Laboratory Evaluation of Two Species of Entomopathogenic Fungi as Biological Control Agents Against The Stored-Grain Insect Pest, Sitophilus granarius L. (Coleoptera: Curculionidae), and their Histological effect on Albino Rats

This study aimed to evaluate the efficacy of two entomopathogenic fungi, Beauveria bassiana, and Metarhizium anisopliae, against the adults of Sitophilus granarius (Coleoptera: Curculionidae), are stored grains primary insect pest at two temperatures 20 and 30 ±2 °C and relative humidity 65±5% under laboratory conditions. The residual impact of the two entomopathogenic fungus on the treated wheat was evaluated concerning histological changes in different organs of rats fed on the treated wheat. Five concentrations were tested from two entomopathogenic fungi, and dead individuals were counted daily, following treatments, for 21 days. Lethal time values (LT₅₀ and LT₉₀) for the two entomopathogenic fungi were calculated. The results demonstrated that the mortality varied according to the temperature and tested the two entomopathogenic fungi. The mortalities increased by increasing the temperature. The mortality percentages of the treated insect by the two entomopathogenic fungi at 10% concentration and 20 °C after 21 days were 87.77%, and 80% for B. bassiana and M. anisopliae, respectively. Whereas, when the temperature increased to 30 °C, the percentage of mortality increased to 90% for  B. bassiana and 86.66% for M. anisopliae. LT₅₀ values for B. bassiana and M. anisopliae were 10.12 and11.42 days, respectively, and LT₉₀ values were 24.33 and 29.96 days, respectively, at 20 °C for S. granarius. While, LT₅₀ values for B. bassiana and M. anisopliae were 9.51 and10.09 days, respectively, and LT₉₀ values were 23.22 and 24.80 days, respectively, at 30 °C. Histological examination for the rats fed on treated wheat with entomopathogenic fungi was done. Overall, the liver; kidney, and lung were affected through the appearance of mild histological changes.  This study indicated that B. bassiana and M. anisopliae had significant potential as biological control agents against S. granarius.