The overall impact includes yield losses in firstyear corn and the additional input costs of bt seed andor soil insecticides to rotated corn. Western and northern corn rootworms are present the piedmont and mountain regions of north carolina, although western corn rootworm adults have also been detected in the coastal plain as far east as martin county. The three species of rootworm found in iowa include the northern corn rootworm ncr, southern corn rootworm scr, and western corn rootworm wcr. Southern corn rootworm, cucumber beetle scientific name. The male rootworm from this type is usually smaller and darker. Western corn rootworm is a widely spread native species, consisting of two recognized strains. Corn volatiles as attractants for northern and western corn rootworm beetles.
The variant western corn rootworm continued its expansion in illinois during the summers of 2001 and 2002. For a second year in a row, corn rootworm abundance is lower than expected in iowa. The western corn rootworm, diabrotica virgifera virgifera leconte, and the northern corn rootworm, diabrotica barberi smith and lawrence, are both important pests of corn in the midwest. Adults have hard shells and are roughly 6 mm 14 in. The western corn rootworm has a yellow body with dark stripes. The economic impact of the variant western corn rootworm that evolved in the eastern corn belt continues to reverberate nearly twenty years later.
A behavioral variant of the western corn rootworm, that appears to have lost its fidelity for corn. Western corn rootworm resistance to plant incorporated bt proteins gmo hybrids has refocused attention to effective and economical management of the corn. Another looming problem for corn growers is the recent resurgence of the northern corn rootworm, which also resists rotation by delaying egg hatch for two years or more. Western corn rootworm, diabrotica virgifera virgifera leconte, has been a major economic pest of maize in the americas for many years. Northern corn rootworm adult northern corn rootworm adult. The book also examines the potential of plant protection techniques currently used in. Sweet corn fields planted after sweet corn or field corn have the highest risk of infestation. This varianttype has adapted to other crops than corn, such as. The northern and western corn rootworms are strictly pests of corn. Rootworm larvae in firstyear corn can cause severe root injury, which may result in lodging and physiological yield reductions. Penn state extension delivers education you can trust. The principal strain is diabrotica virgifera virgifera leconte, which occurs from montana, utah, and arizona east to new york, connecticut and virginia.
With this variant, a large portion of the adult population leaves corn fields to feed on the. Buglogical natural organic gardeners reference catalog provides solutions to pest problems, ladybugs, praying mantis, beneficial nematodes and beneficial insects. In 1995, severe root injury and punishing yield losses occurred in firstyear cornfields across east. In the case of male wcr, the black stripes often merge to the point that the entire wing cover appears black. Corn rootworms pests corn integrated pest management. Survival of the western and northern corn rootworms coleoptera. However, since the early 1990s it has become an increasing threat to crops in europe and is expected to spread to all maize growing areas of the continent. Corn rootworms are the larval stage of the corn rootworm beetle, a pollenfeeder that can cause considerable damage to corn and soybeans. Western corn rootworm adults figure 5ab are yellow to yellowishgreen and black beetles. Nor have any published reports surfaced of corn rootworm resisting the cry3435b1 bt protein. Adults emerge in midsummer and females begin laying eggs about two weeks after emergence. Applied turfgrass science books crop management crop science crop, forage.
It is not too early to make management decisions for next. The western corn rootworm is yellow with black stripes on the wing pad. August and lay eggs almost exclusively in corn fields benorthern corn rootworm adult. Biotechnologyderived bt corn marked a new era for the management of both ecb and rootworm in the united states.
Female northern corn rootworms only lay eggs in corn, regardless if it is from a variant or normal population. The adult is the only developmental form of northern and western corn rootworm that can be distinguished visually without the aid of a microscope figure 2. Controlling corn rootworm preventing corn rootworm. Sampling for larvae and adults, as described previously, is imperative to apply the following management guidelines. Corn rootworms are one of the most economically significant consumers of maize in the united states. Adult wcr are gold in color with a black head and three black stripes on wing covers. Northern corn rootworm definition of northern corn. Pdf management of western corn rootworm diabrotica virgifera. Use invite with caution in areas where adult corn rootworm organophosphate op resistance has been documented. In fact, research in the early 80s in vermont showed very little damage from northern corn rootworm even at high populations. Both sexes of newly emerged adults are cream to light brown and become yellowish to pale green over time. Integrated pest management of corn rootworms in north.
This is due, in part, to exceptionally wet spring conditions in 2014. The larva rootworm is cream colored and about 34inch long when fully developed, with a brown. Western corn rootworm beetle northern corn rootworm corn rootworm larva southern corn rootworm spotted cucumber beetle entomology image gallery beetles corn rootworm beetle. Insecticide recommendations for corn root worm cropwatch. The eggs, which are the overwintering stage, are laid in the soil in cornfields in late summer.
Influence of tillage and western and northern corn rootworm coleoptera. Diabrotica virgifera virgifera western corn rootworm. Adult corn rootworm identification integrated crop. Pdf western corn rootworm wcr was registered for the first time in. Most female western corn rootworm beetles figure 5a have three longitudinal stripes on their forewings.
Chrysomelidae egg populations on larval populations and root damage. Apply in combination with 4 oz penncapm insecticide or other insecticides. Western corn rootworm an overview sciencedirect topics. There are twelve black spots on the wing covers elytra. Surveys were conducted in late july and early august each year by joe spencer, illinois natural history survey, and scott isard, department of geography. Western corn rootworm variant a economic threshold and scouting procedures have been developed for wcr in soybean fields, that will allow growers to make informed decisions regarding the need for a rootwormcontrol product in firstyear corn on a fieldbyfield basis. Northern corn rootworm diabrotica barberi behavioral variant. Further observations on temperature effects on hatching of northern and western corn rootworm eggs. Corn rootworm survey and evaluation of different bt corn.
