Occupation and Emergence of Solitary Bees in Different Types of Trap Nests

Abstract

The study investigated the occupation and emergence of bees that nest in trap-nests and assessed aspects of the structure of such nests, sex ratio, parasitism and mortality of bees in four areas of Baturité Massif, State of Ceará. Samples were taken using three types of trap-nests: dried bamboo internodes, cardboard tubes and rational boxes. In the four studied sites, a total of 185 artificial nests were offered monthly and 34 of them were occupied by bees. Six species of bees, distributed in five genera (Centris, Mesocheira, Euglossa, Megachile and Coelioxys) occupied the 34 trap-nests, but of this total nests, 24 presented emergence of individuals. In the rest of the nests there was mortality of the occupants. Considering the total of nests with emergence, it was obtained 139 individuals: 131 bees (28 kleptoparasite bees) and 8 coleopterans. In 34 bee nests obtained, there were constructed 162 brood cells, the number of cells per trap-nest varied from 1 to 13 brood cells and the length of these nests varied from 2.4 to 14cm. Thirteen nests were parasitized by hymenopterans (Apidae and Megachilidae) and coleopterans (Meloidae), resulting in a parasitism rate of 38.2% of the total of nests founded. In addition, mortality occurred from unknown causes in 29.4% (n=10) of individuals before reaching adult stage. This work identified the bee species that use pre-existing cavities in the Baturite Massif, determined their nesting requirements and constrains for their reproduction. This information may contribute to conservation efforts of these bee species as well as their potential use for pollination services.