The Use of an Invasive Species Habitat by a Small Folivorous Primate: Implications for Lemur Conservation in Madagascar.

The lemurs of Madagascar are among the most threatened mammalian taxa in the world, with habitat loss due to shifting cultivation and timber harvest heavily contributing to their precarious state. Deforestation often leads to fragmentation, resulting in mixed-habitat matrices throughout a landscape where disturbed areas are prone to invasion by exotic plants. Our study site, the Mandena littoral forest (southeast Madagascar), is a matrix of littoral forest, littoral swamp, and Melaleuca swamp habitats. Here, Melaleuca quinquenervia has invaded the wetland ecosystem, creating a mono-dominant habitat that currently provides the only potential habitat corridor between forest fragments. We sought to understand the role of this invasive Melaleuca swamp on the behavioral ecology of a threatened, small-bodied folivore, the southern bamboo lemur (Hapalemur meridionalis). We collected botanical and behavioral data on four groups of H. meridionalis between January and December 2013. Our results confirm Melaleuca swamp as an important part of their home range: while lemurs seasonally limited activities to certain habitats, all groups were capable of utilizing this invasive habitat for feeding and resting. Furthermore, the fact that Hapalemur use an invasive plant species as a dispersal corridor increases our knowledge of their ecological flexibility, and may be useful in the conservation management of remaining threatened populations.

Suppression of native Melaleuca ericifolia by the invasive Phragmites australis through allelopathic root exudates.

PREMISE OF THE STUDY: Invasive plants are a great threat to the conservation of natural ecosystems and biodiversity. Allelopathy as a mechanism for invasion of plants such as Phragmites australis, one of the most aggressive invaders, has the potential to suppress neighboring plant species. Allelopathic interference, through root exudates of P. australis on native Melaleuca ericifolia, was investigated to find out the underlying invasion mechanisms. METHODS: Germination and growth effects of P. australis on M. ericifolia were studied in the greenhouse using potting mix both with and without activated carbon, and a combination of single and repeated cuttings of P. australis as the management tool. KEY RESULTS: P. AUSTRALIS had significant negative effects on germination and growth of M. ericifolia by inhibiting germination percentage, maximum root length and plant height, biomass, stem diameter, and number of growth points with little effect on leaf physiology. Activated carbon (AC) in turn moderately counteracted these effects. The cutting of P. australis shoots significantly reduced the suppressive effects on M. ericifolia compared to the addition of AC to soil. Furthermore, significant changes in soil such as pH, electrical conductivity, osmotic potential, phenolics, and dehydrogenase activity were identified among cutting treatments with little variation between AC treatments. CONCLUSION: The results demonstrated that allelopathy through root exudates of P. australis had relatively low contribution in suppressing M. ericifolia in comparison to other competitive effects. Management tools combining repeated cutting of P. australis shoots with AC treatments may assist partly in the restoration of native ecosystems invaded by P. australis.

Establishment, population increase, spread, and ecological host range of Lophodiplosis trifida (Diptera: Cecidomyiidae), a biological control agent of the invasive tree Melaleuca quinquenervia (Myrtales: Myrtaceae).

The Australian tree Melaleuca quinquenervia (Cavanilles) Blake is an invasive weed in wetland systems of Florida. A biological control program targeting M. quinquenervia has resulted in the release of the gall forming midge Lophodiplosis trifida Gagné (Diptera: Cecidomyiidae). Populations of the introduced herbivore readily established at all 24 release sites across the weed's range in Florida, and there was no evidence that founding colony size (100, 2,000, or 6,000 adults) influenced herbivore establishment or local population growth rates. Landscape level spread of L. trifida from release sites averaged nearly 6 km/yr, ranging as high as 14.4 km/yr. Prerelease host range testing predicted that L. trifida oviposits indiscriminately on test plant species but does not complete development on any of the test species, including congeners present in Florida. To test the predictability of these host range tests, L. trifida was released in a common garden consisting of 18 test plant species that were interplanted with M. quinquenervia. Plant species postulated to be at risk experienced no gall development by L. trifida while intermingled M. quinquenervia trees supported 704.8 (± 158.5) galls per plant. Historically, many introduced Cecidomyiidae have limited effect on plant performance of target weeds because of recruitment of native parasitoids that disrupt biological control efficacy. In contrast to this trend, there has been no evidence to date that parasitoids are exploiting L. trifida in Florida.

