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Image of Delta Green Ground Beetle
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Delta Green Ground Beetle

Elaphrus (Elaphrus) viridis G. Horn 1878

Biology

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The delta green ground beetle, like many of its neighbours, synchronises its lifecycle with the seasonal changes in its habitat (2) (3). Adults are active in winter and early spring, when pools are wet, laying their eggs between January and April (3). When the pools dry up in the summer, the beetles enter an inactive phase called a diapause, in which they bury themselves underground and await the next rainy season (5) (6). The hatching larvae also burrow into the moist clay for food and shelter and spend the hot summer under the soil (3). The larvae then pupate in autumn and emerge as adults in the cool of winter (2) (3). Both larvae and adults are active predators, spending most of the day searching out small invertebrates such as midge larvae (Diptera) and springtails (Collembola) (2) (4).
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Conservation

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The delta green ground beetle is protected by the Lacey Act, which prohibits its import, export, transport, sale, purchase, receipt or acquisition (4). The beetle is also protected through its occurrence in the Jepson Prairie Reserve (5), but other suitable sites nearby are on private land and negotiations over their protection are ongoing (2). Since its life cycle is intricately intertwined with the seasonal changes of its vernal pool habitat, conservation of the delta green ground beetle very much depends upon the protection of this habitat, which is itself endangered (2). Thus, protection of this disappearing habitat must be the top priority in the conservation of not only the delta ground beetle, but also the array of other endangered species that are unique to and depend heavily upon this threatened vernal pool ecosystem.
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Description

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This tiny beetle is adorned with an opulent, metallic emerald-green hue, generally with bronze spots and pits on the elytra (3) (4) (5). Its oval shape and green colouration camouflages this diminutive beetle in the small leaves that sprout around its pool habitat, protecting it from hunting birds and amphibians (3).
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Habitat

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This beetle has been collected in bare areas along trails and roadsides and around the margins of vernal pools, seasonally wet pools that are dry in the summer and fill with the onset of the winter rains (2) (5). However, while some scientists believe that the species prefers more open habitat, such as edges of pools, trails, roads and ditches, it has also been argued that denser cover elsewhere simply hinders observation of this tiny green beetle (5).
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Range

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Now found in just a ten square mile area around Jepson Prairie Reserve in central Solano County, in California's Central Valley (3) (5).
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Status

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Classified as Critically Endangered (CR B1+2abc+3a) on the IUCN Red List 2004 (1).
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Threats

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The historical distribution of the delta ground beetle is unknown, but it is thought reasonable to assume that the species was once found throughout the wetlands and grasslands of California's Central Valley (4). The area has suffered widespread disruption and destruction of its wetland habitat from agricultural development, tapping of vernal pools for irrigation of crops, river channelisation, and encroaching urban development, all of which are thought to have played a role in the demise of this species (2) (4). Additionally, an introduced alien plant, garden lippia (Phyla spp.), poses an immediate threat to the species' remaining range. The plant forms dense mats in vernal pools, crowding out native vegetation and hindering the beetle's foraging (2). Only around 75 individuals have been seen since 1974, and the species' small range places it in very serious danger of extinction (4).
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Elaphrus viridis

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Elaphrus viridis, the Delta green ground beetle, is a species of ground beetle restricted to a small region within Solano County, California. Its color is a metallic-green, usually with bronze spots on its elytra, though some lack these spots. The lack or reduction of circular pits on the elytra helps distinguish it from other ground beetles. Typical adults are about a quarter-inch (0.6 cm) in length.[1][2]

The Delta green ground beetle plays a useful role in its ecosystem by pollinating plants, fruits, and vegetables.

The beetle's common name probably refers to the triangular marking on its pronotum. The species name, viridis, comes from the Latin word for green.[3]

Range and distribution

The Delta green ground beetle is known to only occur in Solano County, California, though it may have historically occurred throughout the Central Valley.[2] It is known to inhabit Jepson Prairie Preserve, south of Dixon, where it is protected;[1] however, the beetle's other known ranges are located on public land.[2]

The beetle occupies vernal pool habitats, around which its life cycle is based: it emerges in January following the filling of vernal pools from winter rains and lies dormant in May (around when the pools dry up) as a means of surviving the summer.[2]

Specimens of the Delta green ground beetle have generally been collected in open habitats, namely the edges of vernal pools and nearby trails, roads and ditches. They may also be present in the surrounding grasslands, but the beetle's small size, camouflage against spring grass, and tendency to hide beneath low growth make it difficult to locate.[1]

Reproduction

The Delta green ground beetle breeds through January and September,[2] with females producing one generation per year.[1]

Diet

The Delta green ground beetle, in both its larval and adult stages, actively hunts soft-bodied arthropods.[2] Based on the habits of other species of Elaphrus, it is likely that the beetle feeds primarily on springtails.[1]

Conservation status

The Delta green ground beetle's current IUCN Red List status is Critically Endangered, owing to the species' extremely limited range and the endangerment of its vital vernal pool habitats.[4] In addition, the species has been federally listed as threatened since 1980.

The destruction of vernal pool habitats in California is largely the result of agricultural development, though urbanization and grazing have played some role in their elimination. Another significant threat to the beetle is the introduced Garden lippia, which grows in dense mats in these habitats and impairs its ability to forage.[2]

References

  1. ^ a b c d e "Delta Green Ground Beetle, Elaphrus viridis". Sacramento Fish & Wildlife Office. Retrieved on 14 August 2006.
  2. ^ a b c d e f g "California's Endangered Insects - Delta Green Ground Beetle". Essig Museum of Entomology - UC Berkeley. Retrieved on 14 August 2006.
  3. ^ "Species Elaphrus viridis - Delta green ground beetle". BugGuide. Retrieved on 14 August 2006.
  4. ^ World Conservation Monitoring Centre (1996). "Elaphrus viridis". The IUCN Red List of Threatened Species. IUCN. 1996: e.T7120A12826416. doi:10.2305/IUCN.UK.1996.RLTS.T7120A12826416.en. Retrieved 9 January 2018. Database entry includes justification for why this species is listed as critically endangered.

Data related to Elaphrus viridis at Wikispecies

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Elaphrus viridis: Brief Summary

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Elaphrus viridis, the Delta green ground beetle, is a species of ground beetle restricted to a small region within Solano County, California. Its color is a metallic-green, usually with bronze spots on its elytra, though some lack these spots. The lack or reduction of circular pits on the elytra helps distinguish it from other ground beetles. Typical adults are about a quarter-inch (0.6 cm) in length.

The Delta green ground beetle plays a useful role in its ecosystem by pollinating plants, fruits, and vegetables.

The beetle's common name probably refers to the triangular marking on its pronotum. The species name, viridis, comes from the Latin word for green.

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