Funded by

This research is currently supported by Agriculture and Food research Initiative (AFRI) competitive grants No. 2018-67013-27820 and 2021-67013-33567 from the USDA National Institute of Food and Agriculture

Since their commercialization in 1996, transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt crops) have revolutionized agricultural pest control. Benefits of these Bt plant incorporated protectants (PIPs) include high efficacy and lack of toxicity to non-target organisms. The most important threat to the susbtainability of Bt PIPs is the evolution of resistance by target pests. After >25 years since their commercialization, there are reports of resistance to Bt PIPs developing in lepidopteran and coleopteran pests. One of the key elements of resistance management mandates for Bt PIPs is monitoring for resistance in target insects populations, which is commonly done using bioassays with larvae from F2 crosses. Our efforts are focused on developing targeted DNA sequencing as a mores sensitive and cost-effective alternative for Bt resistance monitoring.

Our model for this research is resistance to Bt corn producing the Cry1F PIP in populations of the the fall armyworm (Spodoptera frugiperda). This insect is particularly interesting because it has evolved field-evolved practical resistance to the Cry1F PIP at different locations in the native range of S. frugiperda (Puerto Rico, Florida, North Carolina, Brazil, Argentina). Moreover, S. frugiperda is quickly becoming a global super pest threatening global food production.

Our work takes advantage of fall armyworm strains originated in Puerto Rico with field-evolved practical resistance to corn producing Cry1F, as well as our previous work identifying resistance mechanisms to Bt PIPs and alleles responsible.

Our current goals include the use of targeted DNA sequencing to determine the frequency of known resistance alleles to the Cry1F PIP and identify novel candidate resistance alleles and their frequency in S. frugiperda populations from the USA, Puerto Rico, Brazil, and Argentina. In addition, we are using the the same DNA-based tools to asses the risk of resistance to Bt PIPs in the invasive range of S. frugiperda.

Our model for this research are strains of corn earworm (Helicoverpa zea) and fall armyworm (Spodoptera frugiperda) displaying >500-fold resistance to Vip3Aa. is resistance to Bt corn producing the Cry1F PIP in populations of the the fall armyworm (Spodoptera frugiperda). Both insects are key pests of corn and cotton that have evolved practical resistance to Cry1 PIPs in the US. Detection of major Vip3Aa resistance alleles in F2 screens for both species confirms the potential for evolving resistance to Vip3Aa exists. Moreover, S. frugiperda is quickly becoming a global super pest threatening global food production.

Our current work takes advantage of available Vip3Aa-resistant strains of H. zea and S. frugiperda and proteomic and genomic resources to identify the mechanism behind Vip3Aa resistance. Our project includes the use of targeted DNA sequencing to estimate the frequency of Vip3Aa-resistance alleles in field populations of corn earworm and fall armyworm.