Global warming promotes biological invasion of a honey bee pest

Biotic and abiotic stresses on honeybee health

Honeybees are the most critical pollinators providing key ecosystem services that underpin crop production and sustainable agriculture. Amidst a backdrop of rapid global change, this eusocial insect encounters a succession of stressors during nesting, foraging, and pollination. Ectoparasitic mites, together with vectored viruses, have been recognized as central biotic threats to honeybee health, while the spread of invasive giant hornets and small hive beetles also increasingly threatens colonies worldwide. Cocktails of agrochemicals, including acaricides used for mite treatment, and other pollutants of the environment have been widely documented to affect bee health in various ways. Additionally, expanding urbanization, climate change, and agricultural intensification often result in the destruction or fragmentation of flower-rich bee habitats. The anthropogenic pressures exerted by beekeeping management practices affect the natural selection and evolution of honeybees, and colony translocations facilitate alien species invasion and disease transmission. In this review, the multiple biotic and abiotic threats and their interactions that potentially undermine bee colony health are discussed, while taking into consideration the sensitivity, large foraging area, dense network among related nestmates, and social behaviors of honeybees.

Unravelling the impact of climate change on honey bees: An ensemble modelling approach to predict shifts in habitat suitability in Queensland, Australia

Honey bees play a vital role in providing essential ecosystem services and contributing to global agriculture. However, the potential effect of climate change on honey bee distribution is still not well understood. This study aims to identify the most influential bioclimatic and environmental variables, assess their impact on honey bee distribution, and predict future distribution. An ensemble modelling approach using the biomod2 package in R was employed to develop three models: a climate-only model, an environment-only model, and a combined climate and environment model. By utilising bioclimatic data (radiation of the wettest and driest quarters and temperature seasonality) from 1990 to 2009, combined with observed honey bee presence and pseudo absence data, this model predicted suitable locations for honey bee apiaries for two future time spans: 2020-2039 and 2060-2079. The climate-only model exhibited a true skill statistic (TSS) value of 0.85, underscoring the pivotal role of radiation and temperature seasonality in shaping honey bee distribution. The environment-only model, incorporating proximity to floral resources, foliage projective cover, and elevation, demonstrated strong predictive performance, with a TSS of 0.88, emphasising the significance of environmental variables in determining habitat suitability for honey bees. The combined model had a higher TSS of 0.96, indicating that the combination of climate and environmental variables enhances the model's performance. By the 2020-2039 period, approximately 88% of highly suitable habitats for honey bees are projected to transition from their current state to become moderate (14.84%) to marginally suitable (13.46%) areas. Predictions for the 2060-2079 period reveal a concerning trend: 100% of highly suitable land transitions into moderately (0.54%), marginally (17.56%), or not suitable areas (81.9%) for honey bees. These results emphasise the critical need for targeted conservation efforts and the implementation of policies aimed at safeguarding honey bees and the vital apiary industry.

Ecological forecasts of insect range dynamics: a broad range of taxa includes winners and losers under future climate

Species distribution models are the primary tools to project future species' distributions, but this complex task is influenced by data limitations and evolving best practices. The majority of the 53 studies we examined utilized correlative models and did not follow current best practices for validating retrospective or future environmental data layers. Despite this, a summary of results is largely unsurprising: shifts toward cooler regions, but otherwise mixed dynamics emphasizing winners and losers. Harmful insects were more likely to show positive outcomes compared with beneficial species. Our restricted ability to consider mechanisms complicates interpretation of any single study. To improve this area of modeling, more classic field and lab studies to uncover basic ecology and physiology are crucial.

Muscling mussels: Understanding the invasive potential of the South American bivalve Mytella strigata (Hanley, 1843) in the Northern Indian Ocean

In past decades, non-native species invasion has emerged as one of the leading drivers of biodiversity loss in terrestrial and aquatic ecosystems globally. In aquatic ecosystems, invasion by bivalve species has increased substantially due to their evolutionary resilience and adaptability. This study aimed to determine the habitat suitability of the South American bivalve Mytella strigata in the northern Indian Ocean using Species distribution modelling. The species occurrence and environmental data for model building were extracted from GBIF, Bio-ORACLE, The World Bank Data Catalogue and GMED. Pearson's correlation (<0.7) and Variance inflation factor (<10) analyses were used to select the environmental covariates. Individual models were built by combining the native range occurrence data of Mytella strigata with the bioclimatic data under the current climatic setting. Ten individual models were built and ensembled to create the final model using the biomod2 package. The variable importance score and the response curve plot were used to identify the most crucial variable and its influence on the models. Distance to port had the highest influence on predicting the distribution of Mytella strigata. The results indicated that the western coast of India as more susceptible to invasion. Our predictions indicate that the species has the potential to become highly invasive in the region, given the vast habitat suitability and documented introduction and presence of the species in the region. This research generated baseline information on the habitat suitability of M. strigata that will aid in managing and restricting its spread in the region. Considering the substantial impact of the species in other introduced ranges worldwide, immediate action should be initiated for the swift management of M. strigata from the Indian coast.

