Studies on the aphid, Cavariella aegopodii Scop: On secondary hosts other than carrot

Of the eleven cultivated species of Umbelliferae heavily attacked in the field by Cavariella aegopodii Scop., chervil (Anthriscus cerefolium) attracted so many alates that it was killed before a population of alienicolae developed. Carrot was next in order of alate preference and coriander (Coriandrum sativum) and caraway (Carum carvi) were last. Despite its lack of attraction, caraway proved more lastingly suitable as a host and eventually supported the largest population of alienicolae. Of the wild umbellifers tested, wild carrot, Daucus carota ssp. carota, was the species most preferred by the incoming alates and hemlock (Conium maculatum) the least. On hemlock, also, there was little colonization. Although a sequence of wild umbellifers supported C. aegopodii through most of the year, few were suitable winter hosts; the apterae hibernated largely on carrot crops. In spring, cow parsley (Anthriscus sylvestris) was one of the hosts first colonized by immigrant C. aegopodii and carried winged alienicolae before the end of June. The main development of winged alienicolae on Anthriscus and other wild Umbelliferae, however, was in July. The possible role of the wild umbelliferous hosts of C. aegopodii in the spread of motley dwarf virus to carrots is discussed.