Entomopathogenic Action of Wild Fungal Strains against Stored Product Beetle Pests

SIMPLE SUMMARY: Stored product pests cause significant losses to agricultural products every year. Their control depends heavily on the use of fumigants and other insecticides, which have many negative consequences for humans and the environment. Nowadays, the use of fungal entomopathogens is one of the most promising alternatives to reduce the use of chemicals in storage facilities. We tested new wild strains of entomopathogenic fungi from the genera Cladosporium, Condenascus, Lecanicillium, and Penicillium in laboratory bioassays on various storage beetles. All strains caused remarkable mortality in adult beetles, reaching 80% in some cases after 21 days. The results of our study show that insect-pathogenic fungi can be effective biological tools for the protection of stored agricultural products. Research to discover new strains with high pathogenicity and to develop new methods for mass production and standardization of entomopathogens should be continued to enable their practical application in the future. ABSTRACT: There is ample evidence that entomopathogenic fungi can be used as alternative biological control agents for the management of insect pests in storage facilities. As the market demands more environmentally friendly methods and chemical insecticides become increasingly obsolete, more studies are being conducted to evaluate new strains of entomopathogenic fungi for their efficacy in storage facilities. In this context, we tested ten species of fungi isolated from soil, belonging to the genera Cladosporium, Condenascus, Lecanicillium, and Penicillium, for their long-term effects on economically important beetle species. Whole wheat was directly sprayed with a conidial suspension of 10(8) spores/Ml of each of the tested fungi and then adults of Sitophilus granarius, S. oryzae, S. zeamais, Rhyzopertha dominica, and Trogoderma granarium were placed on the sprayed medium to study the mortality effects. Significantly higher mortality than the control was observed in all treatments. The lowest LT(50) (9.164 days) was observed in T. granarium infected with Penicillium goetzii. The isolate with the strongest results was L. dimorphum, which recorded remarkably low LT(50) values in S. oryzae (~11 days), R. dominica (~12 days), T. granarium (~10 days), and S. granarius (~13 days). However, for S. zeamais, it was more than 16 days. Our results confirm the existing literature on the efficacy of EPF on storage beetles, suggest the possible virulence of wild untested strains, and also highlight the importance of EPF specificity.