Advances and knowledge gaps on climate change impacts on honey bees and beekeeping: A systematic review

The Western honey bee Apis mellifera is a managed species that provides diverse hive products and contributing to wild plant pollination, as well as being a critical component of crop pollination systems worldwide. High mortality rates have been reported in different continents attributed to different factors, including pesticides, pests, diseases, and lack of floral resources. Furthermore, climate change has been identified as a potential driver negatively impacting pollinators, but it is still unclear how it could affect honey bee populations. In this context, we carried out a systematic review to synthesize the effects of climate change on honey bees and beekeeping activities. A total of 90 articles were identified, providing insight into potential impacts (negative, neutral, and positive) on honey bees and beekeeping. Interest in climate change's impact on honey bees has increased in the last decade, with studies mainly focusing on honey bee individuals, using empirical and experimental approaches, and performed at short-spatial (<10 km) and temporal (<5 years) scales. Moreover, environmental analyses were mainly based on short-term data (weather) and concentrated on only a few countries. Environmental variables such as temperature, precipitation, and wind were widely studied and had generalized negative effects on different biological and ecological aspects of honey bees. Food reserves, plant-pollinator networks, mortality, gene expression, and metabolism were negatively impacted. Knowledge gaps included a lack of studies at the apiary and beekeeper level, a limited number of predictive and perception studies, poor representation of large-spatial and mid-term scales, a lack of climate analysis, and a poor understanding of the potential impacts of pests and diseases. Finally, climate change's impacts on global beekeeping are still an emergent issue. This is mainly due to their diverse effects on honey bees and the potential necessity of implementing adaptation measures to sustain this activity under complex environmental scenarios.

Mapping current and future habitat suitability of Azolla spp., a biofertilizer for small-scale rice farming in Africa

How do we feed the expanding human population without excessive resource depletion or environmental degradation? Recycling and recapturing nutrients could alleviate these challenges, especially if these strategies are robust to climate change. Co-cultivating rice with Azolla spp. in Asia has demonstrated high yields with reduced fertilizer inputs because Azolla fixes atmospheric nitrogen, limits nitrogen volatilization, recaptures and releases other nutrients, and suppresses weeds. While Azolla is distributed in Africa, this approach has not been widely implemented in African rice-farming. Characterizing the suitability of Azolla is critical in evaluating the potential for Azolla-rice in Africa. To do so, we synthesized 189 field and greenhouse studies from around the world that quantified temperature-dependent growth of A. pinnata and A. filiculoides and developed present and future climate suitability maps at the continental scale using mean temperatures under two Representative Concentration Pathways. Currently, most of Africa is suitable for Azolla with slight differences in regional suitability for each species. We project little change in the continent-wide suitability for both species, but anticipate a regional decline, particularly for A. filiculoides in the Sahel. Collaborating with farmers to validate these projections, evaluate the costs and benefits of Azolla-rice, and facilitate adoption of viable strategies can facilitate equitable food systems that also empower African farmers.

Analyzing Gut Microbial Community in Varroa destructor-Infested Western Honeybee (Apis mellifera)

The western honeybee Apis mellifera L., a vital crop pollinator and producer of honey and royal jelly, faces numerous threats including diseases, chemicals, and mite infestations, causing widespread concern. While extensive research has explored the link between gut microbiota and their hosts. However, the impact of Varroa destructor infestation remains understudied. In this study, we employed massive parallel amplicon sequencing assays to examine the diversity and structure of gut microbial communities in adult bee groups, comparing healthy (NG) and Varroa-infested (VG) samples. Additionally, we analyzed Varroa-infested hives to assess the whole body of larvae. Our results indicated a notable prevalence of the genus Bombella in larvae and the genera Gillamella, unidentified Lactobacillaceae, and Snodgrassella in adult bees. However, no statistically significant difference was observed between NG and VG. Furthermore, our PICRUSt analysis demonstrated distinct KEGG classification patterns between larval and adult bee groups, with larvae displaying a higher abundance of genes involved in cofactor and vitamin production. Notably, despite the complex nature of the honeybee bacterial community, methanogens were found to be present in low abundance in the honeybee microbiota.

Biotechnical Control of Varroa in Honey Bee Colonies: A Trade-Off between Sustainable Beekeeping and Profitability?

Beekeeping faces several challenges, such as the Varroa mite. Few studies have measured the economic performance of farms in relation to the practices used for Varroa control. Our study analyzed various biotechniques (total brood removal, TBR; queen caging, QC; royal cell insertion, CI) and other methods (chemical treatments, CT; thymol use, THY) adopted by Italian beekeepers to show whether the adoption of biotechniques leads to farm profitability or a necessary trade-off between sustainability and profitability. Beekeepers were interviewed about the methods and operations conducted on their farms. The net incomes (NIs) of the farms were calculated and inter- and intrafarm comparisons were performed. A detailed schema of each practice was designed. The net income derived from TBR was the highest in eight out of the nine case studies, followed by CI and then QC. The NI calculated for farms using CT was lower than that for farms using other methods in two of the case studies. We also analyzed different biotechniques applied by the same farm and found that the NI resulting from TBR was higher than that achieved from the use of QC and CI. Our study suggests that use of biotechniques represents a long-term sustainable solution for reducing the level of Varroa infestation, which affects farm net income.

Impacts of climate change on climatically suitable regions of two invasive Erigeron weeds in China

Introduction

Erigeron philadelphicus and Erigeron annuus are two ecologically destructive invasive plants from the Asteraceae family. Predicting the potential distribution pattern of two invasive alien Erigeron weeds can provide a scientific basis for prevent the further spread of these two weeds in China under climate change.

Methods

Based on historical occurrence datasets and environmental variables, we optimized a MaxEnt model to predict the potential suitable habitats of E. philadelphicus and E. annuus. We also analyzed the shifts of distribution centroids and patterns under climate change scenarios.

