Plant feeding mites form an integral and important part of the
natural ecosystem. Some species, especially eriophyoid mites, can be utilised
for the biological control of weeds. Many plant feeding mites are of economic
importance as pests of crop plants. In South Africa about 65 species cause
damage to agricultural crops and ornamental plants.
All eriophyoid mites are plant feeding. They are extremely tiny, the
majority are less than 300 micron long, and essentially invisible to the unaided
eye. They have elongated, worm-like bodies, with only two pairs of legs.
Eriophyoid mites are commonly known as gall mites, bud mites, rust mites,
erineum mites, witches' broom mites, blister mites and so on, referring to the
symptoms caused by a particular species. The feeding of almost half of
eriophyoid species known, though, does not cause visible damage to their plant
The eriophyoid mites belong to three families: Phytoptidae, Eriophyidae and
Diptilomiopidae. About 3 400 species are known, but these probably represent
only as little as 5% or less of extant eriophyoid species. Most woody and many
herbaceous flowering plants, and gymnosperms and ferns most likely host these
minute mites. Most eriophyoid species are highly host specific, restricted to
one or single closely related plant species.
In South Africa 25 eriophyid species are regarded as pests.
Many research activities currently in progress at the ARC-PPRI Arachnology
Unit's Acari Section concern this fascinating and economically important group
of microscopic organisms.
List of eriophyid mites (Acari: Eriophyoidea: Eriophyidae) regarded as pests in
In South Africa 25 eriophyid species are regarded as pests.
The following research projects are in progress:
A systematic appraisal of the Eriophyoidea, including cladistic analyses.
The description of a new Phyllocoptruta sp., in collaboration with R. Ochoa
of USDA-ARS, Beltsville, USA.
The description of a new species collected on Rhus lancea in South Africa.
Systematic study on eriophyoid mites (mostly Trisetacus spp.) collected on
conifers in France, in collaboration with ARC-PPRI Weeds research. (Read more
about mites as control agents of weeds)
Systematic study on eriophyoid mites (mostly Aceria spp.) collected on
Polygalaceae in South Africa and Australia in collaboration with R. Adair,
ARC-PPRI Weeds research, Stellenbosch. (Read more about mites as control agents
All tetranychoid mites are obligate plant feeders, and many species are
well-known agricultural pests. The Tetranychoidea comprises five families:
This family is a large group of plant feeding mites (about 1 200 species
known worldwide), and can probably be regarded as the most important family in
the Acari regarding members that are pests of agricultural crops and other
plants. In southern Africa about 26 species are regarded as pests.
The spider mites have round to oval-shaped bodies, and are as large or
smaller than a pin head (about 0.3 to 0.8 mm long). Their colour vary: green,
red, brown, yellow, orange, black or combinations of any of these, depending on
the species and the life stage.
Most tetranychid species have a wide host range, other than the generally
more host specific Eriophyoidea. Some species, especially Tetranychus spp., can produce extensive webbing
which impedes effective control of these pests. Chemical control of spider mites
is also compounded by development of resistance to acaricides.
The false spider mites are very small (females about 0.2 - 0.4 mm long)
(smaller than the spider mites) and somewhat flattened, and are difficult to see
with the naked eye. They are usually reddish or brown red. They move relatively
slowly and lie very flat against the plant surfaces. Tenuipalpid mites appear to be best adapted to subtropical or tropical
regions. Members of the genera Brevipalpus, Tenuipalpus and Dolichotetranychus
are of particular importance as plant pests. In southern Africa, four species
are regarded as pests of economic importance:
Brevipalpus californicus (Banks) (citrus flat mite) Brevipalpus obovatus
Donnadieu (ornamental flat mite) Brevipalpus phoenicis (Geijskes) (reddish
black flat mite) Dolichotetranychus floridanus (Banks) (pineapple flat mite)
The family Tuckerellidae consists of about 20 described species worldwide. All
belong to the single genus, Tuckerella. Tuckerella ornata (Tucker) was
originally described from citrus in South Africa.
List of Tetranychoidea: Tetranychidae mites (Acari) regarded as pests in
In southern Africa about 26 Tetranychoidea species are regarded as pests.
Identification and information services
We identify Tetranychoidea on a continuous basis, and receive specimens for
identification from various sources, nationally and internationally. The
identification service plays an important role in phytosanitary matters.
The late Dr. Meyer was an internationally acknowledged specialist in the taxonomy of phytophagous mites, especially the Tetranychoidea. Her expertise, however, extends to various other groups, and also encompasses mite bio-ecology, and she was especially an authority on plant feeding mites of agricultural importance.
She has made an enormous contribution to Acarology in Africa in describing more than 700 new species and 25 new genera, mostly mites of agricultural importance. She has published more than a 100 scientific papers, including seven Entomological Memoirs (total of 1032 pages), and a handbook on mites on vegetables and berries (90 pages).
One of her major contributions was in the Tetranychidae (spider mites) and the Tenuipalpidae (false spider mites) on which she published 11 scientific papers, and four Entomological Memoirs. The four memoirs alone total 807 pages.
She is also regarded as one of the specialists on the Eriophyoidea, and described 181 new species in 24 scientific papers.
She also described and published new species of 16 other mite families, and four super families.
She initiated the National Collection of Mites (now the National Collection of Arachnida), an identification service and systematic mite surveys in South Africa.
The first check list of Acari of the Ethiopian Region has been compiled by her, and she organised surveys of mites of economically importance on various crops in several countries in southern Africa, and provided the first list of the 60 most important mite pest species in this region.
