Abstract Background and Aims: Environmental factors can interact with plant life history to determinate the reproductive strategies of adult plants and seedling recruitment. We expect that widely distributed tree species produce heavier seed and with greater variation in seed size than shrubs of restricted geographic distribution. We also predict that widely distributed tree species should be capable to germinate and develop under variable range of light conditions, while sun-adapted shrubs should germinate and develop better under high light intensity. We used as models two congeneric species of Fabaceae. Copaifera langsdorffii is a widely distributed arboreal species and C oblongifolia is a shrub with restricted distribution. Methods: Seeds were collected from two plant species in a Cerrado vegetation area, northern Minas Gerais, Brazil. The effects of light available on seed germination and seedling development was conducted in a germination chamber with controlled photoperiod, temperature and light intensity. Key results: The widely distributed tree (C. langsdorffii) had greater seed mass than the shrub (C. oblongifolia). Seeds of C. langsdorffii germinated faster under available high light, while the shrub C. oblongifolia seeds required less time to germinate under available low light and darkness. Under high light intensity, germination percentage of C. langsdorffii and C. oblongifolia seeds did not vary. However, seeds of the shrub showed a higher germination percentage under low light intensity and darkness. In general, seed mass showed a negative relationship with germination percentage, but this relationship varied in function of species and the availability of light. Copaifera langsdorffii seedlings had larger shoots and roots than C. oblongifolia. In contrast, the root:shoot ratio was higher in shrub than in tree species. Conclusions: Our results have important implications for understanding the patterns of distribution of two Copaifera species and explain the ability of C. oblongifolia to colonize disturbed areas.

Resumen Antecedentes y Objetivos: Los factores ambientales pueden interactuar con la historia de vida de las plantas determinando las estrategias reproductivas de individuos adultos y el reclutamiento de plántulas. Predecimos que las especies de árboles ampliamente distribuidas producen semillas más pesadas y con una mayor variación en el tamaño de las semillas que los arbustos de distribución geográfica restringida. Esperamos que las especies arbóreas ampliamente distribuidas deberían ser capaces de germinar y desarrollarse bajo un rango variable de condiciones de luz, mientras que los arbustos adaptados a condiciones de sol deberían germinar y desarrollarse mejor con una alta intensidad de luz. Usamos como modelo dos especies congenéricas de Fabaceae. Copaifera langsdorffii es una especie arbórea ampliamente distribuida y C. oblongifolia es un arbusto de distribución geográfica restringida. Métodos: Se colectaron semillas de estas especies de plantas en un área de vegetación de Cerrado, al norte del estado de Minas Gerais, Brasil. Los efectos de la disponibilidad de luz sobre la germinación de semillas y el desarrollo de plántulas se realizaron en una cámara de germinación con fotoperíodo controlado, temperatura e intensidad de luz. Resultados clave: El árbol de amplia distribución (C. langsdorffii) tuvo mayor masa de semillas que el arbusto (C. oblongifolia). Las semillas de C. langsdorffii germinaron más rápido bajo alta disponibilidad de luz, mientras que las semillas de C. oblongifolia requirieron menos tiempo para germinar bajo poca luz disponible y oscuridad. En alta intensidad de luz, las semillas de C. langsdorffii y de C. oblongifolia tuvieron similares porcentajes, mientras que las semillas de C. oblongifolia mostraron una mayor germinación en baja intensidad de luz y oscuridad. La masa de semillas mostró una relación negativa con el porcentaje de germinación, pero esta relación varió en función de las especies y de la disponibilidad de luz. Las plántulas de C. langsdorffii tuvieron mayor desarrollo de brotes y raíces que C. oblongifolia. En contraste, la relación raíz:brote fue mayor en arbustos que en árboles. Conclusiones: Nuestros resultados tienen implicaciones importantes para comprender los patrones de distribución de dos especies de Copaifera y poder explicar la capacidad de C. oblongifolia para colonizar áreas perturbadas.

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

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.

