from the ditches. For several well-sampled families, greater abundance on one farm relative to others extended to both ditches and adjacent crops. Our findings indicate that agricultural drainage ditches serve as an existing beneficial semi-natural habitat for parasitoids on farms. Further research into ditch management practices may reveal methods of enhancing parasitoid abundance and conservation biological control while requiring relatively little investment from farm managers.

The host phylogeny and climate determine the gut bacteria of global insects

Insects play an indispensable role in ecosystems; however, in recent years, the rapid decline in global insect diversity and abundance has posed a significant threat to our survival environment. Insect gut microbes play a crucial role in the survival of insects. Understanding their global traits will be advantageous for insect protection, thus safeguarding our environment. In this study, 11,814 samples of 334 insect species from global public databases were analyzed. We found that host phylogeny and climate were decisive factors in shaping the structure of insect gut bacteria. We also identified 168 core gut bacteria of insects, more than half of which were correlated with temperatures during the coldest and wettest periods or temperature fluctuations. Moreover, machine learning predictions showed that future climate warming will lead to a decrease in alpha diversity and core bacteria of insects. Together, our study indicated that insect gut bacteria were closely related to the host, and climate warming may harm the gut bacteria, leading to a decline in insect species and populations worldwide.

Shedding light on dark taxa: exploring a cryptic diversity of parasitoid wasps affected by artificial light at night

Artificial light at night (ALAN) contributes to the globally observed insect decline. ALAN attracts nocturnal insects from their native ecosystems and disturbs their functions in the food web. Road lights in this context are ubiquitous and relevant ALAN sources that are often not considered in conservation approaches. In a previous study we showed that shielded LED road lights are suited to be part of conservation measures by effectively reducing the attraction of nocturnal insects. Here we show that this positive effect holds true for parasitoid wasps in an experimental BACI design (Before-After-Control-Impact). Combining morphological with molecular and phylogenetic analyses, we identified 106 individuals (62 morphotypes) of a minimum of 45 genera out of 13 Hymenoptera families. We were able to identify 21 species, 11 of which are newly reported in Southern Germany (Baden-Württemberg). Further combining knowledge on life history and host appearance from our data and the literature, we discuss potential impacts of ALAN ranging from an influence on nocturnal pollination via parasitoid pressure on moth species and biological control of invasive pest species to tritrophic interactions between primary and secondary parasitoids. We conclusively think that shielded LED road lights will reduce the ecological impact of ALAN on parasitoid wasps in a large and undescribed number of taxa with different host associations, likely affecting associated ecosystem functions such as biological control.

The effect of global change on the expression and evolution of floral traits

BACKGROUND

Pollinators impose strong selection on floral traits, but other abiotic and biotic agents also drive the evolution of floral traits and influence plant reproduction. Global change is expected to have widespread effects on biotic and abiotic systems, resulting in novel selection on floral traits in future conditions.

SCOPE

Global change has depressed pollinator abundance and altered abiotic conditions, thereby exposing flowering plant species to novel suites of selective pressures. Here, we consider how biotic and abiotic factors interact to shape the expression and evolution of floral characteristics (the targets of selection), including floral size, colour, physiology, reward quantity and quality, and longevity, amongst other traits. We examine cases in which selection imposed by climatic factors conflicts with pollinator-mediated selection. Additionally, we explore how floral traits respond to environmental changes through phenotypic plasticity and how that can alter plant fecundity. Throughout this review, we evaluate how global change might shift the expression and evolution of floral phenotypes.

CONCLUSIONS

Floral traits evolve in response to multiple interacting agents of selection. Different agents can sometimes exert conflicting selection. For example, pollinators often prefer large flowers, but drought stress can favour the evolution of smaller flowers, and the size of floral organs can evolve as a trade-off between selection mediated by these opposing actors. Nevertheless, few studies have manipulated abiotic and biotic agents of selection factorially to disentangle their relative strengths and directions of selection. The literature has more often evaluated plastic responses of floral traits to stressors than it has considered how abiotic factors alter selection on these traits. Global change will likely alter the selective landscape through changes in the abundance and community composition of mutualists and antagonists and novel abiotic conditions. We encourage future work to consider the effects of abiotic and biotic agents of selection on floral evolution, which will enable more robust predictions about floral evolution and plant reproduction as global change progresses.

