Diabrotica
Encyclopedia
Diabrotica is a widespread genus of beetle
s, sometimes referred to as cucumber beetles or corn rootworms, in the family Chrysomelidae. Members of this genus include several destructive agricultural pest species.
in the United States
. The Western corn rootworm
, D. virgifera virgifera, and the Northern corn rootworm, D. barberi, are the most devastating rootworm species in Iowa
, a major corn-growing area. A third species, the Southern corn rootworm, D. undecimpunctata howardi, causes much economic damage in other regions. Corn rootworm larvae can destroy significant percentages of corn if left untreated. In the United States, current estimates show that 30 million acres (120,000 km²) of corn, out of 80 million acres (320,000 km²) grown, are infested with corn rootworms and the number of infested acres is expected to grow over the next 20 years. The United States Department of Agriculture
estimates that corn rootworms cause $1 billion in lost revenue each year, which includes $800 million in yield loss and $200 million in cost of treatment for corn growers (The Dow Chemical Company).
Diabrotica was unknown in European countries until the late 1990s and was forbidden even in laboratories because of the difficulty in eliminating it with known chemical insecticides if it escaped. It appears to have entered Europe from the United States
in large numbers during the Yugoslav wars
and is especially widespread around U.S. military airports, whose planes were likely to have carried the pest. It has since spread primarily in Italy
, France
, and Germany
.
. They include:
. They are about half a centimeter long. The larvae are yellowish and wormlike. D. undecimpunctata comprises three subspecies
— Diabrotica undecimpunctata howardi (Southern corn rootworm or spotted cucumber beetle), Diabrotica undecimpunctata tenella (Western cucumber beetle) and Diabrotica undecimpunctata undecimpunctata (Western spotted cucumber beetle).
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, sometimes referred to as cucumber beetles or corn rootworms, in the family Chrysomelidae. Members of this genus include several destructive agricultural pest species.
Range
Corn rootworms are one of the most economically destructive insects of maizeMaize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. The Western corn rootworm
Western corn rootworm
The Western corn rootworm, Diabrotica virgifera virgifera LeConte, is one of the most devastating corn rootworm species in North America, especially in the midwestern corn-growing areas such as Iowa. A related species, the Northern corn rootworm, D...
, D. virgifera virgifera, and the Northern corn rootworm, D. barberi, are the most devastating rootworm species in Iowa
Iowa
Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
, a major corn-growing area. A third species, the Southern corn rootworm, D. undecimpunctata howardi, causes much economic damage in other regions. Corn rootworm larvae can destroy significant percentages of corn if left untreated. In the United States, current estimates show that 30 million acres (120,000 km²) of corn, out of 80 million acres (320,000 km²) grown, are infested with corn rootworms and the number of infested acres is expected to grow over the next 20 years. The United States Department of Agriculture
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
estimates that corn rootworms cause $1 billion in lost revenue each year, which includes $800 million in yield loss and $200 million in cost of treatment for corn growers (The Dow Chemical Company).
Diabrotica was unknown in European countries until the late 1990s and was forbidden even in laboratories because of the difficulty in eliminating it with known chemical insecticides if it escaped. It appears to have entered Europe from the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in large numbers during the Yugoslav wars
Yugoslav wars
The Yugoslav Wars were a series of wars, fought throughout the former Yugoslavia between 1991 and 1995. The wars were complex: characterized by bitter ethnic conflicts among the peoples of the former Yugoslavia, mostly between Serbs on the one side and Croats and Bosniaks on the other; but also...
and is especially widespread around U.S. military airports, whose planes were likely to have carried the pest. It has since spread primarily in Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, and Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
.
Species
Several species of Diabrotica are significant pests in North AmericaNorth America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. They include:
- Banded cucumber beetle, Diabrotica balteata
- Northern corn rootworm, Diabrotica barberi
- Spotted cucumber beetleSpotted cucumber beetleThe spotted cucumber beetle is a major agricultural pest insect . In the adult form it eats and damages leaves of many crops, including cucumbers, soybeans, cotton, beans and many others...
(a.k.a. Southern corn rootworm), Diabrotica undecimpunctata howardi - Western cucumber beetle, Diabrotica undecimpunctata tenella
- Western spotted cucumber beetle, Diabrotica undecimpunctata undecimpunctata
- Western corn rootwormWestern corn rootwormThe Western corn rootworm, Diabrotica virgifera virgifera LeConte, is one of the most devastating corn rootworm species in North America, especially in the midwestern corn-growing areas such as Iowa. A related species, the Northern corn rootworm, D...
, Diabrotica virgifera virgifera - Mexican corn rootworm, Diabrotica virgifera zeae
Diabrotica undecimpunctata
Adults of D. undecimpunctata are greenish-yellow with six large black spots on each elytronElytron
An elytron is a modified, hardened forewing of certain insect orders, notably beetles and a few of the true bugs ; in most true bugs, the forewings are instead called hemelytra, as only the basal half is thickened while the apex is membranous...
. They are about half a centimeter long. The larvae are yellowish and wormlike. D. undecimpunctata comprises three subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
— Diabrotica undecimpunctata howardi (Southern corn rootworm or spotted cucumber beetle), Diabrotica undecimpunctata tenella (Western cucumber beetle) and Diabrotica undecimpunctata undecimpunctata (Western spotted cucumber beetle).
Diabrotica virgifera
Adult rootworms are about 1/4 inch long. Western corn rootworms are yellowish with a black stripe on each wing cover. Northern corn rootworm beetles are solid in color and vary from light tan to pale green (Wright). The eggs are deposited in the soil during the summer, and are football-shaped, white, and less than 0.004 inches long. Larvae hatch in late May or early June and begin to feed on corn roots. Newly hatched larvae are small, less than 1/8 inch long, white worms. Corn rootworms go through three larval instars, pupate in the soil, and emerge as adults in July and August. There is one generation per year. Larvae have brown heads and a brown marking on the top of the last abdominal segment, giving them a double-headed appearance. Larvae have three pairs of legs, but these are not usually visible without magnification. After feeding for several weeks, the larvae dig a cell in the soil and molt into the pupal stage. The pupal stage is white and has the basic shape of the adult.External links
- banded cucumber beetle on the UFUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ IFASInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
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