Herbivorous insects may attack eucalyptus causing economic losses. One of these pests is the moth Euselasia apisaon Dahman, a key pest in the basin of middle Rio Doce. Here we studied the survival of pupae of this moth in Eucalypts and in understorey plants and tested the hypotheses: i) live pupae are more abundant in plants of the understorey than in eucalyptus, ii) there is no difference between the abundance of pupae in different plants of the understorey. We sampled three areas cultivated with eucalyptus in Belo Oriente, MG, and samples were taken in five plots each area, getting five branches of each plant and of five eucalyptus trees that bordered the plot. The proportion of live and dead pupae and the mortality rate were estimated. The abundance of live pupae was higher in the understorey and the mortality rate of pupae was the same among different families of plants of the understorey. It is possible the larger available leaf area of understorey plants justify the greater abundance of live pupae in this habitat, however, avoidance of feeding habitat to finish the life cycle is also a possible explanation. Mortality rate in plants of the understorey points to an equal pressure of natural enemies on the pupae. These appointments help us to understand the dynamics of pests in eucalyptus plantations, providing important information to support actions against pests in natural environments.

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.

Este estudo avaliou os efeitos de remanescentes de Mata Atlântica no controle biológico natural de Euselasia apisaon (Dahman) pelo parasitóide Trichogramma maxacalii (Voegelé e Pointel) em plantios de Eucalyptus. O número de ovos de E. apisaon por folha foi maior no centro que nas bordas dos talhões (23,5 ± 7,61 versus 14,8 ± 3,14), mas o padrão inverso foi observado para as taxas de parasitismo (72,4% no centro e 80,5% na borda). Os resultados sugerem que a regulação natural de E. apisaon por T. maxacalii pode ser aumentada com a preservação de fragmentos de vegetação nativa no entorno de plantios de eucalipto.

This study evaluated the effects of Atlantic Rain Forest remnants on the natural biological control of Euselasia apisaon (Dahman) by the parasitoid Trichogramma maxacalii (Voegelé e Pointel) in Eucalyptus plantations. The number of E. apisaon eggs/leaf was higher in the center than in the edge of the plantations (23.5 ± 7.61 vs. 14.8 ± 3.14), but parasitism showed the reversed pattern (72.4% in the center and 80.5% in the edge). The results indicated that natural regulation exerted by T. maxacalii on populations of E. apisaon may be enhanced by the preservation of fragments of native vegetation surrounding Eucalyptus plantations.

Insetos galhadores desenvolveram várias estratégias para evitar ou reduzir o ataque por inimigos naturais, tais como maior espessura da parede no início de formação, e maior diâmetro e dureza da parede em estágios posteriores do desenvolvimento. Neste estudo, analisamos a eficiência de cada um desses parâmetros na redução da mortalidade das galhas de Atrusca caprone Weld (Hymenoptera: Cynipidae) em Quercus turbinella Greene (Fagaceae), durante os três meses de seu desenvolvimento (junho-agosto). O diâmetro e a dureza das galhas aumentaram do primeiro para o terceiro mês de estudo (ANOVA, diâmetro: F = 88.73, p < 0.0001; ANOVA, dureza: F = 26.13, p < 0.0001). Entretanto, a espessura das galhas apresentou um aumento de junho para julho, diminuindo de julho para agosto (ANOVA, F = 35.84, p < 0.0001). A análise de regressão linear múltipla mostrou que apenas a dureza das galhas influenciou a susceptibilidade das larvas ao ataque por parasitóides (r² = 0.52, F = 13.84, p < 0.01, n = 15). A sobrevivência das galhas foi elevada no primeiro mês, diminuindo com o tempo, provavelmente devido à menor dureza da parede. Estes resultados sugerem que o primeiro mês seja crítico para o estabelecimento das galhas, sendo que galhas não parasitadas neste estágio são menos suscetíveis a um ataque posterior.

