Effect of Bt Maize and Soil Insecticides on Yield, Injury, and Rootworm Survival: Implications for Resistance Management

Petzold-Maxwell, Jennifer L.; Meinke, Lance J.; Gray, Michael E.; Estes, Ronald E.; Gassmann, Aaron J.

doi:10.1603/ec13216

Cited by 50 publications

(47 citation statements)

References 52 publications

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“…In most of the scenarios examined, application of soil insecticides to Bt-protected plants did not provide significant additional root protection except when NIS ratings exceeded 2.0 for the non-Bt treatments. These results are consistent with other published research on Cry3Bb1 susceptible populations (Petzold-Maxwell et al 2013, Estes et al 2015). In this high feeding pressure scenario, there was an improvement in root protection from the addition of a soil insecticide on Cry34Ab1/Cry35Ab1 single trait-protected plants.…”

Section: Discussionsupporting

confidence: 94%

“…For additional root protection against the perceived threat, corn growers began to consider adding prophylactic soil insecticides to single trait and pyramided trait technologies. Petzold-Maxwell et al (2013) found few benefits from adding a soil insecticide to trait-protected corn when the crop is exposed to Bt-susceptible populations of corn rootworm. Tinsley et al (2016) found a significant trend where soil insecticides provided additional root protection in Bt-susceptible populations as compared to Bt single and pyramided traits; however, the magnitude of the difference indicated that even at high pressure, producers were unlikely to experience a positive economic return.…”

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confidence: 99%

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Field Trial Performance of Herculex XTRA (Cry34Ab1/Cry35Ab1) and SmartStax (Cry34Ab1/Cry35Ab1 + Cry3Bb1) Hybrids and Soil Insecticides Against Western and Northern Corn Rootworms (Coleoptera: Chrysomelidae)

Johnson¹,

Campbell²,

Lepping³

et al. 2017

Journal of Economic Entomology

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Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), and northern corn rootworm, Diabrotica barberi Smith and Lawrence (Coleoptera: Chrysomelidae), are important insect pests in corn, Zea mays L. For more than a decade, growers have been using transgenic plants expressing proteins from the bacterium Bacillus thuringiensis (Bt) to protect corn roots from feeding. In 2011, western corn rootworm populations were reported to have developed resistance to Bt hybrids expressing Cry3Bb1 and later found to be cross-resistant to hybrids expressing mCry3A and eCry3.1Ab. The identification of resistance to Cry3 (Cry3Bb1, mCry3A, and eCry3.1Ab) hybrids led to concerns about durability and efficacy of products with single traits and of products containing a pyramid of a Cry3 protein and the binary Bt proteins Cry34Ab1 and Cry35Ab1. From 2012 to 2014, 43 field trials were conducted across the central United States to estimate root protection provided by plants expressing Cry34Ab1/Cry35Ab1 alone (Herculex RW) or pyramided with Cry3Bb1 (SmartStax). These technologies were evaluated with and without soil-applied insecticides to determine if additional management measures provided benefit where Cry3 performance was reduced. Trials were categorized for analysis based on rootworm damage levels on Cry3-expressing hybrids and rootworm feeding pressure within each trial. Across scenarios, Cry34Ab1/Cry35Ab1 hybrids provided excellent root protection. Pyramided traits provided greater root and yield protection than non-Bt plus a soil-applied insecticide, and only in trials where larval feeding pressure exceeded two nodes of damage did Cry34Ab1/Cry35Ab1 single-trait hybrids and pyramided hybrids show greater root protection from the addition of soil-applied insecticides.

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Section: Discussionsupporting

confidence: 94%

mentioning

confidence: 99%

Field Trial Performance of Herculex XTRA (Cry34Ab1/Cry35Ab1) and SmartStax (Cry34Ab1/Cry35Ab1 + Cry3Bb1) Hybrids and Soil Insecticides Against Western and Northern Corn Rootworms (Coleoptera: Chrysomelidae)

Johnson¹,

Campbell²,

Lepping³

et al. 2017

Journal of Economic Entomology

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“…In a field study with Cry3Bb1-resistant western corn rootworm, Gassmann (2012) documented a significant reduction in western corn rootworm adult emergence and root injury with the application of soil insecticide to Cry3Bb1 corn, whereas in a study of Cry3Bb1-susceptibe western corn rootworm, Petzold-Maxwell et al (2013a) found no effect of soil insecticide on root injury to Cry3Bb1 corn but significant reduction in adult emergence. In our study, the application of soil insecticide to Cry3Bb1 corn significantly reduced root injury by western corn rootworm; however, it did not reduce the adult emergence in problem fields (Figs.…”

Section: Discussionmentioning

confidence: 99%

Field-Based Assessment of Resistance to Bt Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae)

