English abstract
Studies on the biology and feeding potential of the predatory coccinellid, Menochilus sexmaculatus were carried out in the laboratory (21 ° C and 68% RH) and the greenhouse (15-25° C and 40-70% RH). The life cycle duration (from egg deposition until adult emergence) was 19.35 +1.11 days. The females lived for 90.5 = 7.53 days, whereas the males lived for 79.75 +7.93 days. The egg, larval and pupal stages lasted for 4.41 +0.51, 9.65 0.61 and 5.29 + 0.59 days, respectively. In the greenhouse, the life cycle duration was 19.13 + 1.36 days. The egg, larval and pupal stages lasted for 4.63 + 0.52, 8.50 + 0.53 and 6.00 = 0.76 days, respectively. The larvae of M sexmaculatus consumed 446.78 275.95 individuals of the cucumber aphids, Aphis gossypii, whereas the adult females and males consumed 5891.60 £700.40 and 4380.83 + 506.20 aphids, respectively. Age of larvae and adults of the predator greatly affected their feeding potential. There was a general decline in food consumption by the adults with the increase in their age. The females of M. sexmaculatus laid 938.89 eggs throughout their life span with 79.26% hatching percentage. Parthenogenesis was observed in this predator but the numbers of eggs produced were negligible. Age had a negative effect on fecundity of the predator. The predator has a wide host range but the cabbage aphid, Brevicoryne brassicae was not a preferred host for it. Temperatures of 30 and 35° C greatly increased the rate of development of different life stages of M sexmaculatus and thus decreased their developmental durations. However, decrease in egg hatching and larval survival were also observed within this range. The preferred range of temperature for rearing the predator was 15 to 25° C. Egg cannibalism by the larvae of M. sexmaculatus was noticed, and the 4th instar larvae, when starved, formed the greatest risk to the eggs. The adults of M sexmaculatus lived for a shorter time when fed on bee pollen, sweetened agar and bee honey than when fed on natural food (aphids).
