Artificial diet development and its effect on the reproductive performances of Propylea japonica and Harmonia axyridis

•Three semi-solid artificial diets were developed and tested to rear immature P. japonica and H. axyridis.•Artificial diet composed of shrimps, beef, beef liver, and egg yolk in a 5:4:8:4 ratios.•Artificial diet also supported adult's survival but no oviposition was observed.•Oviposition was restored in females reared on artificial diet when later fed pea aphids.

The use of augmentative biological controls in greenhouse pest management has increased the demand for predators. To meet demands, suitable artificial diets must be developed to enable fast and cost-effective mass rearing of predators. In this study, three artificial diets were developed and their suitability for immature development and survival of Japanese ladybird Propylea japonica (Thunberg) and Multi-colored Asian ladybird Harmonia axyridis (Pallas) were investigated. An artificial diet composed of shrimp, beef, beef liver, and egg yolk in a 5:4:8:4 ratio is an adequate source of nutrition for the development of immature P. japonica and H. axyridis, resulting in 83% and 68% adult emergence rates, respectively. The reproductive performances of emerging P. japonica and H. axyridis females fed the artificial diet or pea aphids were compared. The pre-oviposition period was shorter in emerging females from immature ladybirds fed an artificial diet compared with those emerging from immature ladybirds fed pea aphids. However, the total fecundity did not vary significantly. When adults were fed artificial diets, females did not lay eggs, but oviposition could be restored by feeding adults on pea aphids. The developed artificial diet can be used for the mass rearing of P. japonica and H. axyridis for biological control applications and rearing of adults during prey shortage.

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