Abstract

A study of the life table of Phenacoccus solenopsis Tinsely on cotton (Gossypium hirsutum L.) for two constitutive seasons at Entomological Farm, Punjab Agricultural University (PAU) Ludhiana revealed that among three phenophases (vegetative, flowering and maturation stage), gross reproductive rate (GRR), net reproductive rate (Ro), intrinsic rate of increase (rm), precise value of rm and finite rate of increase (λ) were maximum (329.83 and 349.10, 65.29 and 278.46, 0.169 and 0.242, 0.183 and 0.246, 1.184 and 1.274) at vegetative stage during 2008 and 2009, respectively. The total life cycle was completed in 32 days at vegetative stage while took maximum (39.00) days at maturation stage. During 2008, apparent mortality (100qx) was maximum (74.33 and 77.31%) at vegetative and flowering, respectively. Survival rate (Sx) was (0.26 and 0.23) in second instar at vegetative and flowering stage, whereas, at maturation stage the corresponding values for apparent mortality and survival rate were 40.69 and 0.59 in third instar. During 2009, maximum apparent mortality (76.35 and 56.91) and minimum survival rate (0.24 and 0.43) were recorded in adults at vegetative and maturation stage respectively. Heavy rainfall, Aenasius sp. (Hymenoptera: Encyrtidae) and Coccinella sp (Coleoptera: coccinellidae) contributed maximum mortality at vegetative and flowering stage, while rain fall and low temperature were major factors for mortality during maturation stage. The study suggested that P. solenopsis population is more affected by the biotic and abiotic factors in the vegetative stage. Therefore, the application of control measures at this stage could be drastically further reduces the population and thus prevents the buildup of population at later in the season.

Key words: Life table, Phenacoccus solenopsis, phenological stages, net reproductive rate (Ro), finite rate of increase (λ), intrinsic of increase (rm).