Li-Juan Wu, Syed Husne Mobarak, Yan Fu, Yu-Sheng Chen, Xing-Lin Yu, Tong-Xian Liu
Menochilus sexmaculatus (Fabricius) (Coleoptera: Coccinellidae) is a predator of aphids and other soft-bodied pests, but practical artificial diets for larval rearing remain poorly developed. We optimized an artificial diet formulation without insect-derived ingredients using an L9 orthogonal array with four ingredients: pork liver, egg albumen powder, soybean powder, and corn germ oil. Diet performance was screened using the proportion of larvae reaching the fourth instar and larval developmental duration, with Aphis craccivora Koch (Hemiptera: Aphididae) as the natural-prey control. The predicted optimal formulation was then evaluated for larval development, offspring development and reproduction, performance after transfer to aphids, predatory capacity, and starvation resistance. The optimized diet supported development to the fourth instar, with 90.5% of larvae from the artificial diet treatment and 95.8% of aphid-fed larvae reaching this stage. However, preimaginal development was significantly longer in the artificial diet treatment. Offspring reared according to parental diet lineage also showed longer preimaginal development and lower hatchability in the artificial diet lineage, whereas fecundity did not differ significantly. When offspring from both parental lineages were subsequently reared on aphids, developmental-timing differences persisted, whereas fecundity and hatchability did not differ significantly. Fourth-instar larvae from the artificial diet treatment retained aphid-feeding activity under laboratory conditions but had significantly lower starvation resistance. These findings identify an artificial diet formulation without insect-derived ingredients that can support larval production of M. sexmaculatus under laboratory conditions. Further refinement of the formulation to improve developmental rate and starvation resistance is needed before reliable use for large-scale rearing.