Agriotes lineatus

Linnaeus, 1767

lined click beetle, wireworm

Agriotes lineatus, the lined , is a click beetle to Europe and western Asia that has become in North America. are 7.5–11 mm long with brownish-black bodies and distinctive longitudinal stripes on the . The , known as , are significant agricultural pests that attack roots, tubers, and seeds of including potatoes, maize, and . The species has a of approximately 3 years with up to 12 larval . Management relies on approaches including , crop , and .

Agriotes lineatus 01 by AfroBrazilian. Used under a CC BY-SA 3.0 license.

Agriotes.lineatus.-.calwer.26.19 by Emil Hochdanz
. Used under a Public domain license.

Click beetle Agriotes lineatus (8736438124) by Pavel Kirillov from St.Petersburg, Russia. Used under a CC BY-SA 2.0 license.

Pronunciation

How to pronounce Agriotes lineatus: //əˈɡraɪ.oʊ.tiːz lɪˈneɪ.ətəs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from similar Agriotes by the shape (as long as or slightly longer than wide) and more prominent longitudinal elytral stripes. Agriotes proximus is nearly identical morphologically and molecularly (>99% COI gene similarity), differing subtly in pronotum proportions and male (shorter , less sharp hooks in A. lineatus). are indistinguishable from A. proximus; from A. obscurus larvae, they differ in having shorter, parallel-sided, subquadrate abdominal and specific mandibular and frontoclypeal angles. Molecular identification is feasible but challenging due to extreme similarity with A. proximus.

Images

Habitat

includes non-farmed areas and grasslands; feed on grass leaves. In agricultural settings, invades fields from adjacent grasslands. inhabit soil, preferring acidic, humus-rich soils with higher moisture. In central Europe, found at higher altitudes (400–500 m) with lower temperatures and higher winter precipitation.

Distribution

to most of Europe (absent from northern Norway, Sweden, Finland, and Russia), western Asia (Armenia, Azerbaijan, Georgia, Iran, Kazakhstan, Kyrgyzstan, Lebanon, Syria, Turkmenistan, Turkey), and the Near East. and in western Canada (British Columbia, Vancouver Island), Washington State (USA), and Atlantic Canada (Nova Scotia). Unconfirmed records exist for Massachusetts, eastern Russia, and Australia.

Seasonality

emerge in spring, with peak activity in late May and early June. laying begins in April, peaking in May and June in central Germany. Adults are active during afternoon and evening hours. Adults have a longer lifespan than some and overwinter.

Diet

feed on leaves of grasses. are , feeding on roots, seeds, and tubers of various plants including cereal (maize, wheat), potatoes, , and sugar beet.

Host Associations

Solanum tuberosum - larval potato tubers attacked, major pest
Zea mays - larval roots and seeds attacked
Triticum - larval roots and seeds of wheat attacked
Fragaria - larval roots attacked
Beta vulgaris - larval sugar beet tubers attacked
Poaceae - feed on grass leaves in grassland

Life Cycle

spans approximately 3 years in central Germany, likely longer further north. are laid in soil close to the surface in spring. emerge after approximately 3 weeks and through up to 12 over 2–3 years. occurs in soil and lasts 3–4 weeks. emerge in spring and can overwinter.

Behavior

exhibit mechanism for righting themselves when overturned. Males are attracted to female (primarily geranyl octanoate with geranyl butanoate). In trap studies, A. lineatus males show higher activity and longer movement distances than A. obscurus; they frequently enter traps baited for other Agriotes unless both trap are present. Adults prefer humid sites during dry weather and avoid hedgerows. are attracted to autoclaved millet substrate used in .

Ecological Role

In grasslands, function as on grasses and as root-feeding /herbivores. In agricultural , larvae become significant pests through root and tuber feeding. Serves as for including brunneum. -based indicates in heterogeneous landscapes.

Human Relevance

Major agricultural pest in Europe and regions, particularly damaging to potato, maize, and cereal production. Larval damage can affect more than 90% of potato tubers in heavily infested fields. Subject to including (10:1 geranyl octanoate:geranyl butanoate in Vernon ), , timed tillage and irrigation to desiccate and , and attempts with and nematodes. Mass trapping and using pheromones have been attempted with limited success. Detected via environmental in green yard waste, indicating potential for spread through waste movement.

Similar Taxa

Agriotes proximusExtremely similar , identical , indistinguishable , >99% COI gene similarity; differs in slightly wider than long and male with thinner, sharper hooks
Agriotes obscurusSimilar pest; differ in abdominal shape (longer in A. obscurus), mandibular angle, and frontoclypeal angle
Agriotes sputatorSimilar striped but stripes less prominent than in A. lineatus
Agriotes modestusSimilar striped but stripes less prominent than in A. lineatus

More Details

Pheromone chemistry

Female contain primarily geranyl octanoate with trace amounts of geranyl butanoate; optimal field attraction uses 10 mg geranyl octanoate with 1 mg geranyl butanoate (10:1 ratio). Attraction range is short, with recapture rates halving at 10 m and again at 20 m from traps.

Taxonomic uncertainty

The separation of A. lineatus and A. proximus as distinct has been questioned due to minimal morphological, chemical, and genetic differences; some authorities treat them as or closely related cryptic species.

Invasion history

to western Canada around 1900, likely via ship ballast or agricultural materials; subsequently spread to Washington State and was detected in Nova Scotia by 1990s. Environmental in green yard waste demonstrates modern potential for human-mediated .