Evaluations of susceptibility of the third instar larvae of Ephestia kuehniella to some extract plants

Usage of synthetic insecticides has resulted in a polluted environment and increased the resistance ofinsects to insecticides. Therefore, employment of environmental friendly alternatives is warranted. In thisstudy, insecticidal activity of ethanolic extracts derived from leaves of Orobanche spp (Convolvulaceae),Calotropis procera (asclepiadaceae) and Nerium oleander (Apocynaceae) was assayed on larvae (thirdinstar) of Ephestia kuehniella (Zell.) (Lepidoptera: Pyralidae) under laboratory conditions. Bioassays werecarried out at 27±1 ºC and 60 ± 5% R. H. under dark condition adopting a complete randomized blockdesign. Five concentrations of ethanolic extract were tested in four replications with 20 larvae (third instar)insect in each replication. Treated filter papers (4 × 5 cm), were placed at the bottom of 280 ml glass jars.Twenty larvae (third instar) were placed in small plastic tubes with open ends covered with cloth mesh. Thetubes were hung at the geometrical centre of the glass jars, which were then sealed with air-tight lids.Mortality was recorded after 24 h. LC50 value for ethanolic extract from Orobonche spp, Calotropis proceraand Nerium oleander were estimated 117.35 ، 58.92 ی 66.39 μl/L air, respectively. The LC95 were calculated259.96 ی 276.17 ی 308.96 μl/L air respectively. The results indicated that the fumigant activities were increasedwith increasing concentration of plant extracts. As a result, ethanolic extract of Nerium oleander showedhighest toxic efficiency against the E. kuehniella

کلیدواژه ها:

Plant extract ، Ephestia kuehniella ، Third instar larvae ، Fumigant toxicity