Plutella xylostella susceptibility to different native isolates of Beauvería bassíana and additional effect to other caulitlower Lepidoptera

Abstract

The diamondback moth, Plutella xylostella L., (Lepidoptera: Plutellidae). a pest of signiflcance in the production of crucíferas in the Antioquean east. Virulence of 17 native isolations and three commercial products of B. bassiana on P. xylostel/a was evaluated. Three of them, wich showed more activity on the mentioned pest, were selected. The effect of these three isolations was also tested on larvae of Copitarsia sp., Peridroma sp. and Leptophobia aripa (Boisduval). which are pests that are also associated with crucíferas in that region. Pathogenicity of B. bassiana on P. xylostella was characterized by means of these variables: percentage of mortality, half-lethal time, and intrinsic mortality. The effect in the field was evaluated in plots of 30 plants, in a randomized complete blocks design, with five treatments and four replications. Treatments involved two native isolations CLS 029 and CLS 003 (those with high biological activity on P. xylostella), the commercial product Bauveril and two controls. Half-lethal concentrations for these three, treatments were 2.7x10⁵, 2.1x10⁶ and 2.4x10⁶ c/ml, respectively. The three examined sources of B. bassiana caused mortality to P. xylostella under field conditions. The infection of CLS 029 isolation stands out on L. aripa larvae. Only one larva of Copitarsia sp. was infected with the CLS 003 isolation. None of the treatments affected Peridroma sp.