Combining radio-telemetry and radar measurements to test optimal foraging in an aerial insectivore bird

Optimal foraging theory posits that foragers adjust their movements based on prey abundance to optimize food intake. While extensively studied in terrestrial and marine environments, aerial foraging has remained relatively unexplored due to technological limitations. This study, uniquely combining BirdScan-MR1 radar and the Advanced Tracking and Localization of Animals in Real-Life Systems biotelemetry system, investigates the foraging dynamics of Little Swifts (Apus affinis) in response to insect movements over Israel's Hula Valley. Insect movement traffic rate (MoTR) substantially varied across days, strongly influencing swift movement. On days with high MoTR, swifts exhibited reduced flight distance, increased colony visit rate, and earlier arrivals at the breeding colony, reflecting a dynamic response to prey availability. However, no significant effects were observed in total foraging duration, flight speed, or daily route length. Notably, as insect abundance increased, inter-individual distances decreased. These findings suggest that Little Swifts optimize their foraging behavior in relation to aerial insect abundance, likely influencing reproductive success and population dynamics. The integration of radar technology and biotelemetry systems provides a unique perspective on the interactions between aerial insectivores and their prey, contributing to a comprehensive understanding of optimal foraging strategies in diverse environments.

Exposure of insects to current use pesticide residues in soil and vegetation along spatial and temporal distribution in agricultural sites

Current use pesticides (CUPs) are recognised as the largest deliberate input of bioactive substances into terrestrial ecosystems and one of the main factors responsible for the current decline in insects in agricultural areas. To quantify seasonal insect exposure in the landscape at a regional scale (Rhineland-Palatine in Germany), we analysed the presence of multiple (93) active ingredients in CUPs across three different agricultural cultivation types (with each three fields: arable, vegetable, viticulture) and neighbouring meadows. We collected monthly soil and vegetation samples over a year. A total of 71 CUP residues in different mixtures was detected, with up to 28 CUPs in soil and 25 in vegetation in single samples. The concentrations and numbers of CUPs in vegetation fluctuated over the sampling period, peaking in the summer months in the vegetation but remaining almost constant in topsoil. We calculated in-field additive risks for earthworms, collembola, and soil-living wild bees using the measured soil concentrations of CUPs. Our results call for the need to assess CUP mixture risks at low concentrations, as multiple residues are chronically present in agricultural areas. Since this risk is not addressed in regulation, we emphasise the urgent need to implement global pesticide reduction targets.

Life-history adaptation under climate warming magnifies the agricultural footprint of a cosmopolitan insect pest

Climate change is affecting population growth rates of ectothermic pests with potentially dire consequences for agriculture and global food security. However, current projection models of pest impact typically overlook the potential for rapid genetic adaptation, making current forecasts uncertain. Here, we predict how climate change adaptation in life-history traits of insect pests affects their growth rates and impact on agricultural yields by unifying thermodynamics with classic theory on resource acquisition and allocation trade-offs between foraging, reproduction, and maintenance. Our model predicts that warming temperatures will favour resource allocation towards maintenance coupled with increased resource acquisition through larval foraging, and the evolution of this life-history strategy results in both increased population growth rates and per capita host consumption, causing a double-blow on agricultural yields. We find support for these predictions by studying thermal adaptation in life-history traits and gene expression in the wide-spread insect pest, Callosobruchus maculatus; with 5 years of evolution under experimental warming causing an almost two-fold increase in its predicted agricultural footprint. These results show that pest adaptation can offset current projections of agricultural impact and emphasize the need for integrating a mechanistic understanding of life-history evolution into forecasts of pest impact under climate change.

Direct and indirect effects of land use on microbiomes of trap-nesting solitary bee larvae and nests

Introduction

The global decline in biodiversity and insect populations highlights the urgent need to conserve ecosystem functions, such as plant pollination by solitary bees. Human activities, particularly agricultural intensification, pose significant threats to these essential services. Changes in land use alter resource and nest site availability, pesticide exposure and other factors impacting the richness, diversity, and health of solitary bee species. In this study, we investigated yet another facet currently less well investigated in such context: Microbial communities associated with wild bees play crucial roles in larval development, metabolism, immunity and overall bee health. However, the drivers and dynamics of healthy microbiome in solitary bees are still poorly understood, especially regarding the direct and indirect effects of land use on the diversity and composition of these microbial communities.

