8H
N. WALOFF
I . INTRODUCTION
Scotch broom, Sarothamnus rrcopariw (L.) Wimmer, is a common
plant in the British Isles. It supports a large fauna of phytophagous
insects, many of which are confined to it, together with their complex
of parasites and predators. Broom grows well on the sandy soil of the
Imperial College Field Station, Silwood Park and in the last 12 years
Professor 0. W. Richards, Dr J. P. Dempster and myself, a t times with
other members of staff at the Field Station, and a group of postgraduate
students have been interested in various aspects of the biology of insects
on this plant. The studies were not conducted simultaneously and most
of them have been limited to 3 years. Nevertheless, we have gained
some idea of the interactions between the different species and also of
the great diversity of factors that affect the magnitudes of populations
of the irdividual species. Although it is usually impossible to say which
factors ultimately rogulate the populations, it is frequently possible to
point out those t h a t check the population growths. -An assemblage of
insects confined to the same host plant is fairly closely held together
and interrelations between the various species, and the phytophagous
speciw and the host plant, are of considerable interest.
We have, by no means, studied all the members of the broom fauna.
At Silwood Park there are 9 Lepidoptera, 5 Diptera, 1 Hymenopteran,
7 Coleoptera, and 13 Hemiptera regularly feeding on broom. The
studies on Lepidoptera are in their early stages and those on most
Diptera have yet to be made. The present survey deals with the various
aspects of biology of 23 phytophagous species and their complex of 70
parasites and about 60 common predators. Since there is a scarcity of
“life-tables” for insects in the literature, any that have been attempted
are included. They are in the form of "budgets", rather than the usual
“life-tables”, because in a short-lived animal the age distribution of a
population is relatively unimportant (Richards, 1961). Similarly, the
methode by which the accumulated data were analysed are also given,
since they were evolved in response to the problems on hand and formed
an integral part of this work. This survey attempts to bring together a
diversity of data which are scattered as publications in different journals and in some unpublished theses. The unifying factor in this work
lies in the environment provided by the relatively ehort-lived host
plant. Sections 11-VII are accounte of the etudies, and Sections VIII-X
are of a, more general nature.
N. WALOFF
I . INTRODUCTION
Scotch broom, Sarothamnus rrcopariw (L.) Wimmer, is a common
plant in the British Isles. It supports a large fauna of phytophagous
insects, many of which are confined to it, together with their complex
of parasites and predators. Broom grows well on the sandy soil of the
Imperial College Field Station, Silwood Park and in the last 12 years
Professor 0. W. Richards, Dr J. P. Dempster and myself, a t times with
other members of staff at the Field Station, and a group of postgraduate
students have been interested in various aspects of the biology of insects
on this plant. The studies were not conducted simultaneously and most
of them have been limited to 3 years. Nevertheless, we have gained
some idea of the interactions between the different species and also of
the great diversity of factors that affect the magnitudes of populations
of the irdividual species. Although it is usually impossible to say which
factors ultimately rogulate the populations, it is frequently possible to
point out those t h a t check the population growths. -An assemblage of
insects confined to the same host plant is fairly closely held together
and interrelations between the various species, and the phytophagous
speciw and the host plant, are of considerable interest.
We have, by no means, studied all the members of the broom fauna.
At Silwood Park there are 9 Lepidoptera, 5 Diptera, 1 Hymenopteran,
7 Coleoptera, and 13 Hemiptera regularly feeding on broom. The
studies on Lepidoptera are in their early stages and those on most
Diptera have yet to be made. The present survey deals with the various
aspects of biology of 23 phytophagous species and their complex of 70
parasites and about 60 common predators. Since there is a scarcity of
“life-tables” for insects in the literature, any that have been attempted
are included. They are in the form of "budgets", rather than the usual
“life-tables”, because in a short-lived animal the age distribution of a
population is relatively unimportant (Richards, 1961). Similarly, the
methode by which the accumulated data were analysed are also given,
since they were evolved in response to the problems on hand and formed
an integral part of this work. This survey attempts to bring together a
diversity of data which are scattered as publications in different journals and in some unpublished theses. The unifying factor in this work
lies in the environment provided by the relatively ehort-lived host
plant. Sections 11-VII are accounte of the etudies, and Sections VIII-X
are of a, more general nature.