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

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.

Characterization of Thermal and Time Exposure to Improve Artificial Diet for Western Corn Rootworm Larvae

“…No evidence for a relationship between contamination and two experimental factors (thermal exposure and time of thermal exposure) was determined. Similarly low contamination rates were observed previously [27].…”

“…All experiments had minor contamination (<3%) except for die perienced a soft-set of the media that were excluded from the analys relationship between contamination and two experimental factors (th time of thermal exposure) was determined. Similarly low contamin served previously [27].…”

“…All designs consisted of 11 design points (diet treatments at different thermal exposure and time of exposure) with 5 model, 3 lack of fit, and 2 pure error degrees of freedom. In all experiments, WCRMO-2 diet made using the standard protocol according to the manufacturer's procedure, with a temperature of 65 • C and time of exposure for 10 min [27], was included as a control (Table 1). A flash sterilization system (Frontier Scientific Services) was utilized to produce WCRMO-2 diet at high thermal exposure (80-141 • C) and short time exposure (0.8-2.3 s).…”

“…The diet plate was then allowed to evaporate excess moisture for 10 min, stored in a refrigerator at 7 °C, and used for assays within 3 days. At mild thermal exposure (50-80 °C), WCRMO-2 diet was made using WCRMO-2 dry mix (WCRMO-2, Frontier Scientific Services) according to the manufacturer's procedure [27]. To prepare 1 L of WCRMO-2 diet, agar (15.8 g) was added to 926 mL of purified water, and the solution was brought to a full boil using a microwave (Hamilton Beach) until agar was completely melted.…”

Western Corn Rootworm, Plant and Microbe Interactions: A Review and Prospects for New Management Tools

“…Further efforts to understand the nutrition requirements of WCR larvae have resulted in the development of artificial diets [131]. Current efforts to improve artificial diet further are focused on understanding the metabolomic responses to maize, in addition to good and poor artificial diets (Huynh et al, unpublished).…”