Search

Since 1955 snails of theEuglandina roseaspecies complex andPlatydemus manokwariflatworms were widely introduced in attempted biological control of giant African snails (Lissachatina fulica) but have been implicated in the mass extinction of Pacific island snails. We review the histories of the 60 introductions and their impacts onL. fulicaand native snails. Since 1993 there have been unofficial releases ofEuglandinawithin island groups. Only three officialP. manokwarireleases took place, but new populations are being recorded at an increasing rate, probably because of accidental introduction. Claims that these predators controlledL. fulicacannot be substantiated; in some cases pest snail declines coincided with predator arrival but concomitant declines occurred elsewhere in the absence of the predator and the declines in some cases were only temporary. In the Hawaiian Islands, although there had been some earlier declines of native snails, theEuglandinaimpacts on native snails are clear with rapid decline of many endemic Hawaiian Achatinellinae following predator arrival. In the Society Islands, Partulidae tree snail populations remained stable untilEuglandinaintroduction, when declines were extremely rapid with an exact correspondence between predator arrival and tree snail decline.Platydemus manokwariinvasion coincides with native snail declines on some islands, notably the Ogasawara Islands of Japan, and its invasion of Florida has led to mass mortality ofLiguusspp. tree snails. We conclude thatEuglandinaandP. manokwariare not effective biocontrol agents, but do have major negative effects on native snail faunas. These predatory snails and flatworms are generalist predators and as such are not suitable for biological control.

This datasheet on Marisa cornuarietis covers Identity, Overview, Distribution, Dispersal, Hosts/Species Affected, Diagnosis, Biology & Ecology, Natural Enemies, Impacts, Uses, Prevention/Control, Further Information.

The ambersnails (Succineidae), found nearly worldwide, are considered a very challenging group to classify and identify with even genus-level identifications requiring dissection. In this study, we use mitochondrial and nuclear DNA markers, shell morphometrics, and anatomical dissection to examine fresh material collected from the type localities of two nominal species in Oxyloma (Neoxyloma). We conclude from these evidence that Oxyloma salleanum (L. Pfeiffer, 1850) and Oxyloma effusum (L. Pfeiffer, 1853) are conspecific, and accordingly reduce O. effusum to the status of junior synonymy. We present a redescription of O. salleanum.

New Zealand’s intensive pastures, comprised almost entirely introduced Lolium L. and Trifolium L. species, are arguably the most productive grazing-lands in the world. However, these areas are vulnerable to destructive invasive pest species. Of these, three of the most damaging pests are weevils (Coleoptera: Curculionidae) that have relatively recently been controlled by three different introduced parasitoids, all belonging to the genus Microctonus Wesmael (Hymenoptera: Braconidae). Arguably that these introduced parasitoids have been highly effective is probably because they, like many of the exotic pest species, have benefited from enemy release. Parasitism has been so intense that, very unusually, one of the weevils has now evolved resistance to its parthenogenetic parasitoid. This review argues that New Zealand’s high exotic pasture pest burden is attributable to a lack of pasture plant and natural enemy diversity that presents little biotic resistance to invasive species. There is a native natural enemy fauna in New Zealand that has evolved over millions of years of geographical isolation. However, these species remain in their indigenous ecosystems and, therefore, play a minimal role in creating biotic resistance in the country’s exotic ecosystems. For clear ecological reasons relating to the nature of New Zealand pastures, importation biological control can work extremely well. Conversely, conservation biological control is less likely to be effective than elsewhere.

To test the hypothesis that the inclusion of the forage herbs chicory (Cichorium intybus L.) or plantain (Plantago lanceolata L.) or both in a grass–legume pasture mix improves persistence of sown vegetation and reduces weed and invertebrate pest ingress, a study was undertaken in 31–44 intensively managed pastures in each of five regions in New Zealand (Northland, Waikato, Bay of Plenty, Taranaki and Canterbury). The regions were stratified according to farm type (dairy or sheep and beef), pasture type (sown with grasses, legumes and herbs or grasses and legumes) and pasture age (young: 1–2 years old; medium: 3–4 years old; and old: 5+ years since sowing, n = 171). Sown species ground cover and emergence from the soil seed bank was greater, and unsown species ground cover and emergence lower, in sheep and beef pastures sown with herbs than without herbs (78% vs 68% ground cover, respectively, averaged over all pasture ages), but there was no difference between pasture types on dairy farms. Invert...