The western corn rootworm is much more damaging to corn than the northern. The adult is about 14inch long, yellowgreen with a black head and antennae. These yellowgreen beetles are elongated, measure up to about 516 inches in length and bear black stripes of various widths or spots on their wing covers. Corn rootworms pests corn integrated pest management ipm. The newly hatched larvae find their way to corn roots, bore in, and begin feeding. Northern corn rootworm ncrw beetles are tan to pale green.
Rootworm damage to corn planted after soybeans has. Lastly, the southern corn rootworm has a green body that is easy to distinguish because of the black spots on its back. Newly emerged beetles are light in color, gradually becoming greener with age. The southern corn rootworm is green with black spots or stripes and is found all over the united states east of the rockies. The western corn rootworm life cycle is similar to the northern corn rootworm. Western corn rootworm wcrw beetles are yellow with a black stripe along the sides of their wing covers. Corn rootworms have long been major economic pests in the united states. Response of northern corn rootworm, diabrotica barberi smith and lawrence, to stereoisomers of 8methyl2decyl propanoate. America, and it reached northern parts of the conti.
Evaluation of insecticides and plantincorporated protectants. The larval stage lasts about three weeks, then they move. The western corn rootworm, diabrotica virgifera virgifera, is one of the most devastating corn rootworm species in north america, especially in the midwestern corngrowing areas such as iowa. Rotationresistant corn rootworms 2007 jon tollefson. The stripes on female wing covers are distinct, with one on the outside of each wing cover and the third one along the middle, where the wing covers meet.
No resistant northern corn rootworm beetles have surfaced. In contrast, the forewings of most male western corn rootworm beetles figure 5b have a nearly solid black marking. This genus includes more than 350 described species, eight of which occur north of mexico texas taxa diabrotica balteata leconte diabrotica cristata harris diabrotica lemniscata j. Adults of all three species can be found until the first frost. Northern corn rootworm and extended diapause corn states. Update on corn rootworm in iowa integrated crop management.
But its western cousin is a different beast and requires some serious attention. After emerging, adults will look for corn fields on which to feed and lay the overwintering eggs. This behavior effectively allowed them to skip the soybean year and hatch again when corn was planted in the traditional cornsoybean rotation. Variant strains extended or prolonged diapause northern corn rootworm selecting for rootworms that were able to remain dormant as viable eggs for more than one winter season adapted behaviors soybean variant western corn rootworm lay eggs in soybean fields resulting in risk of economic injury to corn planted in. They can be used to control a broad range of soilinhabiting insects and aboveground insects in their soilinhabiting stage of life. Resistance to crop rotation by northern corn rootworm does occur in iowa through extended diapause, although this variant is limited in distribution. We study various tools for integrated pest management of rootworm. Western and northern corn rootworm management in pennsylvania.
This is the bt protein in optimum and refuge advanced trait families marketed by dupont pioneer and dow agrosciences, respectively. Invite ec contains cucurbitacin, a corn rootworm specific feeding stimulantarrestant. Its time for rootworm decisions july 1997 this is a. Resistance has so far been limited to western corn rootworm. These hybrids were created with a cry3bb1 bacillus thuringiensis bt variant that is. The eggs hatch late the next spring late mayearly june, and the larvae feed on the roots of. Knowing how to distinguish the three species is important for making management decisions for future growing seasons. Extended diapause is more common in western iowa, but it is possible to find variants in central and eastern iowa. Since a variant of the corn rootworm became the first pest ever to develop a way of foiling crop rotations, corn growers have been seeking a breakthrough in corn rootworm management. Chrysomelidae in different tillage systems throughout the growing season.
A new variant of the corn rootworm is present in ontario and across the u. Corn rootworm biology and management iowa state university. However, where the western corn rootworm variant or the northern corn rootworm extended diapause trait exists in the midwest, crop rotation by itself is no longer an effective management strategy in all regions. Corn rootworm complete only one generation per year. A method of controlling corn rootworm feeding using a bacillus. Eggs of this rootworm variant remained unhatched for a period of 1. Beneficial nematodes seek out and kill all stages of harmful soildwelling insects. Corn rootworm management update integrated crop management. Northern corn rootworm definition is a corn rootworm diabrotica barberi synonym d. Corn rootworm larvae are cylindrical worms with a white body, brown head and 6 small legs behind the head. In the states to our north, there is a biotype or variant of the western corn rootworm. However, scouts and farmers have noticed rebounding populations of adult corn rootworm in the landscape now, especially noting root injury to firstyear corn by northern corn rootworm.
The northern corn rootworm, on the other hand, has a green to yellow body and the female is usually the one that is larger. Western and northern corn rootworms are present the piedmont and mountain regions of north carolina, although western corn rootworm adults have also been. Adult wcr are gold in color with a black head and three black stripes on wing. In fields where large populations of northern corn rootworm are observed, and where the presence of rotation resistance is suspected, farmers should protect firstyear corn against northern corn. Research has been conducted and shown the western corn rootworm variant also lays its eggs in alfalfa, oat, and wheat stubble, although to a much lesser extent. These insects are the most important insect pests of corn in the midwest.
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