Genetically engineered crops help support conservation biological control

In the paper

“There is evidence that Bt crops can reduce target pest populations over broad scales (Carrière et al., 2003;Dively et al., 2018;Hutchison et al., 2010;Wan et al., 2012;Wu et al., 2008;Zhang et al., 2018) resulting in reduced damage on both GE and non-GE crops in the region.”

What the sources say

• Partly supported

  The Abstract reports that abundant Bt cotton suppressed pink bollworm populations across 15 Arizona regions, supporting the broad-scale pest-suppression claim. The Results and Discussion report regional population declines, but do not establish reduced crop damage on both Bt and non-Bt cotton. (LLM, conf=0.86)

  cites Carrière et al., 2003 sourceExperimental — accuracy not yet measured
• Supported

  The Abstract reports regional suppression of target pests associated with widespread Bt maize adoption and decreased crop injury in vegetables outside the Bt maize fields. The Significance section states that this regional suppression benefited vegetable growers through reduced crop damage; the Abstract also describes pest control in Bt crops themselves. (LLM, conf=0.91)

  cites Dively et al., 2018 source
• Supported

  The paper reports that Bt maize use is associated with areawide suppression of European corn borer and that both Bt and non-Bt maize growers benefit. It describes Bt maize as preventing pest damage and attributes benefits for non-Bt growers to areawide suppression (Abstract; page not specified in our copy). (LLM, conf=0.88)

  cites Hutchison et al., 2010 source

In the paper

“The technique has already been successfully applied to crop plants to alter agriculturally important traits such as disease resistance (Wang et al., 2014) and drought tolerance (Shi et al., 2017).”

What the sources say

• Not checked yetcites Wang et al., 2014 source
• Supported

  The Discussion states that this CRISPR-Cas9 study modified an endogenous maize gene to create variants with a positive effect on drought tolerance. Shi et al. is cited for drought tolerance in the citing sentence; disease resistance is separately attributed to Wang et al. (LLM, conf=0.93)

  cites Shi et al., 2017 source

In the paper

“For parasitoids, studies tended to use Bt-resistant hosts more, but again the results were the same regardless of the type of host.”

In the paper

“For predators, the majority of studies used non-susceptible prey and the results were exactly the same whether using non-susceptible or Bt-resistant prey (not shown).”

In the paper

“Effect sizes were generally larger for parasitoids and analyses indicated that reproduction (number of progeny) was actually higher when their hosts had fed on Bt plants compared with non-Bt plants.”

In the paper

“The most commonly used test substance was pollen.”

In the paper

“Overall, the Arizona cotton IPM strategy has cumulatively saved growers over $500 million since 1996 in yield protection and control costs ($274/ha/year), while preventing over 25 million pounds of active ingredient from being used in the environment (Ellsworth et al., 2018).”

What the sources say

• Not checked yetcites Ellsworth et al., 2018

In the paper

“Genetically engineered (GE) crops producing insecticidal proteins from Bacillus thuringiensis (Bt) (mainly Cry proteins) have become a major control tactic for a number of key lepidopteran and coleopteran pests, mainly in maize, cotton, and soybean.”

What the sources say

• Not checked yetcites ISAAA, 2017

In the paper

“Maize pollen is relatively heavy and deposited mainly within or in close proximity to the maize field, which limits exposure of arthropods offcrop, although certain wind conditions may lead to pollen drift over several kilometers (Sanvido et al., 2008).”

What the sources say

• Not checked yetcites Sanvido et al., 2008 source

In the paper

“The European Food Safety Authority (EFSA) assessed the environmental impact of HT maize and soybean and concluded that their cultivation is unlikely to raise additional environmental safety concerns compared to conventional maize or soybean in most conditions”

What the sources say

• Not checked yetcites EFSA, 2011 source
• Not checked yetcites EFSA, 2012 source

In the paper

“In 2017, GE varieties expressing one or several insecticidal genes from Bt were grown on a total of 101 million hectares worldwide, reaching adoption levels above 80% in some regions (ISAAA, 2017; Fig. 1).”

What the sources say

• Not checked yetcites ISAAA, 2017

In the paper

“From a practical standpoint, because not all natural enemies potentially at risk can be tested, a representative subset of species (surrogates) is selected for assessment (Carstens et al., 2014;Romeis et al., 2013b;Wach et al., 2016).”

What the sources say

• Not checked yetcites Carstens et al., 2014 source
• Not checked yetcites Romeis et al., 2013b
• Not checked yetcites Wach et al., 2016 source

In the paper

“These so-called pyramid events are more effective in controlling the target pests and help to slow down the evolution of resistance (Gressel et al., 2017;Huang, 2015;Que et al., 2010;Zhao et al. 2005).”