Athoracophoridae are succineoidean terrestrial slugs that constitute a distinctive faunal element of the South West Pacific biogeographic region, with representatives in New Guinea, Australia, New Caledonia, Vanuatu and New Zealand. Despite many studies on morphology, taxonomy and phylogenetic relationships since the first species description in 1832, the understanding of the diversity within the family, as reported in published literature, remains poor with regional disparities in collection and systematic effort, in taxonomic concepts, and in adherence to type concepts. The systematics of Athoracophoridae needs to be re-evaluated through a modern, phylogenetic approach to properly document infra-familial evolution and taxon diversity, advance understanding of evolutionary relationships with other Eupulmonata, and to delineate evolutionary units for conservation prioritization. A catalogue of all class-, family-, genus- and species-group names erected for or used to include Athoracophoridae over the 185 year period 1832 to 2017 is provided, as a first step towards a systematic revision. The following nomenclatural changes are made: lectotype designation for Aneitea macdonaldii Gray, 1860; lectotype designation for Janella papillata Hutton, 1879; type species designation for Amphikonophora Suter, 1897; and lectotype designation for Athoracophorus verrucosus Simroth, 1889.

Experiments with artificial diets demonstrated that black field cricket (Teleogryllus commodus (Walker)) and Lepidogryllus sp. were highly responsive to presence of lolines in their diet-quantities of diet consumed declined exponentially with increasing loline concentration. Amount consumed by black field cricket and Lepidogryllus sp. on diet containing 5,600 µg/g lolines was only 8 and 2% relative to those on loline-free diet, respectively. Additional experiments with Festulolium seeds demonstrated that both cricket species predated heavily on endophyte-free seed but largely avoided Epichloë uncinata-infected seed. By 12 h, black field cricket had destroyed 98.8% of endophyte-free but only 24.8% of E. uncinata-infected, loline-containing seed. By 36 h, Lepidogryllus sp. crickets had destroyed 40% of endophyte-free but had not fed on E. uncinata-infected, loline-containing seed. Glasshouse experiments demonstrated this aversion to lolines greatly reduces the damage potential of black field cricket in E. uncinata-infected Festulolium. When microswards were sown with E. uncinata-infected Festulolium, seedling numbers were reduced 25-26%, and yields 29-40%, by black field crickets relative to microswards sown without insect infestation. This contrasts with 70-78% reduction in seedling numbers and 67-80% reduction in yields in microswards sown to either endophyte-free Festulolium, endophyte-free perennial ryegrass, or Epichloë festucae var. lolii-infected Festulolium. Yields of mature E. uncinata-infected Festulolium plants were not adversely affected by black field crickets, irrespective of the presence of the endophyte-free standard Festulolium sown as a companion. In contrast, yields of endophyte-free Festulolium, endophyte-free perennial ryegrass, and E. festucae var. lolii-infected Festulolium plants were reduced by 56-61% by crickets.

