Analysis of resistance to Cry1Ac in field-collected pink bollworm,<i>Pectinophora gossypiella</i>(Lepidoptera:Gelechiidae), populations

Ojha, Abhishek; Sree, K. Sowjanya; Sachdev, Bindiya; Rashmi, M. A.; Ravi, K.C.; Suresh, PJ; Mohan, K. S.; Bhatnagar, Raj K.

doi:10.4161/21645698.2014.947800

Cited by 30 publications

(22 citation statements)

References 29 publications

(28 reference statements)

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“…Previous reports on field-evolved resistance mechanisms against Bt cotton in P. gossypiella have shown differential splicing of cadherin transcripts (46) and estimates of reduced Cry1Ac toxin binding in field-collected resistant P. gossypiella insects (47). Although not demonstrated directly, since pink bollworm cadherin binds Cry1Ac (48) and alterations in cadherin are linked to resistance against that toxin (20,49), it is highly plausible that the alterations in cadherin transcripts detected in field-collected P. gossypiella strains may be responsible for reduced Cry1Ac binding and resistance to Bt cotton.…”

Section: Discussionmentioning

confidence: 99%

Field-Evolved Mode 1 Resistance of the Fall Armyworm to Transgenic Cry1Fa-Expressing Corn Associated with Reduced Cry1Fa Toxin Binding and Midgut Alkaline Phosphatase Expression

Jakka

Gong

Hasler³

et al. 2016

Appl Environ Microbiol

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dInsecticidal protein genes from the bacterium Bacillus thuringiensis (Bt) are expressed by transgenic Bt crops (Bt crops) for effective and environmentally safe pest control. The development of resistance to these insecticidal proteins is considered the most serious threat to the sustainability of Bt crops. Resistance in fall armyworm (Spodoptera frugiperda) populations from Puerto Rico to transgenic corn producing the Cry1Fa insecticidal protein resulted, for the first time in the United States, in practical resistance, and Bt corn was withdrawn from the local market. In this study, we used a field-collected Cry1Fa corn-resistant strain (456) of S. frugiperda to identify the mechanism responsible for field-evolved resistance. Binding assays detected reduced Cry1Fa, Cry1Ab, and Cry1Ac but not Cry1Ca toxin binding to midgut brush border membrane vesicles (BBMV) from the larvae of strain 456 compared to that from the larvae of a susceptible (Ben) strain. This binding phenotype is descriptive of the mode 1 type of resistance to Bt toxins. A comparison of the transcript levels for putative Cry1 toxin receptor genes identified a significant downregulation (>90%) of a membrane-bound alkaline phosphatase (ALP), which translated to reduced ALP protein levels and a 75% reduction in ALP activity in BBMV from 456 compared to that of Ben larvae. We cloned and heterologously expressed this ALP from susceptible S. frugiperda larvae and demonstrated that it specifically binds with Cry1Fa toxin. This study provides a thorough mechanistic description of field-evolved resistance to a transgenic Bt crop and supports an association between resistance and reduced Cry1Fa toxin binding and levels of a putative Cry1Fa toxin receptor, ALP, in the midguts of S. frugiperda larvae.

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Section: Discussionmentioning

confidence: 99%

Field-Evolved Mode 1 Resistance of the Fall Armyworm to Transgenic Cry1Fa-Expressing Corn Associated with Reduced Cry1Fa Toxin Binding and Midgut Alkaline Phosphatase Expression

Jakka

Gong

Hasler³

et al. 2016

Appl Environ Microbiol

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“…Direct interspecific comparisons between susceptible strains show that intrinsic susceptibility is much lower for H. zea than pink bollworm for both Cry1Ac (72-fold) and Cry2Ab (485-fold)37. Field-evolved resistance has been documented in populations of H. zea, T. ni , and pink bollworm to Cry1Ac, but only for H. zea to Cry2Ab112223242526454647.…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, pink bollworm populations in India have diverse mutations in cadherin genes associated with field-evolved resistance to Bt cotton producing Cry1Ac23. The risk of resistance is high in both countries, because neither has abundant refuges of non-Bt cotton or other pink bollworm host plants24252628. For populations resistant to Cry1Ac, only the Cry2Ab in two-toxin cotton is effective.…”

Section: Discussionmentioning

confidence: 99%

“…In the United States, refuges of non-Bt cotton and mass releases of sterile moths have sustained pink bollworm susceptibility to Bt toxins for two decades, helping to bring this invasive insect close to eradication in Arizona and other southwestern states921. In India, because farmers have not planted adequate refuges, the efficacy of Bt cotton producing Cry1Ac has been eroded by widespread, field-evolved practical resistance222324252627. In China, where farmers have not switched to two-toxin Bt cotton, small but significant increases in pink bollworm resistance to Cry1Ac have occurred in northern China, where close to 100% of the three million ha of cotton planted yearly produces Cry1Ac as the only Bt toxin2829.…”

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confidence: 99%

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Multi-Toxin Resistance Enables Pink Bollworm Survival on Pyramided Bt Cotton

Fabrick

Unnithan

Yelich

et al. 2015

Sci Rep

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Transgenic crops producing Bacillus thuringiensis (Bt) proteins kill key insect pests, providing economic and environmental benefits. However, the evolution of pest resistance threatens the continued success of such Bt crops. To delay or counter resistance, transgenic plant “pyramids” producing two or more Bt proteins that kill the same pest have been adopted extensively. Field populations of the pink bollworm (Pectinophora gossypiella) in the United States have remained susceptible to Bt toxins Cry1Ac and Cry2Ab, but field-evolved practical resistance to Bt cotton producing Cry1Ac has occurred widely in India. Here we used two rounds of laboratory selection to achieve 18,000- to 150,000-fold resistance to Cry2Ab in pink bollworm. Inheritance of resistance to Cry2Ab was recessive, autosomal, conferred primarily by one locus, and independent of Cry1Ac resistance. We created a strain with high resistance to both toxins by crossing the Cry2Ab-resistant strain with a Cry1Ac-resistant strain, followed by one selection with Cry2Ab. This multi-toxin resistant strain survived on field-collected Bt cotton bolls producing both toxins. The results here demonstrate the risk of evolution of resistance to pyramided Bt plants, particularly when toxins are deployed sequentially and refuges are scarce, as seen with Bt cotton and pink bollworm in India.

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“…However, development of resistance by the insect pests to these toxins is raising concerns in this area of research. One such case has been reported recently where it was shown that the cry1Ac toxin had a reduced binding capacity to the receptors on the brush border membrane vesicles of the field-collected cry1Ac-resistant pink bollworms (Ojha et al 2014). Further, the safety and public acceptance of the genetically modified foods is also raising concerns for the commercialisation of transgenic crops (Shelton et al 2002).…”

Section: Entomopathogenic Bacteriamentioning

confidence: 98%