A Survey on Species Complex of Mealybug and their Natural Enemies on Cottonin Guntur District of Andhra Pradesh

摘要

Cotton, "white gold" is an important fiber as well as cash crop of India.Among all the cotton producing countries in the world, India ranks first in area (122.38 lakh ha~(-1)) with a cotton production of 361 lakh bales and productivity of 501 kg ha-'.In Andhra Pradesh, it is being cultivated in 5.51 lakh ha" 1 with a production of 20 lakh bales and productivity of 688 kg ha~(-1) (AICCIP, Annual Report, 2018-19). Sucking pests of cotton viz., leafhopper (Amrasca devastans Distant), whitefly {Bemisiatabaci Genn), aphids {Aphis gossypii Glover), thrips (Thrips tabaci Lindeman) and mealybug (Phenacoccus solenopsis Tinsely) damage the crop with regular infestation at different growth stages and reduce the yield up to 21.20 per cent (Dhawan el at, 1998). Introduction of transgenic Bt cotton hybrids for commercial cultivation has resulted in an immense increase in the seed cotton yield and reduction in the average number of insecticidal sprays from 3.10 to 1.17 (Barwale et ai, 2004). However, adoption of transgenic Bt cotton hybrids resulted in severe incidence of sucking pests. Rapid development and more fertility of the sucking pests is due to the use of heavy doses of nitrogenous fertilizers which lead to increase in the quantum of some amino nitrogen concentrations in the plant system (Jain and Bhargava, 2007). Cotton mealybug was an invasive pest in India since 1991 (Fuchus et al, 1991). Initially, it was a minor sucking pest and after 2007 it has emerged as a serious pest (Nagare et ai, 2009). It attacks plants by sucking cell sap from the phloem tissue (Aijun et al., 2004). It secretes honeydew which makes sooty mould on the surface of the leaves, that decreases leaf area for photosynthesis, resulting in the death of plant tissues (Mark et al., 2005). In cotton, P. Solenopsis attacked plant parts show bunchy top appearance and stunted growth, chlorosis, and produce fewer bolls of smaller size with bad opening which ultimately affects the seed cotton yield up to 44.21% (Dhawan et al, 2007).