Seasonal Incidence of Tetranychus urticae Koch on Brinjal under Protected Cultivation

Abstract

The two-spotted spider mite Tetranychus urticae Koch is a key pest of many vegetable crops under protected cultivation. The seasonal incidence of two-spotted spider mite on brinjal in four seasons was studied under protected cultivation in 2020 and 2021. Two peaks were observed in mite population during the period of investigation. First peak was observed from mid-September i.e. during 38^th and 39^th SMW (5.4 to 5.6 mites/2 cm leaf area) to first fort night of October i.e. 40^th, 41^st and 42^nd SMW (5.0 to 5.4 mites/2 cm leaf area), in 2020. Second peak was observed during April i.e. 15^th, 17^th and 18^th SMW (5.0 to 5.8 mites/ 2 cm leaf area) to May i.e. 20^th, 21^st and 22^nd SMW (5.0 to 6.0 mites/ 2 cm leaf area) in 2021. The multiple correlation coefficients between the population and abiotic factors were worked out from July 2020 to June 2021. The active stages were found significantly positively correlated with maximum temperature and non-significantly positively correlated with minimum temperature. The morning relative humidity was non-significantly negatively correlated with the population of eggs and significantly negatively correlated with active stages.