Sprouting and genetic structure vary with flood disturbance in the tropical riverine paperbark tree, Melaleuca leucadendra (Myrtaceae).

PREMISE OF THE STUDY: Sprouting in woody plants promotes persistence in the face of disturbance, ultimately influencing population structure. Different disturbance regimes drive variable population responses, but there have been few direct tests of the relative differences in population structure to specific drivers. We measured population structure as genotypic diversity (clonality) as a function of hydrological regime for a riverine tree, Melaleuca leucadendra, a major structural component in flood landscapes in the Australian dry tropics. METHODS: We estimated clonality, genotypic richness, and population allelic diversity. The relationship among disturbance, genetic estimates of clonality, and population distinctiveness was compared with flood regime, characterized by return frequencies and hydrological stress at individual river reaches. KEY RESULTS: Two contrasting patterns of genotypic structure were detected and corresponded to order-of-magnitude differences in flood regime between sites. At mainstem locations characterized by greatest flood intensity, sprouting generated clonal structure to 17 m (30% ramets clonal). By contrast, clonality was atypical at lower-disturbance tributaries (0% clonal). Population allelic distributions showed extensive genetic exchange among mainstem locations, but strong genetic differentiation between mainstem and tributaries. CONCLUSIONS: Population structure and distinctiveness in riverine Melaleuca are determined by differences in sprouting and recruitment responses that depend on localized hydrological regime. Sprouting contributes to population persistence via localized clonal growth. Resprouting following disturbance in M. leucadendra may help explain its numerical dominance in tropical river systems. This study, although preliminary, suggests that flood ecosystems may represent excellent experimental systems to develop a better understanding of whole-organism responses to environmental drivers.

Substratos, concentrações de ácido indolbutírico e tipos de miniestacas no enraizamento de melaleuca (Melaleuca alternifolia Cheel) / Substrates, indolebutyric acid levels and types of minicuttings on the rooting of tea tree (Melaleuca alternifolia Cheel)

Melaleuca alternifolia tem como produto principal o óleo essencial extraído das folhas devido às propriedades antifúngicas e antibacterianas. Pouco se tem relatado sobre a propagação desta espécie, sendo a miniestaquia uma alternativa para a propagação vegetativa de clones superiores visando à implantação de campo de produção. Este trabalho teve como objetivo avaliar o efeito de diferentes substratos, concentrações de AIB, e tipo de miniestaca, no enraizamento de Melaleuca alternifolia. No primeiro experimento foram testados os substratos, areia de granulometria média, Plantmax HT®, Golden-Mix® e vermiculita. No segundo experimento foram avaliadas diferentes concentrações de AIB (0, 500, 1000 e 2000 mg L-1), em dois tipos de miniestacas (apical e mediana). As miniestacas foram confeccionadas com 5 cm de comprimento, mantidas em casa de vegetação com nebulização intermitente, e, após 45 dias do plantio, foram avaliadas as porcentagens de miniestacas enraizadas, com calos e não responsivas, o número de raízes formadas por miniestaca e o comprimento das três maiores raízes (cm). O substrato Golden-Mix® e as miniestacas coletadas da porção apical do ramo submetidas ao tratamento com 500 mg L-1 de AIB apresentaram maior porcentagem de enraizamento e melhor qualidade do sistema radicial.

Melaleuca alternifolia has as major product the essential oil extracted from its leaves due to its antifungal and antibacterial properties. There are scarce reports about the propagation of this species, and minicutting is an alternative for vegetative propagation of superior clones in order to establish a production field. This study aimed to evaluate the effect of different substrates, IBA levels and types of minicuttings on the rooting of Melaleuca alternifolia. In the first experiment, the following substrates were tested: medium sand, Plantmax HT®, Golden-Mix® and vermiculite. In the second experiment, different IBA levels (0, 500, 1000 and 2000 mg L-1) were tested for two minicutting types (apical and medium). Minicuttings were prepared with 5 cm length and were kept in a greenhouse with intermittent mist; then, at 45 days after planting, we evaluated: the percentages of rooted minicuttings, with callus and non-responsive, the number of roots per minicutting and the length of the three longest roots. The substrate Golden-Mix® and the minicuttings collected from the apical part of the branch and treated with 500 mg L-1 IBA presented the largest rooting percentage and the best root system quality.

