Abstract: Effects of larval diets on developmental period, pupal weight, fecundity and flight capacity of the beet armyworm Spodoptera exigua (Hübner) were investigated. Larvae fed with the artificial diet showed a significant shorter larval duration and produced heavier pupae than those fed with maize seedling. Fecundity of the female adults from larvae reared on the artificial diet was significantly greater than that from maize seedling. Based on a 12 hours tethered-flight test of the newly emerged and unfed adults, moths from the larvae reared on the artificial diet and maize seedling could fly 25.5 and 3.3 km and 6.2 and 1.7 h, respectively, and these differences were also significant. The adults flying beyond 10 km and 5 h during the test period accounted for 67.9% and 60.7% of the total in the colony on the artificial diet while both the values only 4.2% in the colony on maize seedling. Most of these parameters from cabbage-fed larvae were similar to or a little poorer than those from the artificial diet-fed ones, but significantly better than those from maize seedling-fed group. These results suggest that growth, development and population dynamics of the beet armyworm must be significantly affected by larval diets. Furthermore, the artificial diet described in this paper might be used as a substitute for the natural foods of the beet armyworm.

Key words: Spodoptera exigua (Hübner), larval food, growth and development, fecundity, flight capacity