Evolution of resistance in pests can reduce the effectiveness of insecticidal proteins from Bacillus thuringiensis (Bt) produced by transgenic crops We analyzed results of 77 studies from five continents reporting field monitoring data for resistance to Bt crops, empirical evaluation of factors affecting resistance or both Although most pest populations remained susceptible, reduced efficacy of Bt crops caused by field-evolved resistance has been reported now for some populations of 5 of 13 major pest species examined, compared with resistant populations of only one pest species in 2005 Field outcomes support theoretical predictions that factors delaying resistance include recessive inheritance of resistance, low initial frequency of resistance alleles, abundant refuges of non-Bt host plants and two-toxin Bt crops deployed separately from one-toxin Bt crops The results imply that proactive evaluation of the inheritance and initial frequency of resistance are useful for predicting the risk of resistance and improving strategies to sustain the effectiveness of Bt crops

Insect resistance to Bt crops: lessons from the first billion acres

More than six decades after the onset of wide-scale commercial use of synthetic pesticides and more than fifty years after Rachel Carson's Silent Spring, pesticides, particularly insecticides, arguably remain the most influential pest management tool around the globe. Nevertheless, pesticide use is still a controversial issue and is at the regulatory forefront in most countries. The older generation of insecticide groups has been largely replaced by a plethora of novel molecules that exhibit improved human and environmental safety profiles. However, the use of such compounds is guided by their short-term efficacy; the indirect and subtler effects on their target species, namely arthropod pest species, have been neglected. Curiously, comprehensive risk assessments have increasingly explored effects on nontarget species, contrasting with the majority of efforts focused on the target arthropod pest species. The present review mitigates this shortcoming by hierarchically exploring within an ecotoxicology fram...

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Pesticide-Induced Stress in Arthropod Pests for Optimized Integrated Pest Management Programs

Transgenic crops have revolutionized insect pest control, but their effectiveness has been reduced by evolution of resistance in pests. We analyzed global monitoring data reported during the first two decades of transgenic crops, with each case representing the responses of one pest species in one country to one insecticidal protein from Bacillus thuringiensis (Bt). The cases of pest resistance to Bt crystalline (Cry) proteins produced by transgenic crops increased from 3 in 2005 to 16 in 2016. By contrast, in 17 other cases there was no decrease in pest susceptibility to Bt crops, including the recently introduced transgenic corn that produces a Bt vegetative insecticidal protein (Vip). Recessive inheritance of pest resistance has favored sustained susceptibility, but even when inheritance is not recessive, abundant refuges of non-Bt host plants have substantially delayed resistance. These insights may inform resistance management strategies to increase the durability of current and future transgenic crops.

Surge in insect resistance to transgenic crops and prospects for sustainability.

When natural habitat fails to enhance biological pest control – Five hypotheses ☆

Pollinator habitat enhancement: Benefits to other ecosystem services

at 36 sites in six provinces of northern China, we show here a marked increase in abundance of three types of generalist arthropod predators (ladybirds, lacewings and spiders) and a decreased abundance of aphid pests associated with widespread adoption of Bt cotton and reduced insecticide sprays in this crop. We also found evidence that the predators might provide additional biocontrol services spilling over from Bt cotton fields onto neighbouring crops (maize, peanut and soybean). Our work extends results from general studies evaluating ecological effects of Bt crops 1–4,6,12,13 by demonstrating that such crops can promote biocontrol services in agricultural landscapes.

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Widespread adoption of Bt cotton and insecticide decrease promotes biocontrol services

The adoption of Bt (Bacillus thuringiensis) crops has improved crop yield, reduced chemical insecticide use, and induced an increase in farmer profits; however, some concerns persist about their potential environmental risks, including the impact on nontarget arthropods (Romeis et al., 2008). In China, Bt cotton was first grown commercially in 1997. As the levels of cultivated Bt cotton increased, populations of the target pest Helicoverpa armigera were found to have substantially declined (Wu et al., 2008). In addition, reduced insecticide use in Bt cotton has shown positive side effects, such as increased pest biocontrol services provided by natural enemies (Lu et al., 2012), but also negative side effects, such as mirid bug outbreaks (Lu et al., 2010). How this shift in pest status may impact interspecific arthropod interactions in Bt cotton needs to be further investigated (Zeilinger et al., 2011; Hagenbucher et al., 2013; Zhang et al., 2018). Mirid bug feeding often causes tattered leaves on host plants, suggesting that interspecific competition with other leaf-feeding insects may occur. Furthermore, mirid bugs may also prey on the cotton aphid Aphis gossypii and other arthropod pests (Jiang et al., 2015). Hence, mirid bugs have the potential to act as arthropod biocontrol agents during their outbreaks. This article is protected by copyright. All rights reserved.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/pbi.13233

Yuying Jiang

Papers

Widespread adoption of Bt cotton and insecticide decrease promotes biocontrol services

The outbreaks of nontarget mirid bugs promote arthropod pest suppression in Bt cotton agroecosystems.