UC Berkeley

The majority of crop species benefit from a plant-pollinator mutualism making animal pollination a essential part of the food systems. In highly pollinator dependent crops, pollination management is important to ensure high yields. While managed pollinators can provide some of these services, in many cases, native pollinators are required to improve pollination efficiency and efficacy. Natural habitat has been shown to export native pollinators to agricultural areas as have habitat restorations. In addition, ecological intensification of management practices have been proposed as a method to increase yields through in-field changes. I studied the effect of these three proposed solutions (habitat conservation, ecological intensification, and habitat restoration) on pollination services across two systems: chocolate in Ecuador and native bee communities in California.

In my first chapter, I focused on the effect of landscape context on the pollination success of managed Theobroma cacao L. within its native range in Ecuador by estimating pollen limitation through hand and open pollination treatments. I found that the presence of rain forest did not alleviate pollen limitation in cacao and that other factors, such as slope or trunk circumference, were statistically more important than landscape context. In my second chapter, I studied the effect of ecological intensification on the pollination rates of T. cacao and incorporated data on prices and the expected Ecuadorean labor market in order to assess the economic viability of implementing new management strategies. I found that increasing decaying plant material in fields increased pollination rates from native pollinators and that these management changes were economically viable for farmers even when off-farm labor was readily available. In my third chapter, I switched systems to the Central Valley of California and studied the effect of restoration plantings (hedgerows) on crop-pollinating native bees. I found that hedgerows have a positive effect on the occurrence, species richness, and response diversity of crop-pollinating bees. Further, I focused in on an economically important crop that is dependent on high efficiency pollinators, watermelon, and found that hedgerows increased the abundance, occurrence, and functional redundancy of high and medium efficiency watermelon pollinators.

These findings are consistent with previous literature on pollination services that suggest that the effect of natural habitat, ecological intensification, and habitat restoration is system-dependent. They also highlight how important the pollination syndrome of the crop, the scale of the intervention, and its feasibility are to its success. Continuing research with this data will expand upon the connections between pollinator communities and pollination services while further research should be informed by scientists, conservationists, and farmers in order to create more synergistic strategies to benefit pollination and native species.