Effect of Thiamethoxam on Entomopathogenic Microorganisms

Abstract

Efeito do Tiametoxam Sobre Microrganismos EntomopatogênicosRESUMO -A compatibilidade de microrganismos entomopatogênicos com tiametoxam e outros inseticidas foi estudada através de ensaios in vitro e em campo. Os microrganismos testados foram: Aschersonia aleyrodis, Bacillus thuringiensis, Baculovirus anticarsia (VPNAg), Beauveria bassiana, Hirsutella thompsonii, Metarhizium anisopliae, Nomuraea rileyi, Paecilomyces farinosus, Sporothrix insectorum e Verticillium lecanii. Em laboratório, foram testadas duas concentrações de cada produto, o que envolveu as recomendações máxima e mínima para uso em condições de aplicação no campo. Os produtos foram adicionados em meio de cultura específico para crescimento dos entomopatógenos. Foram avaliados os crescimentos reprodutivo e vegetativo para fungos e unidades formadoras de colô-nias (UFC) para bactérias. Para os testes conduzidos em campo foram consideradas as UFC para fungos e bactéria e a mortalidade de lagartas para o NPV de Anticarsia gemmatalis (Hueb.). Os resultados mostraram que: (1) a ação dos produtos fitossanitários sobre o crescimento vegetativo e a esporulação dos microrganismos variou em função da natureza química dos produtos, da concentração e da espécie do agente microbiano; (2) ABSTRACT -The compatibility of entomopathogenic microorganisms with thiamethoxam and other insecticides was studied in vitro and under field conditions. The microorganisms tested were: Aschersonia aleyrodis, Bacillus thuringiensis, Baculovirus anticarsia (NPVAg), Beauveria bassiana, Hirsutella thompsonii, Metarhizium anisopliae, Nomuraea rileyi, Paecilomyces farinosus, Sporothrix insectorum and Verticillium lecanii. Two concentrations of each product were tested in the laboratory, based on the maximum and minimum recommended rates for application in the field. The products were added to specific culture medium for growth of the entomopathogens. Reproductive and vegetative growth were evaluated for fungi, and colony forming units (CFU) were evaluated for bacteria. For the field test, CFUs were considered for both fungi and bacteria and caterpillar mortality for the NPV of Anticarsia gemmatalis (Hueb.). Results showed that: (1) the action of the pesticides on the vegetative growth and sporulation of the microorganisms varied as a function of the chemical nature of the products, its concentration and the microbial species; (2) thiamethoxam was compatible with all microorganisms studied; (3) endosulfan, monocrotophos and deltamethrin were the insecticides that most affected B. thuringiensis, B. bassiana, M. anisopliae and S. insectorum; (4) thiamethoxam did not affect the inoculum potential of B. thuringiensis, B. bassiana or M. anisopliae when applied to bean crop (Phaseolus vulgaris); and (5) thiamethoxam did not affect the efficiency of the nuclear polyhedral virus of A. gemmatalis.

Compatibility of conventional agrochemicals used in rice crops with the entomopathogenic fungus Metarhizium anisopliae

“…The compatibility of M. anisopliae with thiamethoxam and lambdacyhalothrin is in agreement with other studies (Batista Filho et al, 2001;Cavalcanti et al, 2002;Loureiro et al, 2002;Neves et al, 2001;Rampelotti-Ferreira et al, 2010). Despite the insecticide thiamethoxam+ lambdacyhalothrin is a combination of two compatible insec- ticides, it was scored as moderately toxic in this study.…”

Action of pesticides to Metarhizium anisopliae in soil

“…Batista Filho et al (2001) reported that imidacloprid did not affect M. anisopliae at the maximum dose recommended for the field but inhibited fungal growth at the minimum dose, thus classifying this insecticide as moderately toxic to the fungus at the maximum dose and incompatible at the minimum dose. However, no toxicity of imidacloprid to M. anisopliae was observed by Loureiro et al (2002), and Neves et al (2001) showed that the product did not inhibit germination, radial growth or fungal reproduction.…”

Natural phytosanitary products effects on Bacillus Thuringiensis SUBSP. Kurstaki (Berliner)

“…Different techniques can be used to evaluate the effects of chemical products on spores of B. thutingiensis subsp. thuringiensis (Btk) such as paper disks impregnation technique with broth products (DOUGHERTY; REICHELDERFER; FAUST, 1971;JIMENEZ;ACOSTA;FERNANDEZ, 1989) and with liquid culture medium (SUTTER et al, 1971, CHEN et al, 1974, and mixing products to the molten culture medium technique from the works of Salerno, Dias and Sagardoy (1999), Batista Filho; Almeida and Lamas (2001), Almeida et al (2003) and Gassen, Batista Filho and Zappelini (2006). The effects of chemical products on Btk using different techniques was studied by Silva et al (2006Silva et al ( , 2008 and the results varied according to chemical group, technique used, concentration, contact time, and development stage of the pathogen.…”