Abstract:
Storage of rice is affected by various types of post-harvest pests like rice weevil, lesser grain
borer, and other insect pests. An assessment was conducted to assess the status of storage insect
pests of rice and an experiment was done to evaluate the efficacy of botanicals against rice
weevils on rice under storage conditions in Fogera District during 2021/22 cropping season.
The assessment was conducted based on interviews and visiting the individual household and
collecting a representative sample of grains. Rice weevil (Sitophilus oryzae), lesser grain borer
(Rhyzopertha dominica), red flour beetle (Tribolium castaneum), and angoumois grain moth
(Sitotroga cerealella) were recorded in the surveyed areas. From these insect pests, rice weevil
and lesser grain borer predominantly occurred. Farmers used traditional storage methods like
Gota (32%), Shirfa (27%), Polypropylene bags (25%), and Fertilizer bags (12%) for storing rice
grains. About 29% of farmers in the study area used chemical insecticides than other
management methods. The experiment consists of botanicals like seed and leaf powders of
Datura stramonium, Lantana camara, and Azadirachta indica, and leaf powders of Phytolacca
dodecandra and Eucalyptus globulus at the rate of 5% w/w. Malathion 5% dust as a standard
check and untreated check were included for comparison. Two rice varieties (Shaga and
NERICA-4) were used and the experiment was arranged in CRD with a factorial arrangement in
three replications. Data on the number of dead weevils, progeny emergence, percent protection,
weight loss, grain damage, and germinated seeds were assessed after treatment applications and
subjected to analysis of variance using SAS software. All botanical powders significantly
resulted in higher weevil mortality, progeny reduction, low grain damages, and weight loss.
About 98.29% of adult mortality of S. oryzae was obtained with P. dodecandra leaf powder
which was a statistically comparable effect with Malathion 5% dust. Next to P. dodecandra leaf
powder, 93.16% and 89.74% of adult weevil mortality were obtained from the seed powders of
A. indica and D. stramonium respectively. The minimum grain damage was recorded from P.
dodecandra leaf powder (0.97%) followed by seed powders of A. indica (1.30%) and D.
stramonium (1.50%). The leaf powder of P. dodecandra and seed powders of A. indica and D.
stramonium were the most effective botanicals in all of the variables measured than the rest of
the treatments. Other botanical treatments were also highly significant than the untreated check.
In general, the result showed that the leaf powder of P. dodecandra and the seed powders of A.
indica and D. stramonium can be used as an alternative control method of S. oryzae under
farmer’s storage conditions.