Oobjetivo da pesquisa foi analisar a suscetibilidade de Plutellaxylostella(L.) (Lepidoptera: Plutellidae) a isolados de BacillusthuringiensisBerliner e avaliar a compatibilidade dos isoladosmais virulentos com inseticidas registrados para o controle de pragas do repolho.Foiavaliadaa eficiência de 13 isolados,através detestesde patogenicidade e virulência (CL50e TL50) em lagartas de segundo instar de P. xylostella. A compatibilidadeentre os isolados e os ingredientes ativos foi realizada a partir da mistura do inseticida no meio de cultura, com posteriorinoculaçãode uma alíquota da suspensão do micro-organismo, sendo avaliado o número de esporos / mL após sete dias de crescimento do entomopatógeno. Os isolados HD-1, HD-4, HD-11, HD-73 e T-07 foramos mais eficientes no controle de P. xylostella, responsáveis por ocasionar mortalidade total das lagartas, com CL50variando entre 0,75 e 11,66 × 103esporos / mL e TL50entre 25,12 e 34,47 h. Os isolados HD-1 e HD-4 apresentaraminteração neutra com o ingrediente ativo tiametoxam, sendo positiva paracom o isolado T-07, comaumento significativo da esporulação.Os demais ingredientes ativos foramconsiderados tóxicos em relação ao desenvolvimento reprodutivo de B. thuringiensis.
The objective of this research was analyze the susceptibility of Plutella xylostella(L.) (Lepidoptera: Plutellidae) to isolates of Bacillus thuringiensisBerliner and to evaluate the compatibility of the most virulent isolates with insecticides registered to control cabbage pests.The efficiency of 13 isolates was evaluated through pathogenicity and virulence tests (LC50and LT50) on second instar larvae of P. xylostella. The compatibility between the isolates and active ingredients was performed by the insecticide mixture in culture medium, and after this was inoculated an aliquot of microorganism suspension, being analyzed the number of spores / mL after seven days of entomopathogen growth. The isolates HD-1, HD-4, HD-11, HD-73, and T-07 were the most efficient on P. xylostella, and responsible to cause total mortality of immature, with LC50varying between 0.75 and 11.66 × 103spores / mL, and LT50 between 25.12 and 34.47 h. The isolates HD-1 and HD-4 showed neutral interaction with the active ingredient thiamethoxam, and positive interaction with the isolate T-07, with significant increase of sporulation. The other active ingredients were toxic in relation to the reproductive development of B. thuringiensis.
