Common asparagus beetle

Description

The common asparagus beetle (Crioceris asparagi) is an important pest of asparagus crops both in Europe and in North America. Asparagus is its only food plant. The beetle is 6.0 mm to 9.5 mm long and slightly elongated. It is metallic blue-black in color with cream or yellow spots on its red-bordered elytra. The larvae are fat gray grubs with dark heads. The adult beetles and the larvae strip the needle-like leaves off the asparagus fronds, depriving the plants of the ability to photosynthesize and store energy for future years. They also chew the spears and lay generous amounts of eggs on them, making the crop unmarketable. The larvae feed on the plants for a few weeks, then drop to the ground to pupate. One year may see two or three generations of the beetle. The adults overwinter in a dormant state underground or in nearby leaf litter. The parasitic wasp, Tetrastichus coeruleus, occurring mainly in the United States and Europe, can cause up to 71% mortality in the field and has been successfully used for biological control. Various insecticides (such as carbamates, pyrethroids, spinetoram, and spinosad) can be considered for pest control. The similar spotted asparagus beetle (Crioceris duodecimpunctata) is also a pest as an adult, feeding on tender shoots and leaves, but since the larvae feed only on the asparagus berries it is not considered to be as important. Crioceris, or asparagus beetle, is a genus of the family Chrysomelidae of beetles. Not all species in the genus Crioceris feed on asparagus (e.g., C. nigropicta). Some studies have found low genetic diversity among groups of isolated Chrysomelidae, and use Wolbachia species as a genetic marker.