Effectiveness and the synergism effects of Ipomoea cairica leaf plant extract and Metarhizium anisopliae fungi (Meta-G4) against larvae of Aedes aegypti Linnaeus and Aedes albopictus Skuse (Diptera: Culicidae).

Insecticide resistance is a major public health concern. Biopesticides, derived from naturally occurring substances such as plant extracts and fungal metabolites, are utilized as natural control agents against mosquito vectors. This study focuses on biopesticides to reduce chemical insecticide use in Penang Island, Malaysia. Ipomoea cairica Linnaeus Sweet (Solanales: Convolvulaceae) leaf extracts, Metarhizium anisopliae s.l. (Metsch) Sorok (Ascomycota: Clavicipitaceae) strain Meta-G4, and synergistic effects of both agents were demonstrated against Aedes albopictus Skuse (Diptera: Culicidae) and Aedes aegypti Linnaeus (Diptera: Culicidae) using larvicidal bioassays. Before assessing synergism, the compatibility of both agents was performed to minimize inhibition of mycelial growth on potato dextrose agar. The results showed that Ae. aegypti field strains (urban and suburban) are significantly more susceptible to I. cairica leaf extracts compared to Ae. albopictus field strains (urban and suburban) due to the lower lethal concentrations (LC50 and LC95). Aedes albopictus suburban field strain is significantly more susceptible than other strains when tested with M. anisopliae due to the lower LC50. The combination of M. anisopliae (1 × 106 conidia/ml) with I. cairica leaf extracts (350 ppm) achieved the lowest LT50 and LT95 against Ae. aegypti urban field strain. This study indicates that the synergistic combination of both agents exhibits significant larvicidal efficacy and holds promise for future biological control strategies targeting Aedes populations.