Bacillus thuringiensis para controle de Musca domestica: seleção de estirpes e avaliação do perfil de hemócitos em larvas

• Autor(a) principal: Stein, Ana Elisabeth Korte
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/7731
• topic: Bacillus thuirngiensis; Musca domestica; Hemócitos; Bacillus thuirngiensis; Musca domestica; Haemocytes; CIENCIAS BIOLOGICAS::PARASITOLOGIA

Musca domestica is considered one of the most harmful pests to the egg industry due to its high reproductive capacity and great potential of acting as a mechanical vector of many pathogenicagens to the egg-laying hens. Currently, the society is interested in alternative methods for pest control, once the constant and indiscriminate use of chemical products has caused intoxication to humans and domestic animals. Also, the irregular use of chemicals has selected resistant fly populations, accumulated chemical residues in the environment and food, and eliminated insects important to the natural control of flies. In order to develop alternative methods to control M. domestica, this study investigated Bacillus thuringiensis strains able to act as promising biological control agents. Twenty two strains of B. thuringiensis were tested in a screening assay for selecting the most virulent ones; one third of them were virulent to M. domestica larva, and two of them were selected for the next tests. Bioassays were conducted with the strains S601 and S599 to determine the larval treatment efficiency; they showed efficiency to control larva of M. domestica in all concentrations tested. The current study also characterized the hemocytes from hemolymph of larva of M. domestica by their identification and quantification; also, we evaluated the effect of the strain S599 of B. thuringiensis infection to the total hemocytes counts, and number and size of hemocyte types, using optical microscopy. Collections were made at the times of 12, 24, 48 and 72 hrs. Five hemocyte types were found: prohemocytes, plasmatocytes, granulocytes, oenocytoids and spherulocytes, in which plasmatocytes were found in superior number. Prohemocytes were the smallest cells observed, and oenocytoids were the biggest ones. The treatment of M. domestica larva with B. thuringiensis did not change morpholigical characteristics of hemocytes, as well as it did not modify the counts of hemocyte types. The total number of hemocytes in the hemolymph, however, increased significantly 48 hours after the larval treatment. B. thuringiensis strains selected in the current study are promising agents for biological control of M. domestica.