Coexistence and Competition in Two Species of Legume Aphids

Doctorate Dissertation: While certain differences in the general biologies of Therioaphis maculate and Macrosiphum pisi may partially explain the coexistence of these two species, this is far from the whole story. If an explanation is forthcoming, it must develop from those features of the species biologies that are expressed by the individual aphids as they inhabit a single host plant or a portion of a host. It was at this level that the present investigation was directed, specifically, 'are there isolating mechanisms inherent within each species that permit a division of the host to a point where competitive influences are minimized', and 'is there a direct interaction between the two species that favors one over the other?'