Influence of Aphis gossypii Glover (Hemiptera: Aphididae) density on life table parameters of Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae) under laboratory conditions

Life table gives the most comprehensive explanation of the survivorship, development, and reproduction of a population. The life table parameters of an aphidophagous midge, Aphidoletes aphidimyza were studied on different densities (5, 10, 20, 40, 60, 80) of third instar nymphs of Aphis gossypii as prey in a growth chamber (25 ± 1 °C, 70 ± 5% RH and a photoperiod of 16L: 8D h). The pre-ovipositional period of female A. aphidimyza was reduced as prey density increased with no significant difference. The oviposition period was 3.833 ± 0.401 and 5.5 ± 0.463 days in lowest and highest prey density, respectively. Fecundity increased significantly with increasing prey density. The lowest fecundity was obtained at density of 5 preys/day (49.667 ± 6.053 eggs) and the highest was at density of 80 preys/day (104.25 ± 7.78 eggs). Intrinsic rate of increase (rm) ranged from 0.110 ± 0.016 to 0.166 ± 0.014 d-1 with increasing prey density. Net reproductive rate (R0) was positively dependent on prey density. The peak reproductive values showed that female aphidophagous midge at ages of 17, 18, 19, 22 and 25 days made the highest contribution to the population when reared on 5 to 80 preys in a day, respectively. However, mean generation time (T) ranged from 22.42 ± 0.55 to 24.47 ± 1.04 days. It was concluded that the increase in the density of third instar nymphs of A. gossypii significantly affected the demographic parameters of A. aphidimyza and it had a better reproductive performance in higher prey densities.