Mechanical limitations on feeding by meadow spittlebugs Philaenus spumarius (Homoptera: Cercopidae) on wild and cultivated host plants

摘要: . 1. Field observations on the distribution of Philaenus spumarius (L.) pearly everlasting (Anaphalis margaritacea) and alfalfa (Medicago sativa) showed that range feeding sites exploited increased with instar. Development trichomes, depth xylem elements, tissue hardness were measured as possible factors determining suitability food plants. 2. Spittlebugs caged outside their normal experienced difficulty feeding. Experimental removal trichomes prevented younger instars from stem. The elements not significant barriers to near stem apex. 3. By caging fourth fifth instar nymphs at increasing distances below terminal bud A.margaritacea stems, we ability declined distance apex, was more restricted in compared instars. A similar decline demonstrated experiments M.sativa. 4. On A.margaritacea, this restriction associated apex presence regions hard tissues. M.sativa a combination reduction availability vessels penetrable region Although tissues impeding stylet penetration differed two hosts, critical factor both species increase amount lignification those bud.