EFFECT OF FEEDING TWO PREDACIOUS INSECTS ON APHIDS TREATED WITH SOME ENTOMOPATHOGENS

Abstract

Chrysoperla carnea (Stephens) and Orius albidipennis (Rueter) are a biological agents commonly used to control insect pests. Three concentrations (107, 108 and 109 spores/ml) of entomopathogenic agents Beauveria bassiana (Balsamo), Metarhizium anisopliae (Metsch) and Bacillus thuringiensis var. kurstaki (Berliner) were evaluated against the 2nd instar larvae of C. carnea and 2nd instar nymph of O. albidipennis. Aphids and its containers were sprayed with each concentration of spores suspension by small sprayer. The treated aphids were offers to predators as prey under laboratory conditions (27 ± 2 oC, 65 ± 10% RH). Mortality was recorded daily from the 2nd day to the 6th day of treatment. The results revealed that , the values of the a cumulative percentage mortalities of C. carnea and O. albidipennis increased gradually from the 2nd day to the 6th day after exposure and increased by increae concentrations of B. bassiana, and M. anisopliae. While the third agent, (Btk.) had no effect on two tested predators till the 5th day and had slight effect on the 6th day. The LT50 values of C. carnea treated with B. bassiana and M. anisopliae were 11.22 and 12.61day at concentration of 107 spores /ml and were 10.05and 11.01day at concentration 108 spores /ml and were 8.004 and 10.73day at concentration 109, respectively. But not detected LT50 values for (Btk) against C. carnea or O. albidipennes at concentrations 107, 108 and 109 spores/ml. Whereas, The LT50 values of O. albidipennes treated with B. bassiana and M. anisopliae were 6.3 and 5.82day at concentration 107 spores /ml and were 6.023 and 5.59day at concentration 108 spores /ml and were 3.56 and 4.32day at concentration 109, respectively.