Methods

We examined bacterial communities in the offspring and nest materials of the Megachilid trap-nesting solitary bee, Osmia bicornis, along a gradient of land use intensification by 16S rRNA gene metabarcoding. Given that landscape composition, climatic conditions, and food resources are known to influence microbial compositions in solitary bee species, we hypothesized that land use changes would alter resources available for food and nest material collection and thereby affecting the microbiomes in offspring and their nest environments. We anticipated reduced microbial diversity and altered composition with increased land use intensification, which is known to decrease the number and diversity of resources, including the pool of floral and soil bacteria in the surrounding environment.

Results

As expected, we observed significant shifts in the bacterial composition and diversity of bees and their nests across varying degrees of land use intensity, differing in management types and the availability of flowers. The Shannon diversity of bacteria in nest materials (larval pollen provision, soil nest enclosure) and larval guts decreased with increasing land use intensity. However, the pupae microbiome remained unaffected, indicating a reorganization of the microbiome during metamorphosis, which is not significantly influenced by land use and available resources.

Discussion

Our findings provide new insights into the factors shaping environmental transmission and changes in solitary bee microbiomes. This understanding is crucial for comprehending the impacts of intensive land use on wild bee health and developing strategies to mitigate these effects.

Telomere Length Differences Indicate Climate Change-Induced Stress and Population Decline in a Migratory Bird

Genomic projections of (mal)adaptation under future climate change, known as genomic offset, faces limited application due to challenges in validating model predictions. Individuals inhabiting regions with high genomic offset are expected to experience increased levels of physiological stress as a result of climate change, but documenting such stress can be challenging in systems where experimental manipulations are not possible. One increasingly common method for documenting physiological costs associated with stress in individuals is to measure the relative length of telomeres-the repetitive regions on the caps of chromosomes that are known to shorten at faster rates in more adverse conditions. Here we combine models of genomic offsets with measures of telomere shortening in a migratory bird, the yellow warbler (Setophaga petechia), and find a strong correlation between genomic offset, telomere length and population decline. While further research is needed to fully understand these links, our results support the idea that birds in regions where climate change is happening faster are experiencing more stress and that such negative effects may help explain the observed population declines.

Radio-tracking urban breeding birds: The importance of native vegetation

As urban areas continue to expand globally, a deeper understanding of the functioning of urban green spaces is crucial for maintaining habitats that effectively support wildlife within our cities. Cities typically harbor a wide variety of nonnative vegetation, providing limited support for insect populations. The resulting scarcity of arthropods has been increasingly linked to adverse effects at higher trophic levels, such as the reduced reproductive success of insectivorous birds in urban environments. However, the responses by which urban breeding birds cope with the challenges of food limitation remain largely unexplored. To address this knowledge gap, in a Central European city, we employed radiotelemetry tracking and real-time observations on urban-breeding female great tits' habitat use, combined with detailed plant surveys and video recordings of nestlings' diet. This integrated approach enabled us to establish direct links between great tits' foraging behavior, vegetation preferences, and nestling diet. We found that besides tree canopies, great tits also frequently foraged on the ground and that the availability of bird feeders notably affected birds' habitat use. Foraging great tits generally avoided nonnative plants, particularly broadleaved species. When searching for nestling food, great tits were most time-efficient on conifers, albeit these trees provided low amounts of caterpillars (a preferred prey type). Great tits were more likely to forage on and deliver nestling food from large native trees and foraged less on and collected fewer prey items from the most abundant tree species. Our results underscore the importance of several factors that may help improve habitat quality for urban insectivorous birds, with preserving large trees and increasing diverse native vegetation being key elements in this endeavor.

Mixture of neonicotinoid and fungicide affects foraging activity of honeybees

The use of plant protection products (PPPs) is a major factor contributing to global insect decline. We here use the honeybee (Apis mellifera) as a model to study combined effects of the last neonicotinoid in the EU (acetamiprid) and different fungicides on live-long foraging flights using radio frequency identification. The mixture of the sterol-biosynthesis-inhibiting fungicide difenoconazole and the insecticide acetamiprid significantly reduced the number of foraging trips per day compared to the control and each PPP alone, while a mixture of the insecticide with the non-sterol-biosynthesis inhibiting fungicide boscalid/dimoxystrobin did not affect behaviour. This potential synergistic effect of the fungicide/insecticide mixture supports the notion that some fungicides can enhance the effect of insecticides, which did not lead to significant changes in behaviour when applied on their own. Our results emphasize the need for more studies on the interaction of different PPPs.

