Book contents
- Frontmatter
- Contents
- List of illustrations
- Preface
- Foreword
- 1 Forestry in the tropics
- 2 An overview of tropical forest insects
- 3 Ecology of insects in the forest environment
- 4 Insect pests in natural forests
- 5 Insect pests in plantations: General aspects
- 6 Insect pests of stored timber
- 7 Population dynamics: What makes an insect a pest?
- 8 Some general issues in forest entomology
- 9 Management of tropical forest insect pests
- 10 Insect pests in plantations: Case studies
- References
- Index
4 - Insect pests in natural forests
Published online by Cambridge University Press: 14 August 2009
- Frontmatter
- Contents
- List of illustrations
- Preface
- Foreword
- 1 Forestry in the tropics
- 2 An overview of tropical forest insects
- 3 Ecology of insects in the forest environment
- 4 Insect pests in natural forests
- 5 Insect pests in plantations: General aspects
- 6 Insect pests of stored timber
- 7 Population dynamics: What makes an insect a pest?
- 8 Some general issues in forest entomology
- 9 Management of tropical forest insect pests
- 10 Insect pests in plantations: Case studies
- References
- Index
Summary
Introduction
It is generally believed that tropical forests, characterised by high species diversity, are free of pest outbreaks, although the trees may support small populations of phytophagous insects. In keeping with this view, mixed tropical forests are usually cited as examples that demonstrate the strong correlation between diversity and stability in relation to pest outbreak. The following statements highlight this conventional wisdom.
No biologist who has penetrated and explored a truly virgin forest in the tropics has ever reported the occurrence of insect epidemics or has seen evidence of extensive defoliation and borer damage. In tropical evergreen forests with their numerous species of trees and still more numerous hordes of insect species, the absence of epidemics is not surprising.
(Beeson, 1941, p. 633)Mixed stands are much safer from insect injury than are pure stands. In fact, we may safely say that the greater the diversification of tree species, the less frequent will be insect outbreaks. This is an illustration of the general principle that other things being equal, the degree of environmental stability is in direct proportion to the number of species living together in an environment.
(Graham and Knight, 1965, with reference to temperate forests, p. 213)It can be generally stated that extensive outbreaks of defoliating insects are uncommon in the high forests of Ghana. This is true because the forests have a high degree of species diversity and most insects have a narrow host range. …[…]
- Type
- Chapter
- Information
- Tropical Forest Insect PestsEcology, Impact, and Management, pp. 78 - 92Publisher: Cambridge University PressPrint publication year: 2007