Biology and Feeding Efficiency of Zigzag Beetle, Menochilus sexmaculatus (Fab.) (Coleoptera: Coccinellidae) Fed on Mustard Aphid, Lipaphis erysimi (kalt.) (Hemiptera: Aphididae) Under Controlled Conditions

Abstract

| Research was conducted to evaluate the biological attributes and feeding efficiency of Menochilus sexmaculata fed on Lipaphis erysimi under laboratory conditions. The mean developmental time from egg till adult emergence was 41.60±0.70 days under laboratory conditions of 24±1c° with 55±5 percent relative humidity (R.H.). The incubation period was 4.00±0.25 days. The pre-oviposition, oviposition, and postoviposition periods were observed at 8.6, 24.1 and 6.0 days, respectively. The total laid eggs/female were 288.4 eggs. The pre-pupae and pupae developmental time was 1.00±0.00 and 6.00±0.08 days, respectively. The overall mean male longevity was 33.40 days, while the mean female longevity was 38.70 days. In larval feeding efficiency, the maximum mean number of aphids (479.6) were consumed by larvae while the minimum mean number of aphids (36.8) were consumed by 1 st larva instar. Female beetle was recorded with a maximum mean number of aphids (2561) consumption as compared to male beetles (1921). Furthermore, the apparent mortality was highest at egg stage, making it the most vulnerable stage in the beetle's life cycle, followed by 1 st instar larval stage, which also showed higher mortality. The maximum survival fraction was observed for pre-pual and fourth instar larvae, while the minimum was found for the egg stage. Mortality survival ratio (MSR) was found to be maximum at the egg stage and minimum at the 4 th instar and pre-pupal stages, while the Indispensable mortality (I.M.) was found to be maximum at the egg stage and minimum at 4 th instar and pre-pupal stages. Life expectancy (ex) was found to be maximum in the egg phase (4.67) and minimum in the pupal phase (1.5). The total K value for the whole generation was 0.33.