Efficiency of indigenous plant extracts against rice weevil Sitophilus oryzae (L.)

Abstract

Rice weevil (Sitophilus oryzae L.) can destroy almost all grains. It is an economically important insect pest and causes decreased quality and quantity of stored product. The objective was studies on repellant, contactant, and fumigant effect of 10 plant extracts including rice paddy herb (Limnophila aromatic Merr.), wildbetal leafbush (Piper sarmentosum Roxb.), Vietnamese coriander (Polygonum odoratumLour.), hoary basil (Ocimum americanum L.), sweet basil(Ocimum basilicum L.), bitter gourd (Momordica charantia L.), tree basil (Ocimum gratissimum L.), gotu kola (Centella asiatica (Linn.) Urban.), dill (Anethum graveolens L) and kaffir lime(Citrus hystrix DC.). The plants were extracted with ethanol solvent, crude extracted were tested against rice grain weevil, Sitophilus oryzae for repellency, contact, and fumigant effect in laboratory condition at the concentrations of 0, 25, 50, 75, and 100% (w/v). The result showed that the most effective for repellency of rice weevils was kaffir lime at the 100% (w/v) concentration (81.69%) after 24 hours followed by hoary basil (73.56%) and sweet basil (71.75%). For contact toxicity, after 72 hours crude extracted of sweet basil at LC₅₀ 43.65 g/ml could killed rice weevil 100%followed by kaffir lime (80%) LC₅₀ 123.03 g/ml and rice paddy herb (46%) LC₅₀151.36 g/ml. For the fumigant effect, at 24, 48, and 72 hours crude extracted of sweet basil at the rate of (%) pave the good mortality of rice weevil at 24, 86, and 100% respectively. This study is the basic knowledge to develop plant extracted for controlling rice weevil in stored product.