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. Thus, when compared to the most recent comprehensive review of insect herbivory (Kozlov et al.), our data set has increased the base of available data for the tropical plants more than 460% (from 33 to 152 species) and the Brazilian sampling was increased 7,300% (from 2 to 146 species). Data on precise levels of herbivory are presented for more than 57,000 leaves worldwide. There are no copyright restrictions. Please cite this paper when using the current data in publications; the authors request to be informed how the data is used in the publications.

Does leaf flushing in the dry season affect leaf traits and herbivory in a tropical dry forest?

In tropical dry forests (TDFs), stem-succulent deciduous species produce leaves during the dry season which coincides with the period of lower herbivore abundance. In this study, we evaluated the effects of abiotic factors (precipitation and day length) on the vegetative phenology of three stem-succulent deciduous species (Cochlospermum vitifolium, Commiphora leptophloeos, and Manihot anomala) during 2 years. In addition, we compared leaf damage by herbivores and leaf defensive traits (specific leaf area, thickness, and content of phenolic compounds) on leaf cohorts produced before and during the rainy season by these stem-succulent deciduous species. We also evaluated herbivory and defensive traits on leaves produced during the rainy season by 14 non-succulent deciduous species. There was a positive effect of precipitation and day length on the amount of green leaves exhibited by the three stem-succulent species. The leaf cohort produced during the dry season by stem-succulent species showed lower leaf damage and content of phenolic compounds than the cohort produced during the rainy season by the same species and by non-succulent deciduous species. Leaf damage was only affected (positively) by the content of phenolic compounds, suggesting the production of induced defenses during leaf expansion. In general, herbivory levels were low in this study (0.57-6.37%) when compared with other TDFs, suggesting that a scape from herbivores due to anticipated leaf production is a weak selective force affecting plant fitness. These variations in leaf traits are mostly related to contrasting water conservation strategies among phenological groups. Further studies should evaluate other defensive and nutritional traits, as well as their variations along the leaf lifespan, to unravel herbivory patterns in TDFs.

Understanding patterns of land-cover change in the Brazilian Cerrado from 2000 to 2015.

Clearing tropical vegetation impacts biodiversity, the provision of ecosystem services, and thus ultimately human welfare. We quantified changes in land cover from 2000 to 2015 across the Cerrado biome of northern Minas Gerais state, Brazil. We assessed the potential biophysical and socio-economic drivers of the loss of Cerrado, natural regeneration and net cover change at the municipality level. Further, we evaluated correlations between these land change variables and indicators of human welfare. We detected extensive land-cover changes in the study area, with the conversion of 23 446 km(2) and the natural regeneration of 13 926 km(2), resulting in a net loss of 9520 km(2) The annual net loss (-1.2% per year) of the cover of Cerrado is higher than that reported for the whole biome in similar periods. We argue that environmental and economic variables interact to underpin rates of conversion of Cerrado, most severely affecting more humid Cerrado lowlands. While rates of Cerrado regeneration are important for conservation strategies of the remaining biome, their integrity must be investigated given the likelihood of encroachment. Given the high frequency of land abandonment in tropical regions, secondary vegetation is fundamental to maintain biodiversity and ecosystem services. Finally, the impacts of Cerrado conversion on human welfare likely vary from local to regional scales, making it difficult to elaborate land-use policies based solely on socio-economic indicators.This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'.

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

BACKGROUND: 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. METHODOLOGY/PRINCIPAL FINDINGS: 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. CONCLUSIONS/SIGNIFICANCE: 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.

Ontogenetic and temporal variations in herbivory and defense of Handroanthus spongiosus (Bignoniaceae) in a Brazilian tropical dry forest.

We compared the richness and abundance of free-feeding herbivore insects (sap-sucking and leaf-chewing), leaf herbivory damage, leaf toughness and total phenolic content between two ontogenetic stages (juvenile and reproductive) of Handroanthus spongiosus (Rizzini) S. O. Grose (Bignoniaceae) throughout the rainy season in a Brazilian seasonally dry tropical forest. Twenty marked individuals of H. spongiosus were sampled per ontogenetic stage in each period of the rainy season (beginning, middle, and end). Herbivore richness and abundance did not differ between ontogenetic stages, but higher percentage of leaf damage, higher concentration of phenolic compounds, and lower leaf toughness were observed for juvenile individuals. The greatest morphospecies abundance was found at the beginning of the rainy season, but folivory increment was higher at the end, despite the fact that leaf toughness and total phenolic content increased in the same period. No significant relationships between leaf damage and both total phenolic content and leaf toughness were observed. These results suggest that insect richness and abundance do not track changes in foliage quality throughout plant ontogeny, but their decrease along rainy season confirms what was predicted for tropical dry forests. The general trends described in the current study corroborate those described in the literature about herbivores and plant ontogeny. However, the lack of relationship between herbivore damage and the two plant attributes considered here indicates that the analyses of multiple defensive traits (the defense syndrome) must be more enlightening to determine the mechanisms driving temporal and spatial patterns of herbivore attack.

