Effective control of tomato leaf miner, Tuta absoluta by combining use of Thiocyclam insecticide and Bacillus thuringiensis

The tomato leaf miner moth, Tuta absoluta (Meyrick) (Lep.: Gelechiidae), is one of the most important and destructive pests of tomatoes in fields and greenhouses and causes severe damage. The integration use of biological and chemical pesticides, with the aim of reducing the consumption and concentration of chemicals, and in order to lessen pollution in the environment and insect resistance, is considered. Therefore, this study aims to investigate the effect of different concentrations of Thiocyclam insecticide (Evisect® SP50%) and biological insecticide Problet® (Bacillus thuringiensis supsp. kurstaki), on the mortality of the 1st and 4th instar larva of T. absoluta with the aim of achieving the most effective insecticide mixture. For this purpose, experiments were performed with 0.5, one, and twice the recommended concentration of insecticides, and their combined use during 48 and 72 hours. The results showed that the mortality rate of the 1st and 4th instar larva of T. absoluta increased with increasing concentration and time of application of two insecticides. The LC50 values for the first and fourth instar larvae of T. absoluta were 15.13 and 32.80 ppm after 72 hours from the application of bacteria and Thiocyclam respectively. The recommended concentrations of insecticides caused 66.07 and 66.41% mortality in 1st larvae after 48 hours for Thiocyclam and bacteria respectively at half their recommended concentration (500 ppm). Thiocyclam + bacteria values for first and fourth instar larvae were 98.25 and 99.25%, respectively, at their recommended concentration (1000 ppm) after 72 hours.