Path analysis of environmental factors affects the population dynamics of American bollworm, Helicoverpa armigera (Hubner) lepidoptera-noctuidae in cotton

Abstract

The path analysis of environmental factors affects the population dynamics of American Bollworm (ABW), Helicoverpa arecmigera (Hubner) Lepidoptera –Noctuidae was assessed at the Jawharlal Nehru Krishi Vishwa Vidhyalaya, Cotton Research Station, Khandwa M.P. The perusal of data on the population of American bollworm, Helicoverpa armigera revealed that the pest was first come into view in the 28th SMW i.e. Ist week of July and remained active till 51st SMW (III week of December). The peak population level was observed during 35th SMW i.e. Ist week of September. The weather condition prevailed during the peak population viz. maximum temperature, minimum temperature, morning relative humidity, evening relative humidity, sunshine hours, wind velocity, rainfall and rainy day were 34.11°C, 25.49°C, 76.54%, 39.56%, 8.29 hours per day, 6.94 kmph, 18.50 mm and 0.50 days respectively. The simple correlation studies between American bollworm eggs population and weather factors revealed that the ABW Eggs population had a significant positive correlation with minimum temperature. The multiple regression computed with eleven parameters as independent variables and ABW population as dependent variables was as follow Y=72.7571.401X1+0.027X2+0.276X3+0.048X4+0.056X5+1.517X6-0.052X7-1.413X8-0.624X9+2.657X10-0.945X11 (R2=0.772). The Path coefficient analysis revealed that minimum temperature had positive and high direct effect on ABW egg population, followed by spider, morning relative humidity and green lacewing respectively.