Colorado potato beetle
| Colorado potato beetle | ||||||||||||||||
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 Least Concern |
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| Leptinotarsa decemlineata Say, 1824[1] |
The Colorado potato beetle (Leptinotarsa decemlineata), also known as the Colorado beetle, ten-striped spearman, the ten-lined potato beetle) is an important pest of potato crops. It is approximately 10 mm (0.4 inches) long, with a bright yellow/orange body and 5 bold brown stripes along the length of each of its elytra, and it can easily be confused with its close cousin and look-alike, the false potato beetle. The beetle was described in 1824 by Thomas Say from specimens collected in the Rocky Mountains on buffalo-bur, Solanum rostratum. The origin of the beetle is somewhat unclear, but it seems to be that Colorado and Mexico are a part of its native distribution in the southwestern North America.[2]
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Life cycle
Colorado potato beetles fed originally on the leaves of buffalo-bur, but when domesticated potatoes were introduced into the beetles' native range, the beetles shifted to potatoes. The beetles also occasionally attack tomatoes and eggplants. Females are very prolific; they can lay as many as 800 eggs. The eggs are yellow to orange, and are about 1.5 mm long. They are usually deposited in batches of about 30 on the underside of host leaves. Development of all life stages depends on temperature. After 4-15 days, the eggs hatch into reddish-brown larvae with humped backs and two rows of dark brown spots on either side. They feed on the leaves. Larvae progress through four distinct growth stages (instars). First instars are about 1.5 mm long; the fourth is about 8 mm long. The larvae in the accompanying picture are third instars. The first through third instars each last about 2-3 days; the fourth, 4-7 days. Upon reaching full size, each fourth instar spends an additional several days as a non-feeding prepupa, which can be recognized by its inactivity and lighter coloration. The prepupae drop to the soil and burrow to a depth of several inches, then pupate. Depending on temperature, light-regime and host quality, the adults may emerge in a few weeks to continue the life cycle, or enter diapause and delay emergence until spring. They then return to their host plant to mate and feed. In some locations, 3 or more generations may occur each growing season.
As a crop pest
The Colorado beetle is a serious crop pest of potatoes. Insecticides are often unsuccessful when used against Leptinotarsa because of the beetle's resistance to toxins and ability to rapidly develop resistance to them. The Colorado beetle has developed resistance to all major insecticide classes. In the United Kingdom, where the Colorado beetle is a rare visitor on imported farm produce, it is a notifiable pest: any found must be reported to DEFRA.
However, due to the spined soldier bug being in Europe, they can be controlled, presumably by releasing thousands of them in an infested crop.
In Europe
In 1877, the Colorado beetle reached Germany where it was eradicated. During, or immediately following WWI it became established near USA military bases in Bordeaux and proceeded to spread by the beginning of WWII to Belgium, the Netherlands and Spain. The population increased dramatically during and immediately following WWII and it spread eastwards and it is now found over much of the continent. During World War II, the Nazi regime in Germany, and many satellite states of Soviet Union used them for propaganda, claiming that the beetles had been dropped by the United States Army Air Forces. The Americans were also blamed by regime propaganda when after World War II, in the Soviet occupation zone of Germany, almost half of all potato fields were infested by the beetle by 1950. In the EU it remains a regulated (quarantine) pest for the UK, Republic of Ireland, Balearic Islands, Cyprus, Malta and southern parts of Sweden and Finland. It is not present in any of these Member States.
Philately
The Austrian postal authority featured the beetle on a 1967 stamp.[3]
The Belgian postal authority featured a drawing of the Colorado beetle and larvae on a 1934 and 1935 propaganda postcard.
Media references
The beetle is featured prominently in the science-fiction/horror novel The Devil's Coach Horse (also known as The Black Horde) by Richard Lewis. In the novel a plague of an evolved and flesh hungry type of the beetle (as well as the titular creature) is unknowingly released in Great Britain and the United States.
References
- ↑ Leptinotarsa decemlineata (TSN 720110). Integrated Taxonomic Information System.
- ↑ University of Florida (2007). "Featured creatures: Leptinotarsa spp.". Retrieved on 11 August, 2008.
- ↑ James L. Skaptason. "Skaps' bug stamps". Retrieved on 1 May, 2006.