Studies on Insect Pests of Okra and Their Management Through Insecticides and Biopesticides Approaches

Abstract

Okra (Abelmoschus esculentus L. Moench), also known as lady's finger or bhendi, belongs to family Malvaceae crop grown throughout the year. Besides India, it is grown in many tropical and subtropical parts of the world. Among the wide array of insect pests infesting okra crop, such as shoot and fruit borer and the sucking pests such as aphid, A. gossypii (Glover), leafhopper, A. biguttula biguttula (Ishida), and whitefly, B. tabaci (Gennadius), are reported to be quite serious during all stages of the crop growth. Keeping in facts in view the investigation the field experiment was carried out during the years 2013 and 2014 at the Crop Research Centre ofSardar Vallabhbhai Patel University of Agriculture and Technology, Meerut-250 110 (U.P.) with the objectives, succession and incidence of major insect pests and their natural enemies at different stages of crop growth, the correlation of insect pests with abiotic factors i.e. temperature, humidity and rainfall, the efficacy of insecticides and biopesticides against major insect pests of okra, percent incidence of yellow vein mosaic disease, transmitted by whitefly under protected and unprotected conditions and assessment of yield losses and cost: benefit ratio in different treatments. The shoot damage was started from last week of June (26th Standard week) and continue throughout the crop period during both the years by E. vittella. The fruit damage was recorded for the first time in fourth week of July (30th Standard week) during both the years. Whitefly appeared as early as in the last week of July (26th Standard week) during the years 2013 and 2014. During both the years under study, the whitefly population remained increasing till it reached the peak in the last week of September (39th Standard week). Aphid (A. gossypii) was first recorded in the first week of July during both years on okra three week of old crop and it was continued to the last week of September (39th Standard week) means till harvest the crop. The population of natural enemies was first time recorded during the second week of July (27th Standard week) during the year 2013, while, it was appeared in third week of July (28th Standard week) in the year of2014. The data on per cent shoot damage showed positive correlation with morning, evening relative humidity and rainfall, while with the maximum and minimum temperature showed negative correlation in the year 2013 and 2014. The minimum temperature, morning and evening relative humidity and rainfall showed positive correlation while maximum temperature showed negative correlation with aphid population during the year 2013 and 2014, respectively. The minimum temperature, morning and evening relative humidity and rainfall showed positive correlation with leafuopper population while maximum temperature showed negative correlation in the respective years of 2013 and 2014. Spinosad @ I 00 ml/ha was found most effective treatment during the both years after third, seven and fifteen days after spraying against Shoot and fruit borer on shoot and fruit damage bases. Imidacloprid @ 300 ml/ha) was most effective insecticide against leafhoppers, whitefly and aphids. All protected treatments were recorded less percent incidence of YVMV in the compression of unprotected control due to effective suppression of whitefly. The maximum fruit yield 73.67 and 72.46 q/ha was obtained from the spinosad @ I 00 ml/ha treated plots and it was superior with other treatments during 2013 and 2014, respectively followed by imidacloprid with the yield of 57.53 q/ha and 56.68 qlha in the respected year of 20 I 3 and 2014. Imidacloprid @ 300 ml/ha ranked first indicating the maximum return ofRs. 8.34 per rupee invested followed by lambda cyhalothrin@ 300 mllha with 1:8.21 Cost benefit ratio. However it was same in sequences in the year 2014.