Life table of Coccinella septempunctata Linn. on different host species in laboratory

Present studies on the effect of host species on life table of C. septempunctata L. were carried out in the Laboratory. One generation of C. septempunctata was observed on different aphid pray i.e. Barley aphid. Schizaphis graminum, mustard aphid, Lipaphis erysimi (Kalt), Nerium aphid, Aphis nerii, Maize aphid, Rhopalosiphum maidis, and berseem aphid, Therioaphis trifolii. The duration of life cycle of C. septempunctata on different hosts varied considerably. The highest egg incubation period was recorded on T. trifolii (3.6 plus minus 0.14) and lowest on A. nerii (3.00 plus minus 0.14). The longest larval period 1st to 4th instars was recorded as on A. nerii (14.6 plus minus 0.22 days) and shortest on T. trifolii (11.08 plus minus 0.16 days). The highest percent emergence of male and female adults were recorded on L. erysimi and S. graminum, (47.49 plus minus 1.40 and 58.08 plus minus 1.35). The on S. graminum and L. erysimi, (42.03 plus minus 1.04 and 52.32 plus minus 1.41). There was no significant difference in the emergence of both sexes (P greater than 0.0.5). The mean sex ratio of male and female adults was 1:1.22. The highest adult longevity of male and female adults was recorded on nerium aphid (42.2 plus minus 1.05 and 50.2 plus minus 2.05) and lowest longevity on berseern aphid (27.2 plus minus 0.98 and 31.4 plus minus 1.08). The maximum weight of 4th larval instar of C. septempunctata was observed as on nerium aphid (31.9 plus minus 3.36 mg) and lowest on Barley aphid (24.2 plus minus 0.49 mg). The maximum body weight of adult male and female was also on nerium aphid and lowest on Maize aphid. The highest net-reproduction rate (Ro) of C. septempunctata was obtained with the diet of Nerium aphid A. nerii (339.7). The lowest (Ro) value was obtained when fed upon berseem aphid T. trifolii (118.80). The mean generation time (G) of C. septempunctata was greatest oil A. nerii (52.90) and shortest oil T. trifolii (37.07). The intrinsic rate of increase (rm.) and subsequently the finite rate of increase (e -rm) were highest (0.141 and 2.91 respectively) when the individuals fed on A. nerii and lowest when fed on T. trifolii (0.111 and 2.59). Mean prey consumption of first, second, third, fourth instar larvae of C. septempunctata during 6 hours was recorded on A. nerii and lower consumption rate was recorded on T. trifolii. The fourth instar devoured significantly highest number of aphids than the rest of instars. The mean feeding rate of male adults of C. septempunctata on different host species varied with the age. The highest male life span and consumption of aphids (36 days and 29.83 aphids/day) was on A. nerii and lowest on T. trifolii. The data reveals that A. nerii was most preferred food of C. septempunctata and T trifolii was least preferred food. It can be concluded that the predator C. septempunctata is a natural enemy of many aphid species. The longest life cycle of C. septempunctata was recorded on nerium aphid, aphis nerii and shortest on berseem aphid Therioaphis trifolii. The maximum fecundity and eggs hatching % of C. septempunctata was observed on T. trifolii. The fourth instar larvae consumed more number of' the aphids than rest of the instars. The female adults lived longer and consumed more food as compared to male adults. The life table parameters of this predator longest on nerium aphid, aphis nerii and shortest on berseem aphid, Therioaphis trifolii.