title: Insect responses to host plant provision beyond natural boundaries: latitudinal and altitudinal variation in a Chinese fig wasp community.
abstract: Many plants are grown outside their natural ranges. Plantings adjacent to native ranges provide an opportunity to monitor community assembly among associated insects and their parasitoids in novel environments, to determine whether gradients in species richness emerge and to examine their consequences for host plant reproductive success. We recorded the fig wasps (Chalcidoidea) associated with a single plant resource (ovules of Ficus microcarpa) along a 1200 km transect in southwest China that extended for 1000 km beyond the tree's natural northern range margin. The fig wasps included the tree's agaonid pollinator and other species that feed on the ovules or are their parasitoids. Phytophagous fig wasps (12 species) were more numerous than parasitoids (nine species). The proportion of figs occupied by fig wasps declined with increasing latitude, as did the proportion of utilized ovules in occupied figs. Species richness, diversity, and abundance of fig wasps also significantly changed along both latitudinal and altitudinal gradients. Parasitoids declined more steeply with latitude than phytophages. Seed production declined beyond the natural northern range margin, and at high elevation, because pollinator fig wasps became rare or absent. This suggests that pollinator climatic tolerances helped limit the tree's natural distribution, although competition with another species may have excluded pollinators at the highest altitude site. Isolation by distance may prevent colonization of northern sites by some fig wasps and act in combination with direct and host-mediated climatic effects to generate gradients in community composition, with parasitoids inherently more sensitive because of declines in the abundance of potential hosts.
authors.affiliation: Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University Sichuan, 621000, China ; School of Ecological and Environmental Sciences, Tiantong National Station of Forest Ecosystem, East China Normal University Dongchuan Road 500, Shanghai, 200241, China ; School of Biology, University of Leeds Leeds, LS2 9JT, UK.
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.affiliation: School of Biology, University of Leeds Leeds, LS2 9JT, UK ; Department of Zoology & Entomology, Rhodes University Grahamstown, 6140, South Africa.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Compton
authors.affiliation: School of Biology, University of Leeds Leeds, LS2 9JT, UK.
authors.forename: Rupert J
authors.initials: RJ
authors.lastname: Quinnell
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences Kunming, 666303, China.
authors.forename: Yan-Qiong
authors.initials: YQ
authors.lastname: Peng
authors.affiliation: School of Biology, University of Leeds Leeds, LS2 9JT, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Barwell
authors.affiliation: Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University Sichuan, 621000, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
keywords: Agaonidae; Ficus microcarpa; climate tolerance; gall; latitudinal gradient; parasitoid; trophic level.