Insecticidal activity of kaffir lime (citrus hystrix) against rice weevil (sitophilus oryzae)

Abstract

Rice weevil, Sitophilus oryzae L. known as one of the major pests of stored grain, they ate the rice and lay eggs inside rice kernels. Bioinsecticide have known as one of the safest insecticide in term of its sustainability and eco-friendly manner. Thus the aim of this study is to identify the potential of using kaffir lime extract as the bioinsecticide and substitution of chemical insecticide. Therefore the insecticidal activity of kaffir lime extract against rice weevils were tested with contact activity, repellency, antifeedant as well as progeny growth and development test under laboratory condition. The mortality of adults increased with increasing concentration of extracts from 10 to 50 mg/L after 24 hours of exposure. The kaffir lime leaves extract (LC50=18 mg/L) showed higher mortality rate compared to fruits peel extracts (LC50=54 mg/L) with 100 % and 60 % mortality, respectively. The leaves extracts with mean repellency of 68 % were significantly repelled rice weevils compared to 42 % repellency of fruits peel extracts. It also found that leaves extract was classified in repellency class IV meanwhile peel extract was in repellency class II. Kaffir lime leaves extracts also showed the ability to prevent antifeedant activity and opposed to progeny production. Furthermore, F1 adults were completely suppressed at the concentration of 20 mg/L with 100 % of inhibition rate. Between leaves and fruits peel extracts, findings in present study revealed that ethanolic extracts of kaffir lime leaves has strong insecticidal activity and were able to protect stored rice against rice weevils. Based on the effective control of rice weevils by the kaffir lime leaves extract, it could be useful in stored grain products and plant protection and also reduce the dependency to synthetic insecticide and risk associated with it.