Efficacy Evaluation of Two Transgenic Maize Events Expressing Fused Proteins to Cry1Ab-Susceptible and -Resistant <I>Ostrinia furnacalis</I> (Lepidoptera: Crambidae)

Abstract

The Asian corn borer, Ostrinia furnacalis (GuenCe), is a major pest of maize in China. Transgenic Bt maize could provide an effective way to control this pest. However, the potential of resistance evolution has been documented in the laboratory-a CrylAb-resistant strain of Asian corn borer (Asian corn borer-AbR) could survive well on two Bt maize events, that is, MON810 and Bt11. Pyramided transgenic crops with multiple dissimilar Bt insecticidal proteins offer a superior route for pests control compared with that with one Bt single gene. In this study, two novel transgenic Bt maize events (N30 and V3), which contained a fused gene Cry1Ab/Cry2Aj and CrylAb /Vip3DA, respectively, were evaluated for their efficacy on protection against CrylAb-susceptible Asian corn borer (Asian corn borer-BtS) as well as their potential for dealing with the Asian corn borer-AbR. In laboratory bioassay, no neonate larvae of Asian corn borer-BtS fed on the whorl leaves, tassels, husks, silks, and kernels of N30 and V3 could survive at 96 h after infestation. In contrast, only 2.0-8.7% larvae died as they fed on non-Bt maize tissues. As Asian corn borer-AbR neonate larvae fed on N30 and V3 silks and kernels, 95.0% even more larvae were killed at 96 h after infestation, and all died at 168 h after infestation, while 10.0-11.67% larvae survived on non-Bt control. In the field test under artificial infestation at middle whorl leaf and silking stages of maize, there were no significant leaf, silk, and stalk damage on Bt maize plants by comparison with severe leaf feeding, stalk born, and ear damage in control, in addition, the expression profiles of a fused protein of CrylAb/Cry2Aj or CrylAb/Vip3DA in different tissues of N30 and V3 were also confirmed. In conclusion, it is clear that both Bt maize events (N30 and V3) show great potential for protecting maize from attack by Asian corn borer that has resistance to Cry1Ab protein.

Consumption of Bt Maize Pollen Containing Cry1Ie Does Not Negatively Affect Propylea japonica (Thunberg) (Coleoptera: Coccinellidae)

“…To date, China has obtained many Bt maize lines, all of which express cry1 and/or cry2 genes targeting lepidopteran pests [4,5,6,7]. Most of the Bt maize lines, such as IE09S034 (expressing a cry1Ie gene), BT-799 (expressing a modified mcry1Ac gene), and Shuangkang12-5 (expressing a fusion cry1Ab/2Aj gene) have proven to be effective against lepidopteran pests [8,9]. In the case of Bt maize expressing cry1Ie , the Chinese Ministry of Agriculture has already approved field trials for assessing the environmental risks, indicating its potential to be commercialized in the near future.…”

Inheritance Patterns, Dominance and Cross-Resistance of Cry1Ab- and Cry1Ac-Selected Ostrinia furnacalis (Guenée)

“…Earlier studies in China showed that Cry1Ab-expressing maize MON810 and Bt11 could effectively protect against the Asian corn borer and other lepidopteron pests [17,18,19,20]. However, the potential of resistance evolution has been documented in the laboratory resulting in Cry1Ab-resistant colonies of ACB with the propensity to survive well on two Bt maize events [21]. Under laboratory conditions and using artificial diets containing Cry1Ab protein, resistance of O. furnacalis towards the Bt toxin increased more than 100-fold after 35 generations [22].…”

Tolerance to Stalk and Ear‐Invading Worms and Yield Performance of Bt and Conventional Corn Hybrids

“…Recent increases in Bt corn adoption are attributed to newly released Bt hybrids with pyramided genes that effectively suppress a wider range of lepidopteran pests and stacked genes for corn rootworm (CRW, including northern corn rootworm, Diabrotica barberi , and western corn rootworm, Diabrotica virgifera virgifera ) (Buntin, 2008; Hoffmann et al, 2014). All Bt hybrids effectively control the ECB, but different Bt events and gene combinations vary widely in their efficacy against other caterpillar pests (Chang et al,2013; Frank et al, 2013; Rule et al, 2014). The cost of Bt corn seed has increased significantly in recent years compared with when it was initially released, especially with the introduction of multiple‐trait hybrids (Fernandez‐Cornejo et al, 2014; National Research Council, 2010).…”