She made an important contribution towards the control of mites on different crops and published papers on mites on citrus, cotton, deciduous fruit, grapes, berries, vegetables, field crops, pastures, tobacco, and ornamental plants.
She further developed collecting techniques for Acari, especially in applied Acarology, and made a great input in the correct use of spraying equipment in the chemical control of mites. In the information service on the control of mites she provided, she made a special effort to promote the biological control of mites with predatory mites, spiders and insects.
She made an important contribution in assisting the then Plant and Quality Control of the Department of Agriculture to prevent the accidental introduction of foreign mite species on plant material and fruit to South Africa.
Dr. Meyer was actively involved in the registration of new acaricides (Act 1936/1947). She assisted chemical firms with the planning and layout of their spray trials on different crops and assisted the Registrar in the evaluation of the data.
She finished her high school training by matriculating at the Helpmekaar Hoër Meisieskool in Johannesburg, South Africa. She continued her education by obtaining a B.Sc. (Botany and Zoology) degree cum laude at the University of Potchefstroom for CHE, and later an M.Sc. degree in Zoology at the same university. She proceeded, and already started making history, by being the first woman at this university to obtain her doctoral degree in zoology, and she did it cum laude in 1959. Simultaneously she also finished a Higher Diploma in Librarianship (again cum laude) in 1958.
Her M.Sc. thesis is titled: "Some parasitoid mites associated with South African beetles", and the D.Sc. thesis: "A survey of the prostigmatic mites (Acarina: Trombidiformes: Prostigmata) associated with plants in South Africa, with description of a new genus and 43 new species."
Apart from her formal training in South Africa, Dr. Meyer also undertook postgraduate studies in Canada with a bursary from the Canadian Research Council.
She was the first acarologist in the Department of Agriculture of South Africa, appointed in 1959 to the then Division of Entomology. Her entire career as an acarologist was undertaken at ARC-PPRI, from 1959 to 1994 when she retired. Since then she has been a Research Associate at this institute.
There were many highlights during her career, apart from her enormous contributions to acarology, to name but a few:
In 1964 she became the head of the subdivision Economic Zoology (Arachnology, Nematology and Mammology)
She was promoted to Assistant-Director in 1970 in 1989 she became one of the first researchers in PPRI to become a Specialist Scientist and was further promoted to Senior Specialist Scientist in 1989
Dr. Meyer's international recognition is illustrated by the collaborative projects she has undertaken with other scientists and the contribution she has made to other countries in assisting them by identifying their mites.
She was a co-worker with researchers from Costa Rica, Israel, Netherlands and Portugal
She identified mites for: Australia, Belgium, Brazil, Canada, Cape Verde Islands, England, Germany, Hawaii, India, Iran, Malagasy Republic, Netherlands, Reunion, Thailand and the USA
She was invited by the governments of Angola, Malawi, Mozambique, Swaziland and Zimbabwe to advise them on economical important mites on different crops
On invitation she published articles on the mite fauna of Cameroon, Cape Verde Islands, Costa Rica, Israel, Zimbabwe and Yemen.
Dr. Meyer went out of her way to help in the training of young scientists in South Africa. She acted as co-supervisor of four M.Sc. and seven D.Sc. students, and she served as external examiner of six M.Sc. and 8 D.Sc. theses.
Dr. Meyer refereed numerous articles for the following journals: Acarologia, International Journal of Acarology, African Plant Protection, Australian Journal of Scientific Research, African Entomology, Biologia, Gallo-hellenica, Israel Journal of Entomology, Koedoe, Phytophylactica and others.
She has served on the editorial board of the International Journal of Acarology since 1980, and was appointed as one of the main editors of this journal in 1997.
Some phytophagous mites, in particular members of the Eriophyoidea, are
increasingly considered as potential control agents of weeds. Some species are
already successfully utilized for the control of weeds, e.g. Aceria chondrillae
(Canestrini) against skeleton weed, Chondrilla juncea L. (Asteraceae), in
Australia and the USA, Aceria acroptiloni Shevtchenko & Kovalev against
Russian knapweed, Acroptilon repens (L.) DC (Asteraceae), in Uzbekistan, and
Aculus hyperici (Liro) against Hypericum perforatum L. (Clusiaceae).
Several eriophyoid species are being considered, are being studied as
potential control agents or have been released for the control of weeds in South
Africa, e.g. on Acacia saligna, Convolvulus arvensis, Lantana camara and
invasive Pinus spp. Others are indigenous to South Africa, and have potential
for weed control in Australia and other countries, e.g. on Acacia nilotica,
Polygala myrtifolia and Chrysanthemoides monilifera. Some of the research is
conducted at the Weeds Research Division, and the systematic research necessary
for some of the projects is undertaken by Biosystematics: Arachnology - mite
section under the umbrella research of the ARC-PPRI Mite Expert Centre.
Other phytophagous species, apart from the Eriophyoidea, that are being used
for weed control include Tetranychus lintearius Dufour (Tetranychidae) for the
control of Ulex europaeus L. (gorse) in New Zealand, and Orthogalumna
terebrantis Wallwork (Galumnidae) for the control of Eichhornia crassipes
(Martius) Solms-Laubach (water hyacinth). The latter species also established on
water hyacinth in South Africa, and appears to affect the weed adversely.
Read more about the potential of eriophyid mites for the biological control
of weeds in South Africa as summarized from an article by C. Craemer, S. Neser
& M.K.P. Smith Meyer (1996).
Contact:S. Neser (firstname.lastname@example.org) (mites
in weed control projects)C. Craemer (email@example.com)
(biosystematic aspects of mites)