Patterns of phenological variation and reproductive investment were studied in the dioecious shrub Baccharis dracunculifolia DC (Asteraceae), and possible consequences on survivorship were evaluated. The sex ratio was determined in a natural field population (n = 921) of B. dracunculifolia in Belo Horizonte, Brazil. Fifty-two males and 56 females were sampled at random from this population. During the reproductive season of 1999, inflorescence production, shoot growth and mortality, and xylem water potential were recorded for each individual. The population sex ratio was male-biased (1.27 : 1, P < 0.05), and was associated with a higher mortality of female shoots (38.4 vs. 23.1 %, P < 0.05), and individuals (17.8 vs. 11.5 %, P < 0.1), despite lower water stress in female plants. Flowering phenology also differed between the sexes, with males producing more inflorescences, and earlier, than females. Owing to fruit maturation, the number of inflorescences supported by females was higher than that supported by males later in the reproductive season. This occurred during the dry season, and drought stress may have been responsible for the greater female mortality. Thus, the male-biased sex ratio in this population of B. dracunculifolia is probably due to different reproductive functions of males and females. Intersexual differences in reproductive phenology had consequences for plant demography.

Summary1. The pattern of attack by the leaf‐galling insect Neopelma baccharidis (Homoptera: Psyllidae) was studied in three populations of the dioecious shrub Baccharis dracunculifolia (Asteraceae) in south‐eastern Brazil. The plant vigour hypothesis, which predicts higher rates of attack and increased herbivore performance on the longest plant shoots, was tested. This work also provides further information for the study of differential herbivory in dioecious plants.2. In total, 9200 shoots were collected randomly from 46 male and 47 female plants belonging to the three populations. Shoot length, number of leaves per shoot, rate of galling, and survival of psyllids did not differ between male and female plants. Another population on the Campus of the Federal University of Minas Gerais was used only to determine the pattern of shoot growth.3. The hypothesis of sex‐mediated herbivory was not corroborated in this study.4. The frequency of galling increased with increasing shoot length, as predicted by the plant vigour hypothesis. Nevertheless, the number of oviposition sites (leaf buds) increased with shoot length.5. The performance of the galling herbivore was not related to shoot length in the plant populations studied.6. In conclusion, Neopelma baccharidis did not select shoots based on length only.

We investigated the distribution patterns of leaf mining insects along an elevational gradient in cerrado vegetation of southeastern Brazil. We tested four hypotheses related to the distribution of mining insects: (1) the “altitudinal gradient hypothesis,” which predicts that mining insect species richness will decrease with altitude or elevation; (2) the “habitat‐mediated richness hypothesis,” which predicts that mining insect species richness will be higher in mesic habitats than in xeric habitats; (3) the “plant species richness hypothesis,” which predicts that mining insect species richness will be positively correlated with plant species richness; and (4) the “plant architecture hypothesis,” which predicts a positive correlation between mining insect species richness and plant structural complexity. A total of 33,000 herbs, 3520 shrubs, and 1760 trees were sampled at 44 sites across an elevational gradient of 700 m. Mining insect species richness and plant species richness showed a negative correlation with elevation in xeric habitats, while in mesic habitats mining insect species and plant species richness did not show any statistically significant relationship with elevation. The differential distribution of mining insect species between xeric and mesic habitats supported the habitat‐mediated richness hypothesis, which states that miners would be more speciose in mesic, more favorable habitats. Mining species richness also increased with increasing plant structural complexity. The results suggest that the mining habit may not represent a strong adaptive strategy in protecting mining insects against desiccation. RESUMEN Nós investigamos os padrões de distribuição de insetos minadores ao longo de um gradiente altiudinal no cerrado, no sudeste do Brasil. Testamos quatro hipóteses relacionadas a distribuição de insetos minadores: (1) a “hipótese do gradiente altitudinal” que prediz que a riqueza de espécies de minadores aumenta com o decréscimo da altitude; (2) a “hipótese da riqueza mediada pelo habitat” que prediz que a riqueza de espécies de minadores deve ser maior em habitats mesicos que em habitats xéricos; (3) a “hipótese da riqueza de espécies de plantas” que prediz que a riqueza de espécies de minas deve ser positivamente correlacionada com a riqueza de espécies de plantas; e (4) a “hipótese da arquitetura da planta” que prediz uma correlação positiva entre riqueza de espécies de minas e complexidade estrutural das plantas. Foram amostradas 33,000 ervas, 3520 arbustos, e 1760 árvores, em 44 sitios ao longo de um gradiente de 700 m: A riqueza de espécies de minadores e de plantas apresentou uma correlação negativa com a altitude em habitats xéricos. Entretanto, em habitats mésicos as espécies de minadores e a riqueza de espécies de plantas não apresentaram nenhuma relação estatisticamente significativa com a altitude. A distribuição diferencial de espécies de minadores entre habitats xéricos e mésicos corroborou a hipótese da riqueza mediada pelo habitat, segundo a qual a riqueza de minas deve...

The dynamics of occurrence of target organs in plant populations produces windows of opportunity that directly and indirectly affect the structure of herbivore communities. However, mechanisms that drive herbivore specialization between resource patches are still poorly known. In this study, we tested three hypotheses related to variation in host plant phenology and community structure (i.e., composition, richness, and abundance) of gall‐forming species: (a) plants with early leaf‐flushing in the season will have greater vegetative growth and high contents of secondary chemical compounds; (b) gall‐inducing insect community structure changes among temporary resource patches of the host; and (c) interspecific competition is a probable mechanism that drives gall‐inducing insect community structure on Copaifera langsdorffii. We monitored daily a total of 102 individuals of the super‐host C. langsdorffii from August 2012 to May 2013, to characterize the leaf flushing time of each host plant. The leaf flushing time had a positive relationship with the number of folioles per branch and a negative relationship with branch growth. We sampled a total of 4,906 galls belonging to 24 gall‐inducing insect species from 102 individuals of C. langsdorffii. In spite of some gall‐inducing species presented high abundance on early leaf‐flushing plants, direct and indirect effects of plant phenology on galling insect abundance was species dependent. At the community level, our study revealed that the quality and quantity of plant resources did not affect the richness and abundance of gall‐inducing insects associated with C. langsdorffii. However, the richness and composition of gall‐inducing species varied according to the variation in leaf flushing time of the host plant. The results of null model analysis showed that galls co‐occurrence on C. langsdorffii trees differ more than expected by chance and that interspecific competition can be one potential mechanism structuring this gall‐inducing insect community.

Effects of Landscape Structure and Eucalyptus Genotype on the Abundance and Biological Control ofGlycaspis brimblecombei Moore (Hemiptera: Psyllidae)ABSTRACT -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.