Crioceris duodecimpunctata Linnaeus Coleoptera Chrysomelidae

Natural History

Distribution. Spotted asparagus beetle is found throughout North America. This insect is of European origin, and was irst observed in the western hemisphere near Baltimore, Maryland about 1881. It spread rapidly in the northeast and midwestern states and eastern Canada, reaching Idaho and Washington in the 1940s and 1950s and British Columbia in 1962. Although it is widespread, it is less abundant than asparagus beetle, Crioceris asparagi (Linnaeus).

Host Plants. This species is very selective in its host preference, attacking only asparagus. It is most commonly observed on wild and home-garden plants, rarely attaining high densities in commercial plantings. The larvae feed only within berries.

Natural Enemies. Little is known concerning the natural enemies of spotted asparagus beetle. Capinera (1974b) was unable to identify significant natural enemies in Massachusetts, but noted that resource availability (lack of berries for the larvae) might be a key factor in regulating insect densities. Ground beetles (Coleoptera: Carabidae) may take a toll on larvae searching the foliage for berries or droping to the ground to pupate, but this has not been measured. The asparagus beetle egg parasitoid, Tetrastichus asparagi Crawford (Hymenoptera: Eulophidae) has been reported in the literature as a parasite of spotted asparagus beetle, but this is an error. A related species, Tetrastichus crioceridis Graham, attacks spotted asparagus beetle eggs in Europe, but attempts to establish it in North America have not been successful (van Alphen, 1980; Hendrickson et al, 1991).

Life Cycle and Description. Two generations occur annually, but the second generation is often small. Overwintered adults are abundant in May and June, followed by first generation adults in July and then the second generation adults in August and September.

  1. The eggs are laid singly, usually on plants bearing berries. The elliptical eggs measure about 1.0-1.2 mm long and 0.4 mm wide, and are glued on their side to asparagus foliage. This method of attachment makes it easy to distinguish C. duodecimpunctata eggs from C. asparagi eggs; the latter are attached on end. The eggs initially are whitish, turning yellow-orange and then olive green or brown as they mature. Eggs hatch in 7-12 days and young larvae burrow into berries to begin feeding.
  2. The larvae are reported to progress through three instars in 21-30 days, increasing in length from about 1 mm to 8.5 mm (Fink, 1913). However, careful study of the sibling species, C. asparagi showed four instars (Taylor and Harcourt, 1978), so Fink may have overlooked one instar. Larvae are pale-yellow or orange. The head is initially black, but at the molt to the second instar the head becomes pale. The thoracic plate is dark throughout the development. The bright color of the larvae immediately distinguishes them

Spotted asparagus beetle egg on plant stem.

Spotted asparagus beetle egg on plant stem.

Bruchus Pisorum Linn
Spotted asparagus beetle larva.

from the gray or brown larvae of C. asparagi. Larvae are normally found only within berries, but because 2-4 berries are required for complete development, they occasionally may be found searching the foliage. Also, berries sometimes fall from the plant as larvae consume the interior, forcing larvae to ascend the plant in search of additional food.

  1. When a larva completes its development it leaves the berry and drops to the soil to pupate. The larva prepares a small pupation chamber from oral secretions and soil particles and pupates within. The pupa is yellow and greatly resembles the adult in form, except that the wings are not fully developed. Duration of the pupal stage is 12-16 days.
  2. The adult is largely orange, with each elytron marked with six black dots. The beetle measures 6-8 mm long. The antennae, eyes, tarsi, distal portion of the femora, and the underside of the thorax are black. When disturbed the adults are quick to take flight, and stridulate loudly if captured (Capinera, 1976). Adults emerge from overwintering in May, usually about a week later than asparagus beetle, Crioceris asparagi. Unlike C. asparagi, they do not commence oviposition soon after emergence. Oviposition is delayed until asparagus flowers are fertilized or berries are present. Adults seek hollow stems of asparagus and other sheltered locations in which to pass the winter. (See color figure 103.)
Adult spotted asparagus beetle.

The biology of this poorly studied insect was given by Fink (1913), Chittenden (1917), and Dingler (1934).

Damage

The only serious damage is caused by adults early in the spring when they gnaw on the emerging shoots, creating small pits in the epidermis. Such damage renders the shoots worthless for commercial purposes. Later in the season the adults also feed on leaves, and remove the outer layer from stems. This latter damage generally has little effect on the growth of the plant, and subsequent yield. Larvae feed inside berries, preventing seed from forming. This is unimportant except where seed is being produced.

Management

This insect does not usually cause significant injury in commercial production. The frequent harvesting of commercial asparagus is believed to discourage feeding. In volunteer plants or homegardens the adults sometimes attain high densities, however, and deform young spears by their feeding. Insecticides are highly effective against asparagus beetles. Collection and destruction of berries has been suggested as a method of guarding against future damage by adults, but this is practical only on the scale of the homegarden.

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