Information on Aphid Vectors
Featured Aphid Vectors of PVY
Green peach aphid (Myzus persicae)
An Aphid Glossary
Alatous or Alates- winged forms.
Aphids are soft-bodied insects with piercing-sucking mouthparts. They feed in the phloem which circulates carbohydrates throughout a plant. Aphids often excrete a sugary waste called ‘honeydew’. Aphids usually feed in colonies on new, succulent shoot tips or young leaves. Heavy infestations delay plant development and impair plant health—causing leaf curling, stunting, or wilting.
In temperate regions, many aphids produce eggs to survive winter on a primary plant host. In spring, eggs hatch and the aphids migrate to secondary, summer host plants. Migration in late summer to early autumn occurs when aphids take flight to find the overwintering host plants to lay eggs. In warmer climates, sexual reproduction may not occur and females give birth to live young throughout the year.
In warm weather, aphids reproduce through parthenogenesis, having several generations. One adult female can birth 20 to 50 nymphs that can mature in 14 to 21 days under summer conditions. Young nymphs periodically develop into alatous adults and migrate to other plants and, depending on the aphid species, may migrate to one or more alternate host plants.
More importantly, many aphids can vector plant viruses, like Potato Virus Y. Aphids vector viruses between plants within a field or long distance to new fields as they migrate, dipping their stylets into plants, tasting in search of their preferred hosts. Aphid movement can be promoted in agricultural settings when cutting fields for hay, cultivating, spraying, or during harvest activities.
Aphids that colonize and reproduce on potato are the most efficient vectors of PVY. Of the aphids featured here, the green peach aphid and the potato aphid are colonizers.
Non-Colonizing, or Transient, Aphids
These aphids will “taste” plants as they move through a potato field in search of a preferred host and in so doing can pick up and transmit PVY. Although non-colonizers may be inefficient vectors of PVY, there can be thousands of individuals moving through a potato field, making the risk of PVY transmission significant.
Important Vectors of PVY in Potato
Green peach aphid
Bird cherry-oat aphid
English grain aphid
Corn leaf aphid
This is perhaps the most efficient vector of PVY in potato.
Description: Body color varies from yellow to all shades of green, to pink, red, or black with a dorsal black patch at the base of abdomen, black thorax, pale-colored on ventral side of abdomen. Cornicles are medium length and slightly swollen with darkened tips.
Distribution: Worldwide, present in all areas of North America.
Host biology: A highly polyphagous species. Exhibits host alternation, overwintering on woody perennial peach or plum (Prunus spp.) and summering on hundreds of plant species from across 40 plant families, including many herbaceous annuals. The green peach aphid has multiple biotypes that exhibit host preference and some that have insecticide resistance.
Description: Large insects with pear-shaped bodies and distinct red eyes. Body color varies from solid pink to green and pink mottled to light green. Long slender cornicles are often the color of the insect body. Nymphs are elongated and have a dark dorsal stripe and a light covering of white-gray wax making them paler than adults.
Distribution: Native of North America, worldwide except the India subcontinent.
Host biology: The potato aphid attacks over 200 plant species including vegetable and ornamental crops, as well as weeds. It overwinters as eggs on cultivated and wild rose (Rosa spp., Family Rosaceae).
Description: Small, greenish-yellow insects with black cornicles.
Distribution: Native to Asia, established in the Midwest and Northeast United States, extending west to North Dakota and south to Mississippi.
Host biology: Exhibits host alternation, overwintering as eggs on woody perennial buckthorn (Rhamnus spp.) and in spring moving to soybean (Glycine max) as secondary summer host with feeding observed on other members of the Family Fabaceae.
Description: Large, long-legged insect, body color a light to deep green with reddish eyes and long, slender cornicles.
Distribution: Throughout the United States and Canada, widespread throughout Europe, Asia, Africa, North and South America, Japan, and Russia.
