Isolation, molecular identification, and efficacy of indigenous entomopathogenic fungus isolates against Tribolium confusum (Coleoptera: Tenebrionidae) larvae and adults

Entomopathogenic fungi (EPF) represent the future of pest control, as they have the capacity to induce serious infections in insects, trigger epizootics, and effectively manage insect populations. The study aimed to identify and test indigenous EPF isolates against Tribolium confusum using soil samples from Northwestern and central Saudi Arabia. Galleria mellonella larvae were used as insect bait to collect EPF from soil samples from date palm groves, fruit groves, and maise fields. Only 27.3% of soil samples tested positive for palm grove-originating EPFs. Polymerase chain reaction (PCR) identified the cultured fungi as Metarhizium anisopliae and Beauveria bassiana. Tribolium confusum pathogenicity was assessed using nine local fungal isolates. Different fungus isolates were tested for their pathogenicity on larval and adult T. confusum. The results showed that M. anisopliae MaSA-2, MaSA-3, and MaSA-4 had infection rates of 85%, 85%, and 75%, respectively, in last-instar T. confusum larvae and 5%, 10%, and 20% in adults within seven days. On the other hand, B. bassiana BbSA-4 showed a 100% infection rate in T. confusum larvae, while BbSA-5, BbSA-6, BbSA-7, BbSA-8, and BbSA-9 had infection rates of 70%, 80%, 80%, 75%, and 95%, respectively. In terms of adult mortality rates, B. bassiana BbSA-4, BbSA-5, BbSA-6, BbSA-7, BbSA-8, and BbSA-9 had rates of 25%, 35%, 35%, 20%, 20%, and 40%, respectively. The research findings show that indigenous B. bassiana and M. anisopliae fungus isolates successfully eliminated T. confusum larvae, although their effectiveness against adults was limited.