Low host specificity and abundance of frugivorous lepidoptera in the lowland rain forests of Papua New Guinea.

We studied a community of frugivorous Lepidoptera in the lowland rainforest of Papua New Guinea. Rearing revealed 122 species represented by 1,720 individuals from 326 woody plant species. Only fruits from 52% (171) of the plant species sampled were attacked. On average, Lepidoptera were reared from 1 in 89 fruits and a kilogram of fruit was attacked by 1.01 individuals. Host specificity of Lepidoptera was notably low: 69% (33) of species attacked plants from >1 family, 8% (4) fed on single family, 6% (3) on single genus and 17% (8) were monophagous. The average kilogram of fruits was infested by 0.81 individual from generalist species (defined here as feeding on >1 plant genus) and 0.07 individual from specialist species (feeding on a single host or congeneric hosts). Lepidoptera preferred smaller fruits with both smaller mesocarp and seeds. Large-seeded fruits with thin mesocarp tended to host specialist species whereas those with thick, fleshy mesocarp were often infested with both specialist and generalist species. The very low incidence of seed damage suggests that pre-dispersal seed predation by Lepidoptera does not play a major role in regulating plant populations via density-dependent mortality processes outlined by the Janzen-Connell hypothesis

Overlap of Lepidoptera species in frugivorous (this study) and leaf-chewer (different study, [68]) guilds.

<p>Overlap of Lepidoptera species in frugivorous (this study) and leaf-chewer (different study, [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0171843#pone.0171843.ref068" target="_blank">68</a>]) guilds.</p

Mean volume for whole fruit, mesocarp and seeds (a) and fleshiness (b) in plant species attacked and not attacked by Lepidoptera.

<p>The differences between attacked and non-attacked species are significant (whole fruit: U _106,151 = 5624, Z = 3.064, P = 0.002; mesocarp: U _106,151 = 5828, Z = 2.69, P = 0.007; seeds: U _106,151 = 5346, Z = 3.574, P < 0.0010), (b) Fleshiness (i.e. proportion of mesocarp in whole fruit) did not have significant effect on infestation (U _106,151 = 6839, Z = 0.83, P = 0.401).</p

The number of plant species attacked (black bar) and not attacked (white bar) by frugivorous Lepidoptera in samples categorized by (a) fruit weight and (b) the number of fruits.

<p>The number of plant species attacked (black bar) and not attacked (white bar) by frugivorous Lepidoptera in samples categorized by (a) fruit weight and (b) the number of fruits.</p

Relationship between seed and mesocarp volume for 268 plant species attacked and not attacked by Lepidoptera.

<p>Relationship between seed and mesocarp volume for 268 plant species attacked and not attacked by Lepidoptera.</p

Density of all frugivorous Lepidoptera, and both specialist and generalists, per fruit.

<p>Host species are ranked from highest to lowest density for 326 plant species with samples of >1 kg and >50 fruits. Note that all plants to the right of each curve exhibited zero density for the herbivore category in question that cannot be shown on the log scale d y axis.</p

Data from: The insect-focused classification of fruit syndromes in tropical rainforests: an inter-continental comparison

We propose a new classification of rainforest plants into eight fruit syndromes, based on fruit morphology and other traits relevant to fruit-feeding insects. This classification is compared with other systems based on plant morphology or traits relevant to vertebrate fruit dispersers. Our syndromes are based on fruits sampled from 1,192 plant species at three Forest Global Earth Observatory plots: Barro Colorado Island (Panama), Khao Chong (Thailand) and Wanang (Papua New Guinea). The three plots differed widely in fruit syndrome composition. Plant species with fleshy, indehiscent fruits containing multiple seeds were important at all three sites. However, in Panama a high proportion of species had dry fruits, while in New Guinea and Thailand, species with fleshy drupes and thin mesocarps were dominant. Species with dry, winged seeds that do not develop as capsules were important in Thailand, reflecting the local importance of Dipterocarpaceae. These differences can also determine differences among frugivorous insect communities. Fruit syndromes and colours were phylogenetically flexible traits at the scale studied, as only three of the eight seed syndromes, and one of the 10 colours, showed significant phylogenetic clustering at either genus or family levels. Plant phylogeny was, however, the most important factor explaining differences in overall fruit syndrome composition among individual plant families or genera across the three study sites