Abstract: 【Aim】 Chemical elicitors have low toxicity to the environment and low frequency to induce pest resistance. Thus, exploiting strategies against pests based on chemical elicitors may largely decrease the application amount of pesticides, thereby promoting sustainable agriculture. This study aims to screen chemical elicitors that can induce the resistance of rice to the brown planthopper (BPH), Nilaparvata lugens. 【Methods】 Rice plants were grown in nutrient solutions containing one of 12 candidate compounds, including jasmonic acid (JA), methyl jasmonate (MeJA), salicylic acid (SA), methyl salicylate (MeSA), brassinolide (BR), benzyl benzoate (BB), strigolactones (SLs), 1-naphthylacetic acid (NAA), 3-indolybutyric acid (IBA), sodium oxalate (SO), potassium silicate (PS), and bismerthiazol (Bis), or smeared with one of these compounds on rice leaf sheathes, and then the egg hatching rate and the number of eggs laid in 24 h by female adults of BPH treated with these compounds were assayed. 【Results】 Among the 12 candidate compounds, only MeJA, BR and BB had significant influence on the egg hatching rate of BPH and the number of eggs laid in 24 h. Rice plants grown in the nutrient solution containing 5 mg/L MeJA significantly reduced the egg hatching rate of BPH to 58.8% (decreased by 20.1%), whereas application of MeJA (0.5 mg per plant) on rice leaf sheathes significantly reduced both the egg hatching rate of BPH to 53.3% (decreased by 35.4%) and the number of eggs laid in 24 h to 203.5 per plant (decreased by 15.6%). Moreover, the higher the concentration of MeJA used, the lower the egg hatching rate of BPH and the number of eggs laid in 24 h. Rice plants grown in the nutrient solution containing 5 mg/L BR decreased the egg hatching rate of BPH to 59.5% (decreased by 22.1%), but had no effect on the number of eggs laid in 24 h. The egg hatching rate of BPH was negatively correlated with the concentration of BR, and the egg hatching rate of BPH on rice plants grown in the nutrient solution containing 20 mg/L BR was decreased by 41.8% as compared to that on the control plants. Besides, the number of eggs laid in 24 h on rice plants grown in the nutrient solution containing 5 mg/L BB significantly reduced to 100.3 per plant (decreased by 26.2%). In vitro bioassay showed that MeJA and BR had no significant influence on the hatching rate of BPH eggs, suggesting that both have no direct toxicity to BPH eggs. 【Conclusion】 These results demonstrate that MeJA, BR and BB can improve the resistance of rice to BPH, among which MeJA and BR function as chemical elicitors.

Key words: Nilaparvata lugens, rice, chemical elicitors, methyl jasmonate, brassinolide