A. abdominalis adult. R.Richard

Aphthona abdominalis (Coleoptera: Chrysomelidae)

by Rich Hansen, USDA-APHIS-PPQ, Forestry Sciences Lab, Montana State University, Bozeman, MT 59717-0278.

Leafy spurge is an Eurasian perennial that was introduced into North America in the 19th century. It infests several million hectares of rangelands and riparian

Leafy spurge-infested rangeland.

areas in the United States and is a serious pest across the northern Great Plains where it displaces desirable grasses and forbs normally consumed by foraging cattle. Cattle and horses usually avoid leafy spurge, but should they eat it, its milky latex may cause sickness and even death. Annual direct and indirect economic losses due to leafy spurge infestation in Montana, South Dakota, North Dakota, and Wyoming are estimated to exceed $120 million. In addition, leafy spurge forms monocultures that often displace native plants and degrade wildlife habitats.

Leafy spurge.

Leafy spurge has a number of biological characteristics that have caused it to be difficult to control with herbicides, and infestations generally occur in remote areas consisting of comparatively low-value land. Thus, classical biological control is envisioned as a potentially valuable spurge management tool in North America. To date, ten Eurasian insect species have been released as biocontrol agents of leafy spurge.

Aphthona abdominalis was originally approved for release in the United States in 1993. It has been released at several sites in Montana and North Dakota.

Appearance

The adult flea beetle is very small (1-2 mm) and yellowish-brown in color. A. abdominalis adults typically hop rather than fly when disturbed. Larvae are found in the soil, on or near leafy spurge roots. They are 1-3 mm long, with short legs, yellow heads, and creamy-white bodies.

Habitat

Leafy spurge-infested grasslands.

Pests attacked

The host range of A. abdominalis appears restricted to plants in the subgenus Esula of the genus Euphorbia. In Europe, this beetle feeds on leafy spurge and several other closely-related spurge species. There are a few native Euphorbia spp. in the U.S. that could potentially be hosts for A. abdominalis, though no feeding has yet been documented under field conditions. A. abdominalis will not feed on poinsettia (Euphorbia pulcherrima), and crop species and native plants outside the genus Euphorbia will not be attacked.

Life cycle

Life cycle information is based on observations in the insect's native European habitats; little information is available on the biology of A. abdominalis under North American field conditions.

Winter is apparently passed in the adult stage; these adults probably become active in late spring. Adults may live for several weeks to several months, feeding on leafy spurge foliage and flowers. Females lay small groups of eggs at, or just below, the soil surface, near the base of a leafy spurge stem. Newly-hatched larvae burrow into the soil and begin feeding on very small leafy spurge roots. Larvae probably feed on progressively larger roots and root buds as they develop. Pupation occurs in a soil cell near leafy spurge roots. There appears to be at least three generations per year in southern Europe, though the number of generations under North American conditions is not yet known.

Relative effectiveness

Other Aphthona flea beetles can kill leafy spurge plants as a direct or indirect consequence of larval feeding on spurge roots. A. abdominalis has the potential advantage of completing several generations per year. However, it is not yet known if this agent can survive and control leafy spurge infestations under field conditions in the U.S.

Pesticide susceptibility

Not known.

Conservation

For general information about conservation of natural enemies, see Conservation in the Tutorial section on this site, or the Volume II, No. 1Feature Article on conservation in the Midwest Biological Control News Online.

Commercial availability

A. abdominalis is not yet available from public or commercial sources.

Reference

Fornasari, L. (1993) Life history of the flea beetle, Aphthona abdominalis Duftschmid, on Euphorbia esula L. (leafy spurge) in Italy. Biological Control 3: 161-175.

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