title: Agrochemical synergism imposes higher risk to Neotropical bees than to honeybees.
abstract: Bees are key pollinators whose population numbers are declining, in part, owing to the effects of different stressors such as insecticides and fungicides. We have analysed the susceptibility of the Africanized honeybee,Apis mellifera, and the stingless bee,Partamona helleri,to commercial formulations of the insecticides deltamethrin and imidacloprid. The toxicity of fungicides based on thiophanate-methyl and chlorothalonil were investigated individually and in combination, and with the insecticides. Results showed that stingless bees were more susceptible to insecticides than honeybees. The commercial fungicides thiophanate-methyl or chlorothalonil caused low mortality, regardless of concentration; however, their combination was as toxic as imidacloprid to both species, and over 400-fold more toxic than deltamethrin forA. mellifera. There were highly synergistic effects on mortality caused by interactions in the mixture of imidacloprid and the fungicides thiophanate-methyl, chlorothalonil and the combined fungicide formulation inA. mellifera,and also to a lesser extent inP. helleri. By contrast, mixtures of the deltamethrin and the combined fungicide formulation induced high synergy inP. helleri, but had little effect on the mortality ofA. mellifera. Differences in physiology and modes of action of agrochemicals are discussed as key factors underlying the differences in susceptibility to agrochemicals.
authors.affiliation: Departamento de Entomologia, Universidade Federal de Viçosa, 36570-900 Viçosa-MG, Brazil; EAG Laboratories, 13709 Progress Boulevard no. 24, Suite S163, Alachua, FL, 32615USA.
authors.forename: Hudson V V
authors.initials: HV
authors.lastname: Tomé
authors.affiliation: Departamento de Entomologia , Universidade Federal de Viçosa , 36570-900 Viçosa-MG , Brazil.
authors.forename: Gabryele S
authors.initials: GS
authors.lastname: Ramos
authors.affiliation: Departamento de Entomologia , Universidade Federal de Viçosa , 36570-900 Viçosa-MG , Brazil.
authors.forename: Micaele F
authors.initials: MF
authors.lastname: Araújo
authors.affiliation: Departamento de Entomologia , Universidade Federal de Viçosa , 36570-900 Viçosa-MG , Brazil.
authors.forename: Weyder C
authors.initials: WC
authors.lastname: Santana
authors.affiliation: Programa de Pós-Graduação em Produção Vegetal , Universidade Federal do Tocantins , Gurupi, TO 77410-530 , Brazil.
authors.forename: Gil R
authors.initials: GR
authors.lastname: Santos
authors.affiliation: Departamento de Entomologia , Universidade Federal de Viçosa , 36570-900 Viçosa-MG , Brazil.
authors.forename: Raul Narciso C
authors.initials: RN
authors.lastname: Guedes
authors.affiliation: Department of Electrical Engineering, São Carlos School of Engineering , University of São Paulo , São Carlos, SP , Brazil.
authors.forename: Carlos D
authors.initials: CD
authors.lastname: Maciel
authors.affiliation: Biological Sciences , University of Southampton , Highfield Campus, Southampton SO17 1BJ , UK.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Newland
authors.affiliation: Departamento de Entomologia , Universidade Federal de Viçosa , 36570-900 Viçosa-MG , Brazil.
authors.forename: Eugênio E
authors.identifier: 0000-0003-1174-6564
authors.initials: EE
authors.lastname: Oliveira
keywords: honeybee; pesticide impacts; pollinators; stingless bee; stressors; synergy