Efficacy of Paederia foetida L. volatile oil as a green insecticide against groundnut seed beetles (Caryedon serratus)

Abstract

The groundnut bruchid, Caryedon serratus is a significant pest of stored groundnut (Arachis hypogaea L., family: Fabaceae, order: Fabales) grains. The pest negatively impacts peanut quality and market acceptance as they internally consume seeds. A study was carried out in the laboratory to determine whether the volatile oil found in the aerial portions of Paederia foetida L. is effective in controlling the groundnut pest Caryedon serratus. The morphological characters, molecular taxonomy, and systematic position of the plant were identified. The volatile oils present in the plant parts were extracted using Clevenger's apparatus and tested as a natural biopesticide against C. serratus. The active phytocompounds found in P. foetida volatile oil were identified by gas chromatography and mass spectrometry (GCMS). Two concentrations of the volatile oil, such as 50 % and 100 %, were applied for 96 h to different stages of C. serratus in the laboratory condition. Both concentrations significantly reduced the mortality rate of C. serratus eggs and adults. The maximum percentages of reduced hatching of eggs and death of larvae of the insects were 95.6 ± 0.07 % and 92.0 ± 0.10 %, respectively. The application of volatile oil resulted in an imbalance in the sex ratio of the insect, and the value was 0.30. The percentage of adult mortality of C. serratus was 91.0 ± 0.02 % after 4 days of the volatile oil treatment. Further, the oil also affected the fecundity of females developed from C. serratus eggs as well as the various developmental phases of insects. The investigation concludes that outcomes are limited to laboratory conditions only, and an extensive field validation is required before recommending large-scale application.