Inbreeding and Outbreeding Depression in Wild and Captive Insect Populations

Major changes in genetic variation are generally considered deleterious to populations. The massive biodiversity of insects distinguishes them from other animal groups. Insect deviant effective population sizes, alternative modes of reproduction, advantageous inbreeding, endosymbionts, and other factors translate to highly specific inbreeding and outbreeding outcomes. We review the evidence for inbreeding and outbreeding depression and consequences across wild and captive insect populations, highlighting conservation, invasion, and commercial production entomology. We not only discern patterns but also explain why they are often inconsistent or absent. We discuss how insect inbreeding and outbreeding depression operates in complex, sometimes contradictory directions, such as inbreeding being detrimental to individuals but beneficial to populations. We conclude by giving recommendations to (a) more comprehensively account for important variables in insect inbreeding and outbreeding depression, (b) standardize the means of measuring genetic variation and phenotypic impacts for insect populations so as to more reliably predict when inbreeding or outbreeding depression applies, and (c) outline possible remediation options, both nongenetic and genetic, including revision of restrictive international trade laws.

New Behavior Records of the Oxysternon palemo Castelnau, 1840 (Coleoptera: Scarabaeidae: Scarabaeinae) in Cerrado

The present study reports new behavioral records for Oxysternon palemo Castelnau, 1840 in Cerrado. According to its nesting habits and resource allocation, this species of dung beetle is traditionally classified as coprophagous and paracoprid, transporting portions of dung through tunnels excavated below the resource. We observed a male individual moving a pequi seed (Caryocar brasiliensis Cambess.) with "head-butting," acting as a secondary seed disperser. At another moment, we recorded necrophagous habits for the species when male individuals were observed moving pieces of domestic pig carcasses (Sus scrofa L., 1758), also with "head-butting." After, we recorded a female O. palemo, accompanied by a male individual, butting a dung mass and burying this resource several meters away from the original source. The behavior of pushing the resource over long distances is typical of telecoprid dung beetles that form dung balls and roll them using hind legs away from the resource source, unlike what is expected for O. palemo. Our hypothesis is that the observed behaviors have developed from competition for resources. Furthermore, the behaviors exhibited by O. palemo contribute to the provision of essential ecosystem services. The ecosystem services include the removal and degradation of decomposing organic matter, as well as secondary dispersal of seeds, thus supporting the maintenance and conservation of plant species.

This is the way the world ends; not with a bang but a whimper: Estimating the number and ongoing rate of extinctions of Australian non-marine invertebrates

Biodiversity is in rapid decline, but the extent of loss is not well resolved for poorly known groups. We estimate the number of extinctions for Australian non-marine invertebrates since the European colonisation of the continent. Our analyses use a range of approaches, incorporate stated uncertainties and recognise explicit caveats. We use plausible bounds for the number of species, two approaches for estimating extinction rate, and Monte Carlo simulations to select combinations of projected distributions from these variables. We conclude that 9,111 (plausible bounds of 1,465 to 56,828) Australian species have become extinct over this 236-year period. These estimates dwarf the number of formally recognised extinctions of Australian invertebrates (10 species) and of the single invertebrate species listed as extinct under Australian legislation. We predict that 39-148 species will become extinct in 2024. This is inconsistent with a recent pledge by the Australian government to prevent all extinctions. This high rate of loss is largely a consequence of pervasive taxonomic biases in community concern and conservation investment. Those characteristics also make it challenging to reduce that rate of loss, as there is uncertainty about which invertebrate species are at the most risk. We outline conservation responses to reduce the likelihood of further extinctions.

Bee pollination and bee decline: A study about university students' Knowledge and its educational implication

Science education plays a crucial role in addressing the pollinator crisis by enhancing knowledge and fostering changes in attitudes toward this environmental challenge. Previous research has been focused on validating a specific instrument related to this subject, although its use for assessing students' knowledge has been little explored. In the present study, we have evaluated the level of awareness regarding the significance of bees as primary pollinators among students of various disciplines at the Universities of Sevilla, in Spain, and Ouro Preto, in Brazil, emphasizing the importance of the plant-bee interaction. 753 students from the fields of biology, agriculture, and education were invited to complete a questionnaire focused on bee biology. The results indicate that knowledge on the subject is closely linked to professional career choice and that the training program for the future teachers effectively increased comprehension of the crucial role played by bees as main supporters of the ecosystem service of pollination.

