Current Status of Insecticide Resistance in <I>Helicoverpa armigera</I> After 15 Years of Bt Cotton Planting in China

Abstract

Insecticide resistance was an important factor responsible for outbreaks of Helicoverpa armigera (Hübner) in China in the early 1990s. Bt cotton has been adopted in China since 1997, and has resulted in a reduction of insecticide use for H. armigera control. After 15 yr of Bt cotton planting, in 2011 we surveyed resistance to fenvalerate, phoxim, and emamectin benzoate in 16 field populations of H. armigera collected from major cotton production areas of China. Fourteen populations from northern China showed very strong resistance to fenvalerate (from 43- to 830-fold) and low levels of resistance to phoxim (3.0- to 8.9-fold) when compared with the susceptible SCD strain of H. armigera, whereas two populations from northwestern China showed low levels of resistance to fenvalerate (3.0- and 10-fold) and no resistance to phoxim (0.7- and 0.9-fold). Synergist bioassays demonstrated that oxidase-based detoxification was involved in fenvalerate resistance and esterase-based detoxification in phoxim resistance in the resistant field populations. In comparison with the resistance in field populations before Bt cotton adoption, we observed a maintenance of high levels of fenvalerate resistance, but a reversion of phoxim resistance from high levels to low levels in the field populations of H. armigera from northern China. All 16 field populations from both northern China and northwestern China were susceptible to emamectin benzoate (with about two-fold variations in LD50s among populations), but the SCD strain has an inherent tolerance of 11-fold compared with the most susceptible field population (Xiajin-1). Emamectin benzoate is not cross resistant to fenvalerate and may provide an alternative option for H. armigera control in China, if the efficacy of Bt cotton is compromised by Bt resistance in the field.

Evaluación de la susceptibilidad a insecticidas en poblaciones de Aedes aegypti (Diptera: Culicidae) del departamento de Caldas, Colombia, en los años 2007 y 2011

“…En el sector agrícola se han reportado varios casos de esta reversión, por ejemplo en el gusano del tabaco (Spodoptera litura) en Asia, en donde la sensibilidad a varios insecticidas se incrementó entre 5 y 9 veces después de 11 generaciones y en ausencia de la presión de selección (37). En el gusano cogollero (Helicoverpa armígera), plaga de varios cultivos como el algodón, se ha evidenciado la reversión de la resistencia a insecticidas con la introducción de algodón transgénico (modificado con Bacillus thurigiensis) y después de 15 años de suspensión del uso de insecticidas (38).…”

Switching among natal and auxiliary hosts increases vulnerability of Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) to insecticides

“…These facts might be attributed to the indiscriminate use of insecticides in cotton crop that is why the cotton‐sourced larvae when shifted to auxiliary hosts show more resistance against insecticides tested. Also, increase in transgenic cotton cultivated area in Pakistan can be considered the main culprit in inducing resistance in the pest (Yang, Li, & Wu, 2013) due to exposure of S. exigua to the sublethal dosage of insecticides applied against sucking insect pests of cotton.…”

Toxicity and sublethal effects of insecticides on Helicoverpa armigera Hbner (Lepidoptera: Noctuidae)

“…However, due to the impacts and the development of strains resistant to the products, it has become necessary to use in rotation insecticides with different modes of action, as well as techniques that can assist in integrated pest management (IPM) (Jacobson et al, 2009;Gunning and Moores, 2010;Perry et al, 2011;Shind et al, 2011;Yang et al, 2013).…”