Toxicity of the insect growth regulator lufenuron on the entomopathogenic fungus Metarhizium anisopliae(Metschnikoff) Sorokin assessed by conidia germination speed parameter
Metarhizium anisopliae has been considered a promising alternative with low environmental impacts for the biological control of a variety of insect-pests. Another alternative is the use of biological pesticides such as insect growth regulators, including lufenuron. An assessment of the potential impact of fungicides on M. anisopliae is of critical importance to integrated pest management, permitting the compatible use of this entomopathogen with chemical defensives. Based on this, this study aimed to evaluate the effect of different concentrations of lufenuron on the conidia germination speed of M. anisopliae. Conidia were incubated at 28°C and sampled throughout 12 h. Bayesian analysis showed an inhibition of conidia germination in the presence of 2.0 mg/ml of lufenuron, whereas their compatibility was observed in the concentrations of 1.0 mg/ml and 700 μg/ml. It indicates that in these last two concentrations, the fungicide has no toxicity on M. anisopliae, what suggests that it can be employed in biological-chemical combinations, maintaining viable the fungal inoculums after its application in the field, with a low environmental impact.
Key words: Entomopathogen, biological control, vegetative development, biological-chemical combinations.