Seasonal Occurence of Major Insect Pests of Rice Grown in Krishna Delta Region of Andhra Pradesh

Abstract

The investigation on seasonal occurrence of major insect pests of rice grown in Krishna Delta of Andhra Pradesh was conducted during kharif 2023-24. Weekly observations on pest population in relation with abiotic factors revealed that the initial and peak incidence of yellow stem borer (YSB) as dead hearts was observed at vegetative stage during SMW 30 and SMW 38 with 0.30% and 5.56% respectively, whereas at reproductive stage the highest and lowest incidence in the form of white ears was observed after panicle emergence at SMW 44 and SMW 42 i.e., 0.33% and 2.20%, respectively. The highest rice leaf folder incidence was recorded at SMW 39 (9.21%) and lowest at SMW 44 (1.00%). The highest and lowest brown planthopper (BPH) mean population was recorded at SMW 39 and SMW 31 and it was 9.60 hoppers/hill and 0.20 hoppers/hill, respectively. On the other hand, highest and lowest white backed planthopper (WBPH) mean population was recorded during SMW 38 and SMW 32 and it was 3.70 and 0.40 hoppers/hill respectively. The YSB showed non-significant negative correlation with maximum temperature and rainfall, while showed non-significant positive correlation with minimum temperature, morning and evening relative humidity. The rice leaf folder population showed non-significant negative correlation with minimum temperature and non-significant positive correlation with maximum temperature, morning and evening relative humidity and rainfall. BPH population showed non-significant negative correlation with maximum and minimum temperature and rainfall, while it was non-significant positive correlation with morning and evening relative humidity. WBPH population showed significant positive correlation with morning relative humidity, non-significant positive correlation with maximum temperature and evening relative humidity and non-significant negative correlation with minimum temperature.