INSECTICIDAL ACTIVITY OF Syzygium aromaticum AND Cinnamomum cassia PLANT VOLATILE OIL AGAINST THE PULSE BEETLE, Callosobruchus maculatus [Fabricius] [Coleoptera : Chrysomelidae]

Abstract

In the present study, insecticidal activity of two plant volatile oils such as Syzygium aromaticum and Cinnamomum cassia were tested for their efficacy against the important stored grain coleoptera pest, the pulse beetle, Callosobruchus maculatus in a conducive environment at laboraroty. The plant volatile oils were individually tested with 50, 100, 150 and 200 mg/ml concentrations on the adult C. maculatus. Initially the grain, Vigna unguiculata were uniformly coated with the selected concentration of the plant volatile oil, air dried, then introduced the adult beetles. After 24, 48, 72 hrs of exposure, the number of insects dead were counted and the percent mortality was calculated by using the standard formula. In the present study, the insecticidal activity of S. aromaticum indicates that the significant mortalities were observed at 200 mg/mL concentration of the S. aromaticum against the insects exposed to 24hrs [82.6%], 48 hrs [88.4%] and 72 Hrs [97.8%]. The trend was followed by 150, 100, 50 mg/mL concentrations with 64.2%, 72.8%, 76.8%; 38.2%, 46.6%, 52.6%; 27.6%, 34.8%, 36.8% at 24, 48 and 72 Hrs respectively.  In the same way, the insecticidal activity of C. cassia indicates that the significant mortalities were observed at 200 mg/mL concentration of the C. cassia against the insects exposed to 24 hrs [80.6%], 48 hrs [86.6%] and 72 Hrs [96.4%]. The trend was followed by 150, 100, 50 mg/mL concentrations with 62.2%, 70.4%, 72.6%; 36.4%, 48.4%, 56.8%; 26.8%, 32.2%, 34.6% at 24, 48 and 72 Hrs respectively.  It is inferred that the plant oils induced remarkable insect mortality on the test insect. Thus, it can be possibly utilized to mitigate the infestation of the pest in stored condition and also phytochemicals are eco-friendly, safer to non-target organisms.