Insecticidal Activity of 11 Bt toxins and 3 Transgenic Maize Events Expressing Vip3Aa19 to Black Cutworm, Agrotis ipsilon (Hufnagel).

Xiaorui Yan,Yin He,Meifeng Ren,Kanglai He,Junjiao Lu,Yueqin Wang,Zhenying Wang

doi:10.3390/insects11040208

Abstract

Black cutworm (BCW), Agrotis ipsilon (Hufnagel), is an occasional pest of maize that can cause considerable economic loss and injury to corn seedlings. This research mainly assessed the susceptibility of BCW neonates to 11 Bt toxins (Cry1Ab, Cry1Ac, Cry1Ah, Cry1F, Cry1Ie, Cry1B, Cry2Aa, Vip3_ch1, Vip3_ch4, Vip3Ca2, Vip3Aa19) by exposing neonates to an artificial diet containing Bt toxins and evaluated the efficacy of three transgenic maize events (C008, C009, C010) expressing Vip3Aa19 toxin against BCW. The toxin-diet bioassay data indicated that Vip3Aa19 protein (LC50 = 0.43 μg/g) was the most active against BCW. Chimeric protein Vip3_ch1 (LC50 = 5.53 μg/g), Cry1F (LC50 = 83.62 μg/g) and Cry1Ac (LC50 = 184.77 μg/g) were less toxic. BCW was very tolerant to the other Bt toxins tested, with LC50 values more than 200 μg/g. Greenhouse studies were conducted with artificial infestations at the whorl stage by placing second-instar BCW larvae into whorl leaf and the fourth-instar larvae at the base of maize seedings. These results suggest that these transgenic maize events expressing Vip3Aa19 can provide effective control for BCW.

Highlights

Black cutworm (BCW), Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), is an occasional pest of maize
We considered two LC50 values to be significantly different only if their 95% fiducial limits did not overlap
The toxicity of Vip3Aa19 was significantly higher compared to other Bt toxins as there was a non-overlap of

Summary

Introduction

Black cutworm (BCW), Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), is an occasional pest of maize. Young A. ipsilon larvae initially feed on the leaves at the whorl stage, leaving holes on the surface of leaves. As BCW larvae feed, they cut stems at or below the growing point and cause seedlings to die, reducing plant populations and crop yield and causing considerable economic loss [1]. A. ipsilon was first recorded in Britain in 1831 and was regarded as native. Of flight records, A. ipsilon was observed in the British Isles in 64 years [2]. It was found in Hawaii, Europe, Australia, New Zealand, North Africa, the Pacific Rim and Asia [3,4]

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Conclusion