Comparative efficacy of certain plant extracts alone and combination with profenofos against Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae).

Ethyl alcohol, acetone, and petroleum ether extracts of three plant species belonging to three different botanical families [Strychnos nux-vomica(Loganiaceae),Euphorbia lathyrus(Euphorbiaceae), andDatura stramonlum(Solanaceae)], a chemical insecticide; profenofos and their combinations were tested against second and fourth instars ofSpodoptera littoralisunder lab conditions. Results revealed that the ethanol extract ofS. nux-vomicawas the most effective among all plant extracts, where the corrected mortality% were 92, 81, 58, and 27% to 2nd instar and 89, 74, 34, and 11% to 4th instar at concentrations 0.5, 0.25, 0.125, and 0.0625%, respectively. Calculated LC50's were 0.11, 0.22, and 0.34% to 2nd instar and 0.17, 0.37, and 0.52% to 4th instar for ethanol, petroleum ether, and acetone extracts, respectively. Acetone extracts of all plants were of lower effect. The chemical insecticide profenofos displayed higher efficacy than plant extracts (LC50= 0.002 and 0.003% forS. littoralis2nd and 4th larval instars, respectively). The co-toxicity factor reached 76 and 60 when mixingS. nux-vomica+ profenofos andD. stramonlum+ profenofos at ratio 1:1 againstS. littoralis2nd instar larvae, thus indicating a potentiating effect. While treatment of the 4th instar larvae by the same mixtures resulted in a co-toxicity factor below 20 at all mixing ratios indicating, only, an additive effect against this instar. [ABSTRACT FROM AUTHOR]