Cross-resistance to toxins used in pyramided Bt crops and resistance to Bt sprays in Helicoverpa zea

Welch, Kara; Unnithan, Gopalan C.; Degain, Ben; Wei, Jizhen; Zhang, Jie; Li, Xianchun; Tabashnik, Bruce E.; Carrière, Yves

doi:10.1016/j.jip.2015.10.003

Cited by 99 publications

(107 citation statements)

References 54 publications

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“…Vip3Aa was found to be equally toxic to one susceptible and three Cry-resistant H. virescens strains (YHD2, resistant to Cry1Ac and Cry1F and slightly cross-resistant to Cry2A, and CXC and KCBhyb, both resistant to Cry1Ac, Cry1Aa, Cry1Ab, Cry1F, and Cry2Aa2) (107). Two studies on Cry1Ac-resistant strains of H. zea showed no significant cross-resistance to Vip3A or Cry2Ab (108,109). A study on two H. armigera populations from Cry1Ac-cotton planting regions in China showed a lack of significant correlation between the responses to Vip3Aa and those to Cry1Ac, suggesting little or no cross-resistance between these two toxins (110).…”

Section: Resistance and Cross-resistancementioning

confidence: 97%

Bacterial Vegetative Insecticidal Proteins (Vip) from Entomopathogenic Bacteria

Chakroun

Banyuls

Bel

et al. 2016

Microbiol Mol Biol Rev

257

261

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SUMMARYEntomopathogenic bacteria produce insecticidal proteins that accumulate in inclusion bodies or parasporal crystals (such as the Cry and Cyt proteins) as well as insecticidal proteins that are secreted into the culture medium. Among the latter are the Vip proteins, which are divided into four families according to their amino acid identity. The Vip1 and Vip2 proteins act as binary toxins and are toxic to some members of the Coleoptera and Hemiptera. The Vip1 component is thought to bind to receptors in the membrane of the insect midgut, and the Vip2 component enters the cell, where it displays its ADP-ribosyltransferase activity against actin, preventing microfilament formation. Vip3 has no sequence similarity to Vip1 or Vip2 and is toxic to a wide variety of members of the Lepidoptera. Its mode of action has been shown to resemble that of the Cry proteins in terms of proteolytic activation, binding to the midgut epithelial membrane, and pore formation, although Vip3A proteins do not share binding sites with Cry proteins. The latter property makes them good candidates to be combined with Cry proteins in transgenic plants (Bacillus thuringiensis-treated crops [Bt crops]) to prevent or delay insect resistance and to broaden the insecticidal spectrum. There are commercially grown varieties of Bt cotton and Bt maize that express the Vip3Aa protein in combination with Cry proteins. For the most recently reported Vip4 family, no target insects have been found yet.

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Section: Resistance and Cross-resistancementioning

confidence: 97%

Bacterial Vegetative Insecticidal Proteins (Vip) from Entomopathogenic Bacteria

Chakroun

Banyuls

Bel

et al. 2016

Microbiol Mol Biol Rev

257

261

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“…Previous reports have shown cross-resistance between the Cry1A proteins (1Ab, 1Ac, Cry1A.105) in H . zea [38,39]. Santos-Amaya et al .…”

Section: Introductionmentioning

confidence: 99%

Field-Evolved Resistance in Corn Earworm to Cry Proteins Expressed by Transgenic Sweet Corn

2016

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BackgroundTransgenic corn engineered with genes expressing insecticidal toxins from the bacterium Bacillus thuringiensis (Berliner) (Bt) are now a major tool in insect pest management. With its widespread use, insect resistance is a major threat to the sustainability of the Bt transgenic technology. For all Bt corn expressing Cry toxins, the high dose requirement for resistance management is not achieved for corn earworm, Helicoverpa zea (Boddie), which is more tolerant to the Bt toxins.Methodology/Major FindingsWe present field monitoring data using Cry1Ab (1996–2016) and Cry1A.105+Cry2Ab2 (2010–2016) expressing sweet corn hybrids as in-field screens to measure changes in field efficacy and Cry toxin susceptibility to H. zea. Larvae successfully damaged an increasing proportion of ears, consumed more kernel area, and reached later developmental stages (4th - 6th instars) in both types of Bt hybrids (Cry1Ab—event Bt11, and Cry1A.105+Cry2Ab2—event MON89034) since their commercial introduction. Yearly patterns of H. zea population abundance were unrelated to reductions in control efficacy. There was no evidence of field efficacy or tissue toxicity differences among different Cry1Ab hybrids that could contribute to the decline in control efficacy. Supportive data from laboratory bioassays demonstrate significant differences in weight gain and fitness characteristics between the Maryland H. zea strain and a susceptible strain. In bioassays with Cry1Ab expressing green leaf tissue, Maryland H. zea strain gained more weight than the susceptible strain at all concentrations tested. Fitness of the Maryland H. zea strain was significantly lower than that of the susceptible strain as indicated by lower hatch rate, longer time to adult eclosion, lower pupal weight, and reduced survival to adulthood.Conclusions/SignificanceAfter ruling out possible contributing factors, the rapid change in field efficacy in recent years and decreased susceptibility of H. zea to Bt sweet corn provide strong evidence of field-evolved resistance in H. zea populations to multiple Cry toxins. The high adoption rate of Bt field corn and cotton, along with the moderate dose expression of Cry1Ab and related Cry toxins in these crops, and decreasing refuge compliance probably contributed to the evolution of resistance. Our results have important implications for resistance monitoring, refuge requirements and other regulatory policies, cross-resistance issues, and the sustainability of the pyramided Bt technology.

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“…27 In comparison to the susceptible strain, we found resistance ratios for the four insecticides were ≤2 for most fields for both the LC 50 and LC 90 values, although there were individual fields where resistance ratios were >2. For malathion, three fields in 2015 (two unsprayed, one conventional) wileyonlinelibrary.com/journal/ps 2014 (malathion LC 50 , t = 0.39, df = 1, 9, P = 0.71; malathion LC 90 , t = 0.27, df = 1, 9, P = 0.80; methomyl LC 50 …”

Section: Resultsmentioning

confidence: 70%

Baseline susceptibility of spotted wing Drosophila (Drosophila suzukii) to four key insecticide classes

Timmeren

Mota-Sánchez

Wise

et al. 2017

Pest Management Science

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BACKGROUND: The invasive drosophilid pest, Drosophila suzukii Matsumura, is affecting berry production in most fruit-producing regions of the world. Chemical control is the dominant management approach, creating concern for insecticide resistance in this pest. We compared the insecticide susceptibility of D. suzukii populations collected from conventional, organic or insecticide-free blueberry sites. RESULTS

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Cross-resistance to toxins used in pyramided Bt crops and resistance to Bt sprays in Helicoverpa zea

Cited by 99 publications

References 54 publications

Bacterial Vegetative Insecticidal Proteins (Vip) from Entomopathogenic Bacteria

Bacterial Vegetative Insecticidal Proteins (Vip) from Entomopathogenic Bacteria

Field-Evolved Resistance in Corn Earworm to Cry Proteins Expressed by Transgenic Sweet Corn

Baseline susceptibility of spotted wing Drosophila (Drosophila suzukii) to four key insecticide classes

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