Cycad Aulacaspis Scale: Introduction
Aulacaspis yasumatsui Takagi, the cycad aulacaspis scale (CAS), was found infesting several species of Cycas and Stangeria in the collection of the Montgomery Botanical Center in Miami in 1995. The scale is now reported from 25 Florida counties. Aulacaspis yasumatsui was described from material collected on cycads in Bangkok, Thailand. It is now known to occur in southern China, Hong Kong, Vietnam, Singapore, Taiwan, New Zealand, Guam, Ivory Coast, Costa Rica, West Indies, Florida, Hawaii, and Texas. Dense infestations are unsightly and may result in the death of the plant. Pest management is very difficult because expensive pesticide applications must be frequent and regular. Florida nurseries no longer may export plants outside the state. On Guam, CAS was first detected in 2003 on an ornamental Cycas revoluta. In the following two years it spread to most of the island. It now has invaded the native forests where it infests Cycas micronesica, an indigenous species unique to Micronesia. In some areas the mortality rate of these 100-year-old trees is 100%. The entire population of 1.5 million C. micronesica trees is now threatened to succumb to CAS before suitable biological control agents are found and released.
Classical biological control of CAS began in 1998 when a parasitic wasp, Coccobius fulvus, and a predatory beetle, Cybocephalus nipponicus, both from Thailand, were imported and released against CAS in Florida. Although these natural enemies became established and spread throughout south Florida, they do not provide adequate control. New and effective natural enemies of CAS are being sought in Asia to introduce in Florida, Guam, and elsewhere and bring about better biological control of the cycad aulacaspis scale. In October 2007, Ru Nguyen and Ronald Cave discovered an undescribed species of Phaenochilus (Coccinellidae) in Thailand. The natural cycads in the area where the beetles were collected had very low levels of CAS. The larvae and adults feed almost exclusively on armored scales, but will consume some whitefly nymphs. The predator is a voracious consumer of CAS.
The entomopathogenic fungus Isaria fumosorosea is also being tested for control of CAS. Laboratory research has provided good results, but results from field experiments have been inconsistent.
- Host range testing of Phaenochilus.
- Development time, longevity, fecundity, and consumption rate of Phaenochilus.
- Infectivity of CAS by Isaria fumosorosea in the field.