The decline of managed and wild pollinators has caused a reduction in viability and quantities of fruits and seeds of crops. In a global scenario of decreased pollination services, the conservation of native pollinators represents a key alternative to crop success; however, only a few studies have documented changes in pollinator communities and their impact on pollination services to crops. It has been proposed that species rich insect communities enhance the pollination efficiency of native plants and crops through complementarity, where both the dominant and less abundant species contribute to reaching a threshold of crop pollination. Moreover, species turnover across landscapes may also be important to ensure this threshold. However, in some agricultural systems, fluctuations in the most abundant pollinator species, rather than changes in species richness, were considered to be the most important drivers of temporal variation in pollination services. In this study we used Cucurbita moschata as a model to investigate temporal variation in pollination services in a Mexican tropical dry forest region. We sampled floral visitors in the coastal region of Jalisco during the wet and dry seasons, and determined the pollination efficiency of all floral visitors.
Results/Conclusions
We found that during the wet season, bees of the genus Peponapis were the main pollinators of C. moschata, whereas generalist and social bees, such as Apis mellifera and Trigona fulviventris dominated the community during the dry season. We found differences in the efficiency of the main pollinator species of C. moschata, with the genus Peponapis being the most efficient. In the wet season, Peponapis is a keystone group for the pollination of C. moschata. Peponapis female bees are the most effective pollinators with the greatest contribution to the reproductive success of C. moschata. In the dry season, other species of pollinators are able to provide the pollination service although they are not as effective as Peponapis. We show that pollinator communities can change at different times of the year for the same crop, with different bee species providing the pollination service on different seasons. We argue that management and conservation schemes should focus on the entire pollinator communities, native and managed, as they ensure pollination services on crops at different times of the year.