The matrix matters: Richness, abundance, and community composition of male euglossine bees in coffee agroecosystems

Background/Question/Methods

The complex ways in which bees--the most important group of pollinators worldwide--are impacted by habitat loss and fragmentation are still poorly understood.  I studied the response of euglossine bees (Hymenoptera:Apidae:Euglossini), a group of ecologically and economically important tropical pollinators, to varying coffee management types (sun coffee in a simple monoculture versus traditional shade coffee) in Southern Mexico. While many studies have addressed the influence that habitat loss and forest fragmentation have on these bees, few studies have considered the impact of the agricultural matrix.

I sampled euglossine bees for four months in an area containing organic and conventional coffee farms as well as forest fragments of varying sizes.  I compared the species richness, relative abundance, and species composition of euglossine bees according to habitat type and coffee management style.  I also analyzed the differences in richness, abundance and species composition within the farms with respect to increasing distances from the forest (1m, 200m, 400m).


Results/Conclusions

The species richness and abundance of euglossine bees was higher in the shade coffee systems than in sun coffee systems. Species composition differed between the two management systems, but was statistically indistinguishable between the forest and the shade coffee. I saw no difference in species composition, richness or abundance with regard to distance from forest, regardless of matrix quality.  An unexpected trend of increasing abundance and richness with increasing distance from the forest was evident in both sun and shade coffee and may be explained by competitive exclusion at forest edge. Given the ecological importance of euglossine bees, it is necessary to better understand how both forest fragmentation and matrix quality influences these bees. This study shows that agricultural “matrix” may be important for retaining habitat for euglossine bees, and could potentially allow for greater movement potential between resource rich areas.  The management of these matrix habitats is key, and diverse, rustically-managed shade coffee appears to have higher habitat value for euglossines than sun coffee monocultures.