Pathogenicity of isolates of three entomopathogenic fungi against soldiers of Atta sexdens sexdens (Linnaeus, 1758) (Hymenoptera : Formicidae)

Leaf-cutting ants attack several crops, pastures and the planted forests, acting on numerous vegetable species. The present work aimed to evaluate the pathogenicity of the fungi Beauveria bassiana (isolates AM 9 and JAB 06), Metarhizium anisopliae (isolates E 9 and Al) and Paecilomyces farinosus (isolates CG 189 and CG 195) against soldiers of Atta sexdens sexdens, in laboratory conditions. These fungi were inoculated on soldiers after collection in nests without pesticides application. Specimens of soldiers were separated in groups of eight insects, which were bathed in suspensions containing 1.0 x 10(6), 1.0 x 10(7), 1.0 x 10(8) and 1.0 x 10(9) conidia/ml. Following the bath, each group of ants was taken to moist chamber units, and maintained for a period of starvation under at 27 ± 1ºC. The mortality was updated on a daily basis. The three species of fungi were highly pathogenic to A. sexdens sexdens soldiers causing high mortality rates, above 80%, killing the ants in the first four days after inoculation. The bests isolates were JAB 06 and AL, at the concentration 1.0 x 10(9) con./ml. The isolates JAB 06, AL and CG 195 showed higher capacity of spore production on ant cadavers and there was a decrease in lethal time with the increase in the spore concentration used.

Beauveria bassiana; Metarhiziun anisopliae; Paecilomyces farinosus; biological control; leaf-cutting ant; microbial control; social insects