Diet improvement strategy for western corn rootworm (Coleoptera: Chrysomelidae) using metabolomic approaches combined with mathematical modeling

Western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte is a serious pest of maize (Zea mays L.) in the United States. Our previous efforts have successfully formulated an artificial diet capable of efficiently rearing WCR larvae. However, diet-reared larvae lag behind those fed on its natural food, maize roots. Our goal is to develop an artificial diet for western corn rootworm larvae that can match the natural food and support the production of WCR. We conducted metabolomics analyses of WCR larvae feed on maize roots and the artificial diet as well as chemical composition analyses of maize roots and the artificial diet to identify nutrients needed for improving the current WCR diet. Subsequently, we utilized response surface modeling to identify and characterize key nutrients to generate an improved diet formation for WCR larvae. For all experiments, multiple life history parameters (survival, weight, and molting) were recorded from 10-d diet bioassays. The results indicated that vitamins were critical components to improve in the current diet. Additionally, amino acid metabolic disorders, upregulation of peptide metabolism and lipid metabolism, downregulation of carbohydrate metabolism, cofactors and vitamin metabolism co-occurred in larvae fed on the artificial diet compared with those reared on maize roots. These findings provide important insights into the regulation of the food streams on WCR nutrition and metabolism and will be used to improve the WCR artificial diet.