Results

The key variables that affect the potential geographical distribution of E. annuus and E. philadelphicus, respectively, are temperature seasonality and precipitation of the driest month. Moreover, topsoil sodicity and topsoil salinity also influence the distribution of E. philadelphicus. Under climate change, the overall suitable habitats for both invasive alien Erigeron weeds are expected to expand. The potential geographical distribution of E. annuus exhibited the highest expansion under the SSP245 climate scenario (medium forcing scenarios), whereas E. philadelphicus had the highest expansion under the SSP126 climate scenario (lower forcing scenarios) globally. The future centroid of E. annuus is projected to shift to higher latitudes specifically from Hubei to Hebei, whereas E. philadelphicus remains concentrated primarily in Hubei Province. The overlapping suitable areas of the two invasive alien Erigeron plants mainly occur in Jiangsu, Zhejiang, Fujian, Jiangxi, Hunan, Guizhou, and Chongqing, within China.

Discussion

Climate change will enable E. annuus to expand into northeastern region and invade Yunnan Province whereas E. philadelphicus was historically the only suitable species. E. annuus demonstrates a greater potential for invasion and expansion under climate change, as it exhibits higher environmental tolerance. The predictive results obtained in this study can serve as a valuable reference for early warning systems and management strategies aimed at controlling the spread of these two invasive plants.

Beekeeping in Europe facing climate change: A mixed methods study on perceived impacts and the need to adapt according to stakeholders and beekeepers

The beekeeping sector is suffering from the detrimental effects of climate change, both directly and indirectly. Despite numerous studies conducted on this subject, large-scale research incorporating stakeholders' and beekeepers' perspectives has remained elusive. This study aims to bridge this gap by assessing the extent to which stakeholders involved in the European beekeeping sector and European beekeepers perceive and experience the impacts of climate change on their operations, and whether they had to adapt their practices accordingly. To this end, a mixed-methods study including in-depth stakeholder interviews (n = 41) and a pan-European beekeeper survey (n = 844) was completed within the frame of the EU-funded H2020-project B-GOOD. The development of the beekeeper survey was informed by insights from literature and the stakeholder interviews. The results highlighted significant regional disparities in the perceived impacts of climate change, with beekeepers in Southern European regions expressing more negative outlooks, while Northern European beekeepers reported more favourable experiences. Furthermore, survey analysis revealed beekeepers who were classified as 'heavily impacted' by climate change. These beekeepers reported lower average honey yields, higher colony winter loss rates and a stronger perceived contribution of honey bees to pollination and biodiversity, underscoring climate change's detrimental impacts on the beekeeping sector. Multinomial logistic regression revealed determinants of the likelihood of beekeepers being classified as 'heavily impacted' by climate change. This analysis indicates that Southern European beekeepers experienced a 10-fold likelihood of being classified as heavily impacted by climate change compared to Northern European beekeepers. Other significant factors distinguishing 'winners' and 'losers' were self-reported level of professionalism as a beekeeper (ranging from pure hobbyist to fully professional, Odds Ratio (OR) = 1.31), number of years active in beekeeping (OR = 1.02), availability of floral resources throughout the bee season (OR = 0.78), beehives located in a forested environment (OR = 1.34), and the presence of local policy measures addressing climate change-related challenges (OR = 0.76).

Climate change impacts on the potential worldwide distribution of the soybean pest, Piezodorus guildinii (Hemiptera: Pentatomidae)

The redbanded stink bug, Piezodorus guildinii (Westwood, 1837), is a highly destructive soybean pest native to the Neotropical Region. In the past 60 yr, P. guildinii has been observed to expand its distribution in North and South America, causing significant soybean yield losses. In order to predict the future distribution direction of P. guildinii and create an effective pest control strategy, we projected the potential global distribution of P. guildinii using 2 different emission scenarios, Shared Socioeconomic Pathways 126 and 585, and 3 Earth system models, with the maximum entropy niche model (MaxEnt). Then, the predicted distribution areas of P. guildinii were jointly analyzed with the main soybean-producing areas to assess the impact for different soybean region. Our results showed that temperature is the main environmental factor limiting the distribution of P. guildinii. Under present climate conditions, all continents except Antarctica have suitable habitat for P. guildinii. These suitable habitats overlap with approximately 45.11% of the total global cultivated soybean areas. Moreover, P. guildinii was predicted to expand its range in the future, particularly into higher latitudes in the Northern hemisphere. Countries, in particular the United States, where soybean is widely available, would face a management challenge under global warming. In addition, China and India are also high-risk countries that may be invaded and should take strict quarantine measures. The maps of projected distribution produced in this study may prove useful in the future management of P. guildinii and the containment of its disruptive effects.

Population Genomics for Insect Conservation

Insects constitute vital components of ecosystems. There is alarming evidence for global declines in insect species diversity, abundance, and biomass caused by anthropogenic drivers such as habitat degradation or loss, agricultural practices, climate change, and environmental pollution. This raises important concerns about human food security and ecosystem functionality and calls for more research to assess insect population trends and identify threatened species and the causes of declines to inform conservation strategies. Analysis of genetic diversity is a powerful tool to address these goals, but so far animal conservation genetics research has focused strongly on endangered vertebrates, devoting less attention to invertebrates, such as insects, that constitute most biodiversity. Insects' shorter generation times and larger population sizes likely necessitate different analytical methods and management strategies. The availability of high-quality reference genome assemblies enables population genomics to address several key issues. These include precise inference of past demographic fluctuations and recent declines, measurement of genetic load levels, delineation of evolutionarily significant units and cryptic species, and analysis of genetic adaptation to stressors. This enables identification of populations that are particularly vulnerable to future threats, considering their potential to adapt and evolve. We review the application of population genomics to insect conservation and the outlook for averting insect declines.

