Baseline Susceptibility and Laboratory Selection of Resistance to Bt Cry1Ab Protein of Chinese Populations of Yellow Peach Moth, Conogethes punctiferalis (Guenée).

Su Mon Shwe,Shuxiong Bai,Kanglai He,Qincheng Li,Yu Chen,Zhenying Wang,Dapeng Jing,Sivaprasath Prabu

doi:10.3390/toxins13050335

Su Mon Shwe, Shuxiong Bai + Show 6 more

Open Access

https://doi.org/10.3390/toxins13050335

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Abstract

Yellow Peach Moth (YPM), Conogethes punctiferalis (Guenée), is one of the most destructive maize pests in the Huang-Huai-Hai summer maize region of China. Transgenic Bacillus thuringiensis (Bt) maize provides an effective means to control this insect pest in field trials. However, the establishment of Bt resistance to target pests is endangering the continued success of Bt crops. To use Bt maize against YPM, the baseline susceptibility of the local populations in the targeted areas needs to be verified. Diet-overlay bioassay results showed that all the fourteen YPM populations in China are highly susceptible to Cry1Ab. The LC50 values ranged from 0.35 to 2.38 ng/cm2 over the two years of the collection, and the difference between the most susceptible and most tolerant populations was sevenfold. The upper limit of the LC99 estimates of six pooled populations produced >99% larval mortality for representative eight populations collected in 2020 and was designated as diagnostic concentrations for monitoring susceptibility in YPM populations in China. Hence, we evaluated the laboratory selection of resistance in YPM to Cry1Ab using the diet-overlay bioassay method. Although the resistant ratio was generally low, YPM potentially could evolve resistance to Cry1Ab. The potential developmentof resistance by target pests points out the necessity to implement resistance management strategies for delaying the establishment of pest resistance to Bt crops.

Highlights

Bacillus thuringiensis (Berliner), a ubiquitous Gram-positive and endospore-forming soil bacterium, produce insecticidal crystal proteins during the sporulation phase of its growth cycle [1,2]
We describe the first survey of baseline susceptibility to Cry1Ab of different Yellow Peach Moth (YPM) geographical populations across major maize growing regions in China, which will be an initial step for the future resistance monitoring program
Before the broad commercial deployment of Bacillus thuringiensis (Bt) maize, the establishment of baseline susceptibility of target pests to Bt protein is the first step for generating an effective resistance monitoring and management program [22]

Summary

Introduction

Bacillus thuringiensis (Berliner), a ubiquitous Gram-positive and endospore-forming soil bacterium, produce insecticidal crystal proteins during the sporulation phase of its growth cycle [1,2] It has been using as an alternative to chemical insecticides to control the critical agricultural pests in the orders Lepidoptera, Coleoptera, and Diptera [3,4,5]. Since 1996, transgenic maize expressing Bt insecticidal proteins has been commercialized and used successfully to manage corn borer problems It is widely grown in the key maize growing regions such as the USA, Brazil, Argentina, Canada, South Africa, and the Philippines and the estimated acreage reached 58.9 million hectares in 2018 [6]. The growing of Bt crops must be carefully managed to delay insect resistance and prolong Bt productslifetime

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