Responses of adult Argentine stem weevil to meadow fescueperennial ryegrass hybrids known as Festulolium infected with the endophyte Epichlo uncinata were investigated and compared with endophytefree Grasslands Wana cocksfoot and Grasslands Samson perennial ryegrass and with Samson infected with wild type and AR37 strains of Epichlo festucae var lolii Epichlo uncinata infection in the Festulolium seedline reduced oviposition but not feeding compared with an endophytefree seedline of the same plant genotype in Petri dish leafcomb and potted plant assays Feeding on Festulolium was similar to that on endophytefree Samson but higher than on Samson infected with wild type and AR37 endophytes In these experiments the numbers of eggs laid on E uncinatainfected plant material was similar to that on Samson perennial ryegrass infected with wild type and AR37 endophytes but lower than on endophytefree Samson

Summary Land-use intensification is increasing dramatically in production systems world-wide. Livestock production is an important component of production land use, and increases in livestock densities have had a wide range of negative consequences. The off-site effects of livestock grazing and trampling on native vegetation adjacent to pastoral land have received less attention than on-farm effects. Moreover, where significant ecological effects of livestock spillover have been identified, the mechanistic determinants of these effects have not typically been investigated. Here, we tested the mechanistic drivers of livestock trampling effects on land snail communities in forest remnants using simulated trampling under field conditions. We used a factorial combination of leaf-litter manipulation and trampling treatments to partition different causal drivers of livestock impacts on land snail communities and related them to five environmental variables that are altered by livestock. We show that even very low frequency trampling caused severe changes to land snail communities. Land snail density, even under the lowest trampling frequency, declined by an average of 42 individuals m−2 and land snail species richness decreased by an average of 10 species per plot compared with control plots. The underlying drivers of changes in land snail communities varied, but were primarily linked to leaf-litter mass, rather than soil compaction. Synthesis and applications. Overall, these results suggest that even minimal disturbance by livestock has large effects on land snail communities, but the underlying drivers of these effects require further investigation in longer duration and more intensive studies. Our results provide strong support for livestock exclusion as an important management tool for native forest remnants embedded within production landscapes.

The South American weevil Listronotus bonariensis (Kuschel) is an important pest of pastures in New Zealand. As a component of management strategies for this pest, the South American parasitoid Microctonus hyperodae Loan (Hymenoptera: Braconidae) was released in northern New Zealand during 1991 as a biological control agent. Over the subsequent 5-6 yr, the reproductive biology of M. hyperodae and its relationship to, and effects on, the reproductive phenology and fitness of L. bonariensis were studied at three sites. M. hyperodae was first recovered in the field in December 1991. Subsequently, the incidence of parasitism in L. bonariensis increased to seasonal maxima of 75-90%. There was variable synchrony between parasitoid generations and the two generations of its host, leading to marked seasonal variation in rates of parasitism and parasitoid abundance. Despite marked inter-year variation, abundance of host adult and egg populations declined in the presence of parasitoids. Parasitized host females had lower ovarian maturity scores, had lower egg loads, and exhibited less investment in wing muscle development than females that had escaped parasitism. There was almost complete elimination of egg maturation in parasitized females and these hosts contributed little to population recruitment. Rate of buildup and seasonal maxima in parasitism, frequency of superparasitism, adult abundances, and wing muscle development in adult L. bonariensis varied among the three sites in a manner that was only partially related to climate differences across the 1.83° gradient of latitude. Site effects were weak to absent in measures of reproductive condition in L. bonariensis females.

A new Alaninema species associated with leaf-veined slugs (Athoracophoridae) in New Zealand is described and illustrated. Alaninema ngata n. sp. is characterised by a very long, cylindrical body, rounded head bearing two circles of cephalic papillae and amphids, shallow stoma with three bifid teeth, muscular, cylindroid pharynx lacking valves, enlarged, rounded cardia, nerve ring crossing the anterior intestine, excretory pore situated just posterior to nerve ring, monodelphic females with post-median vulva, thick-shelled eggs covered with prominent tubercles, monorchic males with short testis reflection, reduced number of male genital papillae, strong equal spicules and gubernaculum and tail tip bearing about 20 digitate processes. It is distinguished from A. venmansi and A. njoroensis by having a larger body size (mean 8.3 mm and 13.8 mm in males and females, respectively vs 8.2 mm females in A. venmansi and 4.8 mm and 5.5 mm in A. njoroensis males and females, respectively) and more anterior vulval position (V = 51.6 vs 70 and 66.4 in A. venmansi and A. njoroensis, respectively). Analyses of a partial 18S rDNA sequence indicate that A. ngata n. sp. is affiliated to the Panagrolaimorpha. The systematic position, host range and distribution of A. ngata n. sp. are discussed.