Galling insects have developed many strategies to preclude or reduce the attack by natural enemies, such as an increased wall thickness early in the season, and switching to larger and tougher walls later in the maturation stage. In this study, we observed the efficiency of each one of these parameters in reducing mortality of the leaf galling wasp Atrusca caprone Weld (Hymenoptera: Cynipidae), on Quercus turbinella Greene (Fagaceae), during the three months of gall development (June-August). Gall diameter and wall toughness increased from the first to the third month of the study (ANOVA, Diameter: F = 88.73, p < 0.0001; ANOVA, Toughness: F = 26.13, p < 0.0001). However, gall wall thickness increased from June to July, decreasing in August (ANOVA, F = 35.84, p < 0.0001). Gall survivorship was only 2 % in June, increasing to 10 % in July and to 29.3 % in August. Multiple regression analyses showed that only gall wall toughness influenced gall susceptibility to parasitoid attack (r² = 0.52, F = 13.84, p < 0.01). Gall survivorship was very low in the first month due probably to low wall toughness, which led to a higher success of oviposition by parasitoids during this phase. These results suggest that the first month is critical to gall establishment, and the galls which are not parasitized at this stage are less likely to be attacked later.

A hipótese do vigor de plantas (HVP) prediz que plantas ou módulos de plantas mais vigorosos são preferencialmente selecionados por fêmeas de insetos galhadores como sítios de oviposição, pois aumentam a chance de sobrevivência da prole. A HVP foi testada para Neopelma baccharidis Buckhardt (Homoptera: Psyllidae) e Rhoasphondylia friburgensis Tavares (Diptera: Cecidomyiidae) que causam galhas em Baccharis dracunculifolia D.C. (Asteraceae), e para duas espécies diferentes de Cecidomyiidae (Diptera) que provocam galhas em Maytenus salicifolia Reiss. (Celastraceae) e Vernonia polyanthes Less (Asteraceae). A abundância de galhas aumentou com o aumento do comprimento do ramo nas quatro espécies, como previsto pela HVP. Entretanto, ao considerarmos a taxa de ataque por unidade de ramo (cm), que inclui nas análises o efeito da disponibilidade de recursos por unidade de comprimento, o padrão de resposta dos quatro galhadores desapareceu. R. friburgensis e o cecidomiídeo que induz galhas em M. salicifolia não responderam ao vigor do ramo (P > 0,05), enquanto as outras espécies responderam diferencialmente. A abundância de galhas de N. baccharidis correlacionou-se negativamente com o aumento do comprimento do ramo (y = 0,185 - 0,007x; r² = 0,21; F = 6,013, P < 0,05), enquanto o número de galhas provocadas pelo cecidomiídeo em V. polyanthes correlacionou-se positivamente com o vigor do ramo (y = 0,09 + 0,002x; r² = 0,34; F = 6,157; P < 0,05). Portanto, apenas o padrão de ataque do cecidomíideo galhador em V. polyanthes suportou a HVP.

The plant-vigor hypothesis (PVH) predicts that females of galling insects preferentially oviposit on the most vigorous plant or plant modules, where their offspring performance is highest. We tested the PVH on Neopelma baccharidis Buckhardt (Homoptera: Psyllidae) and Rhoasphondylia friburgensis Tavares (Diptera: Cecidomyiidae) which induce galls on Baccharis dracunculifolia D.C. (Asteraceae), and on two different Cecidomyiidae (Diptera) species that induce galls on Maytenus salicifolia Reiss. (Celastraceae) and Vernonia polyanthes Less (Asteraceae), respectively. The abundance of galls induced by the four galling species increased with increasing shoot length, as predicted by the PVH. However, when we considered the rate of attack per shoot unit length (cm), which includes in the analyses the effect of availability of resource per unit length, the response patterns of the four gallers disappeared. R. friburgensis and Cecidomyiidae species which cause galls on M. salicifolia did not respond to shoot vigor (P > 0.05) while the other species responded differentially. The abundance of N. baccharidis galls correlated negatively with shoot length (y = 0.185 - 0.007x, r² = 0.21, F = 6.013, P < 0.05) while the number of galls caused by Cecidomyiidae on V. polyanthes showed a positive relationship with shoot vigor (y = 0.09 + 0.002x, r² = 0.34, F = 6.157, P < 0.05). Hence, only the attack pattern of the cecidomyiid galler on V. polyanthes corroborated the PVH.