Transient Foraging of Coccinellids (Woltz)
Coccinellids provide an important service by suppressing populations of soybean aphid in soybeans. Critical interactions between coccinellids and aphids occur in early summer when aphid densities in soybean are too low to support local reproduction of coccinellids. Thus, the ability of coccinellids to suppress aphids likely depends on transient individuals moving through an area. Our goal is to determine how disruptions in coccinellid movement affect aphid suppression.
We manipulated coccinellid movement in soybean fields by covering 1m3 PVC frames to three different extents with mesh to create open, 2-sided and 5-sided plots and monitored resulting changes in aphid populations. Within plots, we measured coccinellid activity-density with sticky traps while using video cameras to directly measure rates of coccinellid foraging in plots. Preliminary data suggest that extremely low numbers of coccinellids foraging in aphid-infested plots are sufficient to suppress aphid populations, while disruptions in this low-level of coccinellid foraging allow aphids to increase unchecked.