|Crop Knowledge Master|
Macrosiphum luteum (Buckton)
Victoria L. Tenbrink, Research Associate
Arnold H. Hara, Entomologist
Beaumont Research Center
This aphid infests orchids of the genera Oncidium, Cattleya, Lycaste, Brassia, Epidendrum, Laelia, and Catasetum. (Swezey, 1945).
Probably a New World tropical species, the orchid aphid was first described from hothouse orchids in England (Pridgeon & Tillman, 1990). Also found in the Far East and the Pacific, it is established in Florida on the U. S. mainland (Blackman & Eastop, 1984; Pridgeon & Tillman, 1990). In Hawaii it infests orchids on Kauai, Oahu, Maui, and Hawaii (Nishida, 1992).
Aphids have sucking mouthparts and feed on the orchid plant juices. Removal of the juices causes stunting and distortion of tender growth.
Like many other soft bodied insects, such as leafhoppers, mealybugs, and soft scales, aphids excrete honeydew. The honeydew supports the growth of sooty mold, an unsightly fungus that robs the orchid plant of sunlight and mars the beauty of the plant.
Aphids may be toxic to orchid plants; they may also inject disease-causing agents, including viruses.
Apparently, all orchid aphids are females; males have not been discovered. Reproduction is by live birth of females (Blackman & Eastop, 1984).
There is no egg stage. Young are born live.
Nymphs are yellow or green. They are similar in shape to the wingless adults, but are smaller.
Adults may be winged or wingless. Orchid aphids are about 1/16 in. long. The color varies from pale yellowish green to bright greenish yellow. The majority of the aphid body is abdomen, and the tip of the abdomen is pale yellow. The wingless form has a black patch on the top surface of the abdomen, as well as a narrow black band just ahead of the abdomen. Winged forms donŐt have the black patch, but they do have dark horizontal lines between segments of the abdomen. Antennae are black except at the bases.
Adults aphids reproduce rapidly; this causes sudden population build up.
Colonies of the orchid aphid infest the leaf and stem (Pridgeon & Tillman, 1990). Ants are often associated with aphids. The ants feed on the honeydew secreted by the aphid. Ants establish new aphid colonies and ward off natural enemies.
Winged adults are not strong fliers; however, they may be carried considerable distances by light winds.
Bloated, tan colored mummies are evidence that wasps are parasitizing the colony.
Biological control experts from the Hawaii Department of Agriculture have introduced ladybird beetles to the Islands to control insects. Coccinella 7-punctata var. brucki was brought in from Okinawa in 1958 and is established on the major Islands (Lai and Funasaki, unpublished data). Other predators that have been successfully introduced to combat aphids include Coelophora inaequalis, C. pupillata, Hippodamia convergens, Scymnodes lividigaster, Diomus notescens (Coleoptera: Coccinelidae), and Nesomicromus navigatorum (Neuroptera: Hemerobiidae) (Hue, unpublished data). The larvae as well as the adults of ladybird beetles and lacewings are very active aphid feeders. Syrphid fly larvae also parasitize aphids.
Chlorpyrifos and acephate foliar sprays have been effective in reducing aphid populations and the attending ants (Hata et al., 1992, Hata & Hara, 1992).
A 3-minute insecticidal dip will eliminate most aphids from orchid stems and blossoms. Wettable powders should be avoided on flowers because they may leave a residue. Emulsifiable concentrates, soaps, and oils should be avoided because of the potential for damage (Tenbrink et al., 1992). Dips longer than 3 minutes may water soak blossoms.
Blackman, R. L. & V. F. Eastop. 1984. Aphids on the WorldŐs Crops: An Identification Guide. John Wiley & Sons: New York. Pp. 353-354.
Nishida, G. M, ed. 1992. Hawaiian Terrestrial Arthropod Checklist. Bishop Museum Press: Honolulu. p. 135.
Pridgion, A. M. & L. L. Tillman, ed. 1990. Handbook on Orchid Pests and Diseases. American Orchid Society, Inc: West Palm Beach, Florida. p. 10.
Swezey, O. H. 1945. Insects associated with orchids. 2. Macrosiphum luteum (Buckton). Proc. Haw. Ent. Soc. 12 (2): 373.
Tenbrink, V. L., B. K. Hu & A. H. Hara. Phytotoxicity of three formulations of insecticidal soap in postharvest dip treatments of dendrobium orchids, 1991. Insecticide & Acaracide Tests 17: 349.