INSECTICIDAL POTENCY OF NATIVE ENTOMOPATHOGENIC FUNGI ISOLATES AGAINST THE Galleria mellonella (LEPIDOPTERA: PYRALIDAE) AND Spodoptera littoralis (LEPIDOPTERA: NOCTUIDAE) Larvae.

Document Type : Original Article

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Department of Pesticide chemistry and Technology, Faculty of Agriculture, Alexandria University

Abstract

The entomopathogenic fungi (EPF) have received considerable attention for their potential use in biological control of insect pests. In this study, twenty four native strains were isolated from Alexandria governorate.  This isolates were identified as 21 Beauveria bassiana (Ascomycota: Hypocreales) isolates and three isolates of Metarhizium anisopliae (Ascomycota: Hypocreales).  Isolates were preliminary evaluated at 1x108 conidia ml-1 under laboratory conditions against 3rd instar larvae of Spodoptera littoralis and 4th instar of G. mellonella larvae. In addition, concentration-mortality relationship was conducted for selected three native B. bassiana isolates compared with two exotic isolates B. bassiana (Bio-power) and M. anisopliae (Bio-magic).  The result revealed that the larvae of G. mellonella were more sensitive than Spodoptera littoralis to all EPF isolates with LT50 range (6.28– 11.21days) and (7.81–13.28 days) respectively.  The results indicated a significance difference (α = 0.05) for 13 native EPF isolates in their speed of kill (LT50) toward G. mellonella than S. littoralis. In addition, the concentration–mortality relationship assay showed that larvae mortality increase in a linear relationship with conidia concentration and the Bb-Mo12 a native isolate causing higher mortality percentage in both tested larvae, while Bio-power caused the lower mortality percentage in both larvae at higher tested concentration. The result show that Bb-Mo12 isolate have a lower LC50 1.3X106 and 1.1X107 conidia ml-1 toward G. mellonella and S. littoralis larvae respectively. from these results, we could conclude that there are a variation between native EPF isolates in their virulence toward insect pest and some isolates have a promising potential for use as biocontrol agents in the field of insect control.
 

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