8 Insect Management
8. Insect Management
8.1 Asparagus Beetle, Crioceris asparagi, and Spotted Asparagus Beetle, C. duodecimpunctata
Time for concern: Spring through summer.
Key characteristics: Common asparagus beetles are 5/16 inch long and black with a blue head, four large yellow spots, and a reddish margin on their abdomen. Spotted asparagus beetles are the same size, but are bright orange with black spots. Adults of both species chew on the spears. Larvae of both species are cream-colored with dark heads and feed for 10 to 14 days. Common asparagus beetles feed on the ferns, whereas spotted asparagus beetles only feed on the fruit on the ferns. Marketable yield can be reduced by feeding damage and the presence of eggs on spears. Feeding on ferns later in the season can reduce plant vigor. See Journal of Integrated Pest Management article The Common Asparagus Beetle and Spotted Asparagus Beetle (Coleoptera: Chrysomelidae): Identification, Ecology, and Management.
| Management Option | Recommendations for Asparagus Beetles |
|---|---|
| Resistant varieties | No resistant varieties are available. |
| Natural enemies | Natural enemies, including the parasitic wasp Tetrastichus asparagi and many generalist predators, help to control asparagus beetle populations. They can be preserved by using pesticides that are less harmful to them. See the Cornell IPM Biocontrol website for identification of natural enemies. Foliar application of the beneficial nematode Steinernema feltiae was shown to cause up to 96% larval mortality in greenhouse trials. Note that beneficial nematodes are often less successful in field trials. |
| Scouting/thresholds | Begin scouting early in the spring (before 120 degree days have accumulated since January 1 from base 10°C) and continue all season. Afternoons are the best time to scout, because that is when adult beetles are most active. Check 20 plants at each of 5 randomly chosen locations in the field and record the numbers of eggs, larvae, and adults. During harvest, consider treatment if more than 2 percent of spears have eggs or if more than 5 percent of spears are infested with asparagus beetle adults. After harvest ends, treat if 10 percent of plants are infested with adults, 2 percent with eggs, 50 to 75 percent with larvae, or if plants are at least 10 percent defoliated. |
| Sanitation | Adult beetles can overwinter in stalks and leaf litter in the field. Remove and destroy stalks after the growing season to kill beetles that are sheltering in them. |
| Site selection and Post-harvest | These are not currently viable management options. |
At the time this guide was produced, the following materials were registered in New York State, labeled for managing this pest, and allowed for organic production. The status of pesticides can and does change. To be used legally in NY, pesticides must be currently registered with the New York State Department of Environmental Conservation (DEC). However, pesticides meeting the federal requirements for minimum-risk (25(b)) pesticides do not currently require registration. Current NY pesticide registrations can be confirmed on the NY DEC Bureau of Pesticides Management Information Portal. ALWAYS CHECK WITH YOUR CERTIFIER before using a new product. |
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8.2 Asparagus Miner, Ophiomya simplex
Time of concern: May through September.
Key characteristics: Adult flies are shiny, black, and small (about 1/8 inch to 1/5 inch long). There are two generations per year, with the second generation overwintering as pupae in asparagus stems. Adults from the overwintering generation emerge in May, and mated females deposit eggs beneath the outer layer (epidermis) of the asparagus stem near ground level. Larvae feed on mines within the stem, then pupate in their feeding mines. The second generation of adults emerges in late July and August, and their offspring eventually develop into overwintering pupae. Asparagus miner feeding rarely causes significant yield reductions, and cosmetic damage is usually minimal because mines do not often extend more than a couple of inches above the soil line. The greatest threat from this insect is due to its suspected role in moving Fusarium into asparagus stems. Larval stem tunneling is associated with increased infection with Fusarium, which can significantly reduce the number of years that an asparagus bed remains economically productive. For photos and more information, see Michigan State University Asparagus Miner Facts and Ontario Crop IPM Asparagus Miner fact sheet.
| Management Option | Recommendations for Asparagus Miner |
|---|---|
| Resistant varieties | No varieties are resistant to asparagus miner. Younger asparagus fields are more susceptible to this insect. |
| Natural enemies | Natural enemies that help to control asparagus miner populations in North America include several species of parasitic wasps, such as Chorebus rondanii and Thinodytes cephalon, as well as many generalist predators. |
| Scouting/thresholds | In Ontario, the recommendation for scouting is to check 10 groups of 10 plants from throughout the field for the presence of mines at the plant base. Record the occurrence and severity of asparagus miner infestation to guide future management decisions. No thresholds have been established for organic production. |
| Sanitation | Remove wild/volunteer asparagus plants around the field. In late fall, remove and destroy dead asparagus stems that can harbor overwintering asparagus miner pupae. |
| Site selection, Post-harvest, and Pesticides | These are not currently viable management options. Insecticide sprays will not reach larvae and pupae, which are protected in plant tissues. |