STUDIES ON INTRA-SPECIFIC VARIATIONS IN THE DIAMONDBACK MOTH, Plutella xylostella, (LEPIDOPTERA: YPONOMEUTIDAE) UNDER DIFFERENT GEOGRAPHICAL REGIONS
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Date
2013
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ABSTRACT
The present studies entitled “Studies on intra-specific variations in the diamondback moth, Plutella xylostella (Lepidoptera:Yponomeutidae) under different geographical regions” was carried out during 2011-2012 in the Department of Entomology, Dr. Y. S. Parmar University of Horticulture and Forestry, Nauni, Solan (HP). Five different geographical regions viz. Hisar (800feet), Kangra (2200feet), Solan (4200 feet), Theog (7500feet) and Kinnaur (9000feet) were selected to study the variations in the developmental and reproductive biology of the diamondback moth under laboratory conditions at 25oC. Significant differences were observed in developmental period for the population of different geographical regions. The total developmental period was maximum for the Kangra population (17.03 days) while it was minimum for the Kinnaur population (14.65 days) and was significantly different from each other. The female from the Kangra population laid maximum eggs (332.16 eggs/female) whereas the number of eggs laid by the female from the Hisar, Solan, Theog and Kinnaur population was 189.53, 207, 252 and 270 eggs/female, respectively. Morphometric studies revealed that length and breadth of eggs were maximum in the Kangra population (0.52 and 0.34mm), whereas these were minimum in the Hisar population (0.46 and 0.28mm). Wing expanse was maximum in the Kinnaur population (13.25 and 14.95mm) and minimum in the Solan population (12.05 and 13.15mm). Both intrinsic rate of natural increase and net reproductive rate were maximum in the Kangra population (0.222 female progeny/female/day and 90.22 female eggs/female). The value of the true intrinsic rate of increase (rm) of the diamondback moth was found to be maximum for the Kangra population (0.222 female progeny/female/day) whereas for the Kinnaur, Theog, Solan and Hisar population it was 0.203, 0.202, 0.182 and 0.151 female progeny/female/day indicating thereby that the Kangra population is more prolific as compared to the population from other geographical regions.