Diversity and Seasonality of Male Euglossine Bees (Hymenoptera: Apidae) in Central PanamÁ

Abstract

Seasonal changes in species richness, composition, and abundance of male euglossine bees were determined by weekly censusing of individuals attracted to 16 chemical baits. Bee populations were monitored for >1 yr in the lowland tropical moist forest of seasonally dry Barro Colorado Island (BCI), Panama. Male euglossine bees were also censused one every 4 wk at three nearby mainland sites, two at low elevation, and one at a middle—elevation locality. Among the lowland sites the male euglossine bee communities varied little; species composition, dominance ranks, species' phenological profiles, and seasonal changes in bee abundance were similar. Male bee populations at these sites were probably influenced by factors of similar timing and magnitude. In contrast, the male bee community of the upland locality differed from lowlands in species composition and timing of seasonal fluctuations in bee abundance. At all census sites the male euglossine bee community had four genera (Eulaema, Euglossa, Eufriesia, and Exaerete), 33—44 censused species, and low evenness of species abundance. On BCI, the relative abundance of individuals in the four genera was not constant throughout the year. Species richness and bee abundance were correlated; both fluctuated seasonally, and peaked in the early wet season. However, species composition, evenness, and dominance ranks were virtually nonseasonal, so some structural continuity existed in the male euglossine bee community.