Potentially Suitable Geographical Area for Monochamus alternatus under Current and Future Climatic Scenarios Based on Optimized MaxEnt Model

M. alternatus is considered to be an important and effective insect vector for the spread of the important international forest quarantine pest, Bursaphelenchus xylophilus. The precise determination of potential suitable areas of M. alternatus is essential to monitor, prevent, and control M. alternatus worldwide. According to the distribution points and climatic variables, the optimized MaxEnt model and ArcGIS were used to predict the current and future potentially suitable areas of M. alternatus worldwide. The optimized MaxEnt model parameters were set as feature combination (FC) = LQHP and β = 1.5, which were determined by the values of AUC_diff, OR₁₀, and ΔAICc. Bio2, Bio6, Bio10, Bio12, and Bio14 were the dominant bioclimatic variables affecting the distribution of M. alternatus. Under the current climate conditions, the potentially suitable habitats of M. alternatus were distributed across all continents except Antarctica, accounting for 4.17% of the Earth's total land area. Under future climate scenarios, the potentially suitable habitats of M. alternatus increased significantly, spreading to a global scale. The results of this study could provide a theoretical basis for the risk analysis of the global distribution and dispersal of M. alternatus as well as the precise monitoring and prevention of this beetle.

Metagenomic analysis of viromes in honey bee colonies (Apis mellifera; Hymenoptera: Apidae) after mass disappearance in Korea

After the nationwide, massive winter losses of honey bees in Korea during the winter of 2021, samplings were conducted from live honey bees in colonies and dead honey bees nearby colonies in the same bee-farms in six regions in Korea. Each sample was subjected to virome analysis using high-throughput sequencing technology. The number of viral reads was the lowest in the live honey bee group sample with 370,503 reads and the highest in the dead honey bee group sample with 42,659,622 reads. Viral contigs were matched with the viral genomes of the black queen cell virus, deformed wing virus, Israeli acute paralysis virus, and sacbrood virus, all of which have been previously reported in Korea. However, Apis rhabdovirus 5, bee macula-like virus, Varroa orthomyxovirus-1, Hubei partiti-like virus 34, Lake Sinai virus 2, 3, and 4, and the Ditton virus, were also discovered in this study, which are the first records in Korea. Plant viral sequences resembling those of Arabidopsis latent virus 1, and a novel viral sequence was also discovered. In the present study 55 complete viral genome sequences were identified. This study is the first virome analysis of domestic honey bees and provides the latest information on the diversity of honey bee viruses in Korea.

Predicting Climate Change Effects on the Potential Distribution of Two Invasive Cryptic Species of the Bemisia tabaci Species Complex in China

Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) are two invasive cryptic species of the Bemisia tabaci species complex (Hemiptera: Aleyrodidae) that cause serious damage to agricultural and horticultural crops worldwide. To explore the possible impact of climate change on their distribution, the maximum entropy (MaxEnt) model was used to predict the potential distribution ranges of MEAM1 and MED in China under current and four future climate scenarios, using shared socioeconomic pathways (SSPs), namely SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5, over four time periods (2021-2040, 2041-2060, 2061-2080, and 2081-2100). The distribution ranges of MEAM1 and MED were extensive and similar in China under current climatic conditions, while their moderately and highly suitable habitat ranges differed. Under future climate scenarios, the areas of suitable habitat of different levels for MEAM1 and MED were predicted to increase to different degrees. However, the predicted expansion of suitable habitats varied between them, suggesting that these invasive cryptic species respond differently to climate change. Our results illustrate the difference in the effects of climate change on the geographical distribution of different cryptic species of B. tabaci and provide insightful information for further forecasting and managing the two invasive cryptic species in China.

Potential global geographical distribution of Lolium temulentum L. under climate change

Invasive alien plants posed a significant threat to natural ecosystems, biodiversity, agricultural production, as well as human and livestock health. Lolium temulentum, an annual invasive alien weed with fibrous roots, can reduce wheat production and cause economic losses. Moreover, the consumption of grains or cereal products mixed with darnel can cause dizziness, vomiting, and even death. Therefore, darnel is regarded as one of ″the worst weeds around the world″. In the present study, we predicted the potential global geographical distribution of L. temulentum using an optimal MaxEnt model, based on occurrence records and related environmental variables. The mean AUC, TSS, and KAPPA were 0.95, 0.778, and 0.75, indicating the MaxEnt model accuracy was excellent. The significant environmental variables, including the mean temperature of coldest quarter (bio 11), precipitation of coldest quarter (bio 19), temperature annual range (bio 7), and annual precipitation (bio 12), produced a great impact on the potential global geographical distribution of L. temulentum. Under the current climate, L. temulentum was primarily distributed in south-eastern Asia, Europe, and south-eastern North America. The widest total suitable habitat was distributed in Asia, covering nearly 796 × 10⁴ km². By the 2050s, the potential geographical distribution of L. temulentum was expected to decrease in the Northern Hemisphere, and shrink gradually in southern America, Africa, and Oceania. Moreover, the distribution center of L. temulentum was expected to shift from Asia to Europe. Based on these predictions, changes in the suitable habitats for L. temulentum between Europe and Asia warrant close attention to prevent further spread.