Selection on herbivory resistance and growth rate in an invasive plant.

The evolution of increased competitive ability (EICA) hypothesis proposes that invasive species evolve decreased defense and increased competitive ability following natural enemy release. Previous tests of EICA examined the result of evolution by comparing individuals from home and introduced ranges, but no previous study of this hypothesis has examined the process of evolution by analyzing patterns of selection. On the basis of EICA, there should be selection for competitive ability without herbivores and selection for defense with herbivores. Selection on competitive ability should be stronger for genotypes accustomed to herbivores (home range genotypes), and selection on defense should be stronger for genotypes unaccustomed to herbivores (introduced range genotypes). Using a field experiment, we tested these hypotheses for the invasive plant Melaleuca quinquenervia. There was a negative genetic correlation between resistance and growth, indicating a trade-off. However, selection for stem elongation (an indicator of competitive ability) was always positive, and selection on resistance was always negative and did not depend on genotype source or the presence of herbivores. The patterns of selection found in this study contrast with predictions from EICA and accurately predict the lack of evolutionary change in growth and resistance following the introduction of this species from Australia to Florida.

Photosynthesis and photoassimilate transport during root hypoxia in Melaleuca cajuputi, a flood-tolerant species, and in Eucalyptus camaldulensis, a moderately flood-tolerant species.

We compared the photosynthetic and photoassimilate transport responses of Melaleuca cajuputi Powell seedlings to root hypoxia with those of Eucalyptus camaldulensis Dehnh. Control and hypoxia treated roots were maintained in a nutrient solution through which air or nitrogen was bubbled. Under root hypoxic conditions, seedlings of M. cajuputi, a flood-tolerant species, maintained height growth, whereas seedlings of E. camaldulensis, a moderately flood-tolerant species, showed markedly decreased height growth compared with control seedlings. Root hypoxia caused decreases in whole-plant biomass, photosynthetic rate and stomatal conductance in E. camaldulensis, but not in M. cajuputi. Photoassimilate transport to roots decreased significantly in E. camaldulensis seedlings 4 days after treatment and starch accumulated in mature leaves. Photoassimilate supply to hypoxic roots of E. camaldulensis seedlings was, thus, limited by reduced photoassimilate transport rather than by reduced photosynthesis. In contrast, M. cajuputi seedlings showed sustained photoassimilate transport to hypoxic roots and persistent photosynthesis, which together provided a substantial photoassimilate supply to the roots. Sucrose accumulated in hypoxic E. camaldulensis roots, but not in hypoxic M. cajuputi roots. A stable, low sucrose concentration in hypoxic roots would let M. cajuputi seedlings prolong photoassimilate transport to the roots. Photoassimilate partitioning among the water-soluble carbohydrates, starch and structural carbohydrates within the roots was unaffected by root hypoxia in E. camaldulensis, but in M. cajuputi, partitioning was shifted somewhat from structural carbohydrates to water-soluble carbohydrates. This suggests that M. cajuputi seedlings are able to increase photoassimilate utilization in metabolism and sustain energy production under root hypoxic conditions.

Nutritional characteristics of the leaves of native plants growing in adverse soils of humid tropical lowlands.

Acid sulfate, peat, sandy podzolic, and saline soils are widely distributed in the lowlands of Thailand and Malaysia. The nutrient concentrations in the leaves of plants grown in these type of soils were studied with the aim of developing a nutritional strategy for adapting to such problem soils. In sago and oil palms that were well-adapted to peat soil, the N, P, and K concentrations were the same in the mature leaves, while the Ca, Mg, Na, and Fe concentrations were higher in the mature leaves of the oil palm than of the sago palm. Melastoma malabathricum and Melaleuca cajuputi plants that were well-adapted to low pH soils, peat. and acid sulfate soils were also studied. It was observed that a high amount of Al accumulated in the M. marabathricum leaves, while Al did not accumulate in M. cajuputi leaves. M. cajuputi plants accumulated large amounts of Na in their leaves or stems regardless of the exchangeable Na concentration in the soil, while M. malabathricum that was growing in saline-affected soils excluded Na. Positive relationships between macronutrients were recognized between P and N, between K and N, and between P and K. Al showed antagonistic relationships with P, K, Ca, Mg, Fe, Zn, Cu, and Na. Na also showed antagonistic relationships with P, K, Zn, Mn, Cu, and Al. Fe showed weak antagonistic relationships with Zn, Mn, Cu, and Al.