Habitat loss is one of the greatest threats to species persistence. Gauging the scale of this problem requires quantitative methods that can predict the number of extinctions resulting from habitat loss. For the past three decades, the species – area relationship, an empirical relationship between the number of species present in an area and the size of that area, has been this tool. However, it fails to incorporate threats to species aside from habitat loss and the heterogeneous distribution of these threats across habitats. Recent studies have improved species – area predictions by incorporating not only direct eff ects of area on richness, but also indirect eff ects of area (through area-mediated predator abundance), on prey species richness. We extend this work to test the hypotheses that the indirect eff ects of the multiple threats of grazing and trampling in addition to fragmentation will amplify the eff ect of area on species richness and that this eff ect will be greatest in zones closest to the fragment edge. Further, we test for species and population level eff ects of fragmentation and grazing, including the non-random pattern of species loss and the decline in population sizes. We test our hypotheses with a fi eld study of land snail richness in fragments with and without the additional threats of grazing and trampling. Our study supports the hypotheses that fragments with multiple threats in addition to habitat loss harbour fewer species than fragments without these threats, and that this eff ect is non-uniform across fragments, populations and species.

Hydrocarbon spills on Antarctic soils occur mainly near settlements where fuel is stored and aircraft and vehicles are refuelled. To investigate those factors that may preclude hexadecane mineralization activity in long-term hydrocarbon-contaminated soils from the Ross Sea Region, samples were collected from Scott Base, the site of former bases (Cape Evans, Marble Point, Vanda Station), and two oil spill sites in the Wright Valley (Bull Pass and Loop Moraine). The soils had low levels of nitrogen ( 24) reflecting hydrocarbon contamination. Following soil water adjustment to 10% (v/w), the influence of nutrient addition (250 mg/kg N added as monoammonium phosphate) and inoculation (spiking with Antarctic soil containing high numbers of hydrocarbon degraders) as required on hexadecane mineralization activity was determined. Hexadecane mineralization activity occurred in contaminated soils from Marble Point, Cape Evans and one sample from Vanda Station without nutrient addition. In contrast soils from Scott Base, Cape Evans, another sample from Vanda Station and Loop Moraine required nutrients, whereas Bull Pass soil required inoculation and nutrients before hexadecane mineralization proceeded. Hydrocarbon degrader numbers were highest in coastal soils from Scott Base and Marble Point (10 7 per gram) and less prevalent in inland soils from Wright Valley ( 5 per gram). The bacterial community structure of the soils differed between sites, but soils from the same sites tended to cluster together more closely, except for those from Vanda Station. Addition of nutrients did not cause large shifts in the soil bacterial communities. Results from this study indicate that hydrocarbon degradation may occur at some sites in summer when water is available. Long-term hydrocarbon-contaminated Antarctic soils may provide a valuable resource of hydrocarbon-degrading bacteria that can serve as inocula for more recent oil spills on land.

Four pedons on each of four drift sheets in the Lake Wellman area of the Darwin Mountains were sampled for chemical and microbial analyses. The four drifts, Hatherton, Britannia, Danum, and Isca, ranged from early Holocene (10 ka) to mid-Quaternary (c. 900 ka). The soil properties of weathering stage, salt stage, and depths of staining, visible salts, ghosts, and coherence increase with drift age. The landforms contain primarily high-centred polygons with windblown snow in the troughs. The soils are dominantly complexes of Typic Haplorthels and Typic Haploturbels. The soils were dry and alkaline with low levels of organic carbon, nitrogen and phosphorus. Electrical conductivity was high accompanied by high levels of water soluble anions and cations (especially calcium and sulphate in older soils). Soil microbial biomass, measured as phospholipid fatty acids, and numbers of culturable heterotrophic microbes, were low, with highest levels detected in less developed soils from the Hatherton drift. The microbial community structure of the Hatherton soil also differed from that of the Britannia, Danum and Isca soils. Ordination revealed the soil microbial community structure was influenced by soil development and organic carbon.

