Journal Article

Toxicity of Cry- and Vip3Aa-Class Proteins and Their Interactions against Spodoptera frugiperda (Lepidoptera: Noctuidae)

Zhang, Tiantao, Liu, Xiaobei, Zhang, Yongjun, He, Kanglai, Dong, Hui, Bai, Shuxiong, Wang, Zhenying, Liu, Shen

2024

Overview

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is one of the most important insect pests affecting corn crops worldwide. Although planting transgenic corn expressing Bacillus thuringiensis (Bt) toxins has been approved as being effective against FAW, its populations’ resistance to Bt crops has emerged in different locations around the world. Therefore, it is important to understand the interaction between different Bt proteins, thereby delaying the development of resistance. In this study, we performed diet-overlay bioassays to evaluate the toxicity of Cry1Ab, Cry1Ac, Cry1B, Cry1Ca, Cry1F, Cry2Aa, Cry2Ab, Vip3Aa11, Vip3Aa19, and Vip3Aa20, as well as the interaction between Cry1Ab-, Cry1F-, Cry2Ab-, and Vip3Aa-class proteins against FAW. According to our results, the LC50 values of Bt proteins varied from 12.62 ng/cm2 to >9000 ng/cm2 (protein/diet), among which the Vip3Aa class had the best insecticidal effect. The combination of Cry1Ab and Vip3Aa11 exhibited additive effects at a 5:1 ratio. Cry1F and Vip3Aa11 combinations exhibited additive effects at 1:1, 1:2, and 5:1 ratios. The combination of Cry1F and Vip3Aa19 showed an antagonistic effect when the ratio was 1:1 and an additive effect when the ratio was 1:2, 2:1, 1:5, and 5:1. Additionally, the combinations of Cry1F and Vip3Aa20 showed antagonistic effects at 1:2 and 5:1 ratios and additive effects at 1:1 and 2:1 ratios. In addition to the above combinations, which had additive or antagonistic effects, other combinations exhibited synergistic effects, with variations in synergistic factors (SFs). These results can be applied to the establishment of new pyramided transgenic crops with suitable candidates, providing a basis for FAW control and resistance management strategies.

• Publisher: MDPI AG,MDPI
• Subject: Animals / Bacillus thuringiensis / Bacillus thuringiensis - genetics / Bacillus thuringiensis Toxins - toxicity / Bacterial Proteins - genetics / Bacterial Proteins - metabolism / Bacterial Proteins - toxicity / Binding sites / bioassay / Bioassays / Biopesticides / Cereal crops / Corn / Crops / cry class / Cry1Ac toxin / Diet / Endotoxins - toxicity / Expected values / Hemolysin Proteins - genetics / Hemolysin Proteins - toxicity / Insecticides / Insecticides - toxicity / Insects / Larva - drug effects / Pest Control, Biological / Pests / Plants, Genetically Modified - genetics / Proteins / Ratios / Spodoptera - drug effects / Spodoptera frugiperda / Synergistic effect / Toxicity / Toxins / Transgenic plants / Vip3Aa class