Analysis of glutathione-S-transferases from larvae of Galleria mellonella (Lepidoptera, Pyralidae) with potential alkaloid detoxification function

The greater wax moth, Galleria mellonella, is a global pest for beehives, doing damage in the larval stage. Although a significant number of studies have reported on larvae and adults, to date no effective pest control has been implemented. In this study, we tested larval resistance to alkaloids from Berberis microphylla, and the objective was to identify enzymes that participate in alkaloid detoxification through enzymatic assays, bioinformatics analysis and qRT-PCR. Findings suggest glutathione-S-transferases (GSTs), from an increased metabolic mechanism, are responsible for alkaloid detoxification rather than cytochrome P450 (CYP), carboxylesterases (CarE). A bioinformatics analysis from transcriptome data revealed 22 GSTs present in both G. mellonella larvae and adults. The qRT-PCR experiments corroborated the presence of the 22 GSTs in larvae, where GST8 and GST20 stood out with the highest expression after berberine treatment. Structural information around GST8 and GST20 suggests that GST8 could bind berberine stronger than GST20. These findings represent an important advance in the study of detoxification enzymes in G. mellonella, expanding the role of delta-class GSTs towards alkaloids. Likewise, GST inhibition by alkaloid analogs is proposed in the framework of integrated pest management strategies.

The Epidemiological Situation of the Managed Honey Bee (Apis mellifera) Colonies in the Italian Region Emilia-Romagna

The recent decades witnessed the collapse of honey bee colonies at a global level. The major drivers of this collapse include both individual and synergic pathogen actions, threatening the colonies’ survival. The need to define the epidemiological pattern of the pathogens that are involved has led to the establishment of monitoring programs in many countries, Italy included. In this framework, the health status of managed honey bees in the Emilia–Romagna region (northern Italy) was assessed, throughout the year 2021, on workers from 31 apiaries to investigate the presence of major known and emerging honey bee pathogens. The prevalence and abundance of DWV, KBV, ABPV, CBPV, Nosema ceranae, and trypanosomatids (Lotmaria passim, Crithidia mellificae, Crithidia bombi) were assessed by molecular methods. The most prevalent pathogen was DWV, followed by CBPV and N. ceranae. Trypanosomatids were not found in any of the samples. Pathogens had different peaks in abundance over the months, showing seasonal trends that were related to the dynamics of both bee colonies and Varroa destructor infestation. For some of the pathogens, a weak but significant correlation was observed between abundance and geographical longitude. The information obtained in this study increases our understanding of the epidemiological situation of bee colonies in Emilia–Romagna and helps us to implement better disease prevention and improved territorial management of honey bee health.

Climate Change Increases the Expansion Risk of Helicoverpa zea in China According to Potential Geographical Distribution Estimation

Simple Summary

Helicoverpa zea is one of the most destructive lepidopteran agricultural pests in the world and can disperse long distances both with and without human transportation. It is listed in the catalog of quarantine pests for plants imported to the People’s Republic of China but has not yet been reported in China. On the basis of 1781 global distribution records of H. zea and eight bioclimatic variables, we predicted the potential geographical distributions (PGDs) of H. zea by using a calibrated MaxEnt model. The results showed that the PGDs of H. zea under the current climate are large in China. Future climate changes under shared socioeconomic pathways (SSP) 1-2.6, SSP2-4.5, and SSP5-8.5 for both the 2030s and 2050s will facilitate the expansion of PGDs for H. zea. Helicoverpa zea has a high capacity for colonization by introduced individuals in China. Customs ports should pay attention to the host plants of H. zea and containers harboring this pest.

Abstract

Helicoverpa zea, a well-documented and endemic pest throughout most of the Americas, affecting more than 100 species of host plants. It is a quarantine pest according to the Asia and Pacific Plant Protection Commission (APPPC) and the catalog of quarantine pests for plants imported to the People’s Republic of China. Based on 1781 global distribution records of H. zea and eight bioclimatic variables, the potential geographical distributions (PGDs) of H. zea were predicted by using a calibrated MaxEnt model. The contribution rate of bioclimatic variables and the jackknife method were integrated to assess the significant variables governing the PGDs. The response curves of bioclimatic variables were quantitatively determined to predict the PGDs of H. zea under climate change. The results showed that: (1) four out of the eight variables contributed the most to the model performance, namely, mean diurnal range (bio2), precipitation seasonality (bio15), precipitation of the driest quarter (bio17) and precipitation of the warmest quarter (bio18); (2) PGDs of H. zea under the current climate covered 418.15 × 10⁴ km², and were large in China; and (3) future climate change will facilitate the expansion of PGDs for H. zea under shared socioeconomic pathways (SSP) 1-2.6, SSP2-4.5, and SSP5-8.5 in both the 2030s and 2050s. The conversion of unsuitable to low suitability habitat and moderately to high suitability habitat increased by 8.43% and 2.35%, respectively. From the present day to the 2030s, under SSP1-2.6, SSP2-4.5 and SSP5-8.5, the centroid of the suitable habitats of H. zea showed a general tendency to move eastward; from 2030s to the 2050s, under SSP1-2.6 and SSP5-8.5, it moved southward, and it moved slightly northward under SSP2-4.5. According to bioclimatic conditions, H. zea has a high capacity for colonization by introduced individuals in China. Customs ports should pay attention to host plants and containers of H. zea and should exchange information to strengthen plant quarantine and pest monitoring, thus enhancing target management.

