The Cultivation of Bt Corn Producing Cry1Ac Toxins Does Not Adversely Affect Non-Target Arthropods

Abstract

Transgenic corn producing Cry1Ac toxins from Bacillus thuringiensis (Bt) provides effective control of Asian corn borer, Ostrinia furnacalis (Guenée), and thus reduces insecticide applications. However, whether Bt corn exerts undesirable effects on non-target arthropods (NTAs) is still controversial. We conducted a 2-yr study in Shangzhuang Agricultural Experiment Station to assess the potential impact of Bt corn on field population density, biodiversity, community composition and structure of NTAs. On each sampling date, the total abundance, Shannon's diversity index, Pielou's evenness index and Simpson's diversity index were not significantly affected by Bt corn as compared to non-Bt corn. The “sampling dates” had a significant effect on these indices, but no clear tendencies related to “Bt corn” or “sampling dates X corn variety” interaction were recorded. Principal response curve analysis of variance indicated that Bt corn did not alter the distribution of NTAs communities. Bray-Curtis dissimilarity and distance analysis showed that Cry1Ac toxin exposure did not increase community dissimilarities between Bt and non-Bt corn plots and that the evolution of non-target arthropod community was similar on the two corn varieties. The cultivation of Bt corn failed to show any detrimental evidence on the density of non-target herbivores, predators and parasitoids. The composition of herbivores, predators and parasitoids was identical in Bt and non-Bt corn plots. Taken together, results from the present work support that Bt corn producing Cry1Ac toxins does not adversely affect NTAs.

Effects of transgenic cry1Ie maize on non-lepidopteran pest abundance, diversity and community composition

“…Therefore, diversity indices and multivariate analyses are often combined together to assess the effects of Bt crops on non-target arthropods in the field, which help to obtain a more comprehensive view of species abundance, diversity and community composition of arthropods in the field. An increasing number of studies have adopted multivariate analyses, such as PRC, CCA and RDA to compare the non-target arthropod communities of Bt crops with those of nonBt crops (Guo et al 2014;Habuštová et al 2014;Li and Liu 2013;Lu et al 2014;Svobodová et al 2013Svobodová et al , 2016. All of these studies have demonstrated that non-target arthropod community in Bt crops are similar to those found in corresponding non-Bt crops, which has been further substantiated by our multivariate analyses results.…”

“…As the area under cultivation with Bt crops has steadily increased worldwide, environmental risk assessments (ERA) of Bt crops on non-target arthropods have attracted increasing attention from a number of researchers (Devos et al 2012;Guo et al 2014;Habuštová et al 2014;Romeis et al 2008). Laboratory and field studies have evaluated the effects of Bt maize on non-target arthropods.…”

“…Likewise, Cry3Bb1 maize did not harm the life history parameters of T. urticae (Li and Romeis 2010) and Cry1F maize did not negatively affected egg production and hatching rate of the corn leafhopper Dalbulus maidis (Virla et al 2010). Field surveys showed that Bt-maize had no significant impact on the field densities of the plant bug Trigonotylus caelestialium (Kirkaldy) (Heteroptera, Miridae) (Rauschen et al 2009) and the leafhopper Zyginidia scutellaris (Herrich-Schäffer) (Hemiptera: Cicadellidae) (Rauschen et al 2010), as well as on the abundance and diversity of non-target arthropods (Guo et al 2014;Habuštová et al 2014;Svobodová et al 2015). The abundance and species of non-target herbivores may not only reflect the potential effects that Bt crops have on non-target arthropods, but may also indirectly affect the abundance of parasitoids or predators through disruption of food webs (Balog et al 2010;Lundgren et al 2009;Svobodová et al 2016).…”

“…Currently, various approaches are utilized for ACB control, including insecticide applications, agricultural control strategies, mating disruption techniques and Trichogramma releases, although each of these approaches have limitations (Guo et al 2014; Electronic supplementary material The online version of this article (doi:10.1007/s11248-016-9968-y) contains supplementary material, which is available to authorized users. Nafus and Schreiner 1991).…”

“…Because of this possibility, field assessments of the effects of new Bt crops on nontarget herbivore insect species that occur in agricultural ecosystems are necessary prior to commercialization of new Bt crops. Although Guo et al (2014) had reported that Bt maize expressing Cry1Ac protein had negligible effects on the density of non-target herbivores, new types of Bt maize, however, must be assessed for, possible unintended effects on non-target herbivores (Zurbrügg and Nentwig 2009).…”