Effect of monoterpenes, phenylpropenes and sesquiterpenes on development, fecundity and fertility of Spodoptera littoralis (Boisduval)

Monoterpenes, phenylpropenes and sesquiterpenes are the major constituents of essential oils of many aromatic plants and possess a wide spectrum of biological activities. In this study, the effect of eleven monoterpenes, phenylpropenes and sesquiterpenes on larval and pupal duration, pupation, pupal weight, adult emergence, fecundity and fertility of Spodoptera littoralis were evaluated. Results showed that larvae fed on the treated diet at 500, 1000 and 2000 mg/kg developed slower than those fed on untreated diet. trans- Cinnamaldehyde (500 mg/kg) was the most effective compound in increasing larval duration of 20.4 days compared to 13.5 days in control, followed by1,8-cineole and (−)-citronellal. Also, treatment with (−)-carvone, (−)-citronellal, eugenol, p-cymene and α-pinene prolonged pupal duration by 1 to 3 days compared to control. On the other hand, the tested compounds significantly reduced pupation percentage and pupal weight of S. littoralis. trans-Cinnamaldehyde was more effective than a reference insect growth regulator, pyriproxyfen, in pupation percent reduction at 500 mg/kg. Furthermore, the tested compounds strongly decreased adult emergence of S. littoralis with 1,8-cineole being the most effective compound as it lowered adult emergence to 23.3, 16.7, and 13.3% at 500, 1000, and 2000 mg/kg, respectively, compared to 90.0% in control. In addition, oviposition and eclosion were significantly reduced by the tested compounds. trans-Cinnamaldehyde, (−)-citronellal, 1,8-cineole, (−)-carvone and (Z,E)-nerolidol were the most effective compounds on oviposition and egg hatching reduction.