Some Effects of Infestation on Plants: A Physiological Viewpoint

INTRODUCTION As a non-entomologist I welcome the opportunity to discuss some physiological aspects of infestation in plants. Traditional university teaching has, in the past, tended to separate the disciplines of zoology and botany, and has not encouraged studies of interdependence of animals and plants. The creation of schools of biology has, to some extent, removed this barrier to communication, but there is still insufficient cross fertilisation of knowledge, resulting in a lack of multidisciplinary research on plant/insect interrelationships. There is an increasing interest in the mutual regulation of growth and development of insects and the plants upon which they feed. This is desirable and needs to be encouraged. Bardner and Fletcher (1974) have pointed out a general lack of information on the detailed relationship between insect infestations and their effects on growth and yield of plants. They believe that an understanding of specific insect-crop relationships will help in attaining the following important objectives: 1 selecting indices of infestation or injury that are most closely correlated with yield, for use in pest assessment studies; 2 predicting the likely results of changes in factors affecting the relationship between infestation and yield; 3 determining the most suitable methods and tactics of pest control. After briefly indicating some of the obvious effects of infestation on plant growth, I want to discuss in more detail some specific physiological responses of hosts to pest attack. Rather than attempt a comprehensive review of the literature, I will dwell on some areas that I consider are of particular interest to the plant scientist, and where a basic understanding could throw some light on the nature of the relationship between pests and plants.