Biology subjects

Poveda, K.

Publications and source records attributed to Poveda, K..

4 recordsLinked to original sources

bioRxiv2025

Colony-level pollen collection reflects visitation of managed bumble bees (Bombus impatiens) in strawberry fields and surrounding landscapes without improving crop yield.

Managed bees are frequently used to supplement pollination of a range of crop plants. Yet, their effectiveness varies and much of their foraging can be outside of the focal crop. Bee foraging behavior is highly sensitive to the availability of alternative floral resources which depend on the composition of the surrounding landscape. To understand how foraging and crop pollination dynamics of the managed common eastern bumble bee (Bombus impatiens) are influenced by landscape composition, we assessed their visitation and pollination in cultivated strawberry fields along a landscape gradient. We also used pollen extracted from bumble bee (Bombus impatiens) colony wax to understand whole-colony foraging over the blooming period. Bumble bee visits to strawberry crop flowers were very low and pollen limitation was not reduced at sites with greater visitation; however, colonies in fields with higher visitation rates had more pollen from the Rosaceae family (including strawberry). We found that landscape composition affected foraging effort on strawberry at the colony level, as a lower proportion of rosaceous pollen was collected in landscapes with more surrounding pasture, while a greater proportion of rosaceous pollen was collected at sites with larger strawberry fields. Overall, our results suggest that managed bumble bees do forage on strawberry crop flowers, but they predominantly forage elsewhere, especially in surrounding pastures when strawberry fields are small. Therefore, the addition of bumble bee colonies may not be economically beneficial for strawberry growers at least in diverse agricultural landscapes similar to that of our study region.

ecology↗

bioRxiv2021

Complex landscapes partially mitigate negative pesticide effects on tropical pollinator communities

Land-use change and pesticides have been identified as two of the main causes behind pollinator decline. Understanding how these factors affect crop pollinator communities is crucial to inform practices that generate optimal pollination and ensure sustainable food production. In this study, we investigated the effects of landscape composition and pesticide residues on bee communities and their pollination services in Solanum quitoense "lulo" crops in Colombia. On 10 farms, located along a gradient of landscape complexity that varied from 0.15 to 0.62 in their natural habitat proportion, we characterized the bee community visiting the crop, and carried out pollination experiments with bagged and open inflorescences to later estimate fruit set, weight, and diameter at every site. Additionally, we performed pesticide analysis on collected anthers through liquid chromatography to estimate pesticide risk coming from the crop fields using hazard quotients (HQ). Bee abundance and species richness decreased with increased HQ, but these negative pesticide effects were less detrimental in farms with higher natural habitat proportions. However, this buffer effect was lost at sites with very high HQs. Imidacloprid was frequently found in the anthers and there were extremely high concentrations in some farms (0.6 to 13063 g/kg), representing the molecule of greater risk for bees in this context. Pollinators importance to crop yield was demonstrated in the exclusion experiments, where we found a reduction in fruit set (51%), weight (39%), and diameter (25%). We found a significant effect of bee richness on fruit set, while landscape composition and HQ had no significant effect on fruit set, suggesting that the last two factors do not affect yield directly, but indirectly through a decrease in pollinator diversity. Our results provide novel evidence that the natural habitat loss due to the expansion of pastures for cattle ranching and pesticide residues in anthers reduce bee diversity and abundance in this Andean cropping system, but strategies to protect and restore natural habitat can help to buffer, until certain levels, these negative effects. Highlights- We explored how landscape composition and pesticide residues impact bee communities and pollination services in Solanum quitoense crops. - As the proportion of natural habitat in the landscape increased, bee richness also increased. While as pesticide hazard quotients in S. quitoense anthers increased, bee diversity and abundance decreased. - The natural habitat surrounding farms mitigates the negative pesticide effects on bees when hazard quotients are low/medium, but not when they are high. - S. quitoense crops are highly dependent on bees for optimum yield.

ecology↗

bioRxiv2020

Reducing ecological complexity using the archetype approach - an application to natural pest control

Natural control of crop pests has the potential to complement or replace intensive agricultural practices, but its mainstream application requires reliable predictions in diverse socioecological settings. In lack of a widely accepted model of natural pest control, we review existing modelling approaches and critically examine their potential to provide understanding and predictions across agricultural landscapes. Models that explicitly represent the underlying mechanisms are better positioned to represent the diversity and context sensitivity of natural pest control than correlative models. Such mechanistic models have used diverse techniques to represent crop-pest-enemy combinations at various spatiotemporal scales. However, certain regions of the world and socioeconomic aspects of natural pest control are underrepresented, while modelling approaches are restricted by a fundamental trade-off between generality and realism. We propose that modelling natural pest control across agroecosystems requires a framework of context-specific generalizations, based on empirical evidence and theoretical expectations. Reviewed models of natural pest control indicate potential attributes of such a general predictive framework.

ecology↗

bioRxiv2019

A global synthesis reveals biodiversity-mediated benefits for crop production

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by few abundant species or rely on high richness remains unclear. Using a global database from 89 crop systems, we partition the relative importance of abundance and species richness for pollination, biological pest control and final yields in the context of on-going land-use change. Pollinator and enemy richness directly supported ecosystem services independent of abundance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.

ecology↗