Biology of Toxoptera aurantii, Planococcus citri, Paracoccus marginatus and Helopeltis bradyi infesting cocoa, Theobroma cacao L.

摘要

Laboratory experiments were conducted to study the biology of major sucking pests of cocoa viz., aphids, Toxoptera aurantii, mealybugs, Planococcus citri Risso, Paracoccus marginatus Williams and Granara de Willink and tea mosquito bug, Helopeltis bradyi in the Department of Agricultural Entomology, TNAU, Coimbatore during 2015. The duration of first, second, third and fourth instar nymphs of T. aurantii was 1.45±0.43, 2.15±0.47, 2.35±0.51 and 2.05±0.37, respectively. The adults started laying young ones after a pre reproductive period of 1.05±0.44 days. A single aphid produced about 52.17±4.19 nymphs during the reproductive period of 4.40±0.40 days with a longevity of 12.10±1.29 days. The egg period, duration of first, second and third instar nymphs of P. citri was 3.50±0.50, 5.17±0.29, 6.17±0.58 and 7.33±0.29 days, respectively with pupal period of 4.83±0.76 days. Adult longevity of male and female was 2.50±0.50 and 18.83±1.61 days, respectively. Total life cycle of male was 29.50±1.50 days and 41.50±1.80 days for females. The oviposition period was 10.17±1.26 days and the fecundity was 358.67±3.06 eggs. Biology of P. marginatus showed that the egg period, duration of first, second and third instar nymphs was 6.50±0.87, 3.67±0.58, 3.92±0.39 and 4.58±0.40 days, respectively with the pupal period of 3.25±0.43 days. Adult longevity of female and male was 19.67±0.59 and 1.52±0.58 days, respectively. Total life cycle was 23.58±1.87 days for males and 39.17±1.04 days for females. The oviposition period was 7.67±0.58 days and the fecundity was 336.67±3.21 eggs. Regarding Helopeltis bradyi, the egg period, duration of first, second, third, fourth and fifth instar nymphs of H. bradyi was 7.54±0.46, 1.60±0.42, 1.10±0.22,1.24±0.18, 1.88±0.40 and 2.52±0.36 days, respectively. Longevity of male and female was 22.20±1.30 and 26.00±0.71 days, respectively. Total life cycle of male was 38.08±1.59 days and 41.88±1.11 days for females. The oviposition period of adult female was 21.80±0.84 days and the fecundity was 137.60±1.82 eggs.