Both native bees and imported honeybees (Apis) provide key pollination services essential to ecosystem health, but traditionally, only honeybees have been placed in agricultural settings. As colony collapse disorder continues to lower the survivability of domestic honeybee hives, many food crops may increasingly depend on pollination by native bees. It is therefore essential to understand the effect that native and introduced bees have on one another. Previous studies have not conclusively determined if resource overlap between Apis and native bees leads to competition, and native bee nesting guilds may interact differently with Apis based on each guild’s unique resource requirements. Our study investigates if specific native bee nesting guilds compete with Apis, as indicated by negative correlations of their local abundances. We sampled bees by pan-trapping and sweep-netting biweekly at six locations of varying levels of land-use, including one commercial agricultural setting, in southeastern Massachusetts from April-October 2016 and April-July 2017. We calculated Pearson correlation coefficients between the abundance of Apis and abundances of four locally dominant nesting guilds, as well between abundances of each guild.
Results/Conclusions
Sampled bee abundances used in correlation analyses included a total of 278 Apis individuals and 3811 individuals of the four dominant native guilds. There was no negative correlation between abundances of Apis and any of the guilds, suggesting a lack of significant competition. Furthermore, the only weak correlation between Apis and a native guild’s abundance (ground nesters) was positive. The native guild abundances were all positively correlated with each other, indicating that the studied nesting guilds thrive in similar settings. The lack of correlation between Apis and native bee abundances may be due to the dependence of Apis abundance on human intervention rather than environmental conditions. Continued research including more study sites in a wider variety of habitats would allow for stronger conclusions. Specifically, including more commercial farms could more conclusively address whether Apis and native bees of any guild compete in agricultural settings.