Studies on population dynamics of major pests of Ailanthus excelsa Roxb

Aim: To study the peak period of incidence of major pest of Ailanthus excelsa. Methodology: Seasonal abundance of major insect pests of A. excelsa viz., ailanthus defoliator and ailanthus webworm were studied in 5-year-old plantation at Forest College and Research Institute, Mettupalayam from April, 2018 to March, 2019. Weekly observations were made on the abundance of major insect and pest population which were correlated with weekly weather parameters. Results: Monitoring the population dynamics of insect pests revealed that the major key pests were ailanthus defoliator and webworm. The highest number of ailanthus defoliator (38.00 larvae per tree) and webworm (33.90 larvae per tree) were recorded during 44th standard week in 5-year-old plantation. Correlation analysis revealed that maximum temperature (Tmax) was negatively correlated with ailanthus defoliator with the r value of -0.299. Regarding webworm, wind velocity and evaporation rate were negatively correlated with the r value of -0.412 and -0.361 and was found to be statistically significant at 1% level. Interpretation: Seasonal abundance of this information helps us to take decision for the management of A. excelsa pests.