Demographic Parameters of Lipaphis erysimi (Hemiptera: Aphididae) on Different Cultivars of Brassica Vegetables

Demographic parameters of the turnip aphid, Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphididae), which is a serious pest of Brassica crops worldwide, were evaluated on five major Brassica vegetables (three varieties of Brassica oieraceae (Linnaeus) (Brassicaceae Brassicales); kohlrabi, cabbage and ornamental cabbage, and two subspecies of Brassica rapa (Linnaeus) (Brassicaceae Brassicales), Chinese cabbage and bak choi). The study was carried out under laboratory conditions at 25 +/- 1 degrees C, 70 +/- 5% RH and 16:8 (L:D) h. Preadult developmental time, survival rate, female longevity, reproduction, and life table parameters were evaluated according to the age-stage specific life table method. The highest population growth parameters, i.e., net reproductive rate (R-0), intrinsic rate of increase (r), and finrte rate of increase (lambda) were recorded on kohlrabi (R-0 = 30.45 offspring, r= 0.2174 d(-1),lambda= 1.2429 d(-1)) These parameters were the lowest on Chinese cabbage (R-0 = 13.00 offspring, r = 0.1503 d(-1), and lambda = 1.1621 d(-1)) and bak choi (R-0 = 16.30 offspring, r = 0.1614 d(-1), lambda = 1.1752 d(-1)). The results attained from population growth parameters, together with population projection estimation based on the age-stage, two-sex life table theory, indicated that both Chinese cabbage and bak choi were less suitable hosts for turnip aphids and should be considered as a possible source for developing resistance in breeding programs and integrated pest management strategies.