Comparative analyses of transcriptional responses of Dectes texanus LeConte (Coleoptera: Cerambycidae) larvae fed on three different host plants and artificial diet

Authors: AGUIRRE-ROJAS, LINA - Kansas State University; Scully, Erin; TRICK, HAROLD - Kansas State University; ZHU, KUN YAN - Kansas State University; SMITH, CHARLES - Retired Non ARS Employee

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2021
Publication Date: 6/1/2021
Citation: Aguirre-Rojas, L.M., Scully, E.D., Trick, H.N., Zhu, K., Smith, C.M. 2021. Comparative analyses of transcriptional responses of Dectes texanus LeConte (Coleoptera: Cerambycidae) larvae fed on three different host plants and artificial diet. Scientific Reports. 11:11448. https://doi.org/10.1038/s41598-021-90932-x.
DOI: https://doi.org/10.1038/s41598-021-90932-x

Interpretive Summary: Soybean stem borer is a major pest of soybean in the Midwestern United States that causes significant yield losses. Because larvae feed inside the stems and are protected from the external environment, no reliable pest management tools currently exist for this insect and pesticides are largely ineffective. Although these insects are major pests of soybean, sunflowers and giant ragweed are alternative host plants for this insect. To understand which genes might be important for this insect's ability to colonize soybean, we the compared gene expression of insects feeding in soybean to the expression levels of genes of insects feeding on both sunflower and giant ragweed. Over 500 genes were expressed at significantly higher levels in insects feeding in soybeans compared to the other two plants, including those involved in breaking down plant cells walls and those involved in breaking down plant toxins that are produced by soybeans in response to insect feeding. The ability of the insects to break down these toxins is probably what allows them to continue feeding in soybeans. These results provide a list of gene candidates that could be targeted to reduce the insect's ability to detoxify soybean defense compounds and reduce damage from this pest in soybean fields.

Technical Abstract: Dectes texanus is an important coleopteran pest of soybeans and cultivated sunflowers in the Midwestern United States that causes yield losses by girdling stems of their host plants. Although sunflower and giant ragweed are primary hosts of D. texanus, they began colonizing soybeans approximately 50 years ago and no reliable management method has been established to prevent or reduce losses by this pest. To identify genes putatively involved when feeding soybean, we compared gene expression of D. texanus third-instar larvae fed soybean to those fed sunflower, giant ragweed, or artificial diet. Dectes texanus larvae differentially expressed 514 unigenes in soybean-fed larvae compared to those fed the other diet treatments. Enrichment analyses of gene ontology terms from up-regulated unigenes in soybean-fed larvae compared to those fed both primary hosts highlighted unigenes involved in oxidoreductase and polygalacturonase activities. Cytochrome P450s, carboxylesterases, major facilitator superfamily transporters, lipocalins, apolipoproteins, glycosyl hydrolases 1 and 28, and lytic monooxygenases were among the most commonly up-regulated unigenes in soybean-fed larvae compared to those fed their primary hosts. These results suggest that D. texanus larvae differentially expressed unigenes involved in biotransformation of allelochemicals, digestion of plant cell walls and transport of small solutes and lipids when feeding in soybean.