Are orchid bees at risk? First comparative survey suggests declining populations of forest-dependent species

A Nemésio

doi:10.1590/s1519-69842013000200017

Abstract

The two largest Atlantic Forest remnants in the state of Espírito Santo, eastern Brazil, namely 'Reserva Biológica de Sooretama' (REBIO Sooretama) and 'Reserva Natural Vale' (RNV), were surveyed for their orchid-bee faunas. Seventeen scent baits were used to attract orchid-bee males. Three-thousand, two hundred and twenty-five males belonging to 24 species were actively collected with insect nets during 100 hours in March, April and December, 2009. In comparison with a previous study in the same area twelve years before, it is evident that the abundance of all forest-dependent orchid bees analysed declined around 50%, and it was statistically significant (P = 0.022) for Euglossa marianae Nemésio, 2011, the most sensitive to anthropogenic disturbances of all Atlantic Forest orchid bees. On the other hand, the abundance of populations of species tolerant to open or disturbed areas rose. Possible explanations are discussed.

Highlights

Studies on the effects of habitat fragmentation on populations of orchid bees (Hymenoptera: Apidae: Euglossina) in the Amazon have shown that some species are much less tolerant to anthropogenic disturbances than others (e.g., Powell and Powell, 1987; Morato et al, 1992; Morato, 1994)
‘Reserva Natural Vale’ is closer to the coast than ‘REBIO Sooretama’ and there are more patches of vegetation situated on sandy soil, the socalled ‘mussunungas’, which consists in sparser and lower vegetation
Two hundred and twenty-five orchid-bee males belonging to 24 species in four genera were collected in ‘REBIO Sooretama’ and Reserva Natural Vale’ (RNV) (Table 1)

Summary

Introduction

Studies on the effects of habitat fragmentation on populations of orchid bees (Hymenoptera: Apidae: Euglossina) in the Amazon have shown that some species are much less tolerant to anthropogenic disturbances than others (e.g., Powell and Powell, 1987; Morato et al, 1992; Morato, 1994). If the same is true for orchid-bee species in the Atlantic Forest domain, a highly fragmented biome, the obvious implications would be that a suitable environment could become very limited for some species. Recent studies (Tonhasca Junior et al, 2002a; Nemésio and Silveira, 2006a; Giangarelli et al, 2009) have suggested that some Atlantic Forest species may be intolerant to disturbed areas and, restricted to the few larger areas that still hold suitable habitats. Biol., 2013, vol 73, no. 2, p. 367-374 orchid-bee species occurring in the Atlantic Forest under

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