Differential insecticide susceptibility of the Neotropical stingless bee Melipona quadrifasciata and the honey bee Apis mellifera

The toxicity of three insecticides frequently used in Neotropical tomato cultivation (abamectin, deltamethrin, and methamidophos) was estimated on foragers of the Neotropical stingless bee Melipona quadrifasciata (Lep.) and the honey bee Apis mellifera (L.). Our results showed that the susceptibility varied significantly with the type of exposure (ingestion, topical, or contact), and there were significant differences between species. While M. quadrifasciata was usually more susceptible to insecticides (except for abamectin) in realistic exposures (via ingestion and contact) than A. mellifera, the former was less susceptible than A. mellifera to topically applied insecticides, a less realistic means of insecticide exposure. These findings challenge the common extrapolation of toxicity bioassays with A. mellifera to all (native) bee pollinators. Such equivocated extrapolation may compromise the significant services provided by native bees in Neotropical ecosystems.