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 about half a centimeter long, 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.
Various insecticides are licensed for 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.
|Common Asparagus Beetle|
Crioceris or asparagus beetle is a genus of the family Chrysomelidae of beetles. The name is neo Latin from Greek κριός, ram and κέρας, horn.
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 as a genetic marker.Eurasian tree sparrow
The Eurasian tree sparrow (Passer montanus) is a passerine bird in the sparrow family with a rich chestnut crown and nape, and a black patch on each pure white cheek. The sexes are similarly plumaged, and young birds are a duller version of the adult. This sparrow breeds over most of temperate Eurasia and Southeast Asia, where it is known as the tree sparrow, and it has been introduced elsewhere including the United States, where it is known as the Eurasian tree sparrow or German sparrow to differentiate it from the native unrelated American tree sparrow. Although several subspecies are recognised, the appearance of this bird varies little across its extensive range.
The Eurasian tree sparrow's untidy nest is built in a natural cavity, a hole in a building or the large nest of a European magpie or white stork. The typical clutch is five or six eggs which hatch in under two weeks. This sparrow feeds mainly on seeds, but invertebrates are also consumed, particularly during the breeding season. As with other small birds, infection by parasites and diseases, and predation by birds of prey take their toll, and the typical life span is about two years.
The Eurasian tree sparrow is widespread in the towns and cities of eastern Asia, but in Europe it is a bird of lightly wooded open countryside, with the house sparrow breeding in the more urban areas. The Eurasian tree sparrow's extensive range and large population ensure that it is not endangered globally, but there have been large declines in western European populations, in part due to changes in farming practices involving increased use of herbicides and loss of winter stubble fields. In eastern Asia and western Australia, this species is sometimes viewed as a pest, although it is also widely celebrated in oriental art.Tetrastichus coeruleus
Tetrastichus coeruleus is a gregarious koinobiont wasp which can be used as a biological control agent for the common asparagus beetle.It was originally named Tetrastichus asparagi Crawford, thus most of the literature about this species has been published under this other name.Tetrastichus coeruleus has populations which are infected with the parthenogenesis-inducing Wolbachia and populations which are not.On average, 4.75 T. coeruleus adults emerge per larva, though this ranges between 2 and 13 specimens per larva.