Potential diet regimens for laboratory rearing of the harlequin ladybird.
Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is an invasive generalist predator, which has been used as a biological model to investigate several research questions and is also an effective biocontrol agent against agricultural pests. Its laboratory colonies are often maintained on natural prey that are costly, and thus alternative dietary regimens are required. We studied the influence of four different food regimens on the developmental and reproductive life history traits of H. axyridis, including body size and the population demographic parameters. The tested diet regimes were: Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs, a commercial mix of E. kuehniella and Artemia sp. (Anostraca: Artemiidae) cysts, a liver-based artificial diet, and the natural prey, Aphis gossypii Glover (Hemiptera: Aphididae). The food regimes affected the investigated life parameters of H. axyridis in various ways. Larvae developed successfully and in the shortest time on moth eggs, but for H. axyridis reared on the artificial diet development was not successful. The mixture of moth eggs and brine shrimp cysts supported the rearing of H. axyridis. However our findings suggest its use only when no other suitable feedstuff is available. The life table approach used in this study could improve the standardized comparison among diet regimes, thus optimizing the rearing protocols of the species.