Efeito de inseticidas na sobrevivência e capacidade de voo da abelha africana Apis mellifera (Hymenoptera: Apidae).

Abstract

The Apis mellifera (Hymenoptera: Apidae) is one of the main pollinators of plants grown by mankind for economic purposes. However, in recent years the bee population has declined in agricultural areas all over the world, one the main causes being the abuse of pesticides, particularly insecticides, directed towards the bee population. Therefore we aim to evaluate the effect of doses of the insecticides Flupyradifurone (Butenolide) as well as Thiacloprid (Neonicotinoid) on the survivability and flight capability of the Africanized bee A. mellifera. The study was conducted in UFCG (Federal University of Campina Grande), inside their Entomology Lab (air-conditioned room, 25 ± 2 ºC, 60 ± 10% UR and daylight regime of 12 hours) located in the CCTA (Center for Science and Agrifood Technology) in their Pombal (city in Paraíba) campus. Adult worker bees of the Africanized bee A. mellifera were used to carry out this study, said bees came from 3 Longstroth based beehives that belong to the CCTA/UFCG. Three commercial doses of the insecticide Flupyradifurone (0.1 g.i.a.L-1, 0.15 g.i.a.L-1 e 0.2 g.i.a.L-1) and of the insecticide Thiacloprid (0.072 g.i.a.L-1, 0.12 g.i.a.L-1 e 0.168 g.i.a.L-1), both registered for pest control in areas of several types of crops. The effects of the pesticide were tested under 3 methods of exposure: direct pulverization over the bees, via contaminated diet, and via a contaminated surface with which the bees interacted. The insecticide Flupyradifurone proved to be highly toxic for the A. mellifera when the bees were exposed to it by direct pulverization (mortality rate of 100%), while it caused a low level of toxicity when the bees were exposed to it via a contaminated diet (mortality rates of 15.6%, 15.97% and 16.4% in doses of 0.1 g.i.a.L-1, 0.15 g.i.a.L-1, and 0.2 g.i.a.L-1, respectively). Upon exposure to Flupyradifurone the motor activity of the A. mellifera was damaged, resulting in high levels of twitching, making the bees prone and paralysis. The insecticide Thiacloprid proved to be less harmful to the A. mellifera causing a lower mortality rate in all methods of exposure. The Thiacloprid insecticide caused low levels of toxicity when supplied via the exposure method of a contaminated diet, with a mortality rate of 8.1%, 25.4% e 33.9% for doses of 0.072 g.i.a.L-1, 0.12 g.i.a.L-1, and 0.168 g.i.a.L-1, respectively. Said insecticide was more toxic when directly pulverized over the bees, and particularly so when the insects interacted with the contaminated surface method of exposure which resulted in mortality rates of 53.7%, 55.9%, and 57.1% from the lowest to the highest of the aforementioned doses, respectively. The Thiacloprid insecticide was less aggressive, though it also caused disturbances in the motor activity of the A. mellifera. It was observed that both insecticides negatively affected the flight capability of the A. mellifera, regardless of dose and exposure method. The information collected will assist in developing strategies which aim to protect these pollinators in agricultural areas.