Impairing Effectiveness of Nerolidol, a Sesquiterpene Compound, on Adult Performance and Reproductive Potential of Egyptian Cotton Leafworm, Spodoptera littoralis (Lepidoptera: Noctuidae).

Abstract

Although Egyptian cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) is native in Africa, it is distributed throughout the world. It is a serious polyphagous insect damaging more than 90 host plants of economic importance. The objective of the current study was to evaluate the disruptive impact of Nerolidol, a Sesquiterpene compound, on the most important parameters of adult performance and reproductive potential of this insect. The newly moulted larvae of 5 th (penultimate) or 6 th (last) instar larvae fed castor bean leaves previously treated with 7 concentrations of Nerolidol (400, 200, 100, 50, 25, 12.5 & 6.25 ppm) for 24 hr. The most important results could be summarized as follows. Nerolidol exhibited an adulticidal activity only at the higher concentrations. Nerolidol exerted an anti-morphogenic activity against adult moths since some malformed adults were produced at the higher concentrations. Regardless the treated larval instar, Nerolidol induced the successfully emerged adults to live remarkably shortened total longevity and oviposition period, but the pre-oviposition period was generally prolonged. Nerolidol exhibited an inhibitory effect on the oviposition efficiency since the oviposition rate was deleteriously regressed, in a dose-dependent course. Nerolidol caused a disturbance of the reproductive capacity since fecundity and fertility were dramatically prohibited. After larval treatment with Nerolidol, the successfully mated adult females laid eggs with a significantly prolonged incubation period, especially at the higher concentration levels.