POPULATION DYNAMICS AND RECOGNITION OF BIOTYPES IN THE PEA APHID (HOMOPTERA: APHIDIDAE)

Abstract

AbstractFive biotypes of the pea aphid, Acyrthosiphon pisum (Harris), from four hosts were recognized by their differential survival and rates of population increase on broom, white clover, alfalfa and broad beans, by body size, colour, and rates of natural increase (rm) on broad beans. A simple method is described which can verify that the differences between rm values measured by life table analysis are not due to chance.Four of the biotypes were sympatric. It is suggested that biotypes in the pea aphid result from annual adaptations to various species of leguminous host plants and therefore other characteristics of the biotypes may vary from year to year. For this reason, only fundatrices and their immediate offspring which have not been subjected to this selection should be used as test organisms in assaying plants for resistance to pea aphids. The use of a biotype of a single year for screening plant varieties may lead to the production of varieties which are highly acceptable to other biotypes.