Eco-friendly botanical insecticides to control brown leafhoppers and their effects on the predators and aquatic environment

Abstract

BACKGROUND AND OBJECTIVES: The brown planthopper (Nilaparvata lugens) (Hemiptera: Delphacidae) is a major pest in rice cultivation, frequently causing severe crop losses. Traditionally, the approach to managing this problem has been predominantly reliant on synthetic insecticides, which carry substantial environmental and health hazards. The objective of this field study was to evaluate the performance of a botanical insecticide in lowering pest populations, boosting rice yield, and sustaining ecological equilibrium.METHODS: The research tested Rajam 65 emulsifiable concentrate (patent number individual development plan 00202007448), a botanical insecticide, alone and in combination with a synthetic insecticide containing buprofezin as the active ingredient. Treatments were applied four times at weekly intervals. The study included observations on pest reduction rates, improvements in rice yields, the dynamics of predator populations, and laboratory toxicity tests conducted on tilapia and common carp to determine aquatic safety.FINDINGS: Results showed that the botanical insecticide alone achieved 97 percent pest mortality, reducing the population from 16.3 to 0.73 individuals per clump and keeping infestations below the economic threshold. Following the combination treatment, pest populations were significantly reduced from 26.63 to 2.17 individuals per clump. Furthermore, there was a notable increase of 16.39 percent in rice yield as a result of the treatment. Natural predator populations, such as spiders and Cyrthorinus lividipennis, remained stable across treatments, demonstrating the insecticide's compatibility with integrated pest management systems. The results of toxicity testing showed that there is a low level of risk to aquatic species like common carp and tilapia. The 96-hour lethal concentration caused 50 percent mortalities values of the botanical insecticide for common carp and tilapia are 0.101 and 0.144 critical concentrate per liters, with toxicity units of 0.025 and 0.017, respectively. Given that these values fall below 0.3, the insecticide poses no harm and is deemed safe for fish farming in the waters of paddy fields.CONCLUSION: The botanical insecticide proved highly effective in controlling N ilaparvata lugenspopulations while demonstrating ecological and economic benefits. By applying treatments on a weekly basis, pest populations were effectively diminished to levels far below the economic threshold, which in turn enhanced rice yield. The insecticide's sustainable attributes, including its eco-friendliness, scalability, and compatibility with integrated pest management, emphasize its potential as a viable alternative to synthetic chemicals for controlling pests in rice cultivation.

Keywords

• botanical insecticides
• eco-friendly
• nilaparvata lugens
• rice