Predation on Colorado Potato Beetle Eggs by Generalist Predators in Research and Commercial Potato Plantings

Field studies quantified predation on Colorado potato beetle [Leptinotarsa decemlineata(Say)] eggs and determined the relationship between predation and egg mass abundance in research and commercial potato plantings in eastern North Carolina. Predator exclusion experiments were conducted weekly in research plantings. In addition, egg mass density and predation on egg masses were monitored throughout the season in research plots and commercial potato fields. Predation was an important source of mortality for Colorado potato beetle eggs. Survivorship of eggs exposed to predators was consistently, significantly lower than survivorship of eggs protected from predation. Averaged over 2 years, the mean survivorship of eggs protected from predation was 69%, compared with 26% survivorship of eggs exposed to predation. Regression analysis failed to detect any relationship between egg mortality due to predation and egg abundance. These results imply that efforts to reduce Colorado potato beetle populations selectively will not be offset by an according decline in abundance of natural enemies and therefore should be fully compatible with naturally occurring biological control.