Decreased bee emergence along an elevation gradient: Implications for climate change revealed by a transplant experiment

Bees experience differences in thermal tolerance based on their geographical range; however, there are virtually no studies that examine how overwintering temperatures may influence immature survival rates. Here, we conducted a transplant experiment along an elevation gradient to test for climate-change effects on immature overwinter survival using movement along elevational gradient for a community of 26 cavity-nesting bee species in the family Megachilidae along the San Francisco Peaks, Arizona elevational gradient. In each of three years, we placed nest blocks at three elevations, to be colonized by native Megachilidae. Colonized blocks were then (1) moved to lower (warmer) elevations; (2) moved to higher (cooler) elevations; or (3) left in their natal habitat (no change in temperature). Because Megachilidae occupy high elevations with colder temperatures more than any other family of bees, we predicted that emergence would decrease in nest blocks moved to lower elevations, but that we would find no differences in emergence when nest blocks were moved to higher elevations. We found three major results: (1) Bee species moved to lower (warmer) habitats exhibited a 30% decrease in emergence compared with species moved within their natal habitat. (2) Habitat generalists were more likely than habitat specialists to emerge when moved up or down in elevation regardless of their natal life zones. (3) At our highest elevation treatment, emergence increased when blocks were moved to higher elevations, indicating that at least some Megachilidae species can survive at colder temperatures. Our results suggest that direct effects of warming temperatures will have negative impacts on the overall survival of Megachilidae. Additionally, above the tree line, low availability of wood-nesting resources is a probable limiting factor on bees moving up in elevation.

Comparative genomics suggests local adaptations in the invasive small hive beetle

Invasive species are a major driver of ecological and environmental changes that affect human health, food security, and natural biodiversity. The success and impact of biological invasions depend on adaptations to novel abiotic and biotic selective pressures. However, the molecular mechanisms underlying adaptations in invasive parasitic species are inadequately understood. Small hive beetles, Aethina tumida, are parasites of bee nests. Originally endemic to sub-Saharan Africa, they are now found nearly globally. Here, we investigated the molecular bases of the adaptations to novel environments underlying their invasion routes. Genomes of historic and recent adults A. tumida from both the endemic and introduced ranges were compared. Analysis of gene-environment association identified 3049 candidate loci located in 874 genes. Functional annotation showed a significant bias toward genes linked to growth and reproduction. One of the genes from the apoptosis pathway encodes an "ecdysone-related protein," which is a crucial regulator in controlling body size in response to environmental cues for holometabolous insects during cell death and renewal. Genes whose proteins regulate organ size, ovary activation, and oviposition were also detected. Functions of these enriched pathways parallel behavioral differences between introduced and native A. tumida populations, which may reflect patterns of local adaptation. The results considerably improve our understanding of the underlying mechanisms and ecological factors driving adaptations of invasive species. Deep functional investigation of these identified loci will help clarify the mechanisms of local adaptation in A. tumida.

Including Host Availability and Climate Change Impacts on the Global Risk Area of Carpomya pardalina (Diptera: Tephritidae)

Fruit flies are a well-known invasive species, and climate-based risk modeling is used to inform risk analysis of these pests. However, such research tends to focus on already well-known invasive species. This paper illustrates that appropriate risk modeling can also provide valuable insights for flies which are not yet “on the radar.” Carpomya pardalina is a locally important cucurbit-infesting fruit fly of western and central Asia, but it may present a risk to other temperate countries where melons are grown. MaxEnt models were used to map the risk area for this species under historical and future climate conditions averaged from three global climate models under two shared socio-economic pathways in 2030 and 2070 from higher climate sensitivity models based on the upcoming 2021 IPCC sixth assessment report. The results showed that a total of 47.64% of the world’s land mass is climatically suitable for the fly; it could establish widely around the globe both under current and future climates with host availability. Our MaxEnt modeling highlights particularly that Western China, Russia, and other European countries should pay attention to this currently lesser-known melon fly and the melons exported from the present countries. The current and expanding melon trade could offer direct invasion pathways to those regions. While this study offers specific risk information on C. pardalina, it also illustrates the value of applying climate-based distribution modeling to species with limited geographic distributions.

A biophysical approach to assess weather impacts on honey bee colony winter mortality

The western honey bee (Apis mellifera) is one of the most important insects kept by humans, but high colony losses are reported around the world. While the effects of general climatic conditions on colony winter mortality were already demonstrated, no study has investigated specific weather conditions linked to biophysical processes governing colony vitality. Here, we quantify the comparative relevance of four such processes that co-determine the colonies' fitness for wintering during the annual hive management cycle, using a 10-year dataset of winter colony mortality in Austria that includes 266 378 bee colonies. We formulate four process-based hypotheses for wintering success and operationalize them with weather indicators. The empirical data is used to fit simple and multiple linear regression models on different geographical scales. The results show that approximately 20% of winter mortality variability can be explained by the analysed weather conditions, and that it is most sensitive to the duration of extreme cold spells in mid and late winter. Our approach shows the potential of developing weather indicators based on biophysical processes and discusses the way forward for applying them in climate change studies.

