''Cecidophyopsis ribis'' is an eriophyid

mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...

which is best known for being a plant parasite, a pest of ''

Ribes ''Ribes'' () is a genus of about 200 known species of flowering plants, most of them native to the temperate regions of the Northern Hemisphere. The species may be known as various kinds of currants, such as redcurrants, blackcurrants, and White ...

'' species, the genus that includes gooseberries and blackcurrants. It is commonly known as the blackcurrant gall mite or big bud mite. It feeds on the plants' buds, forming galls, and transmits a virus which causes blackcurrant reversion disease. The mite is a serious pest of blackcurrant crops in Europe, but rarely on other continents.

Biology

Buds affected by ''Cecidophyopsis ribis'' become swollen and globular and fail to develop normally. They are first noticeable in the autumn when they are unpointed and twice as large as normal buds. Inside the bud, between the closely folded leaves, are thousands of small, spherical

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...

s which later hatch into sausage-shaped mites with short legs near their anterior end. The mites suck sap from the buds and while they are doing so, can transmit the

virus A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are ...

that causes blackcurrant reversion disease. The mites are long. When mature they move out of the buds onto the twigs where they make their way to uninfested buds or may feed on the foliage later in the season causing distortion of the leaves. Crop yields are reduced as a result of the damage they do. The mites are so tiny that they can easily be blown or splashed onto other bushes or carried inadvertently by flying insects. They breed during the summer and autumn, laying their eggs inside new buds. They can also infest the buds of gooseberries, whitecurrants or redcurrants, but in these the affected buds die and "big bud" symptoms do not develop. These alternative host fruit bushes are not susceptible to blackcurrant reversion disease.

Blackcurrant reversion disease

The virus causing blackcurrant reversion is transmitted by ''Cecidophyopsis ribis''. The characteristic leaf symptoms are a smaller number of leaf lobes and a decrease in the number of teeth on the serrated edge of the leaves. The flowers also show symptoms, with the buds being less hairy than normal and, in a severe form of the disease present in Russia and Scandinavia, the

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s appearing to be doubled in number to ten. The vigor of the bush is reduced, and fruit yields diminish. Although spread of the mite can be prevented to some extent, badly affected bushes should be destroyed and replaced with virus-free stock. Until 2019 the virus was found everywhere blackcurrants grew except

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. However, in 2019 it was detected for the first time in

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

, United States. Although these mites are the only known vector, the mites themselves have not been found. It is unknown whether something else is vectoring the pathogen or if this evidences another transmission route is working in this area.

Distribution

''Cecidophyopsis ribis'' is found mainly in

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

, but has also reached

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. It is not found in

and

quarantine A quarantine is a restriction on the movement of people, animals, and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have bee ...

restrictions apply to the import of susceptible plants.

References

{{Authority control Eriophyidae Animals described in 1869 Arachnids of Europe Galls Taxa named by John O. Westwood