Insecticidal and sublethal reproductive effects of Metarhizium anisopliae culture supernatant protein extract on the Mediterranean fruit fly

Abstract

AbstractBecause natural product‐based pesticides are thought to be more rapidly degradable than synthetic chemicals while having a lower ecotoxicological effect, the interest in these products for pest control has grown substantially. Recently, a new insecticide compound, which is the crude soluble protein extract (CSPE) from the fermentation product of the entomopathogenic fungus (EF) Metarhizium anisopliae (strain EAMa 01/58‐Su), has appeared in the literature as a promising insecticide for the control of the Mediterranean fruit fly, Ceratitis capitata. This CSPE has a moderate acute insecticide effect against adults of C. capitata when administered per os at 1 mg of protein/ml, as an exposure time of 8.3 h is necessary to get 50% of mortality. Even though the ingestion of this compound produces serious injuries in the midgut epithelium, it has a very low antifeedant effect on the flies. The effect of sublethal challenges on reproduction of adult flies was studied, and a reduction was found on the female fecundity levels during the first days after the treatment. On the other hand, the sublethal exposure to the CSPE affected neither the egg fertility nor the mortality of the larvae. However, the CSPE did affect the mortality of the pupae from the F1 generation, which suggests that there is a hormetic response from CSPE challenged females. The described sublethal reproductive effects are as important as direct lethal effects in contributing to the total value of the CSPE of the EF M. anisopliae 01/58‐Su strain.