@article{dhammi_krestchmar_zhu_ponnusamy_gould_reisig_kurtz_roe_2022, title={Impact of Caterpillar Increased Feeding Rates on Reduction of Bt Susceptibility}, volume={23}, ISSN={["1422-0067"]}, url={https://www.mdpi.com/1422-0067/23/23/14856}, DOI={10.3390/ijms232314856}, abstractNote={The use of insect-resistant transgenic crops producing Bacillus thuringiensis protein Cry toxins (Bt) to control caterpillars is wide-spread. Development of a mechanism to prevent Bt from reaching its target site in the digestive system could result in Bt resistance and resistance to other insecticides active per os. Increased feeding rates by increasing temperature in tobacco budworms, Chloridea virescens, and bollworms, Helicoverpa zea, decreased Bt Cry1Ac susceptibility and mortality. The same was found in C. virescens for Bollgard II plant extract containing Bt Cry1Ac and Cry2Ab2 toxins. Furthermore, H. zea from the same inbred laboratory colony that fed faster independent of temperature manipulation were less susceptible to Bt intoxication. A laboratory derived C. virescens Bt resistant strain demonstrated a higher feeding rate on non-Bt artificial diet than the parental, Bt susceptible strain. A laboratory-reared Bt resistant fall armyworm, Spodoptera frugiperda, strain also fed faster on non-Bt diet compared to Bt susceptible caterpillars of the same species, both originally collected from corn. The studies in toto and the literature reviewed support the hypothesis that increased feeding rate is a behavioral mechanism for reducing caterpillar susceptibility to Bt. Its possible role in resistance needs further study.}, number={23}, journal={INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES}, author={Dhammi, Anirudh and Krestchmar, Jaap B. and Zhu, Jiwei and Ponnusamy, Loganathan and Gould, Fred and Reisig, Dominic and Kurtz, Ryan W. and Roe, R. Michael}, year={2022}, month={Dec} }
 @article{lawrie_mitchell_deguenon_ponnusamy_reisig_pozo-valdivia_kurtz_roe_2022, title={Characterization of Long Non-Coding RNAs in the Bollworm, Helicoverpa zea, and Their Possible Role in Cry1Ac-Resistance}, volume={13}, ISSN={["2075-4450"]}, url={https://www.mdpi.com/2075-4450/13/1/12}, DOI={10.3390/insects13010012}, abstractNote={Multiple insect pest species have developed field resistance to Bt-transgenic crops. There has been a significant amount of research on protein-coding genes that contribute to resistance, such as the up-regulation of protease activity or altered receptors. However, our understanding of the role of non-protein-coding mechanisms in Bt-resistance is minimal, as is also the case for resistance to chemical pesticides. To address this problem relative to Bt, RNA-seq was used to examine statistically significant, differential gene expression between a Cry1Ac-resistant (~100-fold resistant) and Cry1Ac-susceptible strain of Helicoverpa zea, a prevalent caterpillar pest in the USA. Significant differential expression of putative long non-coding RNAs (lncRNAs) was found in the Cry1Ac-resistant strain (58 up- and 24 down-regulated gene transcripts with an additional 10 found only in resistant and four only in susceptible caterpillars). These lncRNAs were examined as potential pseudogenes and for their genomic proximity to coding genes, both of which can be indicative of regulatory relationships between a lncRNA and coding gene expression. A possible pseudogenic lncRNA was found with similarities to a cadherin. In addition, putative lncRNAs were found significantly proximal to a serine protease, ABC transporter, and CYP coding genes, potentially involved in the mechanism of Bt and/or chemical insecticide resistance. Characterization of non-coding genetic mechanisms in Helicoverpa zea will improve the understanding of the genomic evolution of insect resistance, improve the identification of specific regulators of coding genes in general (some of which could be important in resistance), and is the first step for potentially targeting these regulators for pest control and resistance management (using molecular approaches, such as RNAi and others).}, number={1}, journal={INSECTS}, author={Lawrie, Roger D. and Mitchell, Robert D. and Deguenon, Jean Marcel and Ponnusamy, Loganathan and Reisig, Dominic and Pozo-Valdivia, Alejandro Del and Kurtz, Ryan W. and Roe, Richard Michael}, year={2022}, month={Jan} }