Invasive Plant-Feeding Mite Species (Acari: Prostigmata)
Ronald Ochoa
USDA, ARS, PSI, Systematic Entomology Laboratory
INTRODUCTION
Plant-feeding mites are of major importance as agricultural pests in forestry, fruit production, vegetable and forage crops, ornamentals and stored grains. Mites can cause serious problems as invasive species because they are very small and difficult to detect and have become widely distributed with increased world trade. Once they become established in a new area, certain biological characteristics allow rapid escalation to pest status. These include high egg production, various modes of reproduction, short life cycles, many dispersal techniques, and adaptability to diverse environmental and ecological conditions. In many instances, lack of information about the correct identity of the mite, its biology and ecology have caused serious consequences to U.S. agriculture. Mites in the superfamilies Tetranychoidea (spider mites, flat mites), Eriophyoidea (gall mites, rust mites, bud mites) and some Tarsonemoidea (broad mite, cyclamen mite, grass white mites) included some of the most important invasive plant pests.
1. TETRANYCHOIDEA - Citrus leprosis virus and flat mite threat
The citrus leprosis virus was described from Argentina in 1941. In the early 1960s, the disease was reported in Brazil. Today, it is known to occur in all of the major citrus states in Brazil and to cost more than $100 million dollars annually. This disease is moving northward and was recently discovered in Panamá. Citrus leprosis virus is transmitted by flat mites. Feeding damage by these mites results in symptoms such as chlorosis, necrosis, striation of fruit surfaces, gall formation and malformation of fruit. The severity of the damage is increased when these mites are associated with viruses. The flat mite vectors are present in the U.S., but even through citrus leprosis virus has been reported to occur in Florida, no current records have been produced or verified. Citrus production in the U.S. is a billion dollar industry. If citrus leprosis virus invades and becomes established in the U.S., it will cause serious damage to the economy of all citrus-growing states.
2. ERIOPHYOIDEA - Rust mites
Several ornamental plants in the U.S. have been recently invaded by rust mites. The bougainvillea rust mite was located in 1997 in California and in 1998 in Florida. The rust mite causes extensive edgerolling and rusting of the flowers and leaves. The damage is more severe in white and pink varieties of bougainvillea plants. This mite does not yet occur in Texas and Arizona where bougainvillea plants are popular. The coconut palm mite, introduced in 1984 to Florida, was recently collected in California. This mite is a new serious pest on the queen palm. Queen palm is a very popular indoor ornamental plant throughout the U.S. In coconut palms this mite can affect 60 to 97% of the plants and causes from 20 to 60% losses of the production. These new introductions are a serious threat for the booming ornamental business in the U.S.
3. TARSONEMOIDEA - Rice white mite threat
The mite has not been collected in the U.S. science its first collection and description in 1967. The rice white mite is a serious pest of rice in Asia. In 1997, we were informed that the rice white mite had been collected in Cuba. In 1998, the Systematic Entomology Laboratory identified specimens of rice white mite from the Dominican Republic and Haiti. The rice white mite injures the internal surface of leaf sheaths and causes sterility of rice seeds by transmitting the rice sheath rot fungus and a mycoplasm-like organism. This mite is in the Caribbean; and, if it is reintroduced to the U.S. it will be a serious threat to the rice production of Arkansas, California, Florida and Louisiana.
SUMMARY
The Tetranychoidea, Eriophyoidea and Tarsonemoidea include over 7,000 known species of mites world wide. In the United States these groups include about 1,000 species. Since the 6,000 species that do not occur in the U.S. are mostly plant feeders and are vectors of numerous plant pathogens, the threat of new invasive mite species is as serious as any major economic disaster.