For many taxonomic groups, sparse information on the spatial distribution of biodiversity limits our capacity toanswer a variety of theoretical and applied ecological questions. Modelling community-level attributes (a- andb-diversity) over space can help overcome this shortfall in our knowledge, yet individually, predictions of a-or b-diversity have their limitations. In this study, we present a novel approach to combining models of a- andb-diversity, with sparse survey data, to predict the community composition for all sites in a region. We appliedour new approach to predict land snail community composition across New Zealand. As we demonstrate, thesepredictions of metacommunity composition have diverse potential applications, including predicting c-diversityfor any set of sites, identifying target areas for conservation reserves, locating priority areas for future ecologicalsurveys, generating realistic compositional data for metacommunity models and simultaneously predicting thedistribution of all species in a taxon consistent with known community diversity patterns.KeywordsAlpha, beta, community, dissimilarity, diversity, gamma, metacommunity, macroecology, richness, snail.Ecology Letters (2011) 14: 1043–1051

Poor pasture persistence and ingress of weedy species are major concerns for farmers. The seedbank gives an indication of what weedy species may establish in pastures and compete with sown species. It was hypothesised that the above-ground composition reflects the seedbank. The seedbank was sampled and botanical assessments were undertaken during October-November 2009 in Northland, Waikato, Taranaki and North Canterbury. Above-ground botanical composition did not reflect the weed seedbank composition in any of the regions assessed. While cover of grasses was greater than legumes and herbs above-ground, weedy herbs were most dominant in the seedbank, followed by grasses then legumes. There was no emergence of sown grass from the seedbank, highlighting the lack of a persistent sown grass seedbank, which may contribute to poor pasture persistence.

The Last Glacial Maximum (LGM) severely restricted forest ecosystems on NewZealand’s South Island, but the extent of LGM distribution for forest species is stillpoorly understood. We used mitochondrial DNA phylogeography (COI) and ecologicalniche modelling (ENM) to identify LGM refugia for the mycophagous beetle Agyrtodeslabralis (Leiodidae), a forest edge species widely distributed in the South Island. Boththe phylogenetic analyses and the ENM indicate that A. labralis refuged in Kaikoura,Nelson, and along much of the South Island’s west coast. Phylogeography of this speciesindicates that recolonization of the largely deforested east and southeast South Islandoccurred in a west–east direction, with populations moving through the Southern Alps,and that the northern refugia participated little in interglacial population expansion. Thiscontradicts published studies of other New Zealand species, in which recolonizationoccurs in a north–south fashion from many of the same refugia.Keywords: ecological niche model, fungus beetle, glacial refugia, Leiodidae, Maxent, PleistoceneReceived 26 July 2009; revision received 1 October 2009; accepted 3 October 2009

Aim Using New Zealand land snails as a case study, we evaluated recent spatial modelling approaches for the analysis of diversity in species-rich invertebrate groups. Applications and prospects for improved conservation assessment were investigated. Location New Zealand. Methods The study used a spatially extensive and taxonomically comprehensive, plot-based dataset on community structure in New Zealand land snails. Generalized regression analysis and spatial prediction (GRASP) was used to model and predict species richness as a function of environmental variables (including aspects of climate, soils and vegetation). Generalized dissimilarity modelling (GDM) was used to model turnover in species composition in relation to environmental and geographical distances, and to assess community similarity and the representativeness of the reserve network. Results Observed land snail richness in 20 × 20 m plots ranged from 1 to 74 (mean 17.5). The GRASP model explained a modest 27% of the variation in richness. The GDM model explained 57% of the variation in species turnover and indicated approximately equal amounts related to environmental (Cody’s beta diversity) and geographical distance (Cody’s gamma diversity). Temperature and moisture were the most important environmental variables. Results indicate that snail distributions are not only sorted by environment but are also strongly influenced by historical effects consistent with those expected of poorly dispersing taxa that have persisted in refugia during past climatic change. The GDM model enabled spatial classifications of snail communities, highlighting diverse communities in heterogeneous regions, such as the South Island mountains, and also enabled continuous depictions of community similarity and adequacy of New Zealand’s protected natural areas network. Main conclusions The GRASP and GDM analyses allowed us to model and depict spatial patterns of diversity in land snail communities involving 845 species, and produce community classifications and estimates of community similarity. These tools advance conservation assessment in species-rich groups, but require further conceptual and methodological development.