What the sources say

• Not checked yetcites Gressel et al., 2017 source
• Not checked yetcites Huang, 2015
• Not checked yetcites Que et al., 2010 source

In the paper

“For insecticidal proteins in GE plants to directly affect a natural enemy, the organism has to ingest the toxin (exposure, see Section 4) and be susceptible to it (toxicity, see Section 5).”

In the paper

“GE insect resistant crops have been grown on a large scale for more than 20 years, and there is considerable experience and knowledge on how they can affect natural enemies and how their risks can be assessed prior to commercialization.”

In the paper

“Natural enemies can be exposed to plant produced-Bt proteins when feeding directly on plant tissue, or via prey or host species that have consumed Bt plant material (Fig. 2, routes 1 and 2).”

In the paper

“Care was taken to preserve independence in observations from any one study and to use metrics that reflected the longest exposure to the Cry protein.”

In the paper

“Finally, herbivores and other arthropods that have ingested Bt protein from the Bt crop may leave the field and expose natural enemies off-crop (Fig. 2, route 7).Because of the rapid excretion and digestion, however, this route of exposure is temporally very limited.”

In the paper

“The available data indicate that these pyramided insecticidal proteins typically act additively in sensitive species and cause no unexpected effects in species that are not sensitive to the individual toxins (Graser et al., 2017;Guo et al., 2016;Haller et al. 2017;Kumar et al., 2014;Levine et al., 2016;Raybould et al., 2012;Shu et al., 2018;Su et al., 2015;Svobodová et al., 2017;Tian et al., 2014T”

What the sources say

• Not checked yetcites Graser et al., 2017 source
• Not checked yetcites Guo et al., 2016 source
• Not checked yetcites Haller et al. 2017 source

In the paper

“Relevant data were extracted from the identified studies (Tables S1 and S2) for various life history traits that have a bearing on population dynamics and biological control function (immature development, immature and adult survival, fecundity, parasitism and predation).”

In the paper

“We further retained only data from studies in which the plant was used as the source of the Cry protein, although this plant material could have been incorporated into an artificial diet.”

In the paper

“Pollen, plant debris, and also exudates from living roots or exudes from decaying plant material might enter small streams that often run close to agricultural fields (Rosi-Marshall et al., 2007;Tank et al., 2010).”

What the sources say

• Not checked yetcites Rosi-Marshall et al., 2007 source
• Not checked yetcites Tank et al., 2010 source

In the paper

“The non-Bt plants used were generally isolines or near-isolines of the Bt plants (> 90% of studies); the remaining studies did not provide sufficient information.”

In the paper

“A random effects model was used for analyses to enable a broad inference of effects and bias-corrected, bootstrapped 95% confidence intervals were used to determine if the effect size differed from zero.”

In the paper

“While these studies offer realistic trophic scenarios, because aphids are common prey and hosts in crop fields, they are not suitable for testing the direct effects of Cry proteins on natural enemies.”

In the paper

“With the introduction in 2006 of a selective insecticide for Lygus hesperus (Hemiptera: Miridae) the package was complete and overall insecticide use statewide for cotton was dramatically reduced.”

In the paper

“In the USA, neonicitinoid seed-treatments for cotton is common in some production regions (Allen et al., 2018;North et al., 2018;Toews et al., 2010), where it can provide economic control of thrips during the seedling establishment period (North et al., 2018).”

What the sources say

• Not checked yetcites Allen et al., 2018 source
• Not checked yetcites North et al., 2018 source
• Not checked yetcites Toews et al., 2010 source

In the paper

“The impacts of such usage on arthropod natural enemies in not well understood in cotton, but some data suggest minimal effects at recommended doses (Saeed et al. 2016).”

What the sources say

• Not checked yetcites Saeed et al. 2016 source

In the paper

“Nonetheless, extant data suggests that Bt crops do not alter the function of the natural enemy community and may provide for enhanced biological control services if they prevent or reduce the alternative use of broader-spectrum insecticides for control of the Bt targeted pest.”

In the paper

“Further, it has been suggested that such early tier laboratory studies can conservatively predict non-target effects expected in the field (Duan et al., 2010).”

What the sources say

• Not checked yetcites Duan et al., 2010 source

In the paper

“The quickly increased adoption of Bt cotton led to broad, areawide control of the pest (Carrière et al., 2003) and opened the door for an opportunity to eradicate this invasive pest.”

What the sources say

• Not checked yetcites Carrière et al., 2003 source

In the paper

“In China, a large-scale study demonstrated that the decline in insecticide sprays in Bt cotton resulted in an increased abundance of important natural enemies and an associated decline in aphid populations (Lu et al., 2012).”

