Path analysis to evaluate the direct and indirect effects of climatic variables in the development stages of Tuta absoluta (Lepidoptera: Gelechiidae) in tomato (Solanum lycopersicum L.)

Abstract

The objective of this study was to evaluate the influence of climatic variables on the population dynamics of the tomato moth Tuta absoluta (Meyrick, 1917), (Lepidoptera: Gelechiidae) through correlations and path analysis, on the main variable in organic and conventional tomato crops (Solanum lycopersicum L., Solanaceae). We studied the effects of the pheromone (used Delta traps) on insect phase sampling in two areas of agricultural with tomato cultivation in Alagoas, Northeast Brazil: latitude 09º81´76´´, longitude 36º59´42´´, during the agricultural years 2015-2017. The experimental design was completely randomized with two treatments with 60 replicates. In the path analysis, the main variables were adults, eggs, caterpillars and mines. Rainfall, relative humidity, temperature, wind speed, and solar radiation were explanatory and correlated variables. In the path analysis we observed that rainfall, relative humidity, and solar radiation were the variables of greatest influence on the population dynamics with direct effects in the organic system with correlation coefficients r = 0.83, r = 0.52 and r = 0.45 respectively. The following variables showed negative correlations: wind r = -0.43, and temperature r = -0.19. In the conventional system r = 0.80, r = 0.43 and r = 0.41, for the same variables. The wind speed variable had a negative effect of r = -0.38, and the temperature had a negative effect of r = -0.13. We observed that climatic conditions are variables conditioning the development of insect infestation in the tomato crops studied.