Fluctuations of some characteristics in the common cutworm, Spodoptera litura (Lepidoptera : Noctuidae) reared under different diets

Larval development and some characteristics of newly ecdysed adults of the common cutworm, Spodoptera litura, were compared when the final stadium lar vae were reared on diets varying in quality, by reducing the percentage of artificial diet (100, 80, 60 and 40%) and adding pulp flock. As the quality of the diet was reduced, the larvae fed on smaller amounts of diet, but fo r longer periods, and so consumed similar amounts diet during the final sta dium, the effect being proportionately the greatest for the 40% diet in mal es. The effects in adults were sex related for the following characteristic s: body weight, forewing length and wing loading index declined more promin ently in females, but triacylglycerol (TG) content appeared to decline more prominently in males. Although the fatty acid composition of TG was not af fected by diets of different quality, it differed greatly from the composit ion of those given soybean leaves. These results emphasize the importance o f considering the effects of larval diet on morphological and physiological features related to flight ability when investigating the possibility of i mmigration of this moth.