Sobrevivência e capacidade de voo da abelha Apis mellifera após exposição ao inseticida Etofenproxi.

Abstract

In commercial melon crops, the use of colonies with the honey bee Apis mellifera L. in the production areas and the chemical control of insect pests are essential management practices to ensure fruit production. Therefore, knowing the impacts of insecticides used to control pests on bees is essential for the sustainable management of pollinators in the field. In view of this, the objective was to evaluate the impact of the insecticide Etofenproxi on the survival and flight capacity of the bee A. mellifera. The work was carried out at the Entomology Laboratory of the Center for Agro-Food Science and Technology (CCTA) of the Federal University of Campina Grande (UFCG), Pombal - PB. Three distinct bioassays were carried out, corresponding to the modes of exposure: ingestion of contaminated diet, direct spraying and contact with product residues on melon leaves. The bioassays were carried out in a completely randomized design consisting of four treatments [Absolute control – distilled water; Positive control – Thiamethoxam: 600g/ha (0.30 g i.a. L-1) and two doses of the insecticide Etofenproxy: 40 mL p.c./100 L (0.12 g i.a. L-1) and 60 mL p.c./100 L (0.18 g i.a. L-1)] and 10 replications, with each experimental unit consisting of 10 adult bees. It should be noted that the bioassay concerning residual toxicity was carried out in a 4 X 3 factorial scheme, with the four treatments described above in terms of three exposure times (1 hour, 2 hours and 3 hours). Mortality and behavior (example: prostration, paralysis, tremors and reduced feeding) of the bees were evaluated at 1, 2, 3, 4, 5, 6, 12, 24 and 48 hours after the start of exposure. Flight ability was assessed for all bees that survived after exposure to the insecticide. The insecticide Etofenproxi, via ingestion of contaminated diet, caused 70.8% and 90.5% of mortality from the lowest to the highest dose. As for the mortality of bees in the bioassay via direct and residual spraying, regardless of the dose, 100% mortality of insects was observed, respectively. Etofenproxi was responsible for causing motor disturbances (tremors, prostration and paralysis) before the death of the bees in all exposure modes and evaluated doses. As for the survival rate of bees exposed to the insecticide Etofenproxi, regardless of dose and exposure time, a high rate of mortality was observed in all exposure modes. It was observed that in bioassays via contaminated and residual diet, the Median Lethal Time (TL50) provided by the insecticide Etofenproxy was lower than the absolute control and higher than the positive control. In the bioassay via direct spraying, the TL50 was lower than the absolute control and the positive control. Regarding flight capacity, only bees from the positive control and exposed to Etofenproxi via ingestion were evaluated, with a noticeable reduction in the flight capacity of A. mellifera after contact with the aforementioned insecticide. Thus, Etofenproxi caused a negative impact on the survival and flight capacity of A. mellifera under laboratory conditions. The insecticide Etofenproxi, regardless of the assessed dose and mode of exposure, proved to be highly toxic to A. mellifera.