Evoluatlon of two varieties of Bacillus thuringiensis on the control of Diaphania spp. (Lepidoptera: Pyralidae) in melon

Abstract

An experiment was carried out at the Research Center "Nataima" of Corpoica to evaluate the effect of two varieties of Bacillus thurin­giensis. kurstaki and crizawaii mi the control of borer of the fruit of melon hybrid "Excelsior". Three population levels were studied: (1.1, 0.5 and 0.9 larva/plant (LBP) or per terminal ( LBT), based un which the insecticides were applied. A chemical product based on monocrotophos was used to compare its effect with the bioinsecticides. The damage of the borer began eleven days alter emergency (DAE) and the first application \vas done 18 DAV: al 25 DAE. the insect presented larvae of all ínstars and prepupa. The results of the evaluation of small healthy fruit showed that chemical treatment appears as the host unit at 0.1 (LBP) ley él followed by the kurmarki tube at 0.5 (1SP) level. On his fruit. the result showed that chemical treatment was the use at a level oí 0,1 (LBP). The area under the curve which shows the cumulative population of Dhiphaniu during the evaluation process showed higher pressure of larvae for the con­trol treatment compared with the products used. which demonstrates the lethal efficiency of the insecticides. The determination of lar­va ínstars and damage period initiation are 2 important variables to optimize the effectiveness of bioinsecticides which should be used within al integrated pest management tbelisSed to reduce pesticide applications. without eliminating them completely.