Mortalidade de Apis mellifera após ingestão de alimento contaminado com inseticida Metomil.

Abstract

Bees are the main pollinating agents in agricultural areas, especially Apis mellifera (Hymenoptera: Apidae). In the field, bees can be exposed to insecticides used for pest control, a fact that is even associated with the decline in the population of pollinators. Insecticides can cause mortality and sublethal effects, such as reduced mobility, memory loss, and impairments in flight ability. Given this, it is essential to know the toxicity of insecticides on bees. The objective of this study was to evaluate the toxicity of commercial doses of the insecticide Methomyl on adult workers A. mellifera, through the ingestion of contaminated food. The work was developed at the Entomology Laboratory, belonging to the Center for Agri-Food Science and Technology of the Federal University of Campina Grande, Pombal-PB Campus. The bioassay was carried out in a completely randomized design consisting of four treatments [Absolute control – distilled water; Positive control – Thiamethoxam: 600 g/ha (0.30 g a.i. L-1) and two doses of the insecticide Methomyl: 300 mL b.w./100 L (0.645 g a.i. L-1) and 500 mL b.w./100 L (1.075 g a.i. L-1)] and with 10 replications. The variables evaluated were mortality and behavior (prostration, paralysis, tremors and reduced feeding) of the bees at 1, 2, 3, 4, 5, 6, 12, 24 and 48 hours after the beginning of the ingestion of the contaminated food. Regardless of the dose, the insecticide Methomyl caused 100% mortality in A. mellifera and caused severe motor disorders such as tremors, paralysis and prostration before death, in the first minutes after the beginning of exposure. In addition, the insecticide Methomyl provided a Median Lethal Time (TL50) of 5.05 hours. The insecticide Methomyl, when supplied via a contaminated diet, was highly toxic on adult workers of A. mellifera, regardless of the dose used.