Evaluation of the entomogenous fungí Beauveria bassiana and Metarhizium anisopliae on Tecia solanivora (Lepidoptera: Gelechiidae)

Abstract

The biocontrol activity of native isolates of the entomogenous fungi Beauveria bassiana and Metarhizium anisopliae on Tecia solanivora was evaluated. A method for disinfecting the eggs and third instar larvae using sodium hypochlorite [0.5%] and various rinses with sterile distilled water was standardized. First instar larvae and eggs were inoculated by immersion in a conidial suspension of 108 propagules/ml, during 5 and 60 seconds, respectively. Eight treatments with random design and five replica per treatment were used. They were confirmed by strains, absolute control, and three treated controls: 1) Tween 80 [0.1%]. 2) Sodium hypochlorite [0.5%] + sterile distilled water and 3) Baculovirus phthorimaea. There were differences among controls and treatments for eggs (p= 0.0003), without significant differences among treatments (p= 0.0747). We also found mortality differences in larvae (p= 0.0001), the Bv006, and Bv007 strains exhibiting the highest mortality (12%). The eggs were more susceptible to fungal isolates. M. anisopliae strains were more effective in reducing the level of consumption of the larvae. Disinfection methods for eggs and larvae and treatment with Tween did not affect the eclosion of eggs or the larvae viability and could be used in future studies. The low percentage of mortality showed a low biocontrol activity by strains and for this reason, these strains could not be selected for the control of this pest. We confirmed the low general potential of entomogenous fungi towards T. solanivora and therefore suggest that other control alternatives, using other organisms such as parasitoids or viruses be sought.