Development of a bioassay method for larval western corn rootworm (Coleoptera: Chrysomelidae)

Area of Science:

• Agricultural Science
• Entomology
• Plant Science

Background:

• Western corn rootworm (Diabrotica virgifera virgifera LeConte) is a significant pest of maize (Zea mays L.) in the U.S.
• Larval stages inhabit soil, making in-plant bioassays for novel control methods challenging.
• Effective bioassays are crucial for developing new pest management strategies.

Purpose of the Study:

• To identify optimal growth media for a greenhouse bioassay system.
• To evaluate media effects on maize growth and western corn rootworm larval survival and development.
• To characterize the impact of larval density on rootworm survival within the bioassay.

Main Methods:

• Assessed maize plant growth metrics across different growth media.
• Monitored western corn rootworm larval survival and development in each medium.
• Investigated the influence of varying larval densities on survival rates.

Main Results:

• Agricultural field soil supported robust maize growth but yielded poor larval survival.
• Vermiculite maximized larval survival but resulted in diminished plant growth.
• Potting medium generally supported both favorable plant growth and high larval survival.

Conclusions:

• Potting medium or amended field soil mixtures are suitable for maize-western corn rootworm bioassays.
• This optimized bioassay system can be used to screen insecticides, microbial biopesticides, and plant-incorporated protectants.
• The study provides a foundation for developing effective management tools against this damaging pest.