Preferred age for assessment of qualitative and quantitative characteristics of the essential oil of tea tree (Melaleuca alternifolia) seedlings prior to plantation establishment.

An analytical method for determining the quality and hence the chemical variety status of tea tree transplants is described. The key to the procedure was found to be the leaf age of the test material. Investigation at very early development stages was seen to give misleading results due to the sequential onset of different monoterpenoid biogenetic pathways. For example, in the first few leaves, the high concentration of terpinolene in the terpinen-4-ol variety suggests that the terpinolene variety is under investigation. However, 1,8-cineole percent concentrations in plantation tree leaf were approximately 1.6 times lower than those measured for seedlings prior to transplant. Consequently, the use of a plantation cineole indicator is proposed for estimating plantation cineole from seedling leaf analyses. Although recent investigations enable the chemotype status to be predicted with some certainty, it is now proposed that analysis of leaf set 10 at the age of 6 weeks (seedling age approximately 17 weeks) provides an unambiguous analysis and correlates seedling quality with mature plantation quality. In addition, the oil yield of mature tea tree leaf was found, by steam distillation, to be approximately 5 times higher than that of seedling leaf.

A review of aquatic weed biology and management research conducted by the United States Department of Agriculture-Agricultural Research Service.

Ever-increasing demand for water to irrigate crops, support aquaculture, provide domestic water needs and to protect natural aquatic and riparian habitats has necessitated research to reduce impacts from a parallel increase in invasive aquatic weeds. This paper reviews the past 4-5 years of research by USDA-ARS covering such areas as weed biology, ecology, physiology and management strategies, including herbicides, biological control and potential for use of natural products. Research approaches range from field-level studies to highly specific molecular and biochemical work, spanning several disciplines and encompassing the most problematic weeds in these systems. This research has led to new insights into plant competition, host-specificity, and the fate of aquatic herbicides, their modes of action and effects on the environment. Another hallmark of USDA-ARS research has been its many collaborations with other federal, state action and regulatory agencies and private industry to develop new solutions to aquatic weed problems that affect our public natural resources and commercial enterprises.

Dietary influences on terpenoids sequestered by the biological control agent Oxyops vitiosa: effect of plant volatiles from different Melaleuca quinquenervia chemotypes and laboratory host species.

The weevil Oxyops vitiosa is an Australian species imported to Florida, USA, for the biological control of the invasive species Melaleuca quinquenervia. The larvae of this species feed on the leaves of their host and produce a shiny orange secretion that covers their integument. Previous results indicated that a major component of this secretion, viridiflorol, is sequestered from the host plant and repels a generalist predator, the red imported fire ant, Solenopsis invicta. When the larvae fed on a different chemotype of M. quinquenervia, which lacked viridiflorol but was rich in a different sesquiterpene, (E)-nerolidol, similar protection occurred. Solvent washes of these larvae indicated that (E)-nerolidol was sequestered from M. quinquenervia leaves and repelled S. invicta workers when applied to dog food baits at physiological concentrations (17.5, 35.0, and 52.5 microg/mg). Additionally, beta-caryophyllene also repelled S. invicta workers when applied to dog food baits at concentrations that approximated those in the O. vitiosa larval secretions (3.5 and 35 microg/mg). When the O. vitiosa larvae were fed leaves from laboratory hosts (nonfield hosts), similar repellent activity was found. This activity was traced to several of the same compounds (e.g., 1,8-cineole, viridiflorol) found to be active in their field host M. quinquenervia. These weevil larvae are opportunistic, sequestering the primary terpenoids in their host leaves that confer antipredator activity.