Description

Adult Description: Like other armored scale insects, Aulacaspis scale insects are protected under a waxy cover comprised of old shed skins of the immature. Adult females are different in shape and size than males. The female scale cover is about 1.2 to 1.6 mm in length, flat, circular to pear-shaped, and often distorted due to crowding or the veins of the cycad host plant. The female cover is white and sometimes translucent. The female scale body, which is visible after removal of the scale cover is broad, wingless, legless, and orange in color. The orange colored eggs usually are laid underneath the female scale cover. The male covers are elongate in shape, between 0.5 to 0.6 mm in length, light yellow or white in color, with three parallel ridges. Adult males are orange-brown, and are similar in appearance to tiny flying midges, with one pair of wings, and well-developed legs and antennae.

Larva Description: Orange eggs hatch into larvae that undergo different instar stages until they reach adulthood in about 28 days.

Host Plant: Sago Palms

Ecological Threat

Cycad Aulacaspis Scales cause damage by sucking plant fluids. Initial symptoms of infestation include small yellow spots on the upper surface of fronds. As the infestation progresses, fronds become brown and desiccated. CAS infestations start on the underside of fronds. Heavy infestations contain scales on both upper and lower frond surfaces, rachis, cones, seeds, and main roots as deep as 24 inches (60 cm). Heavy infestations result in multiple layers of live and dead scales forming a waxy white crust on the frond surface with insect counts of several thousands per square inch. Uncontrolled infestations can result in plant death in a few weeks or months. Unlike other species of scale, the Cycad Aulacaspis Scale has been known to attack the roots, and if unchecked can, re-establish a colony from few individuals.

Biology

While unable to become widely-distributed on their own, the Cycad Aulacaspis Scale relies on humans to spread into new habitats. As a result of the horticulture industry, they have been spread throughout the southeastern United States, including California and Hawaii. Further, this species has been found on numerous islands after being brought in on infested sago palms. Once established in an area, the Cycad Aulacaspis Scale has proved very difficult to eradicate. Within its native range their population numbers are controlled by parasites and other biological mechanisms. However, within non-native habitats, these biological mechanisms do not exist, and infestation intensities have been very high and difficult to eradicate.

History

Cycad scale was first discovered in Miami in 1997 infesting King sago palms which were being grown as ornamentals. It probably came into Florida from somewhere in Asia on infested nursery plants. It is difficult to detect on nursery stock because the scale infests roots in the ground as well as trunks and leaflets. The infestation by cycad scale on sago palms quickly spread northward from Miami and is now present just about everywhere sagos are grown. It is estimated that at least 80 percent or more of the sago palms in south Florida are dead. As a result of hitch-hiking, insects have been spread on infected king sago plants to several islands in the Caribbean including Puerto Rico, the Cayman Islands, and the U.S. Virgin Islands, and far away places such as Hawaii, Hong Kong, and Singapore. Some of the more recent infestations have occurred on Guam and Taiwan, where the Cycad Aulacaspis Scale is wreaking havoc in several populations of native Cycas micronesica and Cycas taitungensis.

Native Origin

Thailand.

Current Location

U.S. Habitat: Prefers warmer temperature in which its host plants, sago palms, can grow.

U.S. Present: Currently established in a few states within the United States. Including, Florida, Hawaii, Georgia, Texas, Alabama, California, Louisiana, and South Carolina.

Texas: The Cycad Aulacaspis Scale is currently established in Texas and believed to have entered through Houston.

Resembles

Resembles many of the other scale-type insects. They are most commonly mistaken for the False Oleander Scale (Pseudaulacaspis cockerelli) which is less of a threat, but also non-native (from China).

Management

Fortunately, the Cycad Aulacaspis Scale has a restricted host range and occurs only on sago palms of the genera Cycas, Dioon, Encephalartos, Microcycas, Stangeria and Macrozamia. Therefore, other ornamentals or native plants appear to be unaffected by the Cycad Au;acaspis Scale. Potential management solutions are described from Texas A&M:

Prevent pest problems: Check plants before purchase or prior to installation to make sure they are free of the Cycad Aulacaspis Scale. Look for early infestation symptoms and for scales and scale crawlers on the whole plant, especially leaf undersides. Since crawlers are very small, use a 10x magnification lens to facilitate observation.

Detect infestations quickly and monitor pest populations: Visually inspect plants frequently, weekly or every other week for early infestation symptoms and for the presence of scales. Small populations are always easier to control than large ones.

Act quickly and use effective control tools: The Cycad Aulacaspis Scale have overlapping generations and populations can increase rapidly. Once infestations are detected, act quickly. Continue to monitor populations to determine if your action or treatment is effective.

Cultural control. Avoid plant crowding to reduce movement of scale crawlers from infested to healthy plants and to facilitate spray treatments, if needed. Remove heavily infested fronds (palm leaves) to reduce population density and enhance control. Pruned plant parts must be disposed of properly to avoid contamination to nearby plants. Place infested material inside a double-sealed plastic bag before discarding. Tools used for pruning must be cleaned before use on non-infested plants to minimize the risk of spreading the pest.

Chemical control. Several insecticides are available and registered to control the scale insects.The choice of insecticide is less critical than how the insecticide is applied. Complete plant coverage is essential to control as scales can infest all plant parts. Contact foliar sprays such as horticultural oils and insecticidal soaps require 2 to 3 applications (5 to 10 days apart). Systemic insecticides are usually more effective when applied as soil drenches. Use only products that are registered for ornamental plant use in Texas. See specific suggestions below.

Biological control:Two natural enemies, Cybocephalus binotatus Grouvelle, and a parasitic wasp, Coccobius fulvus have been introduced into Florida with good preliminary results. In Texas, biological control efforts have begun with a survey of natural enemies for possible mass rearing and distribution in affected localities by USDA/APHIS/PPQ.

References

SEARCH Online

Google Search: Aulacaspis yasumatsui
Google Images: Aulacaspis yasumatsui
NatureServe Explorer: Aulacaspis yasumatsui
Bugwood Network Images: Aulacaspis yasumatsui

References

Howard, F. W., A. Harmon, M. McLaughlin and T. Weissling. 1999. Aulacaspis yasumatsui (Homoptera: Sternorrhyncha; Diaspididae), a Scale Insect Pest of Cycads Recently Introduced into Florida. Florida Entomololgy. 82: 14-27.

Marler, T. E., & Lawrence, J. H. 2012. Demography of Cycas micronesica on Guam following introduction of the armoured scale Aulacaspis yasumatsui. Journal of Tropical Ecology, 28(03), 233-242.

Takagi S. 1977. A new species of Aulacaspis associated with a cycad in Thailand (Homoptera: Cocoidea). Insecta Matsumurana New Series 11: 63-72.

Internet Sources

http://insects.tamu.edu
http://www.issg.org
http://polkhort.ifas.ufl.edu
http://www.cycadsg.org
http://entnemdept.ufl.edu


Experts:

Mike Merchant - TAMU AgriLife Extension - m-merchant@tamu.edu

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