Cotton aphid

Scientific name

Aphis gossypii (Hemiptera: Aphididae)

Other common names

melon aphid

Similar species

Aphis frangulae complex

soybean aphid, Aphis glycines

spirea aphid, Aphis spiraecola

Distribution

United States: southeastern and southwestern United States.

Worldwide: cosmopolitan, everywhere host plants are grown.

Diagnostic characteristics

Adults

• Females are typically used for diagnostic purposes. Wingless females are 0.9 - 1.8 mm (0.04 - 0.07 in.). Winged females are 1.1 - 1.8 mm (0.04 - 0.07 in.).
• Pale yellow at high temperatures. Yellow-green to dark blue-green at low temperatures. May appear almost black at lower temperatures.
• Pear-shaped.
• No markings on the wings, but veins are brown.
• Six-segmented antennae.
• Cauda, a pale to dusky triangular or tongue-like protrusion, on the rear of the abdomenabdomen:
  one of the three body segments in insects; the most posterior segment containing the heart, reproductive organs, and digestive organs
  .
• Two black cylindrical tubes on the rear of the abdomenabdomen:
  one of the three body segments in insects; the most posterior segment containing the heart, reproductive organs, and digestive organs
  (siphunculi or corniclescornicles:
  paired, triangular-shaped tubes projecting from the rear of an aphid abdomen; also referred to as siphunculi <a href="http://idtools.org/id/citrus/pests/morphology.php?state[]=abdomen"></a>
  ).
• Tubercles (head area between antennae) are relatively flat instead of having a notched appearance.

Immatures

• Shape is similar to adults.
• Variable colors including tan, gray, and green. The headhead:
  one of the three main body segments in insects; the anterior-most segment containing the many sensory structures including the eyes, antennae, and mouthparts
  , thoraxthorax:
  one of the three main body segments in an insect, located between the head and abdomen, where the wings and legs of the insect attach
  , and wing padswing pads:
  undeveloped or incomplete wing structures that are found on the immature individuals of insects that do not undergo complete metamorphosis, e.g., stink bugs, leaf-footed bugs, grasshoppers
  are often darkened, and the posteriorposterior:
  orientation pertaining to the rear of the body
  tip of the abdomenabdomen:
  one of the three body segments in insects; the most posterior segment containing the heart, reproductive organs, and digestive organs
  is dark green.
• Wax secretions can cause the body colors to appear dull.

Eggs

• Shiny black.

Hosts

Citrus hosts:

All Citrus species and their hybrids.

Non-citrus hosts:

Extemely diverse host rangehost range:
the range of species that a particular organism can feed on to achieve successful growth and reproduction
. Sixty host planthost plant:
the plant the provides sustenance for an insect
species are known from Florida, over 700 host planthost plant:
the plant the provides sustenance for an insect
speices worldwide including those listed below.

• Asparagus spp.
• boneset, Eupatorium petaloiduem
• catalpa, Catalpa bignonioides
• chrysanthemum, Chrysanthemum spp.
• cotton, Gossypium hirsutum
• coffee, Coffea arabica
• dock, Rumex crispus
• eggplant, Solanum melongena
• grasses, Family Poaceace
• Hibiscus spp.
• Lamium amphlexicaule
• melon, Cucumis spp.
• okra, Abelmoschus esculentus
• pomegranate, Punica granatum
• potato, Solanum tuberosum
• squash, Cucurbita spp.
• Theobroma bicolor
• tomato, Solanum lycopersicum
• watermelon, Citrullus lanatus

Host damage

Fruits

• Honeydew honeydew:
  the sugar-rich waste product excreted by aphids, mealybugs, and scales insects as a result of feeding on the phloem of plants
  excreted by mealybugs coats the outside of fruit and promotes the growth of sooty mold fungus that inhibits photosynthesis, weakens the plant, and makes fruit unattractive.

Leaves

• Attack leaf tips or newly emerged leaves causing them to curl downward and pucker.
• Cotton aphids transmit many viruses, including Citrus tristeza. Citrus plants originating from sour orange stock (many domestic varieties) are susceptible to this virus, so cotton aphids are particularly damaging.

Biology

The life cycle is different in the northern and southern United States. In northern climates, female aphids deposit eggs that hatch in the spring on their primary hosts: catalpa, Catalpa bignonioides, and rose of sharon, Hibiscus syriacus. Females utilize asexual reproduction (parthenogenesis) in warm temperatures and revert to sexual reproduction in the fall.

