Managing aphids in vegetables: Population suppression vs. virus prevention

Zsofia Szendrei<szendrei@msu.edu>, Michigan State University, Department of Entomology - July 13, 2026

Successful aphid management begins with identifying the primary production challenge. Matching management tactics to the production goal allows for more effective, economical and sustainable decisions.

Collage showing several examples of aphids on vegetable crops. Large photos show dense aphid colonies feeding on celery stems and leaves, a close-up of a mixed colony of winged and wingless aphids, and a cabbage plant heavily infested with aphids causing curled, distorted leaves. Smaller photos show cabbage aphids clustered on the underside of a leaf and a tan, swollen aphid mummy that has been parasitized by a beneficial parasitoid wasp. — Photos by Zsofia Szendrei, MSU.

Aphids are among the most common insect pests of vegetable crops. They can reduce plant vigor through feeding, contaminate produce with honeydew, and transmit numerous plant viruses. Although aphids are a common pest across many vegetable crops, the best management strategy depends on the production goal.

The first question to ask when aphids are detected is not "What insecticide should I spray?" Instead, ask “Is my crop primarily at risk from aphid feeding or from aphid-transmitted viruses?” The answer determines the most effective management strategy.

Two different management goals

1. Crops where aphid feeding is the primary concern

In many vegetable crops, aphids become problematic only after they establish colonies and populations increase. Colonizing aphids remove plant sap, produce sticky honeydew, contaminate harvested produce, and may reduce plant vigor when populations become large. For these crops, growers can often allow small aphid populations to develop while relying on regular scouting and natural enemies to suppress population growth. Insecticides are applied only when populations reach economically damaging levels or when produce quality is threatened.

2. Crops where virus transmission is the primary concern

Some vegetable crops are highly susceptible to aphid-transmitted viruses. Cucurbits are a classic example because viruses such as cucumber mosaic virus, watermelon mosaic virus and zucchini yellow mosaic virus can cause severe yield and quality losses. Unlike colonizing aphids, even a few winged aphids moving through a field can introduce viruses. Many of these viruses are non-persistent, which means they can be transmitted by probing alone and do not require the aphid to stay and feed on the plant. This means plants can become infected within seconds of an aphid landing on a plant.

Because virus transmission frequently occurs before an insecticide can kill the aphid, simply applying foliar insecticides may do little to prevent primary virus infection. For virus-prone crops, the management objective shifts from killing aphids to reducing opportunities for virus transmission.

Choosing the right tool for your management goal

Insecticide category	Insect contact required?	Systemic?	Typical residual activity	Relative impact on natural enemies	Typical examples	Best for colonizing aphids?	Best for virus-prone crops?
Contact (broad-spectrum) insecticides	Yes	No	Short - moderate	High	Pyrethroids (e.g., bifenthrin, lambda-cyhalothrin), organophosphates (e.g., dimethoate), carbamates	Good knockdown of established colonies	Not effective for reducing virus transmission which often occurs before aphids are killed.
Selective insecticides	Not always	Varies*	Moderate - long	Low to Moderate	Sivanto, Beleaf, Movento, Transform, Assail	Excellent for suppressing established populations	Limited ability to reduce virus transmission.
Soaps and horticultural oils	Yes	No	Short	Low	Insecticidal soaps, horticultural oils, mineral oils	Useful for small infestations	Repeated mineral oil sprays can reduce transmission of many non-persistent viruses.
Biopesticides	Usually yes	No	Short	Low	Beauveria bassiana, Cordyceps fumosorosea, azadirachtin, pyrethrins	Useful with repeated applications	Virus transmission often occurs before aphids are killed.
Seed treatment insecticides	No	Yes	Several weeks after planting	Low to Moderate	Neonicotinoids: thiamethoxam, clothianidin, imidacloprid	Useful for early-season suppression	May reduce colonization but generally is not used to prevent non-persistent virus transmission.

*Systemicity varies among selective insecticides. Products such as Sivanto and Movento are systemic, whereas Beleaf is primarily translaminar with limited movement within the plant.

Management recommendations for colonizing aphids

When aphid feeding is the primary concern, integrated pest management should focus on regular scouting, conserving natural enemies and treating only when populations threaten yield or crop quality. Selective insecticides are often preferred because they suppress aphid populations while minimizing impacts on predators and parasitoids. Rotate insecticides among IRAC mode-of-action groups to delay resistance. Some of the most damaging aphid species found in Michigan are notorious for developing resistance to insecticides.

Management recommendations for virus-prone crops

When aphid-transmitted viruses are the primary concern, management should emphasize preventing virus introduction. Use resistant varieties when available, remove weed hosts and volunteer plants, consider reflective mulches, and apply mineral oils at regular intervals to reduce transmission of many non-persistent viruses. Insecticides alone generally cannot prevent initial virus transmission, but they can help reduce the further spreading of the virus in the crop field.

This work is supported by the Crop Protection and Pest Management Program (grant no 2024-70006-43569) from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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