Panicle compactness along with abiotic factors influence the abundance of earhead feeding insect pests of sorghum [Sorghum bicolor (L.) Moench]

Sorghum [Sorghum bicolor (L.) Moench] is an important cereal crop widely cultivated in tropical and semi-tropical regions of the world. It is the food source for millions of people, especially in African and Asian countries. Sorghum is infested by a number of insect pests throughout the cropping season. Panicle feeding insect pests cause huge damage to sorghum grains. The present study was carried out to evaluate the influence of panicle (earhead) compactness population build-up of panicle feeding insect pests of sorghum. Four genotypes, i.e., SSG59-3 (loose), HC308 (compact), HC136 (compact) and HJ513 (semi-compact), were selected on the basis of panicle compactness and time of emergence. The major panicle feeding insect pests observed during the crop season were sorghum midge (Stenodiplosis sorghicola), earhead bug (Calocoris angustatus), thrips (Haplothrips aculeatus), dusky cotton bug (Oxycarenus latus) and stink bug (Nezara viridula). The mean population of S. sorghicola was highest on SSG59-3, followed by HJ513, HC308, and HC136. The mean population of C. angustatus was highest on genotype HC308, followed by HC136 and HJ513. On genotype SSG 59 - 3, the population of C. angustatus was not observed. The mean highest population of H. aculeatus was observed on genotype SSG59-3, followed by HJ513 and HC308. The minimum thrips population was noticed on genotype HC136. The highest mean population of O. latus was observed on genotype HC308. N. viridula was observed only on two genotypes, i.e., HC308 and HC136. Sorghum midge and thrips preferred loose types of panicle while earhead bug, dusky cotton bug and stink bug showed their preference towards compact panicle for their growth and bild-up. Effect of abiotic factors on population build-up of these major earhed feeding insect pests was also studied. The population of panicle feeding insects is variably correlated with different abiotic factors.