Fumigant and contact toxicities of individual and additive combinations of biorational-essential oils for control of rice weevil (Sitophilus oryzae.

Fumigant and contact activity of individual and combination of
EOs (cumin seed and black pepper oil) were conducted against
rice weevil (Sitophilus oryzae). Cumin seed and black pepper oil
individually exhibited 100% insecticidal activity (Contact and
Fumigant) against S. oryzae at 24 and 168 h of exposure in the
absence and presence of food, respectively. Overall, differential
insect mortality rates were observed with individual EOs; however,
cumin seed EO showed higher insecticidal activity in both fumi�gant and contact bioassays than black pepper EO. Binary mixtures
of cumin seed and black pepper oil at 60:40 and 80:20 ratios
showed higher toxicity than individual EOs against S. oryzae and
further, additive interaction of binary combinations of EOs
resulted in complete insecticidal activity of S. oryzae. Thus, we
conclude binary mixtures of cumin seed and black pepper EOs
might be a promising prophylactic treatment solution for control
of S. oryzae to prevent stored grain infestation.