Comparison of Six Artificial Diets for Western Corn Rootworm Bioassays and Rearing

Authors

Lisa N. Meihls, USDA-ARS Plant Genetics Research Unit
Man P. Huynh, University of Missouri & Can Tho University
Dalton C. Ludwick, University of Missouri & Can Tho UniversityFollow
Thomas A. Coudron, USDA-ARS Biological Control of Insects LaboratoryFollow
B. Wade French, North Central Agricultural Research LaboratoryFollow
Kent S. Shelby, USDA-ARS Biological Control of Insects LaboratoryFollow
Andrea J. Hitchon, University of Guelph
Jocelyn L. Smith, University of Guelph
Art W. Schaafsma, University of Guelph
Adriano E. Pereira, USDA-ARS Plant Genetics Research Unit
B. E. Hibbard, USDA-ARS, University of Missouri-ColumbiaFollow

ORCID IDs

http://orcid.org/0000-0002-9901-7026

http://orcid.org/0000-0001-8067-4416

Date of this Version

9-5-2018

Citation

US Government employee(s) and is in the public domain in the US

Abstract

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is considered the most important maize (Zea mays L.) pest in the U.S. Corn Belt. Bioassays testing susceptibility to Bacillus thuringiensis Berliner (Bt) and other toxins of corn rootworm larvae often rely on artificial diet formulations. Successful bioassays on artificial diet for corn rootworm have sometimes been challenging because of microbial contamination. Toward the long-term goal of developing a universal artificial diet for western corn rootworm larvae, we compared larval survival, dry weight, and percentage of molt in 10-d bioassays from six current diets of which we were aware. In addition, as part of longer term rearing efforts, we recorded molting over an extended period of development (60 d). Six different artificial diets, including four proprietary industry diets (A, B, C, and D), the first published artificial diet for western corn rootworm (Pleau), and a new diet (WCRMO-1) were evaluated. Western corn rootworm larval survival was above 90% and contamination was 0% on all diets for 10 d. Diet D resulted in the greatest dry weight and percentage molting when compared with the other diets. Although fourth-instar western corn rootworm larvae have not been documented previously (only three instars have been previously documented), as many as 10% of the larvae from Diet B molted into a fourth instar prior to pupating. Overall, significant differences were found among artificial diets currently used to screen western corn rootworm. In order for data from differing toxins to be compared, a single, reliable and high-quality western corn rootworm artificial diet should eventually be chosen by industry, academia, and the public as a standard for bioassays.