Host biology: Overwintering and summer hosts are limited to members of Legume Family (Fabaceae). Important overwintering hosts include vetch (Vicia spp.) and crimson clover (Trifolium incarnatum) with alfalfa, Medicago sativa), cultivated and wild legumes as summer hosts. High infestations often occur during cool temperatures in early spring (May, June) and early fall (September, October). Aphids immediately fall off plants when disturbed.
Description: Body color ranges from orange-green to olive-green to dark green, sometimes greenish-black. Wingless forms often with reddish-orange patch near the base of cornicles, rounded bulb-like body shape, antennae more than half the length of the body. Cornicles short, dark, swollen and tapered.
Distribution: Worldwide, throughout the United States.
Host biology: Host alternation, overwinters on woody perennials bird cherry (Padus racemosa) or plum (Prunus spp.), summer hosts mainly in Family Poaceae, especially maize, barley, oats, millet, and wheat. Heavy colonization occurs on winter wheat in early spring and late fall.
Description: Small to medium-sized insects. Body color is greenish white to yellowish green, with pale-colored appendages and a subrectangular solid black dorsal abdominal patch. Very long cornicles have dusky colored tips. Antennae as long as, or longer than, the body length.
Distribution: Native to Europe, found throughout temperate and warm temperate regions of the world, Australia, New Zealand, New Guinea, India.
Host biology: Host alternation, overwinters as eggs on Elaeagnus spp., with summer secondary hosts mainly thistles (Cirsium spp., Carduus spp., and Cynara spp.) in the Family Compositae. It may also feed on plants in the Family Polygonaceae. Thistle aphid colonies often cluster on the undersides of the lower leaves of summer host plants.
Description: Yellow-green, pear-shaped body, with a dark green stripe down the abdomen. The uniformly dark antennae extend more than half as long as the body. Tips of the cornicles and legs are almost black.
Distribution: Found in Central and South America, Europe, Africa, the Middle East and Asia, widespread throughout the United States.
Host biology: This species does not alternate between overwintering and summer hosts. Important agricultural hosts include: sorghum, wheat, barley, corn, millet, oats, rice, and rye. Lawns may harbor greenbug infestations. Eggs are laid into leaf sheaths of winter cereals or other grasses (Family Poaceae). Greenbugs inject toxin into plant hosts while feeding, killing plant cells near the feeding area. They possess a bacterial endosymbiont (Buchnera aphidicola) important for insect amino acid metabolism. Nine biotypes differ in host preference.
Description: A relatively small aphid. The adult is usually shiny black while the nymph is slate gray, often dull not shiny. The appendages are whitish, antennae darkening towards the tips and legs with dark “feet”.
Distribution: Worldwide, including North America.
Host biology: Polyphagous, though prefers members of Legume Family (Fabaceae). Cowpea aphid secretes a toxin while feeding and, when present in high numbers, can cause wilting, discoloration, stunting and death of the plant.
Description: Body color yellow-green to reddish brown with long black legs and black cornicles, giving it a spider-like appearance. This medium-sized aphid with black antennae and black leg joints measures ? inch when mature.
Distribution: Worldwide, all areas of North America with preference to cool, temperate climate zones.
Host biology: Host alternation. Overwinters on winter cereals and cereal weed species. In summer, occurs primarily on cereals including maize, wheat, and rice. Can develop on many cultivated or wild species of Family Poaceae, in addition to some species in the Families Juncaeae and Cyperaceae. Usually appears later in the season than other cereal aphids (late August, September).
Description: Small insects with rectangular-shaped body, bluish-green to dark olive with a purplish patch near the base of cornicles. Short antennae and prominent black cornicles. Can be confused with R. padi, the bird cherry-oat aphid.
Distribution: Worldwide, throughout the United States.
Host biology: No host alternation, feeding primarily on grasses, preferring sorghum as a host but also corn, barley, millet, sudan grass, and other cereals. Infestations occur in late summer (August, September).
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