Date of this Version
The behavior of turfgrass-infesting scarab grubs in response to soil physical properties may affect the stress that each species exerts on turfgrass and the efficacy of control tactics. To gain a more realistic picture of the events that occur within the soil matrix, we have developed a nondestructive X-ray technique to study soil insect movement and behavior in simulated and natural soil blocks in the laboratory Laboratory studies using this technique were done to determine the effect of some soil physical factors on scarab grub movement patterns. Species-specific differences were demonstrated in the responses of four scarab grub species (Japanese beetle, Popillia japonica Newman; European chafer, Rhizotrogus mqalis (Razoumowsky); oriental beetle, Anomala orientalis Waterhouse; and northern masked chafer Cyclocephala borealis (Arrow) ) to changing temperature and moisture conditions. Studies also were done to determine the effect of soil moisture on the movement and persistence of an insecticide (isofenphos) applied to turfgrass and its effect on European chafer grub movement and mortality This study showed that isofenphos was relatively nonmobile under our experimental conditions, and that insecticide efficacy depended on factors, such as soil moisture, that influence the position of grubs in the soil profile. We believe that a better understanding of the interactions among grub behavior, insecticide persistence, and movement, as illustrated by this research, will improve our ability to manage scarab grubs in turfgrass and will be applicable to additional soil systems.