title: Interaction between Varroa destructor and imidacloprid reduces flight capacity of honeybees.
abstract: Current high losses of honeybees seriously threaten crop pollination. Whereas parasite exposure is acknowledged as an important cause of these losses, the role of insecticides is controversial. Parasites and neonicotinoid insecticides reduce homing success of foragers (e.g. by reduced orientation), but it is unknown whether they negatively affect flight capacity. We investigated how exposing colonies to the parasitic mite Varroa destructor and the neonicotinoid insecticide imidacloprid affect flight capacity of foragers. Flight distance, time and speed of foragers were measured in flight mills to assess the relative and interactive effects of high V. destructor load and a field-realistic, chronic sub-lethal dose of imidacloprid. Foragers from colonies exposed to high levels of V. destructor flew shorter distances, with a larger effect when also exposed to imidacloprid. Bee body mass partly explained our results as bees were heavier when exposed to these stressors, possibly due to an earlier onset of foraging. Our findings contribute to understanding of interacting stressors that can explain colony losses. Reduced flight capacity decreases the food-collecting ability of honeybees and may hamper the use of precocious foraging as a coping mechanism during colony (nutritional) stress. Ineffective coping mechanisms may lead to destructive cascading effects and subsequent colony collapse.
authors.affiliation: Resource Ecology Group, Wageningen University and Research Centre, Droevendaalsesteeg 3a, Wageningen 6708 PB, The Netherlands Bees@wur, Wageningen University and Research Centre, Droevendaalsesteeg 1, Wageningen 6708 PB, The Netherlands.
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Blanken
authors.affiliation: Resource Ecology Group, Wageningen University and Research Centre, Droevendaalsesteeg 3a, Wageningen 6708 PB, The Netherlands.
authors.forename: Frank
authors.identifier: 0000-0001-8870-0797
authors.initials: F
authors.lastname: van Langevelde
authors.affiliation: Bees@wur, Wageningen University and Research Centre, Droevendaalsesteeg 1, Wageningen 6708 PB, The Netherlands coby.vandooremalen@wur.nl.
authors.forename: Coby
authors.initials: C
authors.lastname: van Dooremalen
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects / Q000502:physiology; D001516:Bees / Q000187:drug effects* / Q000469:parasitology* / Q000502:physiology; D001835:Body Weight / Q000187:drug effects; D005426:Flight, Animal / Q000187:drug effects* / Q000502:physiology; D007093:Imidazoles / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000633:toxicity*; D057077:Varroidae / Q000502:physiology*
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; C082359:imidacloprid
keywords: Apis mellifera; body mass; flight performance; pollination; wing dimensions