Entomopathogenic Fungi from South Sumatra, in Solid-dried Formulations, Stored for Three Months and Their Insecticidal Activities
Spodoptera frugiperda is a major pest of maize that can cause substantial yield losses. This study aimed to develop dried solid formulations of entomopathogenic fungi, evaluate their stability during three months of storage, and assess their insecticidal activity against S. frugiperda larvae. Conidia of Beauveria bassiana, Metarhizium anisopliae, and Penicillium citrinum were separately formulated using compost, wheat flour, or rice flour as carriers. The formulations were stored for one, two, and three months and subsequently tested against first-instar larvae at a concentration of 1 × 1010 conidia mL-1 through topical application. All fungal formulations significantly reduced larval body weight and fecal production compared with the control (P<0.05). They also caused significantly higher larval mortality than the control (P<0.05). After one month of storage, larval mortality ranged from 59.33 to 76.67%. The B. bassiana formulation with compost as the carrier maintained relatively high insecticidal activity, causing 76.00%, 70.00%, and 59.33% mortality after one, two, and three months of storage, respectively. After three months of storage, this formulation also resulted in the lowest pupation percentage (40.67%) and adult emergence (20.00%). In addition, the fungal treatments reduced the number of eggs laid by surviving female adults. Overall, the dried solid formulation of B. bassiana with compost showed the most consistent insecticidal activity during storage and therefore has potential as a bioinsecticide candidate against S. frugiperda. Further formulation optimization is required to improve conidial stability and extend product shelf life.