Fróðskaparrit - 01.01.2009, Side 118

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PLANT GALLS AND GALL MIDGES OF THE FAROE ISLANDS IN THE ATLANTIC OCEAN
flowers of Galium anisophyllum; and the fungi
Cronartium ribicola galling leaves of Ribes nigrum,
Melampsora caprearum on leaves of Salix phylicifolia
and Puccinia violae on leaves of Viola riviniana. Three
non-galling gall midges were associated with gall-
causing organisms, viz. Mycodiplosis melampsorae and
Clinodiplosis cilicrus, both phytosaprophagous species
associated with decaying plant matter, and Feltiella
acarisuga, a zoophagous species preying on tetra-
nychid mites. Oligotrophus juniperinus, Contarinia
floriperda and Puccinia violae are native to the Faroe
Islands with regard to the origin of their host plants;
and the remaining species are alien and were intro-
duced to the Faroe Islands by man. From the biogeo-
graphical point of view Oligotrophus juniperinus,
Contarinia floriperda, Aceria pseudoplatani and Aculus
anthobius are European species, Mycodiplosis melamp-
sorae and Clinodiplosis cilicrus are Euro-Siberian species
and Feltiella acarisuga is a cosmopolitan species. The
finding of C. floriperda in the Faroe Islands is the most
northern occurrence in Europe. The low species
number of gall-causing organisms in the Faroe Islands
is the result of geographical isolation and natural con-
ditions of these islands with relatively poor vegetation
and lack of trees and shrubs, which may be potential
host plants of gall-causing organisms.
Introduction
A gall (in Latin „cecidium") is defined as any
deviation in the normal pattern of plant
growth produced by a specific reaction to
the presence and activity of a foreign organ-
ism (animal or plant) (Bloch, 1965). An in-
terdisciplinary scientific discipline at the bor-
der between botany and zoology, directed
to the study of plant galls at all levels, is
named cecidology. Galls caused by animals
are called zoocecidia and animals causing
galls are cecidozoa, galls caused by plants are
phytocecidia and such plants are called ce-
cidophyta. The ability of organisms to in-
duce galls on plants has evolved independ-
ently many times during the evolution of in-
sects as well as of other groups (Roskam,
1992).
At the beginningof the 20th century one
thousand and five hundred gall-causing ani-
mals were known in Europe, associated with
about four thousands host plants (Houard,
1908-1909). Cecidology quickly developed
and in the second half of the 20th century
about three thousand gall-causing and as-
sociated organisms were known to occur in
Central and Northern Europe (Buhr,1964-
1965). They belong to various groups of or-
ganisms: about one third to bacteria and
fungi, two thirds to animals. Three groups of
animals are the species richest causers of
galls on various plants, viz. the gall midges
(Cecidomyiidae, Diptera) with about 600
species, eriophyid mites (Eriophyoidea, Aca-
rina) with about 350 species and aphids
(Aphidoidea, Hemiptera) with about 370
species. Since that time many new species of
gall-causingorganisms have been discovered
and described and the number of these or-
ganisms is at present much higher.
Knowledge of galls has a long history.
The famous Italian physician and researcher
Marcello Malpighi (1628-1694), the founder
of microscope anatomy, is considered to be
also the founder of cecidology. In 1679 he
published the comprehensive work „Anato-
mes Plantarum" in which he included the
chapter called „De Gallis" (in English: About
galls). This chapter is the first scientific ap-
proach to the study of galls on plants and,
therefore, Malpighi is recognized as the fa-
ther of cecidology. Redfern et al. (2008)
translated this fundamental work on galls
from Latin to English. The cooperation of
these three authors makes it possible to be