Population Dynamics of Natural Enemies in Okra Agro-ecosystem in Relation to Abiotic Factors

Abstract

The present experiment was carried out to access the relationship between population fluctuation of natural enemies and abiotic factors in okra agro-ecosystem at the Research Farm, Tirhut College of Agriculture, Dholi, Muzaffarpur (Bihar). From pooled data of two consecutive Kharif seasons i.e. 2018 and 2019 it was inferred that the highest coccinellids population was registered during 35th standard week (4.56 coccinellids/ 5 plant). Thereafter, the population gradually decreases and reached to 1.19 coccinellids/ 5 plant during 41st standard week i.e. end of the crop. Correlation studies of coccinellids population with abiotic factors indicated that the maximum temperature had positive and highly significant effect on coccinellids. While, minimum temperature and relative humidity at 7 hrs showed positive but non-significant effect on coccinellids. The relative humidity at 14 hrs and rainfall had negative and non-significant correlation with coccinellids population. All the weather parameters together governed 49.90 per cent to the coccinellids population build up (R2 = 0.4990). In case of spider, incidence commenced in 27th standard week however, the maximum population (3.94 spiders/ 5 plant) was observed in 35th standard week. Correlation analysis of spider population with abiotic factors exhibited that the maximum temperature had highly significant and positive effect on spider population. Unlike it, minimum temperature and relative humidity at 7 hrs indicated positive and non-significant effect on spider population. However, the effect of relative humidity at 14 hrs and rainfall on spider population was found negative and non-significant. However, all the prevailing weather parameters together contributed 48.23 per cent towards spider incidence (R2 = 0.4823).