How much leaf area do insects eat? A data set of insect herbivory sampled globally with a standardized protocol

Herbivory is ubiquitous. Despite being a potential driver of plant distribution and performance, herbivory remains largely undocumented. Some early attempts have been made to review, globally, how much leaf area is removed through insect feeding. Kozlov et al., in one of the most comprehensive reviews regarding global patterns of herbivory, have compiled published studies regarding foliar removal and sampled data on global herbivory levels using a standardized protocol. However, in the review by Kozlov et al., only 15 sampling sites, comprising 33 plant species, were evaluated in tropical areas around the globe. In Brazil, which ranks first in terms of plant biodiversity, with a total of 46,097 species, almost half (43%) being endemic, a single data point was sampled, covering only two plant species. In an attempt to increase knowledge regarding herbivory in tropical plant species and to provide the raw data needed to test general hypotheses related to plant–herbivore interactions across large spatial scales, we proposed a joint, collaborative network to evaluate tropical herbivory. This network allowed us to update and expand the data on insect herbivory in tropical and temperate plant species. Our data set, collected with a standardized protocol, covers 45 sampling sites from nine countries and includes leaf herbivory measurements of 57,239 leaves from 209 species of vascular plants belonging to 65 families from tropical and temperate regions. They expand previous data sets by including a total of 32 sampling sites from tropical areas around the globe, comprising 152 species, 146 of them being sampled in Brazil. For temperate areas, it includes 13 sampling sites, comprising 59 species

Plant phenology and absence of sex-biased gall attack on three species of Baccharis.

Dioecy represents a source of variation in plant quality to herbivores due to sexual differences in intensity and timing of resource allocation to growth, defense and reproduction. Male plants have higher growth rates and should be more susceptible to herbivores than females, due to a lower investment in defense and reproduction.We compared resource investment to growth and reproduction and its consequences to herbivore attack on three Baccharis species along one year (B. dracunculifolia, B. ramosissima, and B. concinna). Phenological patterns presented by the three species of Baccharis were quite different over time, but the number of fourth-level shoots and plant growth rate did not differ between sexes in any studied species. Intersexual difference in reproductive investment was only observed for B. concinna, with female individuals supporting higher inflorescence density than male individuals throughout the year. Gall abundance on the three Baccharis species was not influenced by plant sex. However, all plant traits evaluated here positively influenced the gall abundance on B. concinna, whereas only the number of fourth-level shoots positively influenced gall abundance on B. ramosissima and B. dracunculifolia.The absence of differential reproductive allocation may have contributed to similar growth and shoot production between the sexes, with bottom-up effects resulting in gender similarities in gall abundance patterns. The number of fourth-level shoots, an indicator of meristem availability to herbivores, was the most important driver of the abundance of the galling insects regardless of host plant gender or species. Albeit the absence of intersexual variation in insect gall abundance is uncommon in the literature, the detailed study of the exceptions may bring more light to understand the mechanisms and processes behind such trend

Average number of galls (mean ± s.e.) on male and female individuals of (a) <i>Baccharis dracunculifolia</i>, (b) <i>B. concinna</i> and (c) <i>B. ramosissima</i>.

<p>Galls were counted every three weeks during one year.</p

ANOVA of the minimal linear mixed-effects (LME) models to evaluate the effects of plant sex on the number of shoots, relative growth rate and inflorescence density in three species of <i>Baccharis</i>.

<p>ANOVA of the minimal linear mixed-effects (LME) models to evaluate the effects of plant sex on the number of shoots, relative growth rate and inflorescence density in three species of <i>Baccharis</i>.</p

Average number of fourth-level shoots (mean ± s.e.) in male and female individuals of (a) <i>Baccharis dracunculifolia</i>, (b) <i>B. concinna</i> and (c) <i>B. ramosissima</i>.

<p>Fourth-level shoots were counted every three weeks during one year.</p

ANOVA of the minimal linear mixed-effects (LME) models to evaluate the effects of date, sex and plant traits on gall abundance in three species of <i>Baccharis</i>. Non-significant terms were deleted from complete models through stepwise removal.

<p>ANOVA of the minimal linear mixed-effects (LME) models to evaluate the effects of date, sex and plant traits on gall abundance in three species of <i>Baccharis</i>. Non-significant terms were deleted from complete models through stepwise removal.</p

Average density of inflorescences (mean ± s.e.) in male and female individuals of (a) <i>Baccharis dracunculifolia</i>, (b) <i>B. concinna</i> and (c) <i>B. ramosissima</i>.

<p>Inflorescences were counted every three weeks during one year.</p