Population trends of insect pollinators in a species-rich tropical rainforest: stable trends but contrasting patterns across taxa

Recent reports of insect decline have raised concerns regarding population responses of ecologically important groups, such as insect pollinators. Additionally, how population trends vary across pollinator taxonomic groups and degree of specialization is unclear. Here, we analyse 14 years of abundance data (2009-2022) for 38 species of native insect pollinators, including a range of Coleoptera, Lepidoptera and Hymenoptera specialists and generalists from the tropical rainforest of Barro Colorado Island, Panama. We estimated population trends across taxonomic groups to determine whether specialist species with a narrower range of interacting mutualistic partners are experiencing steeper population declines under environmental change. We also examined the relationship between climate variables and pollinator abundance over time to determine whether differences in sensitivity to climate predict differences in population trends among pollinator species. Our analyses indicated that most pollinator populations were stable or increasing, with few species showing evidence of decline, regardless of their degree of specialization. Differences in climate sensitivity varied among pollinator species but were not associated with population trends, suggesting other environmental factors at play for tropical insect pollinators. These results highlight the need for long-term population data from diverse tropical taxa to better assess the environmental determinants of insect pollinator trends.

Dying of thirst: Osmoregulation by a hawkmoth pollinator in response to variability in ambient humidity and nectar availability

Climate-induced shifts in flowering phenology can disrupt pollinator-floral resource synchrony, especially in desert ecosystems where rainfall dictates both. However, baseline metrics to gauge pollinator health in the wild amidst rapid climate change are lacking. Our laboratory-based study establishes a baseline for pollinator physiological state by exploring how osmotic conditions influence survivorship in a desert hawkmoth pollinator, Manduca sexta. We sampled hemolymph osmolality from over 1000 lab-grown moths at 20 %, 50 %, and 80 % ambient humidity levels. Starved moths maintained healthy osmolality of 350-400 mmol/kg for 1-3 days after eclosion regardless of ambient humidity, but it sharply rose to 550 mmol/kg after 4-5 days in low and moderate humidity, and after 5 days in high humidity. Starved moths in low humidity conditions perished within 5 days, while those in high humidity survived twice as long. Moths fed synthetic Datura wrightii nectar, synthetic Agave palmeri nectar, or water, maintained osmolality within a healthy range of 350-400mmol/kg. The same was true for moths fed authentic floral nectars from Datura and Agave plants, although moths consumed more synthetic than authentic nectars, possibly due to non-sugar constituents. Simulating a 4-day mismatch between pollinator emergence and nectar availability, a single nectar meal osmotically rescued moths under dry ambient conditions. Our findings highlight hemolymph osmolality as a rapid and accurate biomarker distinguishing dehydrated from hydrated states in insect pollinators.

Evidence for bottom-up effects of moth abundance on forest birds in the north-boreal zone alone

Insect declines are raising alarms regarding cascading effects on ecosystems, especially as many insectivorous bird populations are also declining. Here, we leveraged long-term monitoring datasets across Finland to investigate trophic dynamics between functional groups of moths and birds in forested habitats. We reveal a positive association between the biomass of adult- or egg-overwintering moths and the biomasses of resident and long-distance migrant birds reliant on caterpillars as breeding-season food in the north-boreal zone. Contrary to expectations, similar signs of moth bottom-up effects on insectivorous birds were not observed in other Finnish regions or for moths overwintering in other life stages. In fact, some negative associations between moths and birds were even detected, possibly attributable to opposite abundance trends. While supporting the existence of bottom-up effects in the north-boreal zone, our study emphasizes the need for further investigation to elucidate moth-mediated trophic dynamics in areas characterized by the insect decline.

Vibrational noise disrupts Nezara viridula communication, irrespective of spectral overlap

Insects rely on substrate vibrations in numerous intra- and interspecific interactions. Yet, our knowledge of noise impact in this modality lags behind that in audition, limiting our understanding of how anthropogenic noise affects insect communities. Auditory research has linked impaired signal perception in noise (i.e., masking) to spectral overlap. We investigated the impact of noise with different spectral compositions on the vibrational communication of the stink bug Nezara viridula, examining courtship behaviour and signal representation by sensory neurons. We found negative effects of vibrational noise regardless of spectral overlap, challenging common expectations. Noise impaired the ability of males to recognize the female signal and localise its source: overlapping noise decreased sensitivity of receptor neurons to the signal and disrupted signal frequency encoding by phase-locking units, while non-overlapping noise only affected frequency encoding. Modelling neuronal spike triggering in sensory neurons linked disrupted frequency encoding to interference-induced alterations of the signal waveform. These alterations also affected time delays between signal arrivals to different legs, crucial for localisation. Our study thus unveils a new masking mechanism, potentially unique to insect vibrosensory systems. The findings highlight the higher vulnerability of vibration-mediated behaviour to noise, with implications for insect interactions in natural and anthropogenically altered environments.