Heat Tolerance, Energetics, and Thermal Treatments of Honeybees Parasitized With Varroa

Ongoing global change affects both wildlife and economically relevant species, which are now subjected to combined challenges from climate change and higher exposure to pathogens. Honeybee colonies worldwide are under threat by higher temperatures and the ectoparasitic mite Varroa destructor, hence we studied the impact of these combined challenges in the thermal biology and energetics of Apis mellifera. We estimated the heat tolerance and energy expenditure (CO2 production and VCO2) of honeybees acclimated to different temperatures (32 and 38°C) and subjected to different levels of parasitism (0, 1, and 2 mites). Heat tolerance was quantified employing thermal death time (TDT) curves describing how survival times vary as a function of temperature, which differed significantly between treatments. Warm-acclimated uninfected bees exhibited a higher thermal tolerance than their cold-acclimated counterparts, but parasitism by Varroa resulted in a substantial drop in tolerance rendering TDT curves of parasitized bees virtually indistinguishable. Accordingly, VCO2 increased dramatically in parasitized bees (46.5 and 67.1% with 1 and 2 Varroa, respectively), suggesting that Varroa impinges on substantial costs on energy expenditure which, in combination with lower fat reserves due to parasitism, should have synergistic effects on bees’ survival and performance. Results provide conclusive evidence of the detrimental impact of Varroa on heat tolerance that undermines potentially adaptive responses associated with thermal acclimation. Results also show that heat treatments are a realistic venue to control Varroa, and we discuss how TDT curves may be employed to optimize management strategies in this context.

Risk assessment of insect pest expansion in alpine ecosystems under climate change

BACKGROUND

Growth in insect pest populations poses a significant threat to ecosystem functions and services, societal development, and food security in alpine regions under climate change. Risk assessments are important prioritization tools for pest management, which must be used to study insect pest expansion in alpine ecosystems under global warming. We used species distribution modeling to simulate the current and future distribution probabilities of 58 insect pest species in the Qinghai Province, China, based on a comprehensive field investigation. Subsequently, general linear modeling was used to explore the relationship between the distribution probability of these species and the damage caused by them. Finally, we assessed the ecological risk of insect pest expansion across different alpine ecosystems under climate change.

RESULTS

Climate change could increase the distribution probabilities of insect pest species across different alpine ecosystems. However, the presence of insect pest species may not correspond to the damage occurrence in alpine ecosystems based on percent leaf loss, amount of stunting, and seedling death of their host species. Significant positive relationships between distribution probability and damage occurrence were found for several of the examined insect pest species. Insect pest expansion is likely to increase extensively in alpine ecosystems under increasing carbon dioxide (CO₂ ) emission scenarios.

CONCLUSION

The relationships between distribution probability and damage occurrence should be considered in species distribution modeling for risk assessment of insect pest expansion under climate change. Our study could improve the effectiveness of risk assessment of insect pest expansion under changing climate conditions. © 2021 Society of Chemical Industry.

An Easy Mixed-Method Analysis Tool to Support Rural Development Strategy Decision-Making for Beekeeping

The EU has long-recognised the functions and contributions of beekeeping in sustainable rural area development. In 2018, the EU adopted the Pollinator Initiative to strengthen its pollinator conservation policies. To support the design of effective rural development actions, this work describes and tests an easy-to-apply, mixed-method tool for use with SWOT analysis. A two-step methodology was trialled with beekeepers in Piedmont Region (NW Italy). In step one, two independent groups of beekeepers operating in separate protected and intensive agricultural areas completed a SWOT matrix. In step two, three expert panels (beekeeper association leaders, honey market organisation leaders, and entomologists) prioritised the effects of the SWOT items with a quantitative weighting and rating process. Results suggest that the sector needs better-targeted incentives and that ‘soft’ policies on extension, advisory, and institutional measures could play a relevant role. The method was also confirmed as suitable for use with non-expert evaluators, such as policy officers and practitioners.

Characterization of Cold Tolerance of Immature Stages of Small Hive Beetle (SHB) Aethina tumida Murray (Coleoptera: Nitidulidae)

The small hive beetle (SHB) Aethina tumida Murray, (Coleoptera: Nitidulidae) is now a global invasive pest of honey bees, but its cold tolerance potential has not been yet explored. Therefore, we measured the supercooling point (SCP) of different stages of SHBs and also the impact of acclimation on their SCPs and survival as a measure for cold tolerance. Combinations of different temperatures (0, 3, 5, 7, and 10 ∘C) for different hours (1, 3, 5, 7, 12, 24, 35, and 48 h) were used to assess SHB survival. The supercooling points occurred at lower temperatures (-19.4 ∘C) in wandering larvae than in the other stages (pupae: -12.5 ∘C, and feeding larvae: -10.7 ∘C). A lethal temperature (LT50) of feeding larvae was achieved earlier at 4.9 ∘C after 7 h exposure than the wandering larvae (3.7 ∘C at 48 h) and pupae (5.6 ∘C at 48 h). The sum of injurious temperature (SIT) is the most suitable estimation to describe cold resistance of the SHB immatures. The wandering larvae were the most cold tolerant, followed by pupae and feeding larvae based on SIT values of -286.8, -153.7 and -28.7 DD, respectively, and also showed more phenotypic plasticity after acclimation than feeding larvae and slightly more than pupae. Our results show that all stages, i.e., feeding larvae, wandering larvae and pupae, are chill susceptible. However, these stages, especially wandering larvae and pupae, showed the capacity to acclimate to cold temperatures, which may help them to survive in winter for the continuity of the SHB population, especially in a scenario of climate change.

Pathways for Novel Epidemiology: Plant-Pollinator-Pathogen Networks and Global Change

Multiple global change pressures, and their interplay, cause plant-pollinator extinctions and modify species assemblages and interactions. This may alter the risks of pathogen host shifts, intra- or interspecific pathogen spread, and emergence of novel population or community epidemics. Flowers are hubs for pathogen transmission. Consequently, the structure of plant-pollinator interaction networks may be pivotal in pathogen host shifts and modulating disease dynamics. Traits of plants, pollinators, and pathogens may also govern the interspecific spread of pathogens. Pathogen spillover-spillback between managed and wild pollinators risks driving the evolution of virulence and community epidemics. Understanding this interplay between host-pathogen dynamics and global change will be crucial to predicting impacts on pollinators and pollination underpinning ecosystems and human wellbeing.

