Do Not Divide Count Data with Count Data; A Story from Pollination Ecology with Implications Beyond

Integrating new variables into a framework to support cacao denomination of origin: a case study in Southwest Colombia

BACKGROUND

Cocoa quality plays a pivotal role in establishing denominations of origin, with genotypes, geography, climate and soil conditions being key variables. However, these factors have not been comprehensively explored in defining cacao denominations of origin. The present study addresses this gap by laying the foundation for cacao denomination of origin, focusing on the Buenaventura region on Colombia's Pacific coast. Our goal is to provide a holistic understanding of the elements underpinning cacao denomination of origin, emphasizing Buenaventura's unique cocoa quality and geographical significance.

RESULTS

Through the Buenaventura case, we propose a robust framework applicable to other cacao-producing regions, elevating the recognition and value of cacao denomination of origin. Our framework encompasses geography, agronomy, genetics, microbial diversity, pests and diseases and cocoa quality. In a pioneering move, we propose a cacao denomination of origin in Colombia, specifically examining Bajo Calima, Sabaletas and Cisneros within Buenaventura region. Buenaventura stands out for its cocoa quality, characterized by fruity flavors attributed to the rich biodiversity of the lowland rainforest.

CONCLUSION

Our analysis indicates specific geographical indicators for each of the study zones, with Buenaventura identified as a region with natural characteristics to produce fine flavour cocoa products. Each zone exhibited a high differentiation and diversity of cacao cultivars. Buenaventura has the potential to be designated as a future denomination of origin for cacao from the Pacific region of Colombia, characterized by its unique fruity-aroma chocolates. Our framework is adaptable to other cacao-producing regions, facilitating the establishment of denominations of origin within the cocoa industry and agriculture. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Anthropogenic air pollutants reduce insect-mediated pollination services

Common air pollutants, such as nitrogen oxides (NO_x), emitted in diesel exhaust, and ozone (O₃), have been implicated in the decline of pollinating insects. Reductionist laboratory assays, focused upon interactions between a narrow range of flowering plant and pollinator species, in combination with atmospheric chemistry models, indicate that such pollutants can chemically alter floral odors, disrupting the cues that foraging insects use to find and pollinate flowers. However, odor environments in nature are highly complex and pollination services are commonly provided by suites of insect species, each exhibiting different sensitivities to different floral odors. Therefore, the potential impacts of pollution-induced foraging disruption on both insect ecology, and the pollination services that insects provide, are currently unknown. We conducted in-situ field studies to investigate whether such pollutants could reduce pollinator foraging and as a result the pollination ecosystem service that those insects provide. Using free-air fumigation, we show that elevating diesel exhaust and O₃, individually and in combination, to levels lower than is considered safe under current air quality standards, significantly reduced counts of locally-occurring wild and managed insect pollinators by 62-70% and their flower visits by 83-90%. These reductions were driven by changes in specific pollinator groups, including bees, flies, moths and butterflies, and coincided with significant reductions (14-31%) in three different metrics of pollination and yield of a self-fertile test plant. Quantifying such effects provides new insights into the impacts of human-induced air pollution on the natural ecosystem services upon which we depend.

Can Conflicting Selection from Pollinators and Nectar-Robbing Antagonists Drive Adaptive Pollen Limitation? A Conceptual Model and Empirical Test

AbstractPollen limitation is widespread, despite predictions that it should not be. We propose a novel mechanism generating pollen limitation: conflicting selection by pollinators and antagonists on pollinator attraction traits. We introduce a heuristic model demonstrating antagonist-induced adaptive pollen limitation and present a field study illustrating its occurrence in a wild population. For antagonist-induced adaptive pollen limitation to occur, four criteria must be met: (1) correlated attraction of pollinators and antagonists; (2) greater response by antagonists than pollinators to altered investment in attraction traits; (3) reduced investment in pollinator attraction, leading to pollen limitation; and (4) higher fitness for plants with reduced investment in pollinator attraction. We surveyed nectar robbery and reproductive output for 109 Odontonema cuspidatum (Acanthaceae) plants in a pollen-limited population over 2 years and used experimental floral arrays to evaluate how flower number affects pollination and nectar robbery. Both pollinators and nectar robbers preferred larger floral displays and nectar robbery reduced reproductive output, suggesting conflicting selection. Survey and experimental data agreed closely on the optimum flower number under antagonist-induced pollen limitation; this number was substantially overrepresented in the population. While criteria for antagonist-induced adaptive pollen limitation are restrictive, the necessary conditions may often be realized. Considering interactions beyond the plant-pollinator dyad illuminates previously overlooked mechanisms generating pollen limitation.

