Toxicometabolomic profiling of resistant and susceptible western corn rootworm larvae feeding on Bt maize seedlings

Abstract

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is the most serious pest of maize (Zea mays L.) in the U.S. Corn Belt and parts of Europe. Transgenic maize hybrids expressing at least one of the four currently available insecticidal toxins from Bacillus thuringiensis (Bt) Berliner, currently the most widely adopted control method in continuous maize, have faltered due to the emergence of resistance. The resistance mechanisms of WCR to Bt toxins are not fully understood. We identified metabolic profiles of susceptible and resistant WCR larvae fed on maize hybrids expressing each of three available Cry3 proteins (eCry3Ab1, mCry3A, and Cry3Bb1) targeting corn rootworms and a control non-Bt maize via an untargeted metabolomics approach. Over 580 unique metabolites found in WCR larvae were classified into different pathways (amino acids, carbohydrates, cofactors and vitamins, energy, lipid, nucleotide, peptide, and xenobiotics). By exploring shifts in WCR larval metabolome exclusively by Bt toxins, several candidate metabolites and metabolic pathways were identified in susceptible and resistant larvae that may be involved in defense against or recovery from Bt ingestion by these larvae. These findings would provide mechanistic insights into altered metabolic pathways associated with the resistance mechanisms of WCR to Bt toxins.

A universal artificial diet for corn rootworm (Diabrotica spp.) larval biopesticide assays

“…Non-diapausing eggs of a WCR colony were obtained from the USDA-ARS Plant Genetics Research Unit in Columbia, MO. This WCR colony was developed from non-diapausing eggs originally purchased from Crop Characteristics (Farmington, MN) ( 37 ). Non-diapausing eggs of an NCR colony were supplied by the USDA-ARS North Central Agricultural Research Laboratory in Brooking, SD.…”

Host search behaviors of specialist and generalist root feeding herbivores (Diabrotica spp.) on host and non-host plants

“…Eggs from a non-diapausing WCR strain were obtained from the USDA-ARS Plant Genetics Research Unit in Columbia, MO. This strain was derived from a non-diapausing strain originally purchased from Crop Characteristics (Farmington, MN) as described previously 53 . Eggs from a non-diapausing NCR strain were obtained from the USDA-ARS North Central Agricultural Research Laboratory in Brookings, SD.…”