Efficacy of tobacco and tea leaf extracts for controling brown planthopper (Nilaparvata lugens (Stål, 1854)) and their impact on green mirids (Cyrtorhinus lividipennis Reuter) in rice paddy fields

Abstract

This study aimed to investigate the efficacy of tobacco leaf and tea leaf oil extracts in controlling brown planthoppers (Nilaparvata lugens Stål, 1854) and their impacts on green mirid (Cyrtorhinus lividipennis Reuter) in rice paddy fields in Ongkharak District, Nakhon Nayok Province, Thailand. Field experiments were conducted from January to April 2024 via a randomized complete block design (RCBD) with three replications. The treatments were composed of tobacco leaf extracts at 5% and 10% conc., tea leaf oil extracts at 5 and 10% conc., with three controls (a petroleum oil-based insecticide (SKN Spray 99) at 60 cc./20 lts of water, cypermethrin insecticide at 20 cc./20 lts of water and water). The results of the present study revealed that 75 days after transplanting (DAT), water with an average of 11.15 insects per hill and 5% tea leaf oil extract (9.73 insects per hill) resulted in a high brown planthopper density that caused economic damage. However, the use of plant extracts can control the brown planthopper population to a level that does not cause economic damage, as can the use of chemicals, namely, 10% tobacco extract (3.37 insects per hill), 5% tobacco extract (3.62 insects per hill), 10% tea leaf oil extract (5.00 insects per hill), petroleum oil (60 cc per 20 liters of water) (3.46 insects per hill), and cypermethrin (20 cc per 20 liters of water) (2.57 insects per hill). In terms of green mirid (Cyrtorhinus lividipennis Reuter) populations, the application of plant extracts at different concentrations resulted in statistically significant differences in their abundance. At 75 days after transplanting (DAT), the water had the greatest number of green mirids (6.00 insects per hill), followed by 5% tobacco extract (4.50 insects per hill), 10% tea leaf oil extract (4.25 insects per hill), 5% tea leaf oil extract (4.00 insects per hill), 10% tobacco extract (3.00 insects per hill), petroleum oil (60 cc per 20 liters of water) (2.50 insects per hill), and cypermethrin (20 cc per 20 liters of water) (1.25 insects per hill). However, the use of cypermethrin (20 cc per 20 liters of water) was more effective at reducing brown planthopper populations than plant extracts were, but it also had a detrimental effect on the green mirid population, which plays a crucial role in controlling brown planthoppers. All the treatments exhibited statistically significant differences at a confidence level of p < 0.05