Cinara strobi

(Fitch, 1851)

White Pine Aphid

Cinara strobi, the pine , is a large aphid specialized on white pine (Pinus strobus). It is notable for exceptionally high autumn that produce copious , attracting stinging and creating nuisance conditions. The species exhibits parthenogenetic during the growing season, with live birth of accelerating population growth. Uniquely among Cinara aphids, C. strobi harbors three bacterial endosymbionts—Buchnera aphidicola, Sodalis sp., and Serratia symbiotica—representing an intermediate stage of replacement where the latter has become metabolically incompetent yet persists.

Cinara strobi eggs by Beatriz Moisset. Used under a CC BY-SA 4.0 license.

Cinara strobi eggs closeup by Beatriz Moisset. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Cinara strobi: //ˈsɪnərə ˈstroʊbaɪ//

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Identification

Distinguished from other by on pine, large size relative to most aphids, and extremely long . Autumn producing heavy are diagnostic. Distinguished from other Cinara by association with white pine rather than other conifer .

Images

Appearance

Large with an exceptionally long () at the of the adapted for tapping into phloem. Body coloration not explicitly described in sources but typical of Cinara aphids (dark, often or black). and found clustered on pine branches and needles.

Habitat

pine (Pinus strobus) trees in forested and urban settings. Found on branches and needles where phloem feeding occurs.

Distribution

North America, associated with the range of its pine (Pinus strobus). Documented in eastern North America including the DMV (DC-Maryland-Virginia) region.

Seasonality

Peak in autumn (September-October). Overwinters as on pine needles. Parthenogenetic during growing season transitions to producing eggs as cold weather approaches.

Diet

Phloem sap from pine (Pinus strobus). Excess excreted as .

Host Associations

Pinus strobus - obligate pine; sole for feeding and

Life Cycle

Complex with seasonal shift in reproductive mode. During growing season: parthenogenetic females give live birth to daughters (), with embryos of next carried before birth, compressing generation time. In autumn: winged sexual males and females produced, mate, and females on pine needles. Eggs survive winter cold, hatch in spring.

Behavior

Forms dense on pine branches. Produces large quantities of that falls from trees, attracting yellowjackets, bald-faced , European hornets, and . Parthenogenetic allows rapid increase from few individuals to thousands.

Ecological Role

Phloem feeder that transfers nutrients from to via . Honeydew supports in autumn and provides substrate for growth, which blackens plant surfaces. Serves as model organism for studying bacterial endosymbiont replacement and erosion.

Human Relevance

Nuisance pest when abundant due to sticky falling on sidewalks, vehicles, and people. Attracted create safety concerns in urban areas. Not a direct agricultural pest but can reduce aesthetic value of ornamental pines.

Similar Taxa

Other Cinara speciesOther Cinara feed on different conifer (spruce, fir, cedar, larch); C. strobi distinguished by pine specificity and exceptionally long
Longistigma caryaeGiant bark also produces copious and attracts , but feeds on hardwood trees (oak, hickory) rather than conifers

More Details

Endosymbiont biology

Cinara strobi uniquely harbors three fixed bacterial endosymbionts: Buchnera aphidicola (provides ), Sodalis sp. (co-primary , contributes to nutrition), and Serratia symbiotica (highly eroded , pseudogenized, no longer contributes to nutrition). This represents an intermediate stage of symbiont replacement where a once-competent symbiont is retained despite providing no apparent benefit.

Honeydew production

Phloem sap is nitrogen-poor but -rich. To obtain sufficient nitrogen, must ingest large volumes of sap, excreting excess carbohydrates as . A single colony can produce enough honeydew to create visible wet on pavement and vehicles beneath infested trees.