State of the ART: Using artificial refuge traps to control invasive crayfish in southern California streams

Invasive species are a widespread threat to stream ecosystems across the planet. In Southern California, USA, the invasive red swamp crayfish Procambarus clarkii (Girard, 1852) poses a significant threat to native aquatic fauna. Studies have suggested that artificial refuge traps (ARTs) resembling crayfish burrows can be used to remove invasive crayfish, but, to date, no studies have focused on optimizing ART design and deployment to maximize crayfish catch. This month-long study tested the effect of modifications on ART diameter, color, and soak time on P. clarkii catch effectiveness across 160 traps. We evaluated catch data by creating multiple candidate generalized linear mixed models predicting P. clarkii catches with different modeling parameterizations and a priori hypothesized predictor variables. During the study period, ARTs removed a total of 240 red swamp crayfish with no incidental bycatch. Larger P. clarkii (2-6-cm carapace length) were found more frequently in 5.1-cm-diameter traps, and smaller P. clarkii (1-4 cm) were found more frequently in 2.5-cm-diameter traps. Catch numbers varied between trap types, with black-colored 5.1-cm-diameter traps removing the greatest amount of the total P. clarkii caught in the study (mean = 0.27, SD = 0.29; 35% of the total caught) and black-colored 2.5-cm-diameter traps removing the least amount (mean = 0.09, SD = 0.55; 12% of the total). Further, ART deployment duration was an important predictor variable for candidate models, where ARTs with 4-d and 7-d deployment durations had lower catch/unit effort than traps with 1-d and 2-d deployments. This factorial experiment is the 1st study to suggest specific design modifications to ARTs that optimize invasive red swamp crayfish removal without incurring non-target incidental bycatch. This study demonstrates that ARTs can be a valuable tool for conservation managers interested in restoring streams through invasive crayfish removal, especially where there are sensitive biological resources.

Facilitation with a grain of salt: reduced pollinator visitation is an indirect cost of association with the foundation species creosote bush (Larrea tridentata)

PREMISE

In arid ecosystems, shrub facilitation is a critical process driving plant community structure and assembly, often resulting in increased densities of annual plants beneath shrub canopies. Pollinator-mediated interactions can have fitness consequences for both plant interactors but are largely unexplored as an indirect consequence of direct shrub-annual facilitation.

METHODS

We tested the capacity of the geographically widespread creosote bush (Larrea tridentata) to influence pollinator visitation to its annual understory during its phenological shift into spring flowering. We used small video cameras to record pollinator visitation and foraging behavior on potted transplants of a representative flowering annual. We concurrently evaluated L. tridentata's positive role as a foundation plant in this system by measuring the associated plant and arthropod communities and deploying data loggers to measure understory microclimates.

RESULTS

Pollinator visitation to the flowering annual desert dandelion, Malacothrix glabrata, was lower when beneath the canopy of L. tridentata, and further declined throughout the study site as L. tridentata entered full bloom. We confirmed the role of L. tridentata as a foundation species in this system through its concurrent, positive effects on annual plant cover (a proxy for biomass), the abundance and richness of the understory arthropod community and its ability to create stable microclimates.

CONCLUSIONS

Direct and indirect shrub effects on other species function simultaneously to shift net outcomes even within predominantly net positive facilitation complexes.

Honey bees and wild pollinators differ in their preference for and use of introduced floral resources

Introduced plants may be important foraging resources for honey bees and wild pollinators, but how often and why pollinators visit introduced plants across an entire plant community is not well understood. Understanding the importance of introduced plants for pollinators could help guide management of these plants and conservation of pollinator habitat. We assessed how floral abundance and pollinator preference influence pollinator visitation rate and diversity on 30 introduced versus 24 native plants in central New York. Honey bees visited introduced and native plants at similar rates regardless of floral abundance. In contrast, as floral abundance increased, wild pollinator visitation rate decreased more strongly for introduced plants than native plants. Introduced plants as a group and native plants as a group did not differ in bee diversity or preference, but honey bees and wild pollinators preferred different plant species. As a case study, we then focused on knapweed (Centaurea spp.), an introduced plant that was the most preferred plant by honey bees, and that beekeepers value as a late-summer foraging resource. We compared the extent to which honey bees versus wild pollinators visited knapweed relative to coflowering plants, and we quantified knapweed pollen and nectar collection by honey bees across 22 New York apiaries. Honey bees visited knapweed more frequently than coflowering plants and at a similar rate as all wild pollinators combined. All apiaries contained knapweed pollen in nectar, 86% of apiaries contained knapweed pollen in bee bread, and knapweed was sometimes a main pollen or nectar source for honey bees in late summer. Our results suggest that because of diverging responses to floral abundance and preferences for different plants, honey bees and wild pollinators differ in their use of introduced plants. Depending on the plant and its abundance, removing an introduced plant may impact honey bees more than wild pollinators.

