Insecticidal and oviposition deterrent properties of some spices against coleopteran beetle, Sitophilus oryzae.

Eighteen spices were screened for their insecticidal
potential and antiovipositional properties against the
rice weevil- Sitophilus oryzae—a serious insect pest of
stored food grains. The bioefficacy of the powders and
hexane extracts of selected spices were determined by
assessing the toxicity, effect on F1 progeny, contact toxicity,
persistence and seed viability. Responses varied with the
spices, dosage and exposure time. Powders of mace and
pepper, at 1% level were highly effective resulting in total
mortality of S. oryzae by one week followed by nutmeg and
clove with 100% mortality and cinnamon and star anise
with 90% mortality at 5% concentration. These spices also
completely inhibited F1 progeny. The hexane extracts of
these spices at 1,000 ppm showed insecticidal activity, with
pepper extract recording 100% mortality by 5 days. S.
oryzae was susceptible to clove oil resulting in 92%
mortality. Mortality was 51.63% in nutmeg, 66.6% in
cinnamon, and 79.8% in case of mace and star anise.
Hexane extracts of star anise, cinnamon and clove at
0.59 μl/cm2 on filter paper discs induced 100% mortality
by 72 h. These spices offered protection to wheat up to
9 months without affecting seed germination thereby
showing promise as grain protectants.