Nesting biology of two species of Megachile (Moureapis) (Hymenoptera: Megachilidae) in a semideciduous forest reserve in southeastern Brazil

Abstract

-Nests of Megachile (Moureapis) benigna and Megachile (Moureapis) maculata were obtained during a 12-month trap-nesting program in a semideciduous forest reserve in southeastern Brazil. Trap nests were bamboo culms wider than those usually used in trap-nesting studies and it is suggested that species of Moureapis may prefer to nest in wide cavities. Nest construction was concentrated in the warm rainy season, but M. benigna had a secondary peak of nesting activity in the mid dry season, suggesting it is a bivoltine species. No species occupied the entire length of trap nests, but several linear series of cells were frequently packed inside a single culm. Nests of M. benigna were parasitized by one unidentified species of Coelioxys. Unidentified chalcidoid wasps emerged from some nests and phorid flies emerged from another one. In both cases, the developing host bees were killed. An unidentified conopid fly emerged from an adult female M. maculata found dead inside an incomplete nest.

Nest architecture, life cycle, and natural enemies of the neotropical leafcutting bee Megachile (Moureapis) maculata (Hymenoptera: Megachilidae) in a montane forest

“…In general, our observations on the nesting biology of M. maculata is in agreement with what is known for the few other studied species of Megachile (Moureapis ) (e.g., Buschini et al 2009;Sabino and Antonini 2011;Cardoso and Silveira 2012) and described (Krombein 1967) for other leafcutter bee species (e.g., Laroca et al 1987;Zillikens and Steiner 2004;Torretta et al 2012). Specifically, all these studies reported the use of pre-existing cavities, a layer of overlapped pieces of leaves covering the entire chamber and an inner layer of pieces of leaves with the bottom of the brood cells formed by bending leaf pieces upwards from the base of the brood cells (Medler 1965;Kim 1992).…”

“…The male-biased sex ratio we found differed from that observed by Filho and Garófalo (2016) for Megachile (Crysosauros ) guaranitica and by Cardoso and Silveira (2012) for M. benigna , but was similar to the male-biased ratio found by Cardoso and Silveira (2012) for M. guaranitica . However, Megachile sex ratios can exhibit considerable intraspecific variation, as reported by Teixeira et al (2011), who found a male-biased ratio for M. benigna , whereas Cardoso and Silveira (2012) observed a slightly female-biased ratio for the same species.…”

“…Cardoso and Silveira (2012) Ecology and nesting biology of Megachile maculata speculated that the limited number of nests they found may be a result of M. maculata being rare in the specific environment they studied (semideciduous forest) or that this bee species does not use the bamboo culms as trap nests (that, in general, mimic wood). Contrary to this, however, our results show M. maculata to be abundant in semi-deciduous forest, nesting in trap nests made of tubes.…”

“…The reasons for differences in sex ratio for species of Megachile remain very speculative, and this interesting issue is in need of more study. Cardoso and Silveira (2012), for example, pointed out that Megachile (Moureapis ) may actually prefer to use wide cavities (they used 3 cm) based on a few observations for two species. In our study, however, we offered four different sizes of trap nests and M. maculata predominantly used traps of 0.9 mm.…”

“…Buschini et al (2009 studied the pollen in nests of an unidentified species of this subgenus. Teixeira et al (2011) and Cardoso and Silveira (2012) described the nesting biology of Megachile benigna Mitchell, 1930, andCardoso andSilveira (2012) also reported on some aspects of the nests of M. maculata , but based on only two nests.…”