The Effect of Host-Plant Species on Adult Weight and the Reproductive Potential of Aphids

Abstract

(1) In excess of 200 samples of adult aphids were collected from known host-plants in the field and up to twelve individuals of the alate and apterous morphs were weighed and their embryo content assessed. (2) Seventeen of the aphid species recorded were feeding on more than one host-plant and these data are used to study the effect of host-plant differences on both adult weight and an index of reproductive potential. (3) For alate morphs, seven of the eight comparisons indicate that adult weight is significantly affected by host-plant differences and 63% of the comparisons also indicate that embryo content is affected. (4) For apterous morphs, seventeen of the twenty-two comparisons show that hostplant influences adult weight and in 75% of the cases embryo content is likewise influenced. (5) The adult weight and embryo content of Aphisfabae and A. pomi decline during the summer, then increase. The influence of host-plants on these variables is discussed. (6) Adult weight and embryo content of the host-alternating A.fabae and Macrosiphum rosae are compared on their primary woody host-plant and the secondary herbaceous plant. Neither host provides a clear reproductive advantage over the other.