Toxicity and chemical compounds of Piper aduncum fruit extract against storage pest Sitophilus oryzae and Callosobruchus maculatus

Abstract

Insect pests of rice weevil of Sitophilus oryzae and cowpea beetles of Callosobruchus maculatus can reduce the quality and quantity of stored products. Various alternatives development to control insect pests more safely were necessary. Botanical insecticides can be used as an alternative control because of their several advantages. One of the potential plants as a source for botanical insecticides is Piper aduncum (Piperaceae). This study aimed to determine the chemical constituents of ethyl acetate extract of P. aduncum fruit (Ea-Pa) and to assess its toxicity against S. oryzae and C. maculatus female adults by contact residue. The most abundant chemical compound of Ea-Pa was dillapiol (61.54%). Dillapiol was one compound that might be responsible for the insecticidal properties, as well as ylangene, naphthalene, piperitone, hexadecanoic acid, β-eudesmene, α-cubebene, δ-cadinene, myristicin, cis-vaccenic acid, pregnane steroids, octacosane, pyridine, sitosterol, and caryophyllene. The toxicity assay results showed that the Ea-Pa was more toxic against female adults of C. maculatus than S. oryzae. The LC₅₀ values for female adults of S. oryzae and C. maculatus were 4.05% and 0.17%, whereas LC₉₅ values were 116.40% and 4.95%, respectively. Therefore, the Ea-Pa could be further improved as a natural insecticide to manage pest insects in storage.