Shrestha¹,

Jakka²,

French³

et al. 2016

J Econ Entomol

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Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a serious pest of corn and is managed with corn that produces insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Beginning in 2009, resistance to Cry3Bb1 corn, and severe injury to Cry3Bb1 corn in the field, was observed in Iowa. However, few data exist on how Cry3Bb1-resistant western corn rootworm interact with various management practices in the field. Using a field experiment, we measured adult emergence and feeding injury to corn roots for both Cry3Bb1-resistant and Cry3Bb1-susceptible populations of western corn rootworm when tested against various Bt corn hybrids and a soil-applied insecticide. Between 2012 and 2013, we evaluated five fields that were associated with greater than one node of feeding injury to Cry3Bb1 corn by western corn rootworm (i.e., problem-field populations), and a laboratory strain that had never been exposed to Bt corn (i.e., control population). Adult emergence for western corn rootworm and root injury to corn were significantly higher in problem-field populations than control populations for both Cry3Bb1 corn and mCry3A corn. By contrast, corn with Cry34/35Ab1, either alone or pyramided with Cry3Bb1, significantly reduced adult emergence and root injury in both problem fields and control fields. In problem fields, application of the soil-applied insecticide to Cry3Bb1 corn significantly reduced root injury, but not adult emergence. Our results are discussed in terms of developing strategies for managing western corn rootworm with resistance to Cry3Bb1 and mCry3A, and delaying the additional evolution of Bt resistance by this pest. KeywordsDiabrotica virgifera virgifera, Bt corn, cross-resistance, insect resistance management Disciplines Agronomy and Crop Sciences | Ecology and Evolutionary Biology | Entomology | Plant Breeding and Genetics CommentsThis article is published as Shrestha, Ram B., Siva RK Jakka, B. Wade French, and Aaron J. Gassmann. "Fieldbased assessment of resistance to Bt corn by western corn rootworm (Coleoptera: Chrysomelidae)." Journal of economic entomology 109, no. 3 (2016): 1399-1409. doi: 10.1093/jee/tow087. Posted with permission. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.

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“…; Petzold‐Maxwell et al. ). Across field collections in experiment 1, the average total emergence period in the greenhouse was 33 days.…”

Section: Methodsmentioning

confidence: 99%

Effects of adult emergence timing on susceptibility and fitness of Cry3Bb1‐resistant western corn rootworms

Wangila

Meinke

2016

J Applied Entomology

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Field‐evolved resistance by the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte to the Cry3Bb1 trait expressed in maize, has been documented in areas of Nebraska USA. Currently, only limited information is available on life‐history traits of Cry3Bb1‐resistant field populations. Therefore, the Gassmann on‐plant bioassay was used to investigate the potential variability among four Cry3Bb1‐resistant WCR field collections made in 2011–2012 by focusing on the key parameters: larval survival, developmental stage and weight with specific emphasis on the impact of adult emergence timing on these parameters in subsequent progeny. Key results: In three of four collections, the susceptibility of larval progeny from adults that emerged early or late within a generation from Cry3Bb1 plants was similar. Each of the three collections exhibited complete resistance; that is, survival on Cry3Bb1 plants was greater or equal to survival on non‐Bt isoline plants. Bioassays from an additional field collection from one site 2 years (2013) after the original collection (2011) (both from Cry3Bb1 maize) indicated that resistance to Cry3Bb1 was maintained over time at the site despite Bt trait rotation in 2012. In general, comparative WCR life‐history parameter data from Cry3Bb1 and isoline maize indicate that fitness of field collections exhibiting complete resistance was similar on each hybrid. The mean proportion of larvae in third instar and mean weight of larvae recovered in bioassays from progeny of early‐ and late‐emerged adults was not significantly affected by emergence period. This suggests that delays in development and associated mean adult emergence commonly observed in populations that are susceptible to Cry3Bb1 may become smaller as populations become resistant to Cry3Bb1. Results from this article will inform Cry3Bb1 resistance mitigation efforts and contribute to the development of sustainable WCR management programmes.

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Effect of Bt Maize and Soil Insecticides on Yield, Injury, and Rootworm Survival: Implications for Resistance Management

Cited by 50 publications

References 52 publications

Field Trial Performance of Herculex XTRA (Cry34Ab1/Cry35Ab1) and SmartStax (Cry34Ab1/Cry35Ab1 + Cry3Bb1) Hybrids and Soil Insecticides Against Western and Northern Corn Rootworms (Coleoptera: Chrysomelidae)

Field Trial Performance of Herculex XTRA (Cry34Ab1/Cry35Ab1) and SmartStax (Cry34Ab1/Cry35Ab1 + Cry3Bb1) Hybrids and Soil Insecticides Against Western and Northern Corn Rootworms (Coleoptera: Chrysomelidae)

Field-Based Assessment of Resistance to Bt Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae)

Effects of adult emergence timing on susceptibility and fitness of Cry3Bb1‐resistant western corn rootworms

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