A Qualitative Analysis of Beekeepers' Perceptions and Farm Management Adaptations to the Impact of Climate Change on Honey Bees

Simple Summary

This paper addresses climate change effects on honey bees and beekeeping, as observed by the beekeepers. Focus groups were used to identify the perceptions, thoughts and impressions of two groups of beekeepers, regarding their viewpoints and direct observations on the effects of climate change on honey bees and management strategies. Beekeepers reported several consequences related to severe weather events (weakening or loss of colonies; scarcity of nectar, pollen, and honeydew; decrease or lack of honey and other bee products; intensive transhumance; greater infestation by varroa; decline in pollination), making it necessary to provide supplemental sugar feeding, more effective and sustainable techniques for varroa control, and increased production of nuclei. Thanks to their strong motivation and collaborative attitude, beekeepers succeed in adopting strategies that are able to limit the climatic adverse effects. However, the institutional and financial support for the beekeeping sector should be strengthened and better targeted in order to help beekeepers to cope with the specific issues arising due to climatic stresses.

Abstract

(1) Background: Bees are the primary animal pollinators in most ecosystems, and honey bees (Apis mellifera L.) are important providers of pollination ecosystem services and products. Climate change is one of the major threats for honey bees. (2) Objectives and methods: Qualitative research using focus group discussions was carried out in northwestern Italy, to investigate the beekeepers’ perceptions of climate change effects, the relevant management adaptations, and the main issues affecting the sector. (3) Results: Beekeepers reported several consequences related to severe weather events (weakening or loss of colonies; scarcity of nectar, pollen, and honeydew; decrease or lack of honey and other bee products; greater infestation by varroa; decline in pollination), making it necessary to provide supplemental sugar feeding, intensive transhumance, more effective and sustainable techniques for varroa control, and increased production of nuclei. A strengths, weaknesses, opportunities, and threats (SWOT) analysis was completed, displaying the factors able to strengthen or weaken the resilience of the beekeeping sector to climate change. (4) Conclusions: Thanks to their strong motivation and collaborative attitude, beekeepers succeed in adopting farm and bee hive adaptation strategies that are able to limit the climatic adverse effects. However, these findings highlight how the institutional and financial support for the beekeeping sector should be strengthened and better targeted.

Successful Pupation of Small Hive Beetle, Aethina tumida (Coleoptera: Nitidulidae), in Greenhouse Substrates

The small hive beetle, Aethina tumida Murray, is an invasive pest that has spread globally. Western honey bees, Apis mellifera Linnaeus (Hymenoptera: Apidae), are considered the most important host and infestations can lead to collapse of colonies. Larvae feed on honey, pollen, and brood inside the hive and leave the hive as postfeeding wandering larvae to pupate in the surrounding soil. Other host species include bumble bees, stingless bees, and solitary bees, all of which can facilitate small hive beetle reproduction and are used for greenhouse crop pollination worldwide. Here, we investigated if small hive beetles can complete their life cycle when soil is absent by pupating in plant root-supporting substrates commonly used in greenhouses. Wandering small hive beetle larvae were introduced into containers with coconut fiber, perlite, a mixture of both and stone wool substrates to investigate pupation success and development time. Sand was used as control substrate. In all but one substrate (perlite), small hive beetles developed into adults equally well as they did in the sand. Development time ranged between 23 and 37 d and was not different from that of the control. We showed that small hive beetles can pupate in greenhouse substrates. This could constitute a problem for greenhouse pollination as well as it could facilitate small hive beetle survival in areas which otherwise would be deemed unsuitable or marginal environments for small hive beetles to become established. Our study highlights the opportunistic nature of the small hive beetle as an invasive species.

Predicting the Potential Distribution of Apple Canker Pathogen (Valsa mali) in China under Climate Change

Apple valsa canker (AVC), caused by Valsa mali, is a serious wood disease of apple trees. The pathogen decays the barks and branches of trees and ruins entire orchards under severe conditions. However, studies have rarely focused on the suitable habitat of the pathogen, especially on a relatively large scale. In this study, we applied the maximum entropy model (MaxEnt 3.4.1, Princeton, NJ, USA) to predict the distribution of V. mali using climate factors, topographic factors, and soil factors under current and future climate scenarios. We measured the area of suitable habitat, change ratio of the suitable habitat area, increase and decrease maps under climate change, direction and distance of range shifts from the present to the end of the 21st century, and the contribution of environmental variables. The results showed that the area of suitable habitat is currently 183.46 × 104 km2 in China, among which 27.54% is moderately suitable habitat (MSH) and 13.13% is highly suitable habitat (HSH). Compared with current distribution, the area of MSH and HSH increases in future and the change ratio are positive. The Shared Socioeconomic Pathways (SSPs) 3–70 is considered the optimum climate scenario for V. mali. The suitability of V. mali increased mainly in Northwest, North, and Northeast China. V. mali will shift to the northwest with climate change. The shift distance optimistically increased from the SSP1–26 to the SSP5–85, with the biggest shift distance of 758.44 km in the 2090s under the SSP5–85 scenario. Minimum temperature of the coldest month (bio6) was the most critical climate factor affecting the distribution of the pathogen, and topographic factors played a more important role than soil factors. This study demonstrates that the potential distribution of V. mali is vitally affected by climate change and provides a method for large–scale research on the distribution of pathogens.