Performance of two monophagous leaf feeding beetles (Coleoptera: Chrysomelidae) on each other's host plant: Do intrinsic factors determine host plant specialization?

• Published in: Journal of evolutionary biology 1998-07, Vol.11 (4), p.403-419
• Main Author: Keese, M. C.
• Format: Article
• Language: English
• Subjects: Ambrosia artemisiifolia; Chrysomelidae; Coleoptera; Iva frutescens; Ophraella
• ISSN: 1010-061X
• DOI: 10.1007/s000360050096

There has been much recent debate on whether physiological tradeoffs in performance across hosts or ecological factors such as predation are the primary determinants of host plant specialization in plant-herbivore interactions. This paper examines the relative role of intrinsic behavioral and physiological factors in host specialization of two species of leaf-feeding beetles (Coleoptera: Chrysomelidae). Ophraella notulata and Ophraella slobodkini are sister taxa that feed exclusively on the asteraceous plants Iva frutescens and Ambrosia artemisiifolia, respectively. Ambrosia is the ancestral host plant for this pair of beetles. I performed full-sib breeding experiments in both the laboratory and the field to assess mean responses of each species to both its native host and the host of its congener, genetic variation within each species for traits associated with using each host, and tradeoffs in performance across hosts. I reared each beetle species on each host plant and measured larval consumption, survival, development time and growth. I measured only survival and growth in the field. Genetic correlations were calculated to assess tradeoffs in performance across hosts. In the laboratory experiment, larval survival of O. slobodkini on I. frutescens was lower and development time longer than on A. artemisiifolia. Survival of O. notulata on A. artemisiifolia was marginally lower than on I. frutescens while development time did not differ. There was little genetic variation among families in host use traits for either species. None of the estimates of genetic correlations were negative. The results of the field experiment support the results of the laboratory experiment. I conclude that O. notulata, the species with the derived host association, retains considerable ability to utilize the ancestral host plant, while O. slobodkini, the species with the ancestral host association, does not show a similar ability to utilize the derived host. Tradeoffs in performance across hosts were not documented for either species of Ophraella. That O. notulata performs so well on A. artemisiifolia suggests that intrinsic factors may not provide a sufficient explanation for the host specialization of this species on I. frutescens.