What the sources say

• Not checked yetcites Lu et al., 2012

In the paper

“Thus, Bt crops represent a highly selective control tactic that should conserve natural enemies and contribute to enhanced management of pests, especially if Bt crops replace the application of broad-spectrum insecticides for control of Bt targeted pests.”

In the paper

“This provided clear evidence that the commonly used insecticides harmed the internal parasitoid while Cry1C did not.”

In the paper

“Overall, Brookes and Barfoot (2018) estimate massive reductions in foliar insecticide use in Bt cotton production globally, pointing strongly to the potential for conservation biological control to play an important and ever increasing role in IPM more broadly in this crop system.”

What the sources say

• Not checked yetcites Brookes and Barfoot (2018)

In the paper

“Bt cotton became a cornerstone element in the pink bollworm eradication program initiated in 2006 in Arizona, and insecticide use for this pest ceased entirely by 2008 (Naranjo and Ellsworth, 2010).”

What the sources say

• Not checked yetcites Naranjo and Ellsworth, 2010

In the paper

“This pattern was associated with a disproportionately larger reduction in broad-spectrum insecticides resulting in a situation where most of the few insecticides now applied are those that more selectively target the pests and conserve natural enemies.”

In the paper

“Again, adverse effects on the natural enemies were observed in the pyrethroid treatment but not in the case of Bt broccoli.”

What the sources say

• Not checked yetcites Tian et al., 2015 source

In the paper

“The use of seed treated with various neonicitinoids has become pervasive in several field crops in the USA (Douglas and Tooker, 2015;Papiernik et al., 2018) and potentially negates to some degree the reduction in insecticides possible through the deployment of Bt crops.”

What the sources say

• Not checked yetcites Douglas and Tooker, 2015
• Not checked yetcites Papiernik et al., 2018 source

In the paper

“They noted that when biological control was disrupted, it often led to an 'insecticide treadmill' for the pests which, in turn, led to their eventual resistance to the insecticides.”

What the sources say

• Not checked yetcites Smith and Hagen, 1959
• Not checked yetcites Stern and van den Bosch, 1959
• Not checked yetcites Stern et al., 1959

In the paper

“Studies on the widespread adoption of Bt maize in the Midwestern USA corn belt have demonstrated a dramatic decline in populations of O. nubilalis, and thus the need for insecticide treatments for this key lepidopteran pest.”

In the paper

“Simulations demonstrated that parasitism by D. insulare provided the most reliable long-term control of P. xylostella within this system and always delayed the evolution of resistance to Bt broccoli.”

What the sources say

• Not checked yetcites Onstad et al., 2013 source

In the paper

“However, as noted, there has been a trend in the USA to add neonicotinoid seed treatments and to date virtually all maize seeds sold are treated (Douglas and Tooker, 2015;Sappington et al., 2018).”

What the sources say

• Not checked yetcites Douglas and Tooker, 2015
• Not checked yetcites Sappington et al., 2018 source

In the paper

“This insurance approach is targeting a number of early-season pests that occur only sporadic but for some of which rescue treatments are not available (Gray, 2011;Sappington et al., 2018).”

What the sources say

• Not checked yetcites Gray, 2011 source
• Not checked yetcites Sappington et al., 2018 source

In the paper

“where cowpea is the most important grain legume (Murdock et al., 2008).”

What the sources say

• Not checked yetcites Murdock et al., 2008

In the paper

“Recent work suggests that seed treatments in maize can negatively impact some natural enemy populations early season even though there is recovery later on (Disque et al., 2018).”

What the sources say

• Not checked yetcites Disque et al., 2018

In the paper

“In a greenhouse study over multiple generations, use of C. maculata and Bt broccoli provided excellent control of P. xylostella while delaying resistance in P. xylostella to Bt broccoli (Liu et al., 2014).”

What the sources say

• Not checked yetcites Liu et al., 2014

In the paper

“Furthermore, this study demonstrated that Bt sweet corn provided better control of lepidopteran pests, and did not negatively affect the predation rates of sentinel egg masses of the European corn borer, as did lambda cyhalothrin and indoxacarb.”

What the sources say

• Not checked yetcites Musser and Shelton, 2003 source

In the paper

“Unlike most of the cotton production region in the US, the use of treated seed in Arizona is relatively rare (< 13% of acreage, P. Ellsworth, personal communication), mainly because plants in this production environment can quickly outgrow any minor thrips damage and some species such as Frankliniella occidentalis (Thysanoptera: Thripidae) are actually considered beneficial (Gonzalez et al., 1982;”

What the sources say

• Not checked yetcites Gonzalez et al., 1982
• Not checked yetcites Trichilo and Leigh, 1986

In the paper

“While these studies document lower pest pressure because of wide spread adoption of Bt maize and less need for insecticidal sprays, by implication they also suggest that widespread conservation of natural enemies may be occurring.”

