|Wang, Yan Hua|
|Wu, Sheng Gan|
|Zhu, Yu Cheng|
|Liu, Feng Yi|
|Zhao, Xue Ping|
|Ping Bo, Xian|
|Shen, Jin Liang|
Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2008
Publication Date: 2/19/2009
Citation: Wang, Y., Wu, S., Zhu, Y., Chen, J., Liu, F., Zhao, X., Wang, Q., Li, Z., Ping Bo, X., Shen, J. 2009. Dynamics of imidacloprid resistance and cross-resistance in the brown planthopper, Nilaparvata lugens. Entomologia Experimentalis et Applicata. 131:20-29. Interpretive Summary: Because the plant hopper has developed significant resistance to imidacloprid, other neonicotinoids, buprofezin, and fipronil are currently implemented for the insect control and resistance management. However, it was not clear whether the imidacloprid-resistant populations had already developed cross-resistance to other neonicotinoids, buprofezin, and fipronil, and whether stopping or reducing imidacloprid applications would allow susceptibility to be recovered in the field resistant populations. In order to develop better resistance management strategies, this study was designed to examine dynamic change of the imidacloprid resistance under different selection pressures, and to investigate whether cross resistance to other neonicotinoids, buprofezin, and fipronil existed in the imidaclopri-resistant strain. Results showed strong evidences that insecticide selection pressure was major driving force for resistance development in the economically important insect. The populations of the insect had ability to develop very high resistance when the populations received constant insecticide treatments. However, the resistance declined when the insecticide application stopped. This valuable information can be used for formulating resistance management strategy through alternating and rotating insecticides to reduce selection pressure and to recover susceptibility to imidacloprid in the target insect.
Technical Abstract: Dominant and extensive use of imidacloprid for suppressing the brown planthopper, Nilaparvata lugens, has placed heavy selection pressure on the target insect. A systematic study was carried out to determine imidacloprid resistance dynamics and cross-resistance. A 3-yr monitoring data (2005-2007) showed that the resistance levels in Nanning (Guangxi), Haiyan (Zhejiang), Nanjing and Tongzhou (Jiangsu) populations ranged from 200.1 to 799-fold in 2005. However, the resistance levels decreased to 135-233-fold in 2007 due to reduced application of the chemical. A laboratory population was selected continuously with imidacloprid in the laboratory. After 23 generations, the resistance ratio increased from 200.1 to 1298.5-fold. The results showed that continuous selection with imidacloprid could further increase the resistance level even a high resistance level had already developed in the population. Stopping selection with imidacloprid led to rapid reduction of the resistance level from 759-fold to 114.1-fold after 17 generations, after which resistance remained stable without further decrease. Similar result was also obtained from study of a field population (RR=625.4-fold) collected from Tongzhou, which showed initial rapid decrease in resistance when the use of imidacloprid was stopped, and resistance then stabilized at a level of 105-129-fold. More interestingly, the resistance increase again as the selection resumed. In addition, the resistance strain selected with imidacloprid showed obvious cross-resistance to imidaclothiz (1.8-fold), thiacloprid (1.8-fold) and acetamiprid (1.6-fold), but there was no cross-resistance to dinotefuran, thiamethoxam, nitenpyram, buprofezin, and fipronil. The information from this study was valuable for formulating resistance management strategies.