Efficacy of Sudanese isolates of entomopathogenic fungi against the Khapra beetle Trogoderma granarium (Everts) (Coleoptera: Dermestidae)

Abstract

The current study evaluated the bio-control activity of Sudanese isolates of entomopathogenic-fungi against 3 rd larval instars of Khapra beetle ( Trogoderma granarium ) (Everts) in Sudan and morphologically and molecularly characterized the virulent isolates. Fungi were isolated using Galleria-baiting method and tested against the larvae using immersion-technique at concentration of 1×10 7 conidia ml -1 . Commercial product, Eco-Bb® was used as standard treatment. Twenty of the 3 rd instar larvae were immersed in 10 ml of fungal suspension for five seconds. Control larvae were immersed in sterilized-distilled water. Dead insects were counted daily for seven days after inoculation. Microscopic examination of the cadavers was conducted to explain whether or not the test organisms caused the death of test larvae. Virulent isolates were identified morphologically and confirmed by molecular techniques as Beauveria bassiana isolate Sud-afro.18 (MK046654), Metarhizium anisopliae isolate Dmazeen F1 (MK046658), Metarhizium anisopliae isolate Dmazeen R1 (MK046659), Albifimbria viridis isolate Shmbat-fo1 (MK046656), Purpureocillium lilacinum isolate Khartoum f1 (MK046655), B. bassiana isolate Sud-afro.20 (MK046652), B. bassiana isolate Giddo6RF (MN598664), B. bassiana isolate GiddoR (MN598665), and B. bassiana isolate HammadR7,F (MN598666). Mortality induced by various isolates ranged from 40.0-90.4% compared to 96 and 7.9% induced by standard treatment Eco-Bb® and untreated control respectively. LT 50 values of B. bassiana isolate Sudafro.18 and M. anisopliae isolate DmazeenF1 is comparable to that induced by Eco-Bb®.