Spatio-temporal variation of insect pests of tomato with special reference to leaf miner, Liriomyza trifolii Burgess

Abstract

The present investigation revealed that the population of the insect pests of tomato and their activities varied with the prevailing weather conditions, sowing and transplanting time and different growth stages of crop. Correlation studies with different weather parameters revealed that weather inputs had neutral effects on the population build-up of the various insect pests of the crop. Weather indices-based prediction models were developed using Principal Component Multinomial Regression (PCMR) method. The models were found to be fitted for describing the insect population build-up of a tomato leaf miner (L. trifolii), Spodoptera litura and Helicoverpa armigera and among the various weather factor inputs, temperature (maximum, minimum, day and night) was observed to have the most pronounced influence on them. From the biological studies of L. trifolii under different temperature regimes of 15C, 20C, 25C, and 30C, it could be concluded that with a gradual increase in temperature the developmental period of the different life stages also gradually decreased. Thus, the temperature was found to have an inverse relationship with the developmental days of the leaf miner. Among the different insecticidal treatment schedules consisting of both chemical and non-chemical insecticides evaluated against the various insect pests of tomato, Emamectin benzoate 5% SG was the most effective treatment for leaf miner while Novaluron 5.25% + Indoxacarb 4.5% SC treatment recorded the lowest population of aphid, whitefly, thrips, S. litura and H. armigera. For natural enemies populations consisting of spiders and coccinellids, treatments with botanicals and microbials were found to be relatively safer over the other treatments.