In southern climates, cotton aphids reproduce asexually throughout the year and are known to overwinter on dock, Rumex crispus; Lamium amphlexicaule; boneset, Eupatorium petaloiduem; and citrus, Citrus spp. Many aphids are host-specific, but the cotton aphid is somewhat unusual because it has a very wide host rangehost range:
the range of species that a particular organism can feed on to achieve successful growth and reproduction
. Cotton aphid can semi-persistently transmit over 50 viruses.

The aphid overwinters in greenhouses or interiorscapes and can be introduced to colder regions.

Comments

Cotton aphids are reported to have a greater diversity in terms of hosts, life cycle, and range, than any other aphid. A separate key may be required to differentiate the forms. If damage is unusual or on an unlisted host planthost plant:
the plant the provides sustenance for an insect
, submit a sample of the insect to your local extension agent or state diagnostic lab for determination.

All phloem-feeding, honeydew-producing pests have the potential to be tended by ants. The ants feed on the honeydewhoneydew:
the sugar-rich waste product excreted by aphids, mealybugs, and scales insects as a result of feeding on the phloem of plants
excreted by the pest and protect the pest from natural enemies. This protection can disrupt biological control programs.

References

Blackman, R.L., and V.F., Eastop. 2007. Taxonomic issues, pp. 10-11. In H.F. Van Emden, and R. Harrington (Eds.). 2007. Aphids as crop pests, CABI Ltd. Wallingford, Oxfordshire, U.K.

Browning, H.W., C.C. Childers, P.A. Stansly, J. Peña, and M.E. Rogers. 2010. 2010 Florida citrus pest management guide: Soft-bodied insects attacking foliage and fruit. ENY-604. University of Florida. (http://edis.ifas.ufl.edu/cg004).

Capinera, J. 2009. Featured Creatures fact sheet - melon aphid or cotton aphid Aphis gossypii Glover (Insecta: Hemiptera: Aphididae) (http://entnemdept.ufl.edu/creatures/veg/aphid/melon_aphid.htm).

Carter, C.C. 1983. Melon aphid Aphis gossypii Glover, Aphididae pp. 1-173. In K. Sorensen, and J. Baker (eds.), Insect and related pests of vegetables: Some important, common and potential pests in Southeastern United States. (http://ipm.ncsu.edu/ag295/html/melon_aphid.htm).

Komazaki, S. 1993. Biology and virus transmission of citrus aphids. Technical bulletin / ASPAC Food and Fertilizer Technology Center (ISSN 0379-7627; no. 136) (http://library.wur.nl/WebQuery/clc/901387).

Margaritopoulos, J.T., M. Tzortzi, K.D. Zarpas, J.A. Tsitsipis, and R.L. Blackman. 2006. Morphological discrimination of Aphis gossypii (Hemiptera: Aphididae) populations feeding on Compositae. Bull. Entomol. Res. 96: 153-165.

Miyazaki, M. 2001. Important aphid vectors of fruit tree virus diseases in tropical Asia. Food and Fertilizer Technology Center. Plant Protection No. 2001-1. (http://www.agnet.org/library.php?func=view&style=&type_id=6&id=20110714101309&print=1).

Stoetzel, M.B. 1994. Aphids (Homoptera: Aphididae) of potential importance on Citrus in the United States with illustrated keys to species. Proc. Entomol. Soc. Wash. 96: 74-90.

Stoetzel, M.B., G.L. Miller, P.J. O'Brien, and J.B. Graves. 1996. Aphids (Homoptera: Aphididae) colonizing cotton in the United States. Flor. Entomol. 79: 193-205.

(USDA, NPGS) United States Department of Agriculture, National Plant Germplasm System. 2007. Germplasm Resources Information Network (GRIN) database. (http://www.ars-grin.gov/npgs/searchgrin.html).

Yokomi, R.K., and S.M. Garnsey. 1988. Host effects on natural spread of Citrus Tristeza Virus in Florida p. 77-81. In Tristeza and related diseases. S.M. Garnsey and L.N. Timmer (eds.). Proceedings, 10th Conference of the International Organization of Citrus Virologists.

Authors

Weeks, J.A., K.W. Martin, A.C. Hodges, and N.C. Leppla