1Boyce Thompson Institute for Plant Research, Cornell Univ., Tower Rd., Ithaca, NY 14853, USA.
2Department of Applied Zoologie/Animal Ecology, Freie Universitat Berlin, 12163 Berlin, Germany.
Possible effects of performance on feeding preferences of the polyphagous tansy leaf beetle Galeruca tanaceti (Coleoptera: Chrysomelidae) were investigated on two different food plants: an original host, tansy (Tanacetum vulgare L., Asteraceae), and a crop plant, Chinese cabbage (Brassica pekinensis Ruprecht, Brassicaceae). Performance of G. tanaceti feeding on cabbage was much better (higher larval body mass, shorter developmental time, lower mortality, higher fecundity) than performance on tansy. Chemical analyses of primary compounds of both plants revealed that cabbage leaves contained higher amounts of water and nutrients (nitrogen, glucose, fructose) than tansy leaves. Solvent soluble secondary compounds of tansy did not influence the performance. The preference of the host plant was positively correlated with the performance of G. tanaceti. Larvae and adults that were reared on either tansy or cabbage avoided tansy and preferred cabbage in dual choice experiments. Preference of cabbage was an innate feeding behaviour. However, the degree of avoidance of tansy was dependent on the feeding experience of G. tanaceti. While 30 % of individuals experienced with cabbage accepted tansy, only 7 % of larvae and no single adult experienced with tansy fed on this plant. Thus, the tansy-reared individuals showed an aversion learning against tansy. Up to now, aversion learning was unknown in Coleoptera.