Population dynamics and effect of abiotic factors on spider Oxyopes kohaensis (Araneae: Oxyopidae) in an organic mango orchard

Abstract

Spiders are potential biological control agents in agricultural ecosystems and are major integral part of IPM. Understanding the biology and the factors like biotic and abiotic components influencing the occurrence and diversification of spiders are required for exploiting them to the full extent. In the past few decades global warming is a hot topic where it not only affects the physiological activity of the predator/prey but also the survival to different temperatures. Hence the present study was aimed at determining the abundance of spiders in organic mango orchard and to study the impact of abiotic factors on their occurrence. The peak population of Oxyopes kohaensis was found during the months of September during vegetative phase and March - April during flowering and fruiting phase of mango. The peak population of O. kohaensis was found during the first week of April 2015 where the total number of spiders was found to be 4.21/tree. Correlation matrix showed that there was a significant positive correlation with the maximum and minimum temperature and negative correlation with relative humidity. Further the significant variables were regressed, the highest coefficient of determination was found in maximum temperature (R2 =0.64). The present study suggested that the spider can thrive up to a maximum temperature of 33.50oC. The highest spider density was found in the optimum temperature range between 29.75-33.50oC.