Published online by Cambridge University Press: 10 July 2009
A laboratory evaluation of growth, food consumption and food utilisation by larvae of Spodoptera littoralis (Boisd.) was made from the beginning of the fifth instar to the prepupal stage on cabbage, cotton, kenaf and Congo jute (Urena lobata). Growth, measured by daily larval fresh weight, was highest on cabbage and similar on kenaf, Urena and cotton. Development was fastest on cabbage and slowest on cotton and Urena. Larvae underwent an extra moult on the latter two food-plants. Weight gain was highest on cabbage, followed by cotton, Urena and kenaf, in that order. Total food consumption was highest on cotton and lowest on kenaf and Urena. Cabbage was most efficiently digested, followed by kenaf, cotton and Urena, in that order. Digestive efficiency on all four plants declined with larval age. The efficiency of conversion of ingested food to body material was highest on cabbage and lowest on cotton and kenaf. Digested portions of Urena were most efficiently converted to body substance while digested portions of cabbage and kenaf were most inefficiently converted to body material. It is concluded that S. littoralis is better adapted to cabbage than any of the other three plants and that increasing cultivation of cabbage in Ghana is likely to enhance the pest status of the insect.