Efficacy of plant extracts for controlling of rice weevil (Sitophilus oryzae)

Abstract

Rice weevils (Sitophilus oryzae) are one of the most important insect pests. This insect cause serious damage in stored agricultural product in terms of quality and quantity damages. Currently, the organic rice is produced. Therefore, plant extracts are used for control of insect pest during the organic rice production process. This study examined the efficacy of 6 plant extracts including black pepper (Piper nigrum), tobacco (Nicotiana tabacum), neem (Azadirachta indica), turmeric (Curcuma longa), galangal (Alpinia galangal) and kaffir lime leaves (Citrus hystrix) as a control agent for rice weevils, S. oryzae.The plant extract concentration was 1,000,000 mg/L. A complete randomized trial (CRD) was planned for 7 treatments with 4 replications. The insects were used in the adult stage of 10 individual per replication. The results showed that the crude extracts from plants showedstatistically significant different efficacy for control of rice weevils (p<0.001). Black pepper extracts were the most effective in killing rice weevils of 100%, followed by tobacco and neem extract with 27.5% and 20.0%, respectively, which were statistically significant different from the control treatment using water (p<0.001). Rice weevils have an increasing cumulative mortality rate after exposure with plant extracts. The black pepper extract showed the highest insect mortality rates after spraying for 24, 48, 72 and 96 hours of 72.5%, 87.5%, 97.5% and 100%, respectively. The turmeric, galangal and kaffir lime leaves extracts did not have significant different with the percentage of insect mortality compared to the water treatment. Moreover, none of insect death was found after spraying with galangal and leech lime leaf extracts. Our result conclude that black pepper extracts can be use in the control of important agricultural pests to reduce the use of chemical.