Abstract
The Egyptian cotton leafworm, Spodopteralittoralis, is destructivepest of cotton and various crops in Egypt and someparts of the world. The present study was carried outaiming to assess the disruptive effects of cycloheximide on survival, growth,development, metamorphosis and reproductive potential of this pest. Four doses:180, 120, 60 and 30 µg/larva had been topically applied (once) onto the newlymoulted last instar larvae. cycloheximide exhibited toxic effect on larvae,pupae and adults.Unexpectedly, no mortality was observed at the highestdose.LD50 was estimated at 0.013 µg/larva.Themaximal weightsof the treated larvae increased and the larval growthwas remarkably enhanced. Thelarval and pupal durations were shortened.Some larvae appeared as'giant larvae', only at the lower two doses.They enlarged insize and appeared heavier than other treated and control larvae. They survived2-times longer period than of the control larvae and perished without pupation.Topical treatment of larvae only with the lower two doses induced a stateof suspended development, 'permanent prepupae' which failed to pupate.Cycloheximideexerted an inhibitory action on the pupation rate after treatment only with thelower three doses. Some deformed pupae were produced. The adult emergence wasconsiderably blocked at lower three doses.The oviposition wascompletely prevented, at the higher two doses, but partially inhibited at thelower two doses. No fecundity could be determined at the higher two dosesbecause no oviposition was carried out. At the lower two doses, fecundity wasdramatically reduced. All eggs failed to hatch indicating complete sterility ofS. littoralis.
Highlights
The cotton leafworm Spodoptera littoralis has been considered as a destructive herbivorous pest of cotton and other field crops all over the year in Egypt (Shonouda and Osman, 2000; Adham et al, 2009)
Toxic Effect of Cycloheximide on S. littoralis After topical application of cycloheximide onto the newly moulted last instar larvae, toxicity of the tested compound was expressed in mortality among larvae, pupae and adults
An extended toxic effect of cycloheximide was exhibited on adult females, reversely correlated with the dose level (13.3, 16.7 and 33.3% adult mortality, at 120, 60 and 30 μg/larva, respectively, vs. 0% mortality of control adults)
Summary
The cotton leafworm Spodoptera littoralis has been considered as a destructive herbivorous pest of cotton and other field crops all over the year in Egypt (Shonouda and Osman, 2000; Adham et al, 2009). It is widely distributed throughout Africa, Mediterranean Europe, and several parts of Asia (Azab et al, 2001). During heavy infestation they can penetrate flowers and bolls (Sutanto et al, 2014). To control this pest, several types of conventional insecticides have been used over the last five decades.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
