Abstract
Laboratory tests and a semi-field trial were carried out to determine the efficiency of two commercial preparations of the entomopathogenic fungi,Beauveriabassiana and Metarhiziumanisopliae namely; Biosect w.p., and Bioranza10 % w.p., against the first instar larvae of the cotton leaf worm, Spodoptera littoralis(Boisd.) and, Agrotis ipsilon(Hfn.)(Lepedoptera : Noctuidae). Newly hatched, one- day and two- day old larvae of the two insects were allowed to feed on castor oil leaves (100 gram / replicate) treated with different concentrations of the two entomopathogenic fungi for 48hrs at three different temperatures, 20, 25 and 305C. Mortality rate increased by increasing the concentration, or post treatment period and temperature. Newly hatched larvae were the most sensitive to the toxic effect especially at highest concentration and temperature(305C), while the two- day old larvae were the most tolerant and the one-day old larvae expressed a moderate tolerance. S. littoralis was more sensitive than A. ipsilon. Calculated LC50s values for initial mortality of the newly hatched larvae were (0.458, 0.309 and 0.279 mg/ml. when treated with Biosect and (0.676, 0.352 and 0.317 when treated with Bioranza) at 20, 25 and 25 5C, respectively. Consumed castor oil leaves were decreased by increasing the concentration and temperature but were lower than the control.
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