Spatial and temporal diversity and resource use patterns of anthophile insects (Hymenoptera: Apoidea; Diptera: Bombyliidae, Syrphidae) in Cuatro Cienegas, Coahuila, Mexico

Background/Question/Methods

Bees and flies are the main pollinators that maintain plant diversity and crop production. Studies on pollinator communities have focused on bees, and little is known of the community structure of flies that visit flowers. In this study we describe and compare the diversity and resource use patterns of six Apoidea (Andrenidae, Apidae, Colletidae, Halictidae, Megachilidae, and Melittidae) and two Diptera (Bombyliidae and Syrphidae) anthophile families in Cuatro Cienegas in the northeast of Mexico. The following questions were formulated: 1) are there spatial or temporal patterns in the abundance, species composition, and diversity of these families or in the number of plant species visited by these insects? and 2) how similar are these patterns between families? Sampling was carried in two distinct geographic units (valley/mountains) and two seasons (rainy/dry). We describe and compare with ordination analysis the spatial and temporal patterns in species composition and abundance of these groups of insects. The number of plant species visited by each family and the diversity of each group were compared between geographic locations and seasons.

Results/Conclusions

We found different patterns of diversity and resource use for each family. Species richness is similar between seasons and locations for all families except Colletidae. But diversity is higher in rainy season for Andrenidae, Colletidae, and Syrphidae. Apidae is more diverse in the valley, while Halictidae, Melittidae, Bombyliidae, and Syrphidae are more diverse in the mountains. Apidae and Megachilidae have the same resource use patterns visiting more plant species during rainy season and in the mountains whereas Halictidae and Syrphidae visit the same number of plant species in both seasons and both locations. Ordination diagrams show that Andrenidae and Bombyliidae have both spatial and temporal structure while in contrast Megachilidae and Colletidae communities do not have any apparent structure. The possible causes of these differences between community structures are discussed, which may be the differences in life histories, resources needed during the larvae stage and foraging behaviors. This study confirms that although these families use flowers as their primary food resource, the community structures and resource use patterns are different. These differences are relevant in management and conservation programs that could benefit one group of pollinators but harm others with different responses.