Juvenile hormone III improves honeybee resistance to imidacloprid by protecting the midgut

Imidacloprid is one of the most commonly used insecticides and seriously threatens the survival of honeybees. Juvenile hormone III (JHIII), an important hormone in honeybees, plays a central role in the life cycle of honeybees; however, the mechanism by which JHIII responds to imidacloprid stress has not been determined. In this study, the resistance of Apis cerana cerana (Acc) to imidacloprid was greater than that of Apis mellifera (Am), and the application of JHIII significantly increased the resistance of both species of honeybees. RTqPCR revealed that two genes, juvenile hormone acid methyltransferase (JHAMT) and methyl farnesoate epoxidase (MFE), which are involved in JHIII biosynthesis, are key genes for improving resistance to imidacloprid via JHIII in honeybees. Silencing JHAMT and MFE with RNAi resulted in a lower content of JHIII in Acc and reduced resistance to imidacloprid. The exogenous application of JHIII compensated for the reduced resistance phenotype caused by gene silencing. Furthermore, histological examination of paraffin sections revealed that imidacloprid treatment caused loose intestinal cell arrangement, slight damage to columnar digestive cells and muscle cells, and chromatin condensation in basal layer cells. JHIII treatment reduced the degree of damage to the honeybee midgut cells and improved resistance to imidacloprid. The results of this study provide a new perspective and molecular basis for the study of the regulation of JHIII and the toxicity of imidacloprid in honeybees.

Milkweed in agricultural field margins - A neonicotinoid exposure route for pollinators at multiple life stages

Neonicotinoid insecticides move from targeted crops to wildflowers located in adjacent field margins, acting as a potential exposure source for wild pollinators and insect species of conservation concern, including monarch butterflies. Monarchs rely on milkweed over multiple life stages, including as a host plant for eggs and a food source for both larvae (leaves) and adults (flowers). Milkweeds, which are closely associated with field margins, can contain neonicotinoid residues, but previous assessments are constrained to a single plant tissue type. In 2017 and 2018, we sampled milkweeds from 95 field margins adjacent to crop fields (corn, soybean, hay, wheat, and barley) in agricultural landscapes of eastern Ontario, Canada. Milkweeds were sampled during the flower blooming period and leaves and flower tissues were analysed. The neonicotinoids acetamiprid, clothianidin, thiamethoxam, and thiacloprid were detected. Maximum concentrations in leaf samples included 10.30 ng/g of clothianidin in 2017, and 24.4 ng/g of thiamethoxam in 2018. Clothianidin and thiamethoxam percent detections in flowers (72 % and 61 %, respectively) were significantly higher than detections in leaves (24 % and 31 %, respectively). Thiamethoxam concentrations were significantly higher in paired flower samples than leaf samples (median 0.33 ng/g vs <0.07 ng/g) while clothianidin concentrations also trended higher in flowers (median 0.18-0.55 ng/g vs <0.18 ng/g). Only thiamethoxam showed significant differences between years, and we found no effect of crop type, with hay, soybean and corn fields all yielding 50-56 % detections in leaves. We found significantly higher concentrations in older milkweed flowers than young flowers or leaves (medians 0.87 ng/g vs <0.18 ng/g and 0.45 ng/g vs <0.07 ng/g for clothianidin and thiamethoxam, respectively). Our results highlight the importance of considering variation in milkweed tissue type and age of flowers in neonicotinoid exposure risk assessments. Efforts to increase milkweed availability in agricultural landscapes should consider how exposure to neonicotinoids can be mitigated.

