Determinación de la concentración letal 50 de dos cepas de hongos entomopatógenos aisladas y dos cepas comerciales de Beauveria sp Y Metarhizium sp, en larvas de la Polilla Guatemalteca de la papa, Tecia solanivora (Lepidoptera: Gellechiidae)

Abstract

In the present study two strains of Beauveria sp y two strains of Metarhizium sp fungi where applied in third instar Tecia solanivora (potato tuber moth) larvae. For both genus of pathogenic fungi one commercial strain and one field isolated strain where evaluated. In the first part of the study the conidia application techniques where evaluated Galleria melonella larvae: aspersion vs immersion, with or without the addition of tween 80 as a tensoactive. Once the immersion of Galleria melonella larvae in a suspension of conidia with the addition of the tensoactive was proven to be the best method for the fungus infection, the bioassay with third instar larvae of Tecia solanivora was held. The four fungi strains where evaluated in concentrations in the orders of 103, 104, 105 y 106 conidias per ml. It was found that commercial strains of Beauveria sp y Metarhizium sp have a better response on larvae mortality. Commercial Metarhizium sp strain had the best effect with a lethal concentration 50-96 of 6x102 conidia/ml and a mortality of 83% of treated individuals.