title: Low doses of the common alpha-cypermethrin insecticide affect behavioural thermoregulation of the non-targeted beneficial carabid beetle Platynus assimilis (Coleoptera: Carabidae).
abstract: Sub-lethal effects of pesticides on behavioural endpoints are poorly investigated in non-targeted beneficial carabids. Conspicuous changes in locomotor activity of carabids exposed to sub-lethal doses of neurotoxic insecticides suggest that many other behaviours of these insects might be severely injured as well. We hypothesize that behavioural thermoregulation of carabids may be affected by low doses of neurotoxic pyrethroid insecticide alpha-cypermethrin which may have direct deleterious consequences for the fitness and populations of the beetles in the field. Automated video tracking of the carabid beetle Platynus assimilis Paykull (Coleoptera: Carabidae) on an experimental thermal mosaic arena using EthoVision XT Version 9 software (Noldus Information Technology, Wageningen, The Netherlands) showed that brief exposure to alpha-cypermethrin at sub-lethal concentrations (0.1-10mgL(-1)) drastically reduces the ability of the beetles for behavioural thermoregulation. At noxious high temperature, a considerable number of the beetles died due to thermo-shock. Other intoxicated beetles that survived exposure to high temperature displayed behavioural abnormalities. During heating of the arena from 25 to 45°C, insecticide treated beetles showed a significant fall in tendency to hide in a cool shelter (20°C) and prolonged exposure to noxious high temperatures, accompanied by changes in locomotor activity. Next day after insecticide treatment the beetles recovered from behavioural abnormalities to a large extent but they still were considerably longer exposed to noxious high temperatures compared to the negative control beetles. Our results demonstrated that behavioural thermoregulation is a sensitive and important etho-toxicological biomarker in ground-dwelling carabids. Prolonged exposure to unfavourably high temperatures has an array of negative effects decreasing fitness and survival of these insects at elevated thermal conditions with deep temperature gradients, typical of agricultural habitats. These results may have importance in IPM programs promoting reduced insecticide use.
authors.affiliation: Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, 1 Kreutzwaldi Street, 51014 Tartu, Estonia. Electronic address: Enno.Merivee@emu.ee.
authors.forename: Enno
authors.initials: E
authors.lastname: Merivee
authors.affiliation: Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, 1 Kreutzwaldi Street, 51014 Tartu, Estonia.
authors.forename: Ene
authors.initials: E
authors.lastname: Tooming
authors.affiliation: Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, 1 Kreutzwaldi Street, 51014 Tartu, Estonia.
authors.forename: Anne
authors.initials: A
authors.lastname: Must
authors.affiliation: Estonian University of Life Sciences, Institute of Forestry and Rural Engineering, 1 Kreutzwaldi Street, 51014 Tartu, Estonia.
authors.forename: Ivar
authors.initials: I
authors.lastname: Sibul
authors.affiliation: Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, 1 Kreutzwaldi Street, 51014 Tartu, Estonia.
authors.forename: Ingrid H
authors.initials: IH
authors.lastname: Williams
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001833:Body Temperature Regulation / Q000187:drug effects*; D001517:Coleoptera / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D023381:Endpoint Determination; D006358:Hot Temperature; D007306:Insecticides / Q000633:toxicity*; D007928:Lethal Dose 50; D011722:Pyrethrins / Q000633:toxicity*; D014741:Video Recording
chemical_list: D007306:Insecticides; D011722:Pyrethrins; C017160:cypermethrin
keywords: Alpha-cypermethrin; Heat stress; Knockdown; Locomotor activity; Platynus assimilis; Video-tracking