Ecoevolutionary dynamics of crop-pollinator interactions

Pollinators are critical to the reproduction of plants in both natural and agricultural environments, but both plants and landscapes have changed drastically with the advent of plant domestication and modern agricultural practices. Little is known about how these vast environmental changes have impacted the important interactions of plants and their pollinators. In North America, cucurbits (i.e. squash and pumpkin) are an excellent system to investigate these questions, as there are multiple independent domestication events, as well as a widespread pollinator, the eastern squash bee, that has extended its ancestral range northwards with the domestication of cucurbits. In collaboration with the Ali Lab (PSU), we are quantifying changes in morphological and chemical plant traits across both wild and domesticated cucurbit species. In parallel, we are investigating how this variation in plant traits is perceived by pollinators, resulting in altered patterns of foraging behavior across their range.

Bee population connectivity

Bee community studies in agricultural landscapes have revealed that areas surrounded by higher proportion of natural habitat tend to have richer and more abundant native bee communities and receive greater benefit in terms of pollination services. However, the mechanisms underneath this relationship remain poorly known. We are investigating the role of functional landscape connectivity in human-dominated landscapes as one possible mechanism to explain the positive relationship between natural habitat and more diverse pollinator communities. Specifically, we are quantifying landscape connectivity of the main pollinators in cotton agroecosystems in the US and Brazil to determine how to optimally manage agricultural landscapes to enhance connectivity, effective population sizes and pollination services using a combination of genome-wide markers and geospatial analyses. 

Picture credits: Sam Droege

Sensory Evolution in Specialist Pollinators

Pollinators can have a wide range of floral preferences from broad generalists to narrow specialists. However, our understanding of how floral host breadth shapes pollinator sensory system is unknown. Eucerine bees provide an excellent taxonomic group to ask these questions because it comprises pollen generalists and specialists bees. An important challenge faced by specialist bees is locating and discriminating host flowers, especially within highly heterogeneous agricultural landscapes. Insect olfactory systems have been shown to be highly sensitive to minute concentrations of airborne odorant molecules and form an ideal system to study sensory processes underlying host flower discrimination. Using a combination of genomic, behavioral, electrophysiological, and chemical ecology approaches, we are seeking to understand the olfactory basis of host plant detection in oligolectic bees.