Abstract:
Essential oils have been used as an alternative method to reduce postharvest losses from rice
weevil, Sitophilus oryzae in traditional rice varieties cultivated in Sri Lanka. In the present study
essential oils extracted from Cinnamon leaves (Cinnomomum zeylanicum) and Citronella leaves
(Cymbopogon nardus) were used to control rice weevil, in three traditional rice varieties,
Rathkanda al, Pachchaperumal, Suwandal along with a hybrid variety, White raw rice
cultivated in Sri Lanka. Kaolin pellets treated with test essential oil mixture, C. zeylanicum and
C. nardus (2: 1 v / v) were used to test the effect on rice. The major components of the essential
oils of C. zeylanicum leaf oil and citronella oil were eugenol, citronellal and geraniol. Number
of S. oryzae in treated rice samples throughout the test period were significantly decreased
compared with the controls. A significant decrease of % seed damage was also observed during
the 6 months of storage of rice in polyethylene bags. Flavor, aroma, and stickiness of cooked
rice have enhanced significantly in all treated rice varieties compared to controls. The physical
and organoleptic properties of cooked rice were not significantly different with controls after 6
months of treatment. Only 5 % weigh loss of kaolin tablets was revealed after completing the
test. The insecticidal activity of the above essential oil mixture showed the highest effect on the
rice type Suwandal.
