Investigating the plant metabolite potential as botanical insecticides against Spodoptera litura with different application methods

AbstractThis study investigated the effectiveness of botanical insecticides derived from leaf extracts of Azadirachta indica, Aglaia odorata, and Ageratum conyzoides against third instar larvae of Spodoptera litura through different application methods. The plant materials were mixed in a 1:1:1 ratio, extracted with 96% ethanol. The results showed that the botanical insecticides were effective in killing the S. litura larvae through both oral and topical application techniques. The topical application was more effective, with an average mortality rate of 98.75% compared to 82.5% for oral application. The LT50 values were 5.9991 and 3.8555 days for oral and topical treatments, respectively. The topical application was 35.73% faster in inducing mortality in S. litura compared to oral application. The larvae-treated with oral application had the highest total quinine-equivalent alkaloid content at 312.52 mg L−1, while the larvae-treated with topical application had the highest total flavonoid content at 3963.60 µg L−1 in the total flavonoid test. The highest value of total tannic acid-equivalent tannins was observed in larvae-treated with oral application at 1.76% w/v. All larvae that were treated, both orally and topically, in this study were found to contain terpenoids within their body. In conclusion, the botanical pesticides derived from the extracts of A. indica, A. odrata, and A. conyzoides have proven to be effective in controlling S. litura. The topical application technique has been found to be more efficient than oral application in inducing mortality. However, it is crucial to conduct further testing in both greenhouse and field conditions in the future