Maintenance of soldier-producing aphids on an artificial diet.

In our efforts to understand the biology of soldier-producing aphids, we attempted to maintain them in the laboratory using a chemically defined artificial diet. The ability of 16 species from the subfamilies Eriosomatinae and Hormaphidinae, most of which are soldier-producing species, to survive on the artificial diet was examined. Some species neither fed nor grew on the diet, whereas other species accepted the diet, grew to some extent, and managed to produce a small number of short-lived offspring. Although they performed poorly on the diet in general, aphid performance was correlated with the stage in the life cycle and the developmental stadium in that aphids of the gall generation tended to accept the diet and survive on it, whereas aphids of the non-gall generation did not. Also, old insects tended to perform better on the diet than young nymphs. Notably, only one species, Tuberaphis styraci, a gall-forming aphid that produces 2nd instar sterile soldier, showed good performance on the diet. Insects collected from galls (generation G0) survived on the diet, grew well, and produced many progeny. Three successive generations (G1, G2 and G3) were produced on the diet. Developmental period, adult body size, and age of first reproduction were almost constant through G0, G1 and G2 whereas fecundity, adult longevity and daily offspring production declined as the generations proceeded. These results are comparable to previous studies in which pest aphids have been maintained on similar artificial diets for several generations. Therefore, it is suggested that the artificial-diet rearing system will provide a useful tool to investigate various biological aspects of the soldier-producing eusocial aphid, T. styraci.