Analysis of volatile components in Piper nigrum and Cinnamomum cassia and their repellent activity against Megalurothrips usitatus
The cowpea faces a severe pesticide residue issue,primarily due to chemical control targeting Megalurothrips usitatus.It is urgent to implement eco-friendly pest control.Utilizing plant volatiles for pests repellence is an important pest control method.In this study,the volatile compositions of Piper nigrum and Cinnamomum cassia were analyzed using GC-MS,and the effects of P.nigrum,C.cassia,and five major volatiles on the behavioral response of M.usitatus were measured using a Y-tube olfactometer.The results showed that P.nigrum contained 27 volatile components,with P-caryophyllene being the main component(43.1%).C.cassia contained 21 volatile components,with cinnamaldehyde(28.4%),α-copaene(15.4%),α-muurolene(14.1%),and γ-cadinene(14.9%)being the main components.Behavioral response tests showed that P.nigrum and C.cassia had significant repellent activity against M.usitatus.β-caryophyllene,cinnamaldehyde,and α-copaene at concentrations of 10% and 1%exhibited significant repellent activity against M.usitatus,and 10% α-muurolene and 10% γ-cadinene had significant repellent activity against M.usitatus.This study holds crucial significance for the development of eco-friendly control methods and repellents targeting M.usitatus on cowpea crops.