Endophytic Lecanicillium lecanii and Beauveria bassiana reduce the survival and fecundity of Aphis gossypii following contact with conidia and secondary metabolites

Lecanicillium lecanii and Beauveria bassiana are important entomopathogens of Aphis gossypii. Their capacity to colonize crop plants is also becoming widely recognized. Their presence in crop plants indicates the possibility of a much greater potential for contact between insect and fungus than previously recognized. The present experiment aimed to study the effects of endophytic strains of these fungi on the survival, and reproduction of A. gossypii. Contact with conidia of both fungi significantly reduced the rate and period of reproduction of A. gossypii. The culture filtrates of L. lecanii and B. bassiana significantly increased mortality and feeding-choice experiments indicate that insects may be able to detect metabolites of the fungi. The culture filtrate of L. lecanii also significantly reduced the reproduction of the aphid. The ethyl acetate and methanolic fractions of the culture filtrate and of mycelia of L. lecanii also caused significant mortality and reduced fecundity of A. gossypii. The methanolic fractions of mycelia of B. bassiana caused significant mortality of A. gossypii. The present investigations indicated that A. gossypii is affected by contact with both conidia and fungal metabolites. This broad influence indicates that these fungi may have a role in regulating insect pest populations. (c) 2010 Elsevier Ltd. All rights reserved.