Host search behaviors of specialist and generalist root feeding herbivores (Diabrotica spp.) on host and non-host plants

Authors: HUYNH, MAN - University Of Missouri; GEISERT, RYAN - University Of Missouri; LUDWICK, DALTON - Texas A&M Agrilife; Pekarcik, Adrian; Hibbard, Bruce

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2023
Publication Date: 10/16/2023
Citation: Huynh, M.P., Geisert, R.W., Ludwick, D.C., Pekarcik, A.J., Hibbard, B.E. 2023. Host search behaviors of specialist and generalist root feeding herbivores (Diabrotica spp.) on host and non-host plants. Scientific Reports. 13. Article 17583. https://doi.org/10.1038/s41598-023-44760-w.
DOI: https://doi.org/10.1038/s41598-023-44760-w

Interpretive Summary: Northern, southern, western, and Mexican corn rootworms are serious pests of corn. Southern corn rootworm are generalists, feeding on many plant families while the others are specialists on corn and a few other grasses. Many aspects of basic rootworm biology may eventually be applied to manage these pests. Toward this long-term goal, we used a video tracking system to evaluate the search behavior of neonate rootworm larvae on six plant species of varying host acceptability. After a 5-min exposure to plant roots, behavioral parameters were automatically recorded and used to quantify the search behavior. After exposures to corn roots, all neonates exhibited the localized search behaviors (i.e., shortening total distance traveled, lowering movement speed, increasing turn angle, moving farther from origin) which are used to stay in and search within root systems. When larvae contacted roots of wheat, barley, oats, soybean, or controls, they expanded the search area by extending the travel path, increasing velocity, and reducing turn angles and total distance moved. The intensity of the search expansion is highly associated with the host preferences known for the rootworm species and subspecies. Neonates of each corn rootworm exhibited distinct search behaviors. In fact, NCR larvae had the highest speed, the greatest travel path, and the lowest turn angle, whereas MCR larvae had the highest turn angle and moved faster than WCR and SCR larvae. These data add to our basic knowledge of these major pests. This information may help develop improved pest management approaches in the future.

Technical Abstract: Western, northern, Mexican, and southern corn rootworms (WCR, NCR, MCR, and SCR) are serious corn pests. We evaluated host search behavior of these pests on six plant species using a video tracking system. After a 5-min exposure to plant roots, behavioral parameters were automatically recorded and used to quantify the search behavior. The search behavior was not observed for sorghum since no neonates survived after contacting sorghum roots. After exposures to corn roots, all neonates exhibited the localized search behaviors (i.e., shortening total distance traveled, lowering movement speed, increasing turn angle, moving farther from origin) which are used to stay in and search within root systems. When larvae contacted roots of wheat, barley, oats, soybean, or controls, they expanded the search area by extending the travel path, increasing velocity, and reducing turn angles and total distance moved. The intensity of the search expansion is highly associated with the host preferences known for the four rootworm species and subspecies. Neonates of each corn rootworm exhibited distinct search behaviors. In fact, NCR larvae had the highest speed, the greatest travel path, and the lowest turn angle, whereas MCR larvae had the highest turn angle and moved faster than WCR and SCR larvae.