Exploring the biocontrol efficiency of indigenous entomopathogenic fungus on Cadra cautella (Lepidoptera, Pyralidae) larvae in controlled laboratory conditions

Cadra cautella (Walker, 1863) is a global pest of agricultural stored commodities, particularly date fruits, in the field and storage. To reduce C. cautella populations in stored agricultural goods, it is recommended to use ecologically friendly methods rather than chemical treatments. In this regard, current research evaluated the efficacy of various indigenous strains of the entomopathogenic fungus Beauveria bassiana (Bals.-Criv.). Vuill. (1912), fungal isolates against C. cautella last-instar larvae under laboratory conditions. The last instar larvae were incubated in Petri plates with dry Beauveria bassiana inoculum (1 × 107 conidia/mL) for five minutes per fungal isolate. The susceptibility of C. cautella larvae to fungal infection was tested until either 100% mortality across all treatments was achieved or the control larvae had transformed into pupae. The results showed that, compared with the control treatment, all fungal isolates were pathogenic to C. cautella larvae, with varying levels of reaction and durations of mortality. After four days of inoculation, the B. bassiana isolates BbSA-5, BbSA-8, and BbSA-9 infected treated C. cautella larvae at rates of 16.66%, 23.33%, and 43.33%, respectively. The death rate of C. cautella larvae increased significantly, reaching 91.66% for BbSA-5 isolates after eight days of the treatment, while BbSA-5 and BbSA-9 isolates achieved 100% mortality after sixteen days. The control treatment resulted in no larval mortality. Furthermore, all C. cautella larvae in the control group pupated and successfully matured into adults. It is determined that the examined dry formulations of local fungal isolates have the capacity to protect stored agricultural commodities, including date fruits, from C. cautella infestation.