Bioatividade do Bacillus thuringiensis var. kurstaki (Berliner, 1915) para adultos de Apis mellifera Linnaeus, 1758 (Hymenoptera: Apidae)

Abstract

RESUMOAvaliou-se a influência do Bacillus thuringiensis var. kurstaki (Berliner) sobre adultos de Apis mellifera Linnaeus. Os experimentos foram realizados em laboratório a 28 ± 2 o C, UR 70 ± 10% e fotofase de 12 horas. B. thuringiensis foi aplicado com pulverização sobre adultos, e fornecido através de solução aquosa de mel a 50% e em adição à pasta Cândi, utilizando o produto comercial Dipel ® PM. Esse produto quando aplicado com pulverização ou incorporado à pasta Cândi ou à solução aquosa de mel provocou mortalidade de adultos de A. mellifera em todas as concentrações utilizadas, com exceção de 0,25 g de Dipel ® /100 mL adicionado à solução aquosa de mel a 50%. Ao ser incorporado à pasta Cândi, a CL 50 correspondeu a 0,325 g e a CL 90 2,127 g do B. thuringiensis var. kurstaki/60 g de pasta. Adicionado à solução aquosa de mel a 50%, a CL 50 foi de 1,403 g e a CL 90 foi de 7,759 g do B. thuringiensis var. kurstaki/100 mL de solução. Sintomas de infecção pelo B. thuringiensis foram identificados nas abelhas adultas e através do isolamento obteve-se uma cultura dessa bactéria o que comprovou a patogenicidade para adultos de A. mellifera. Termos para indexação:Abelha, toxicidade, inseticida biológico. ABSTRACTThe effects of Bacillus thuringiensis var. kurstaki (Berliner) on adults of Apis mellifera Linnaeus were evaluated. The bioassays were carried out under controlled conditions at 25±2 o C, RH 70±10% and 12-h photophase. Adults of A. mellifera were exposed to the commercial product Dipel ® PM. The following methods were used: direct spraying; supplying Bt with honey aqueous solution; and by a Candy paste added to Bt. B. thuringiensis caused mortality on A. mellifera adults, independent of the method used, except at 0.25 g of Bt/100 mL added to the honey aqueous solution. B. thuringiensis added to the Candy paste showed CL 50 and CL 90 of 0.325 g and 2.127 g of the product to 60 g of Candy paste, respectively. Dipel ® PM added to the honey aqueous solution showed CL 50 and CL 90 of 1.403 g and 7.759 g of B. thuringiensis/100 mL, respectively. Infection symptoms by B. thuringiensis were identified on bees adult and by isolation of this bacterium, the toxicity of B. thuringiensis on A. mellifera was confirmed.

Effect of different Bacillus thuringiensis strains on the longevity of Africanized honey bee

“…This was also observed when B. thuringiensis var. kurstaki (commercial name Dipel ® PM -concentration of 0.5 g 100 mL -1 -commercial dosage) sprayed onto the adult workers caused significant mortality in 52.4% of the bees by the end of a 96-h experiment (BRIGHENTI et al, 2007).…”

“…Although B. thuringiensis does not act by contact, only by ingestion, contamination may have occurred because social insects, including the young A. mellifera bees, exhibit a hygiene habit in which one bee clears the integument from another bee. This can cause them to ingest bacterial spores from their body or from other worker bees, causing changes (BRIGHENTI et al, 2007;TRIPLEHORN;JOHNSON, 2011) and leading to mortality shortly after spraying and/or contact.…”

“…kurstaki (commercial name Dipel ® PM) proved toxic to adults of A. mellifera in the laboratory when sprayed on the workers and when added to the candy paste (BRIGHENTI et al, 2007). However, B. thuringiensis sub sp.…”

Short communication. First field assessment of Bacillus thuringiensis subsp. kurstaki aerial application on the colony performance of Apis mellifera L. (Hymenoptera: Apidae)

“…The effect on bees have been developed in some f ield and laboratory studies, although the majority of the experiments tested the toxicology of Btk used in genetically modif ied crops (O'Callaghan et al, 2005;Duan et al, 2008). These studies showed no adverse effect on A. mellifera (Malone & Pham-Delègue, 2001;Hanley et al, 2003;Malone et al, 2004;Porcar et al, 2008), however, some authors conf irmed a toxicity of Btk under controlled conditions (Ramirez-Romero et al, 2005;Brighenti et al, 2007). It is worth to note that it must be considered that the field results using Btk aerial application differ from the laboratory experiments and some authors require more information about effect under field apicultural conditions (Rose et al, 2007; …”

“…Some authors as Brighenti et al (2007) have reported some mortality rate attributed to Btk in laboratory tests involving direct spraying or food poisoning and Ramírez-Romero et al (2005) concluded that Bt toxins may have an antifeedant effect in high concentrations. However, it must be considered that insecticide field applications differ from laboratory experiments.…”