Effectiveness of entomopathogenic fungi and plant extract against the rust-red flour beetle <i>Tribolium castaneum</i> (Coleoptera: Tenebrionidae) adults

Abstract

The darkling beetle, also known as the rust-red flour beetle Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a major pest that destroys grains and flour. It is also commonly used for research on ethology and food safety. The use of entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae, and Verticillium lecanii) and chemical insecticides to control T. castaneum has been limited due to concerns about environmental sustainability. As a result, there is a pressing need to find environmentally friendly insecticides against this pest. This study evaluates the effects of entomopathogenic fungi and an extract from the green shoots of Arta, Calligonum comosum L'Hér., on adult T. castaneum. The fungi used in this study were isolated from soil in Egypt, while the plant extract samples were collected from natural vegetation in southern Sinai, Egypt. Different concentrations of the ethanolic plant extract (50, 75, and 100%) were applied to T. castaneum, and the effects were observed every 3 hours over a 24 hrs. period. The entomopathogenic fungi proved to be effective against adults of T. castaneum, B. bassiana, and V. lecanii causing 86.67% and 60.0% mortality, respectively, after seven days of infection at a concentration labeled as (C3). M. anisopliae, on the other hand, resulted in 100% mortality after seven days when infecting the (C3) concentration. The shoot extract of Arta, C. comosum, also exhibited effectiveness, with total mortality rates recorded after 48, 72, and 72 hrs. corresponding to concentrations of 100, 75, and 50, respectively. This study concludes that both the entomopathogenic fungi and C. comosum extract contain bioactive compounds that are toxic to T. castaneum.