Interactions Between the Nematode Heterorhabditis amazonensis JPM4 and the Predator Macrolophus basicornis: Two Natural Enemies of Tuta absoluta Native to South America

Entomopathogenic nematodes (EPNs) and predatory mirids are among the most effective natural enemies for the control of Tuta absoluta, a key pest of tomato worldwide. In the case of South America, the native EPN Heterorhabditis amazonensis and the predator Macrolophus basicornis (Stal) coexist in tomato. The intraguild interactions of two ENPs, H. amazonensis JPM4 and the widely used Steinernema carpocapsae, with the predator M. basicornis, were studied in laboratory setups with the objective of evaluating the potential interactions between them. We hypothesized that the two natural enemies do not interact negatively. The first nymphal stage of the predator was not affected when exposed to tomato leaves directly sprayed with both EPNs, which we attributed to the small size of its stylet. Individuals treated with H. amazonensis JPM4 had low mortality rates in all developmental stages with a maximum of 1.3%. Mortality was higher when the predator was exposed to S. carpocapsae (28% for adults) and correlated positively with increasing developmental stages. In prey choice tests between larvae infected with H. amazonensis and uninfected larvae, M. basicornis fed indistinctively showing no clear preference. When presented with choice larvae infected with S. carpocapsae, the consumption of healthy larvae was higher. In a no-choice prey acceptance experiment, M. basicornis preyed on both healthy and infected larvae with no difference in larvae consumed. Predators that had fed from infected larvae did not exhibit signs of nematode infection and survived. Our results indicate that the South American native H. amazonensis JPM4 and M. basicornis do not show a negative interaction and are promising candidates for combined use in T. absoluta biological control.

Experimental loss of generalist plants reveals alterations in plant-pollinator interactions and a constrained flexibility of foraging

Species extinctions undermine ecosystem functioning, with the loss of a small subset of functionally important species having a disproportionate impact. However, little is known about the effects of species loss on plant-pollinator interactions. We addressed this issue in a field experiment by removing the plant species with the highest visitation frequency, then measuring the impact of plant removal on flower visitation, pollinator effectiveness and insect foraging in several sites. Our results show that total visitation decreased exponentially after removing 1-4 most visited plants, suggesting that these plants could benefit co-occurring ones by maintaining high flower visitor abundances. Although we found large variation among plant species, the redistribution of the pollinator guild affected mostly the other plants with high visitor richness. Also, the plant traits mediated the effect of removal on flower visitation; while visitation of plants which had smaller inflorescences and more sugar per flower increased after removal, flower visitors did not switch between flower shapes and visitation decreased mostly in plants visited by many morpho-species of flower visitors. Together, these results suggest that the potential adaptive foraging was constrained by flower traits. Moreover, pollinator effectiveness fluctuated but was not directly linked to changes of flower visitation. In conclusion, it seems that the loss of generalist plants alters plant-pollinator interactions by decreasing pollinator abundance with implications for pollination and insect foraging. Therefore, generalist plants have high conservation value because they sustain the complex pattern of plant-pollinator interactions.

Disruptive sexual selection on male body size in the polyphenic black scavenger fly Sepsis thoracica

Sexual selection has 2 main components, female preference and male–male competition, which can lead males to adopt alternative reproductive tactics to optimize their reproductive success. Two traits that significantly influence reproductive success are body size and coloration, as they can facilitate access to females through male contests or as female attractors. We investigated whether, and if so which mechanism of sexual selection contributes to the maintenance, and possibly even the establishment, of 2 almost discrete male morphs in the polyphenic black scavenger fly Sepsis thoracica (Diptera: Sepsidae): small and black, or large and amber. We performed 2 complementary laboratory experiments to evaluate the mating success of the different male morphs and the behaviors (of both males and females) presumably mediating their mating success. We found evidence for intraspecific disruptive sexual selection on male body size that is mediated by male–male interactions, and significant positive directional selection on body size that interacted with (directional) selection on coloration, likely contributing to the origin and/or maintenance of the threshold relationship between the 2 traits in this species. The simultaneous occurrence of disruptive selection and polyphenism in S. thoracica supports the role of sexual selection in the intraspecific diversification of coupled traits (here body size and coloration), which could be a speciation starting point.