title: Host-Plant Specialization Mediates the Influence of Plant Abundance on Host Use by Flower Head-Feeding Insects.
abstract: Among-population variation in host use is a common phenomenon in herbivorous insects. The simplest and most trivial explanation for such variation in host use is the among-site variation in plant species composition. Another aspect that can influence spatial variation in host use is the relative abundance of each host-plant species compared to all available hosts. Here, we used endophagous insects that develop in flower heads of Asteraceae species as a study system to investigate how plant abundance influences the pattern of host-plant use by herbivorous insects with distinct levels of host-range specialization. Only herbivores recorded on three or more host species were included in this study. In particular, we tested two related hypotheses: 1) plant abundance has a positive effect on the host-plant preference of herbivorous insects, and 2) the relative importance of plant abundance to host-plant preference is greater for herbivorous species that use a wider range of host-plant species. We analyzed 11 herbivore species in 20 remnants of Cerrado in Southeastern Brazil. For 8 out of 11 herbivore species, plant abundance had a positive influence on host use. In contrast to our expectation, both the most specialized and the most generalist herbivores showed a stronger positive effect of plant species abundance in host use. Thus, we found evidence that although the abundance of plant species is a major factor determining the preferential use of host plants, its relative importance is mediated by the host-range specialization of herbivores.
authors.forename: Paola A F
authors.initials: PA
authors.lastname: Nobre
authors.forename: Leonardo L
authors.initials: LL
authors.lastname: Bergamini
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Lewinsohn
authors.forename: Leonardo R
authors.initials: LR
authors.lastname: Jorge
authors.forename: Mário
authors.initials: M
authors.lastname: Almeida-Neto
mesh_terms: D000818:Animals; D019659:Asteraceae / Q000502:physiology*; D044822:Biodiversity; D001938:Brazil; D020387:Food Chain; D060434:Herbivory; D056626:Inflorescence / Q000502:physiology; D007313:Insecta / Q000502:physiology*; D013045:Species Specificity