Swede Midge Contarinia Nasturtii

Swede midge Contarinia nasturtii

Description

Identified in North America in 2000, when it was first discovered in Ontario, Canada. The first U.S detection was in Niagara County, New York in

2004. Has spread to at least 7 states and 6

Canadian provinces.

Identification

2 millimeters in length, with hairy wings and a light brown or orange body.

Habitat

Native to Europe and southwestern Asia. Host plants include cultivated and non-cultivated brassica and mustard plants that span the entire growing season, including broccoli, cabbage, cauliflower, Brussels sprouts, kale, collards, rutabagas, radishes, horseradish, turnips, canola,

Source: MISIN. 2021. Midwest Invasive Species Information Network. Michigan State University - Applied Spatial Ecology and Technical Services Laboratory. Available online at https://www.misin.msu.edu/facts/detail.php?id=329. wild mustard, shepherd?s purse, stinkweed, field peppergrass and yellow rocket

Reproduction

3-5 generations from May to October, with each generation taking 21-44 days to develop. Emerge from overwintering pupae in May and fly 1-5 days looking for mates and host plants. Females lay up to 100 eggs in clutch sizes of 2-50 eggs.

Hatch within 3-5 days, growing 3-4 millimeters long and transparent to yellow in color.

Communally feed for 2-3 weeks before jumping from the plant to pupate in the soil for 2 weeks.

Pupate in the top 0.75 inches of soil but if buried below 2 inches, can persist for 2 years and can emerge if tillage brings them to a favorable depth.

Impact

Larvae feed on leaf bases and flower buds emerging from the growing tip of the plant by secreting digestive fluids that break down the waxy plant cuticle. This results in twisting, curling, crinkling and drawstring damage to leaves, and swollen leaf stems where they meet the main stalk. Heading cole crops can grow "blind" if feeding occurs before button stage, leaving only a brown scar in place of the head or stalk.

There are many species of native midges that specialize on different host plants. It is difficult to tell them apart, and a trained professional is required to accurately identify swede midge adults captured in sticky traps or reared from soil samples.

Monitoring and Rapid Response

A study in Ontario determined that using traps to time sprays was economically beneficial in cabbage with an action threshold of five males per trap per day, and a minimum of a seven-day spray interval.

Adults are weak fliers, so scouting fields in low and sheltered areas is also important since that is where they will be most prevalent. Planting in open fields with better crosswinds can help deter adults from establishing. Systemic neonicotinoids are a useful tool for controlling this pest. In a New York greenhouse study, foliar applications of Assail 30SG (acetamiprid) controlled larvae on cauliflower transplants using nine-day spray intervals. Clothianidin and thiamethoxam seed treatments offered 100 percent control of larvae for three to five weeks, and soil drenches of acetamiprid, imidacloprid and thiamethoxam were 100 percent effective for up to seven weeks to control the feeding larvae. There are a number of biocontrols that have been laboratory tested, including lady beetles, and four species of entomopathogenic nematodes were tested.

Credits

The information provided in this factsheet was gathered from the Michigan State University

Extension.Individual species images that appear with a number in a black box are courtesy of the

Bugwood.org network (http://www.invasive.org). Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All

Source: MISIN. 2021. Midwest Invasive Species Information Network. Michigan State University - Applied Spatial Ecology and Technical Services Laboratory. Available online at https://www.misin.msu.edu/facts/detail.php?id=329. other images appear courtesy of Google (http://images.google.com).