|Wikispecies has information related to: Diabrotica|
Diabrotica is a widespread genus of beetles, sometimes referred to as cucumber beetles or corn rootworms, in the family Chrysomelidae. Members of this genus include several destructive agricultural pest species.
Corn rootworms are one of the most economically destructive insects of maize 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 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. Estimates of economic damage to corn growers from corn rootworms are about $1 billion.
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 US military airports, whose planes were likely to have carried the pest. It has since spread primarily in Italy, France, and Germany.
Several species of Diabrotica are significant pests in North America, including:
- D. balteata - banded cucumber beetle
- D. barberi - northern corn rootworm
- D. undecimpunctata
- D. virgifera
Adults of D. undecimpunctata are greenish-yellow with six large black spots on each elytron. They are about 1/5 inches (5 mm) long. The larvae are yellowish and wormlike.
Adult rootworms are about a quarter of an inch long. Western corn rootworm adults 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. The eggs are deposited in the soil during the summer, and are football-shaped, white, and less than 0.004 inches (0.10 mm) 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 in (3.17 mm) long, white worms. Corn rootworms go through three larval instars, pupate in the soil, and emerge as adults in July and August, with 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.
- "Diabrotica". Integrated Taxonomic Information System.
- R. Wright, L. Meinke & K. Jarvi (July 1999). "Corn Rootworm Management". University of Nebraska. Retrieved 2007-02-03.
- Staff, Purdue University Extension Service. Corn Rootworms
- Marra, M.C., Piggott, N.E., & Goodwin, B.K. (2012). The impact of corn rootworm protected biotechnology traits in the United States. AgBioForum, 15(2), 217-230
- Erin W. Hodgson, Utah State University Extension and Utah Plant Pest Diagnostic Laboratory. Western corn rootworm
- Miller N et al. Multiple Transatlantic Introductions of the Western Corn Rootworm. Science 310: 992. November 11, 2005
- Kiss, J. Edwards et al. Monitoring of western corn rootworm (Diabrotica virgifera virgifera LeConte) in Europe 1992-2003. in Western corn rootworm: ecology and management, Editors: Stefan Vidal, et al. CABI 2005