Low-density migratory beekeeping induces intermediate disturbance effects on native bee communities in Tibetan Plateau alpine meadows

Ecological disturbance can promote or reduce community biodiversity depending on its severity. Beekeeping activities represent a type of ecological disturbance when large numbers of honey bees are introduced to a landscape and interact with the local plant and pollinator community. In this study, we characterized the effect of immediate and long-term low-density migratory beekeeping on the diversity and abundance of native bees in the Qinghai-Tibet Plateau (China). We found that the presence of apiaries and the number of honey bees reduced native bee abundances in the local bee community, likely through displacement from floral resources. However, in locations where apiaries were previously kept for decades but are not currently present, native bee abundances recovered, and phylogenetic diversity increased; yet community relative abundances and dominant species were distinct from those that had never been stocked. Our results suggest that the presence of a transient, intermediate number of migratory honey bee colonies (60-100 colonies spaced ≥15 km from each other) may represent an intermediate ecological disturbance and not permanently reduce native bee abundances past a critical threshold that may lead to local extirpation. Yet, our study demonstrates the potential for even intermediate-scale low-density beekeeping to alter native bee communities in the long-term.

Nonlinear transcriptomic responses to compounded environmental changes across temperature and resources in a pest beetle, Callosobruchus maculatus (Coleoptera: Chrysomelidae)

Many species are experiencing drastic and multidimensional changes to their environment due to anthropogenic events. These multidimensional changes may act nonadditively on physiological and life history responses, and thus may not be predicted by responses to single dimensional environmental changes. Therefore, work is needed to understand species' responses to multiple aspects of change. We used whole-transcriptomic RNA-Sequencing and life history assays to uncover responses to singly-applied shifts in resource or temperature environmental dimensions, in comparison to combined, multidimensional change, in the crop pest seed beetle, Callosobruchus maculatus. We found that multidimensional change caused larger fecundity, developmental period and offspring viability life history changes than predicted by additive effects of 1-dimensional changes. In addition, there was little overlap between genes differentially expressed under multidimensional treatment versus under altered resource or temperature conditions alone. Moreover, 115 genes exhibited significant resource × temperature interaction effects on expression, including those involved in energy metabolism, detoxification, and enhanced formation of cuticle structural components. We conclude that single dimensional changes alone cannot determine life history and transcriptomic responses to multidimensional environmental change. These results highlight the importance of studying multidimensional environmental change for understanding the molecular and phenotypic responses that may allow organisms including insects to rapidly adapt simultaneously to multiple aspects of environmental change.

Pervasive sublethal effects of agrochemicals on insects at environmentally relevant concentrations

Insect biomass is declining globally, likely driven by climate change and pesticide use, yet systematic studies on the effects of various chemicals remain limited. In this work, we used a chemical library of 1024 molecules-covering insecticides, herbicides, fungicides, and plant growth inhibitors-to assess the impact of sublethal pesticide doses on insects. In Drosophila melanogaster, 57% of chemicals affected larval behavior, and a higher proportion compromised long-term survivability. Exposure to sublethal doses also induced widespread changes in the phosphoproteome and changes in development and reproduction. The negative effects of agrochemicals were amplified when the temperature was increased. We observed similar behavioral changes across multiple insect species, including mosquitoes and butterflies. These findings suggest that widespread sublethal pesticide exposure can alter insect behavior and physiology, threatening long-term population survival.

A survey of keys for the identification of newly described insect genera: recommendations for authors, reviewers, editors, and publishers

Large numbers of new taxa are described annually and while there is a great need to make them identifiable, there seems little consistency in how this might be facilitated. 427 papers published in 2021 and 2022 were surveyed, which described 587 new insect genera. Only 136 of these papers included keys, and these allowed the identification of 233 of the new genera (31.9% of papers and 39.7% of the new genera). The proportion of papers that included a key varied significantly among insect orders but not among the handful of journals wherein the bulk of the new genera were described. Overall, for 17 key-related variables assessed in a binary fashion (optimal vs suboptimal), the average key had almost six criteria that were scored as being suboptimal. For example, less than one-fifth facilitated retracing and less than 12% had illustrated keys where the images were conveniently located close to the relevant key couplets. Progress towards confirming a putative identification was possible in all papers, through the inclusion of a diagnosis, habitus images, or both. Based upon this analysis, and expanding on previous suggestions for key construction, 23 recommendations are made on how to make an identification key maximally useful for users and I indicate the relative ease with which each could be adhered to. Identification keys should accompany all new taxon descriptions, guidelines for effective key construction should be added to journals' instructions to authors, editors and reviewers should check keys carefully, and publishers should be attentive to the needs of users through, for example, permitting duplication of images to make keys easier to use. Recommendations are likely relevant to all levels in the taxonomic hierarchy for all organisms, despite the data being derived from generic-level keys for insects.