Interaction between pesticides and other factors in effects on bees

Abstract

Bees are important pollinators of both managed crops and wild flora. An overview of the interactions between pesticides and other factors in effects on bees considered: 1) The importance of the different exposure routes in relation to the overall exposure of bees to pesticides; 2) Multiple exposure to pesticides (including substances used in bee medication) and potential additive and cumulative effects; and 3) Interactions between diseases and susceptibility of bees to pesticides. Nectar foraging bees are likely to experienced highest exposure to both sprayed and systemic seed and soil treatments compounds followed by nurse and brood-attending bees. In both cases the major contribution to exposure was contaminated nectar with direct overspray playing a significant role in exposure. However, there are a variety of other routes (and other bee species) where there is currently insufficient data to fully total exposure: There are a large number of studies that have investigated the interactions between pesticides in bees. By far the majority have related to the interactions involving EBI fungicides and can be related to their inhibition of P450. The scale of the synergy is shown to be dose and season-dependent in acute exposures but there are few data relating to the effect of time between exposures, the effect of route of exposure or on chronic exposure effects at realistic exposure levels. There are a wide range of factors which affect the immunocompetence of bees including diet quality, pest and diseases. Although there are a limited number of laboratory based studies which suggest effects of a pesticide on disease susceptibility there is no clear evidence from field-based studies that exposure of colonies to pesticides results in increased susceptibility to disease or that there is a link between colony loss due to disease and pesticide residues in monitoring studies. KEY WORDSHoneybees, bumble bees, pesticides, disease, mixtures, synergism DISCLAIMERThe present document has been produced and adopted by the bodies identified above as author. This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author, awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the rights of the authors. The present document has been produced and adopted by the bodies identified above as author. This task has been carried out exclusively by the author in the context of a contract between the European Food Safety Authority and the author awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as...

Single and interactive effects of Varroa destructor, Nosema spp., and imidacloprid on honey bee colonies (Apis mellifera)

“…But, how does our exposure relate to the field? Nectar foragers are however more likely to experience the highest exposure to both sprayed and systemic seed and soil treatment compounds (Thompson 2012). Over the whole exposure period, our colonies consisted on average of 13,000 bees.…”

Modulation of pesticide response in honeybees

“…This is also true for honeybees (Thompson 2012;Johnson 2015). By far the majority of studies have reported synergistic interactions involving the inhibition of insecticide-metabolizing enzymes; such is the case of piperonyl butoxyde (PBO), one of the most commonly registered synergists used in plant protection formulations to enhance insecticide efficiency.…”

“…As an example, prochloraz, tebuconazole, flusilazole, and difenoconazole elevate the mortality rate of bees exposed to deltamethrin, alpha-cypermethrin, or lambda-cyhalothrin (Belzunces and Colin 1993;Pilling and Jepson 1993;Thompson and Wilkins 2003). In addition, the toxicity of the acaricides tau-fluvalinate and flumethrin (pyrethroid) can be enhanced by prochloraz and flusilazole, respectively (Thompson 2012). Data from Pilling et al (1995) indicates that the mechanism underlying these interactions is an inhibition of CYP450 activity by EBI fungicides, slowing detoxification of pyrethroid in bees.…”

Reported prevalence and quantitative LC-MS methods for the analysis of veterinary drug residues in honey: a review

“…Hives suffering from colony collapse have been shown to have a higher burden of viral, bacterial and fungal pathogens. Multiple studies indicate an increased toxic effect of certain pesticides in the presence of viral and fungal pathogens (Thompson 2012). It has also been suggested that prophylaxis of foulbrood disease with antimicrobials could upset the balance of gut flora in honeybees and negatively impact their health, as these bacteria aid digestion and detoxification (Tian et al 2012).…”