An experimental test of rainfall as a control agent of Glycaspis brimblecombei Moore (Hemiptera, Psyllidae) on seedlings of Eucalyptus camaldulensis Dehn (Myrtaceae)

An experimental test of rainfall as a control agent of Glycaspis brimblecombei Moore (Hemiptera, Psyllidae) on seedlings of Eucalyptus camaldulensis Dehn (Myrtaceae). Glycaspis brimblecombei is one the greatest threats to eucalyptus plantations in Brazil. The effects of rainfall to reduce the abundance of lerp of Glycaspis brimblecombei on experimentally infested seedlings of Eucalyptus camaldulensis were assessed. The number of lerps on the adaxial and abaxial surfaces of every leaf of 60 seedlings was recorded, before and after submission to the following treatments: "artificial rain", "leaf wetting" and control. A drastic reduction in lerp abundance per plant was observed after the treatments "leaf wetting" and artificial rain (F = 53.630; p < 0.001), whereas lerp abundance remained roughly constant in the control treatment along the experiment (F = 1.450; p = 0.232). At the end of the experiment, lerp abundance was significantly lower in both the "artificial rain" and "leaf wetting" than in the control treatment. Two days of rainfall simulation were sufficient to decrease more than 50% of the lerp population, with almost 100% of effectiveness after 5 days of experiment. Our results indicate that lerp solubilization and mechanical removal by water are potential tools to the population regulation of G. brimblecombei on E. camaldulensis seedlings.

Teste experimental da chuva como agente de controle de Glycaspis brimblecombei Moore (Hemiptera, Psyllidae) em mudas de Eucalyptus camaldulensis Dehn (Myrtaceae). Glycaspis brimblecombei é uma das maiores ameaças das plantações de eucalipto do Brasil. Foram avaliados os efeitos da água na redução da abundância de conchas desse inseto em mudas de Eucalyptus camaldulensis infestadas experimentalmente. Foi quantificado o número de conchas nas superfícies adaxial e abaxial de todas as folhas de 60 mudas, antes e após a aplicação dos seguintes tratamentos: "chuva artificial", "molhamento das folhas" e controle. Foi observada uma drástica redução na abundância de conchas nos tratamentos "chuva artificial" e "molhamento das folhas" (F = 53,630; p < 0,001), o que não ocorreu para o tratamento controle ao longo do experimento (F = 1,450; p = 0,232). Ao final do experimento, a abundância de conchas foi significativamente menor no tratamento "chuva artificial" e "molhamento das folhas" do que no tratamento controle. Dessa forma, dois dias de chuva mostraram ser eficientes para diminuir mais que 50% da população de conchas, com quase 100% de eficiência após 5 dias de experimento. Nossos resultados indicam que a solubilização das conchas e a remoção mecânica pela água são potenciais ferramentas para regulação populacional de G. brimblecombei em mudas de E. camaldulensis.

[Effects of landscape structure and Eucalyptus genotype on the abundance and biological control of Glycaspis brimblecombei Moore (Hemiptera: Psyllidae)]. / Efeito da estrutura da paisagem e do genótipo de Eucalyptus na abundância e controle biológico de Glycaspis brimblecombei Moore (Hemiptera: Psyllidae).

Glycaspis brimblecombei Moore is an Australian native pest of Eucalyptus detected in Brazil in 2003. Since then, it has spread fast and colonized plantations in several states of the country. This study aimed to investigate the influence of cerrado remnants on the abundance and biological control of G. brimblecombei. We placed yellow sticky card traps to capture insects in four plantations of hybrid clones of Eucalyptus urophylla x Eucalyptus grandis ('Urograndis') and four plantations of E. urophylla x Eucalyptus camaldulensis ('Urocam'). Traps were placed in three areas of these plantations: center, border with cerrado and border without cerrado. We also collected leaves from the same clones to estimate psyllid egg and lerp abundance. The abundance of G. brimblecombei was lower in the plantation-cerrado border, and the inverse pattern was observed for microhymenopterans. The leaf abaxial surface showed a higher abundance of eggs and nymphs, probably as a consequence of a lower parasitism rate and mechanical removal by wind and rain. Egg number was higher on Urograndis than in Urocam clones, but the number of psyllid lerps was higher in the latter. Thus, the establishment of first instars is probably a critical event to psyllid infestation, and these differences may be caused by morphological, anatomical and biochemical leaf features of distinct clones. Our results suggest that the maintenance of native vegetation around plantations is a promising management practice to promote the natural biological control of G.brimblecombei, a strategy that would also enhance the preservation of cerrado remnants.

Efeito da estrutura da paisagem e do genótipo de Eucalyptus na abundância e controle biológico de Glycaspis brimblecombei Moore (Hemiptera: Psyllidae) / Effects of landscape structure and Eucalyptus genotype on the abundance and biological control of Glycaspis brimblecombei Moore (Hemiptera: Psyllidae)

Glycaspis brimblecombei Moore is an Australian native pest of Eucalyptus detected in Brazil in 2003. Since then, it has spread fast and colonized plantations in several states of the country. This study aimed to investigate the influence of cerrado remnants on the abundance and biological control of G. brimblecombei. We placed yellow sticky card traps to capture insects in four plantations of hybrid clones of Eucalyptus urophylla x Eucalyptus grandis ("Urograndis") and four plantations of E. urophylla x Eucalyptus camaldulensis ("Urocam"). Traps were placed in three areas of these plantations: center, border with cerrado and border without cerrado. We also collected leaves from the same clones to estimate psyllid egg and lerp abundance. The abundance of G. brimblecombei was lower in the plantation-cerrado border, and the inverse pattern was observed for microhymenopterans. The leaf abaxial surface showed a higher abundance of eggs and nymphs, probably as a consequence of a lower parasitism rate and mechanical removal by wind and rain. Egg number was higher on Urograndis than in Urocam clones, but the number of psyllid lerps was higher in the latter. Thus, the establishment of first instars is probably a critical event to psyllid infestation, and these differences may be caused by morphological, anatomical and biochemical leaf features of distinct clones. Our results suggest that the maintenance of native vegetation around plantations is a promising management practice to promote the natural biological control of G.brimblecombei, a strategy that would also enhance the preservation of cerrado remnants.