Do host alternating aphids know which plant they are on?

Abstract

Abstract. To determine whether an aphid is ‘aware’ of which plant it is on, clones of a host alternating aphid, Cavariella aegopodii Scop., reared on its primary (Salix) or secondary (Daucus) host, were subjected to autumnal conditions. Old clones produced males and egg laying females when exposed to autumnal conditions on the primary host but autumnal migrants and males when on the secondary host. Unlike some other host alternating aphids, Cavariella did not have to spend a period on the secondary host or go through the spring migrant stage before producing sexuals. The adaptive significance of a host alternating aphid being ‘aware’ of which host plant it is on is discussed in the light of these results.