Towards the comparative ecotoxicology of bees: the response-response relationship

Abstract

Background: When an ecological system is exposed to an anthropogenic toxin, each species has an idiosyncratic sensitivity, but it is reasonable to expect some generality in response, especially among related species such as bees. If two species are similarly sensitive to a toxin their dose-response relationships will be similar. We propose a method to facilitate comparison between dose-response relationships, namely the response-response relationship, which can be applied to any biomarkers whose responses to the same pollutant are measured across a similar range of doses. We apply the method to bumble bees ( Bombus terrestris ) and honey bees ( Apis mellifera ) exposed to a dietary pesticide, imidacloprid, and we investigate both lethal and sublethal biomarkers. Results: We found cross-species similarity in dose-dependent responses, but only in certain sublethal biomarkers. In honey bees, sublethal biomarkers were more sensitive than mortality. In bumble bees, fecundity was the most sensitive biomarker. Conclusion: Our results provisionally suggest the existence of cross-species generalities. The greater sensitivity of sublethal biomarkers than mortality suggests that testing protocols which are overly focussed on mortality may underestimate the ecological impacts of toxic pollutants. Keywords: Apis mellifera, Bombus , dose-response, imidacloprid, neonicotinoid