Effect of NeemAzal-T/S 1% Azad, entomopathogenic fungus, Verticillium lecanii and their combination on the survival and fecundity of cotton aphid, Aphis gossypii

Ahmed E. M. Hassan

Abstract


The toxic effects of NeemAzal T/S 1% Azad. and isolate (VA) of Verticillium lecanii, on cotton aphid, Aphis gossypii were measured, singly and in dual manner, in the laboratory. Aqueous suspensions of NeemAzal T/S 1% Azad. (varying from 12.5 ppm to 100 ppm) were, added by mist spray on cucumber leaves. The conidial suspensions (varying from 0.156x105 to 1000x105 conidia/ml) were added by immersion of mother aphids (for 5-10 seconds) after feeding on cucumber leaves sprayed with distilled water. For combination test, insects were fed on NeemAzal T/S 1% Azad. (50 ppm) for three days, and then immersed in conidial suspension(0.3x105 conidia /ml) and continued to be fed on treated leaves for extra 5 days. Based on the results of the laboratory experiment, Verticillium lecanii and NeemAzal T/S1% Azad., were both killing the insect in a dose dependent manner, at various insect stages. There was sub-additive synergism in the association of Verticiullium lecanii (0.30 x 105 conidia /ml) and NeemAzal T/S 1% Azad. (50 ppm).The effect of the two bio-agents on insect progeny size was discussed.


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