Noctuidae)

*Autor para correspondência. ABSTRACT. There are many compounds extracted from plants, called allelochemicals that affect insect biolology and behavior. Among these substances the terpenoids are efficient on inhibiting reproduction, feeding and larval development. This research, developed at the Universidade Estadual Paulista, Botucatu, evaluated the bioactivity of Java grass, Cymbopogon winterianus Jowitt (Poaceae) essential oil (rich in citronellal and citronellol) on Spodoptera frugiperda (J.E. Smith). Two bioassays were conducted. The first assay, corn leaves with 10 cm long and 4 cm wide were divided in 3 equal parts. One of the end part was dipped into solutions containing 1.0, 0.5, 0.1, 0.05, 0.01, 0.005 and 0.001 % of Java grass essential oil diluted in 0.05 % emulsifier Tween 20. The other end part was dipped into water with 0.05 % of the emulsifier Tween 20. Four neonate larvae were released in the center third of the leaves. The second assay, Petri dishes surfaces were treated with 1.0, 0.5, 0.1, 0.05 % of Java grass essential oil solutions diluted in 0.05 % emulsifier Tween 20. A blank treatment 0.05 % emulsifier Tween 20 was also used. After dried, the surfaces received 10 new hatched larvae and were covered with a plastic sheet. The results showed that Jav