THE EFFECT OF PARASITISM BY APHIDIUS SMITHI (HYMENOPTERA: APHIDIIDAE) ON REPRODUCTION AND POPULATION GROWTH OF THE PEA APHID (HOMOPTERA: APHIDIDAE)

Abstract

AbstractParasitism by Aphidius smithi reduced the fecundity and population growth of pea aphid, Acyrthosiphon pisum. Aphids that were parasitized during the first or second instar period died as fourth instars without producing offspring. Parasitized third or fourth instars usually reached maturity and produced a variable number of progeny. Parasitized adult aphids stopped producing nymphs approximately 7 to 8 days following attack by A. smithi. Equations are given for the relationship between the mean total fecundity, the intrinsic rate of increase, and the doubling time of apterous and alate viviparous pea aphid and the aphid age at the beginning of parasitism.