Effect of abiotic factors against the infestation of bollworms complex on different nectarid and nectariless varieties of cotton under unsprayed conditions

The present project was conducted to see the effect of Abiotic factors against the infestation fluctuation of bollworms complex of cotton i.e., pink bollworm, spotted bollworm and American bollworm on different nectaried and nectariless varieties of cotton under unsprayed conditions. It was concluded that: Maximum infestation of pink bollworm was recorded in the month of October on flowers, squares and green bolls on V7 and V8. The maximum damage of pink bollworm recorded when the temperature was 30.08 degree C, relative humidity was 53.50% and there was no rainfall. It was also noted that there was less infestation on nectariless varieties i.e., V2 and V1 and V3. The minimum infestation of pink bollworm was recorded in the month of July and early August on V2, V1 followed by V3. Correlation among pink bollworm infestation and weather factors showed that temperature and relative humidity significantly positively effected while the rainfall had no significant effect. Maximum infestation of spotted bollworm on flowers, squares and green bolls was recorded in the month of September on V7 and V8, when the average temperature was 30.62 degree C, relative humidity was 59.21%, and the rainfall was only 0.10 mm. The minimum infestation was recorded on nectariless varieties i.e., V2, V1 followed by V3 in the month of July and early August. Correlation between weather factors and infestation of spotted bollworm indicated that temperature and ref humidity was positively correlated while the rainfall was negatively correlated in different varieties of cotton except V7 for which rainfall affected positively. American bollworm infestation on flowers, squares and green bolls was maximum on V7 and V8 in the 2nd and last week of September when the temperature was 32.06 degree C, relative humidity was 61.68% and rainfall was 0.125 mm. The minimum infestation was recorded on and V2 and V1 followed by V3. Correlation between infestation of American bollworm and weather factors indicated that temperature and humidity affected positively while the rainfall was negatively correlated. It can be concluded that there might be a number of other factors too that influence the activity and infestation of cotton bollworms, these can be physico- morphological or bio-chemical factors that may correlate with each other to have some positive or negative effect in combination to influence the infestation of bollworms in different nectaried and nectariless cotton varieties under unsprayed conditions.