Generalist natural enemies of a willow leaf beetle (Phratora vulgatissima): abundance and feeding habits

The natural enemies attacking eggs ( and young larvae) of the willow leaf beetle Phratora vulgatissima were identified in the field. Three heteropterans were common natural enemies. The mirid Orthotylus marginalis was the most abundant and had an intermediate consumption rate in the lab, whereas the mirid Closterotomus fulvomaculatus was the least abundant but had the highest consumption rate. The anthocorid Anthocoris nemorum was intermediate in abundance but had the lowest consumption rate. However, the experimental situation ( in petridish or on shoot) affected the ranking of the predators and illustrates behavioral differences. The anthocorid was very mobile and could be characterized as a "run and eat" predator, whereas the mirids were less mobile and behaved to a "find and stay" principle. Possible consequences of interspecific variation in behavior, from a biological control perspective, are discussed.