author(s)
GR Bhanderi, RD Patel, HR Desai and RK Patel

abstract
Investigation on incidence and estimation of yield losses due to mealybug (Phenacoccus solenopsis Tinsley) was carried out on cotton farmers’ fields of South Gujarat during 2015-16 to 2017-18. Total of 21 villages of two districts were surveyed for assessment of losses due to mealybug infestation during the harvesting seasons (October to December). The average intensity of mealy bug was 9.32 and 19.93 per cent within 8.50 and 16.56% infested plants in villages of Umarpada and Olpad taluka of Surat district, respectively. Whereas it was 13.84, 16.50, 21.02 and 21.15 per cent within 12.13, 14.11, 17.33 and 17.44% infested plants in villages of Hansot, Amod, Valia and Bharuch taluka of Bharuch district, respectively. The management practices followed by farmers and the data on natural parasitism of mealybug by Aenasius bambawalei Hayat was also recorded in the surveyed villages which indicated per cent parasitism in the range of 6.56 to 9.21 in Olpad and 4.73 to 7.08 per cent in Umarpada taluka whereas it was 4.90 to 11.07 in Hansot, 6.79 to 13.14 in Amod, 10.53 to 14.60 in Valia and 8.00 to 12.61 per cent in Bharuch taluka. The yield loss due to mealybug was assessed based on prevalence of plants having four grade injuries and was estimated to be 0.69 to 1.49% in villages of Olpad taluka whereas it was nil in villages of Umarpada taluka. In Bharuch district, it was 0 to 0.74, 0.68 to 2.63, 1.07 to 2.44 and 1.87 to 2.97% in villages of Hansot, Amod, Bharuch and Valia taluka, respectively. Under farmers’ practices, the overall loss estimated was 1.07% worth of Rs. 4800/-per ha comprising of Rs. 2800/-for seed cotton yield and Rs. 1987 for mealybug management.