Development of an improved and accessible diet for western corn rootworm larvae using response surface modeling

Man P Huynh,Kent S Shelby,Randall P Niedz,Stephen L Lapointe,Thomas A Coudron,Bruce E Hibbard,Michael Vella

doi:10.1038/s41598-019-52484-z

Abstract

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an important pest of maize (Zea mays L.). Published WCR diets contain corn root powder, which is not available for purchase, thereby limiting the practical use of diets containing this ingredient. We applied response surface modeling combined with mixture designs to formulate a WCR diet that does not require corn root powder. We developed the new formulation by systematically exploring eight protein ingredients from animal, plant, and yeast sources based on simultaneous evaluation of three life history parameters (weight, molting, and survival). This formulation (WCRMO-2) without corn root powder supported approximately 97% of larval survival and successful molting. Larval weight gain after 10 days of feeding on WCRMO-2 was 4-fold greater than that of larvae feeding on the current best published WCR diet. Additionally, there was no significant difference in these larval performance traits when larvae were reared on WCRMO-2 and the best proprietary WCR diet. A commercial version of WCRMO-2 was tested and found to perform comparably for these traits. These improvements met our goal of a diet comprised of available ingredients that supports performance of WCR larvae equal to or better than publicly available formulations and proprietary formulations.

Highlights

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an important pest of maize (Zea mays L.)
We previously developed an improved diet for WCR larvae, hereafter referred to as “WCRMO-1”18, an optimization of the ingredients in a previously published diet for WCR
In order to develop an ideal diet for WCR, this study focused on the development of a WCR diet with improved larval development and without corn root powder, making the WCR diet more widely available for researchers

Summary

Introduction

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an important pest of maize (Zea mays L.). Pleau et al.[19] developed the first WCR diet, which was modified from a diet for southern corn rootworm (SCR), D. undecimpunctata howardi Barber[20,21,22], by adding corn root powder, removing formalin, optimizing the pH and changing the concentrations of wheat germ and linseed oils These modifications resulted in a diet that doubled larval weight gain compared to larvae reared on the SCR formulation[19]. We improved the Pleau et al diet by optimizing the concentration of several ingredients (i.e., agar, casein, cellulose, corn root powder, linseed oil, and sucrose) and by adding wheat germ oil[18] This resulted in a formulation that supported approximately 99% of larvae for survival and molting and further. The application of mixture experiments in combination with response surface modeling allows concurrently varying multiple ingredients to identify and characterize key components and predict an optimum formulation that maximizes all desired developmental traits[17,18,27,30,31]

Methods

Results

Conclusion