Importance of color for artificial clay caterpillars as sentinel prey

Authors: Roeder, Karl; DORLAND, MATTHEW - Former ARS Employee; Daniels, Jesse

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2022
Publication Date: 10/22/2022
Citation: Roeder, K.A., Dorland, M.S., Daniels, J.D. 2022. Importance of color for artificial clay caterpillars as sentinel prey. Entomologia Experimentalis et Applicata. 171(1):68-72. https://doi.org/10.1111/eea.13251.
DOI: https://doi.org/10.1111/eea.13251

Interpretive Summary: Sentinel prey—dead or live insect eggs, larvae, pupae, and adults—have been one useful method for quantifying predation pressure by beneficial insects under real field conditions. However, sentinel prey studies often vary in their methodology making comparisons of predation pressure challenging. One promising type of standardized sentinel prey that could alleviate this methodological issue are artificial clay caterpillars that mimic naturally occurring pest Lepidoptera. Yet one aspect of clay caterpillar experimental design remains relatively unexplored—their color. In the summer of 2021 we tested if color was an important variable by deploying 1920 brown, cream, green, gray, terracotta, or white clay caterpillars onto corn, soybean, and prairie plants. In doing so we found that lighter colored caterpillars (green and terracotta) performed the best while brown and gray caterpillars performed the worst. Combined, our results suggest artificial clay caterpillars could be useful for rapid ecosystem function assessments, but only when their color is considered.

Technical Abstract: The use of artificial clay caterpillars to quantify predation pressure under real field conditions is one method that has garnered recent support for quantifying ecosystem services that beneficial insects provide. Here, we focus on color and ask if it is an important variable that should be considered in studies using clay caterpillars as sentinel prey. We deployed a total of 1920 brown, cream, green, gray, terracotta, or white clay caterpillars onto corn, soybean, and prairie plants to test if lighter colored caterpillars will be attacked and retrieved more than caterpillars with darker colors. As hypothesized, color was a significant predictor with green and terracotta caterpillars performing best while brown and gray caterpillars performed the worst. Interestingly, clay caterpillars were also attacked proportionally to the number of insects in the surrounding habitat. Combined, we suggest artificial clay caterpillars could be useful for rapid ecosystem function assessments, but only when their color is considered.