Willow hybridization differentially affects preference and performance of herbivorous beetles

Abstract

We examined the preferences and performances of five beetle species (four chrysomelids and one scarab) on two species of willows (Salix sericea and S. eriocephala) and their interspecific hybrids. Beetle species differed markedly in their responses. In preference assays, two chrysomelid beetle species (Calligrapha multipunctata bigsbyana and Plagiodera versicolora) preferred hybrids, two chrysomelids (Chrysomela scripta and Ch. Knabi) preferred hybrids and S. sericea, and the scarab beetle (Popillia japonica) preferred S. eriocephala. Experiments with purified salicortin indicated that salicortin concentration may contribute to these preferences. The relative performance (growth rate, pupal/adult weight and survivorship) of these beetles on the three willow taxa did not correspond with their feeding preferences. Three species exhibited intermediate performance on hybrid willows (the two Chrysomela spp. and P. japonica); the Chrysomela spp. performed best on S. sericea, while P. japonica performed best on S. eriocephala. One species performed equally well on all three taxa (C. multipunctata bigsbyana). The performance of Pl. versicolora was not tested. Our results support the general pattern that willow taxa with phenolic glycosides are more acceptable to specialist willow herbivores while those taxa without phenolic glycosides are more acceptable to generalist herbivores. We also show that to predict the relative susceptibility of hybrid and parental plants to herbivores, consideration must be given to the inheritance of traits affecting both preference and performance.

Phenolic secondary compounds as determinants of the host plant preferences of the leaf beetle Agelastica alni

“…Analogously, salicin and the more complex salicylate, salicortin, are shown to equally inhibit the feeding of another leaf beetle, Phratora vulgatissima L. (Kelly & Curry 1991). Current results are consistent with earlier studies which have suggested that salicylates are potent plant defenses against attacking insects (Tahvanainen et al 1985;Lindroth et al 1988;Kelly & Curry 1991;Gross & Hilker 1994/1995Ruuhola et al 2001) and that salicylaterich willow species are consequently avoided by insects which are not willow specialists (Rowell-Rahier 1984;Orians et al 1997). On the other hand, the leaves of some willow species contain specific non-salicylic phenolic glucosides instead of salicylates (Julkunen-Tiitto 1986;1989).…”

“…This appears to be largely due to the fact that each insect species is adapted to a specific subset of a myriad of secondary compounds present in the plant kingdom. For many insect herbivores secondary metabolites of regularly used host plants are essential feeding and oviposition stimulants (Matsuda & Matsuo 1985;Rank 1992;Soetens & Pasteels 1994;Gross & Hilker 1994/1995Kolehmainen et al 1995;Orians et al 1997;Roininen et al 1999). In contrast, secondary constituents of non-host plants frequently act as deterrents and inhibitors for feeding and oviposition (Kraft & Denno 1982;Matsuda & Senbo 1986;Kelly & Curry 1991;Gross & Hilker 1994/1995Ikonen et al 2001).…”

Preferences of six leaf beetle species among qualitatively different leaf age classes of three Salicaceous host species

“…On the other hand, there are some Salicaceae-associated leaf beetle species, many Chrysomela species for example, which are adapted to use salicylate-type phenolic glucosides as precursors for their defensive larval secretion and which, consequently, tend to survive best on salicylate-rich hosts (Rowell-Rahier & Pasteels 1982;Pasteels et al 1983;Smiley et al 1985;Denno et al 1990). Following evolutionary logic, positive correlations of preference patterns of these well adapted insects with high leaf phenolic glucoside content (Smiley et al 1985;Tahvanainen et al 1985;Soetens & Pasteels 1994;Orians et al 1997) are expected. Accordingly, Chrysomela scripta F. has been found to prefer more phenolic glucosidecontaining young poplar leaves (Bingaman & Hart 1992, 1993.…”

“…Host utilization patterns of herbivorous insects often strongly depend on the distribution of secondary compounds in plants (Smiley et al 1985;Tahvanainen et al 1985;Kelly & Curry 1991;Soetens et al 1991;Soetens & Pasteels 1994;Hemming & Lindroth 1995;Van Dam et al 1995;Orians et al 1997). In many cases, herbivorous insects avoid high concentrations of plant secondary metabolites, but for some well adapted herbivore species secondary compounds of the preferred hosts act as positive stimulants (Kelly & Curry 1991;Gross & Hilker 1994Kolehmainen et al 1995;Ikonen et al 2001).…”

Contribution to the knowledge of development and harmfulness of imported willow leaf beetle (Plagiodera versicolora) (Coleoptera, Chrysomelidae)

“…and S. eriocephala Michx. and their hybrids it has been proved that species with phenolglycosides are more looked up by special willow herbivorous species whereas species without phenolglycosides are more suitable for general herbivores (ORIANS et al 1997). HALLGREN (2002) found the different content of phenolglycosides and tannins in S. caprea, S. repens L. and S. aurita L. and their hybrids.…”