Effects of .Oils of Eight Different Plants against the Angoumois Grain Moth, Sitotroqa cerealella (Olivier)(Lepidoptera: Ge1echiidae)in Rice.
ASHAMO, M.O., MORAWO, T.O. AND OKE, B.I.
ABSTRACT: The efficacy of oils from eight indigenous plants against Angoumois grain moth, Sitotroga cerealella (Olivier) infesting rice (Oryza sativa L.) was investigated in the laboratory at ambient temperature and relative humidity (28±2°C, 75±5%RH). Oils extracted
from the seeds of Piper guineense Schum and Thonn, Monodora myristica Dunal, Tectona grandis L, Ricinus communis L, Arachis hypogaea L, Elaeis guineensis, the bulb of Allium sativum L, and the rhizome of Zingiber officinale Roscoe, Jacq. were tested at 1- 3%
concentration. Results showed that the oils significantly (P<0.05) prolonged developmental period for eggs, suppressed adult emergence and reduced longevity compared with effects on similar parameters in the control. P. guineense had the highest insecticidal activity by totally preventing adult emergence at 2% oil concentration. P. guineense, A. sativum and A. hypogaea
were able to prevent adult emergence at 3% oil concentration. At all concentrations, not more than 10% adult emergence was recorded for M myristica, when compared with P. guineense showing that it also exhibited a high level of insecticidal activity. Adult emergence was also significantly higher (P<0.05) in the controls (46.7 and 48.3%) than in seeds treated with E. guineensis. Developmental period was longest (39.0 days) in seeds treated with M myristica at 3% concentration. The adults in the controls lived longer than those in treated seeds while females generally lived longer than the males. Seed germination was not affected by the oil treatments as the values were virtually at par with those obtained from untreated seeds.