Pollination by Non-Apis Bees and Potential Benefits in Self-Pollinating Crops

Abstract

Abstract The diversity and abundance of native bees (Hymenoptera: Anthophila) are important in providing pollination services to a diverse array of crops. An extensive literature base is available on the contributions of bees as crop pollinators. The focus of the majority of these studies are on honey bees (Apis spp.) pollinating crops that depend on cross-pollination to produce a yield. Self-pollinating crop species, including cotton, soybeans, coffee, and canola, can self-pollinate but there is increasing evidence that they can also benefit from cross-pollination by insects. These crops can see a considerable benefit when visited by bees in general, but contradictory evidence is not fully understood in some systems. For example, recent studies have shown that bee visitation to cotton blooms can increase yield up to 15%. Including nesting habitat for non-Apis bees within soybean dominated landscapes increases in-field yields. However, in these same systems, some studies show none or minimal yield increases. Additional literature (both recent and historical) of non-Apis bees in mass-flowering self-pollinating crops and their potential benefits to the crops also exists but is previously unsynthesized in cotton and soybeans in particular. In our review of literature on these select self-pollinating crops, there appears to be apparent gaps in the literature base on these and other understudied cropping systems. With the exception of graminaceous and cereal crops, all the crops discussed herein seem to have all have benefited from visitation by both Apis and non-Apis bees. Some provide known resource benefits to native bee pollinators like canola, but others like cotton and soybean are not well understood. Further, with an apparent yet small literature base in cotton and soybean there are many facets between the native bee pollinators and crop such as nutritional benefits of nectar and pollen to the bees themselves that still need to be addressed. To examine these underlying mechanisms, additional studies into the basic biology and natural history, including nesting habitats and preferences along with foraging preferences of abundant bee species will help understand how these bees seem to persist and possibly thrive in intensified agricultural systems.