Toxicity of Acmella oleracea (L.) R.K. Jansen Crude Extracts to the Nymphal Instars of the Brown Planthopper (Nilaparvata Iugens)

Abstract

     Rice brown planthopper (BPH) also known as Nilaparvata Iugens is a very serious pest that attacks rice plants, resulting in crop loss. One of the strategies in controlling this pest is use of herbal plants as insecticides. In this current study, therefore, toxicity test of hexane and methanolic crude extracts from Acmella oleracea obtained from Soxhlet technique was evaluated on N. Iugens nymphs. All trails were done by spraying with different concentrations of extracts (0, 1, 250, 2,500, 5,000 and 10,000 ml/L) and the insect mortality was observed at 12, 24, 36, and 48 hours after exposure. It was found that A. oleracea hexane extract displayed LC₅₀ of the treated N. Iugens in 12, 24, 36, and 48 hours of 17,548.70, 5,937.99, 4,191.06 and 2,792.34 ml/L. Meanwhile, LC₅₀ A. oleracea methanolic extract valued 13,594.35, 3,418.03, 2,015.15 and 1,270.18 respectively. Regarding the mortality rate, the concentration at 10,000 ml/L of A. oleracea methanolic extract showed the highest effectiveness in killing N. Iugens with 100% mortality after exposure for 48 hours. Nonetheless, no significant difference in the mean total mortality of N. Iugens from both extracts in all times of exposure (p≥0.05). From these results, both extracts are likely to be further applied in preventing this N. Iugens in the agricultural system.