Bee Assemblage in the Southern Chihuahuan Desert: The Role of Season, Year, and Trap Color in Abundance

SIMPLE SUMMARY: There is increasing evidence of declining bee populations due to anthropogenic factors. We assessed the abundance of nine wild bee species over a four-year study period, estimating changes through monthly captures. Apis mellifera, the Lasioglossum (Dialictus spp.) complex, and Macrotera sinaloana had the largest population sizes and densities. Seasonal fluctuations were seen in most species in spring (March–May) coinciding with the flowering period of the main plant species and a low abundance during the winter months (December–January). Moreover, 77.7% of the populations showed a tendency to remain constant over time, with yellow tray traps capturing a higher number of individuals. ABSTRACT: Recognizing how populations fluctuate over time is a crucial factor in determining the environmental elements affecting population persistence. However, the limited information on wild bee populations complicates the estimation of the impact of anthropogenic threats leading to changes in population size. To address this, we conducted a study capturing and monitoring nine species of wild bees through monthly samplings over four years. Tray traps were placed in permanent plots, and capture records were used to determine population size (N) and density (D). A generalized linear model (GLM) was employed to determine how the use of traps affected bee species captures. The families Apidae and Halictidae represented the most captures. Apis mellifera, the Lasioglossum (Dialictus spp.) complex, and Macrotera sinaloana exhibited the largest number of captures and highest population density. Most species (77.7%) showed a tendency to remain constant over the years and to have a higher number of captures in the spring months. Moreover, yellow traps were the most effective in capturing bee individuals. We suggest that the availability of essential resources and the reduction in environmental stressors positively affected the capture of wild bee populations.