In the paper

“Furthermore, this decline occurred not only for those who adopted Bt maize, but also for surrounding maize farmers that did not (Hutchinson et al., 2010).”

What the sources say

• Not checked yetcites Hutchinson et al., 2010

In the paper

“A similar 'halo' effect of lepidopteran suppression by the widespread adoption of Bt maize in the eastern USA has also been documented, as well as the benefits of pest declines in surrounding vegetable fields (Dively et al., 2018).”

What the sources say

• Not checked yetcites Dively et al., 2018 source

In the paper

“As described previously, multiple studies have shown that Cry1 proteins expressed in plants control targeted Lepidoptera but do not harm important natural enemies, thus conserving them to function as biological control agents.”

In the paper

“While two lines expressing a cry1Ab/Ac fusion gene have received biosafety certificates by the Ministry of Agriculture already in 2009, no Bt rice is commercialized yet (Li et al., 2016).”

What the sources say

• Not checked yetcites Li et al., 2016

In the paper

“As expected and intended, the insecticidal proteins deployed today have a narrow spectrum of activity and cause no detrimental unintended effects to natural enemies.”

In the paper

“Overall, the change in insecticide use has benefitted non-target species in general and biological control in particular.”

In the paper

“These techniques allow the knock-out of a specific gene.”

In the paper

“A compound that is of particular interest is the alpha-amylase inhibitor αAI-1 from the green bean that has been introduced into various other legumes and shown to provide very high levels of protection from certain (susceptible) bruchid (Coleoptera: Bruchidae) species (Lüthi et al., 2013a;Morton et al., 2000).”

What the sources say

• Not checked yetcites Lüthi et al., 2013a
• Not checked yetcites Morton et al., 2000 source

In the paper

“Suppression of Snf7 has been reported to cause increased D. v. virgifera larval mortality leading to reduced root damage (Bolognesi et al., 2012).”

What the sources say

• Not checked yetcites Bolognesi et al., 2012 source

In the paper

“The potential of RNAi for pest control has first been demonstrated in 2007 for H. armigera and Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) (Baum et al., 2007;Mao et al., 2007).”

What the sources say

• Not checked yetcites Baum et al., 2007 source
• Not checked yetcites Mao et al., 2007 source

In the paper

“In addition to Bt, effective toxins have also been isolated from other bacteria including species of Pseudomonas (Anderson et al., 2018) and Chromobacter (Sampson et al. 2017) that might be expressed in future insect-resistant GE plants.”

What the sources say

• Not checked yetcites Anderson et al., 2018 source
• Not checked yetcites Sampson et al. 2017 source

In the paper

“Other examples of nonconstitutive promoters include tissue-specific and inducible promoters that may help not only limit exposure to natural enemies but can be used for resistance management (Bates et al., 2005).”

What the sources say

• Not checked yetcites Bates et al., 2005 source

In the paper

“Interestingly, resistance was not sequence-specific but caused by an impaired luminal uptake, indicated by cross resistance to other dsRNAs tested.”

What the sources say

• Not checked yetcites Khajuria et al., 2018 source

In the paper

“The first insect-resistant dsRNA-expressing GE crop was registered by the US Environmental Protection Agency (US EPA) in June 2017 (https://www.epa.gov/newsreleases/epa-registers- innovative-tool-control-corn-rootworm).”

What the sources say

• Not checked yetcites https://www.epa.gov/newsreleases/epa-registers- innovative-tool-control-corn-rootworm

In the paper

“In general, dietary RNAi works very well in Coleoptera but less so in Lepidoptera (Baum and Roberts, 2014).”

What the sources say

• Not checked yetcites Baum and Roberts, 2014

In the paper

“The efficacy of Bt-transgenic crops in controlling important target pests has been very high.”

In the paper

“Consequently, such insect-resistant GE varieties can not only help to increase yields and provide economic benefits to farmers but also improve environmental and human health.”

In the paper

“New plant breeding techniques, such as genome editing that are protein-mediated or based on sequence-specific nucleases are continuously been developed (Baltes and Voytas, 2015).”

What the sources say

• Not checked yetcites Baltes and Voytas, 2015

In the paper

“There is compelling evidence that GM crops can contribute to sustainable development goals with benefits to farmers, consumers, the environment and the economy.”

What the sources say

• Not checked yetcites EASAC, 2013