Studies on population fluctuation and effect of biotic and abiotic stresses on the population of Myzus persicae (Sulz.) infesting potato in the gangetic basin of West Bengal

Investigation was conducted at ‘C’ unit farm of Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal (22058’52” N; 88026’30” E, 10 m above sea level), India to study the seasonal incidence of aphids and the role of various abiotic and biotic factors influencing their population for consecutive two years during rabi season of 2016-17 and 2017-18. The results revealed that aphid first appeared on the crop in the 2nd week of January in during rabi 2016-17. Thereafter, the density of aphid increased gradually with a peak in the second week of February and then the population started declining. During rabi 2017-18 aphid population first observed on the crop in the last week of December and reached to peak in the third week of February. The aphid species showed a significant positive correlation with maximum temperature and significant negative correlation with the morning, evening and average relative humidity in the first season and in the second season the aphid population were significantly positively correlated with maximum temperature and significantly negatively correlated with morning and evening relative humidity. During both the season the population of coccinellid beetle, staphylinid beetle and spiders was positively correlated with aphid population at 1% and 5% level of significance.