Three new species of Punctoidea from Chilean-Argentine Patagonia are described in the family Charopidae: Lilloiconcha aysensis n. sp., Radiodiscus villarricensis n. sp. and Stephadiscus stuardoi n. sp. The new species of Lilloiconcha and Stephadiscus are known only from type localities in Chile, at Aysen and Concepción, respectively. In addition to this being the first record of Lilloiconcha in Chile; Stephadiscus celinae (HYLTON SCOTT, 1969) and S. testalbus (HYLTON SCOTT, 1970) previously known from Argentina are now recorded from southern Chile. The new species of Radiodiscus was collected from several localities ranging from Concepción in Chile to National Park Nahuel Huapí in Argentina, and thus extends eastward the range of Radiodiscus previously known from southern United States of America to Tierra del Fuego. Fil: Miquel, Sergio Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Barker, Gary M.. Crown Research Institutes. Landcare Research; Nueva Zelanda

In many agricultural landscapes, significant biodiversity gains can be made by improving the ecological condition of degraded remnants of semi‐natural habitat. Recent emphasis has been on the level of management intervention required to initiate vegetation recovery in small forest remnants, but no comparable emphasis has been placed on benefits for invertebrate communities. In the Waikato region, New Zealand, we tested the effects of livestock exclusion, mammalian pest control, and their interaction, on leaf‐litter invertebrate communities in 30 forest remnants, using a space‐for‐time substitution approach. A total of 87 376 invertebrates were extracted from 964 leaf‐litter samples. Invertebrate density was an order of magnitude lower in remnants than in nearby large forest reserves. For key taxa, such as Diplopoda, Isopoda, Coleoptera and Mollusca, 10‐ to 100‐fold lower densities were recorded in remnants with no pest control, particularly where livestock were not excluded. By contrast, other ta...

A recently discovered and threatened large land snail, Powelliphanta augusta n. sp. is described from Mt Augustus on the western scarp of the Stockton Plateau, North Westland. On shell characters it is readily distinguishable from all other Powelliphanta, with narrow red spiral lines underlying irregular and variable dark reddish‐brown axial bands, a small adult size and sculptured dorsal surface. Differences in the shell morphology of P. augusta, its closest phylogenetic relative P. lignaria, and its closest geographic neighbour P. patrickensis, were investigated using principal components analysis. P. lignaria is much larger than either P. augusta or P. patrickensis, and there are significant differences in shell shape between the three taxa. Earlier mitochondrial DNA sequencing data, which supported specific status of P. augusta, is discussed. The snail's only habitat on the Mt Augustus ridgeline is described, but most has now been removed by coal mining. Snails salvaged before the destruction...

The value of biodiversity lies in its option value for the future, the greater the complement of contemporary biodiversity conserved today, the greater the possibilities for future biodiversity because of the diverse genetic resource needed to ensure continued evolution in a changing and uncertain world. From this perspective, biodiversity option value can be equated with richness in the different features expressed by species. An individual species of greater value is one contributing more novel features to a given subset. The feature diversity of species and communities is difficult to estimate directly, but can be predicted by the phylogenetic relationships among the species. The ‘Phylogenetic Diversity’ measure (PD) (Faith, 1992a) estimates the relative feature diversity of any nominated set of species by the sum of the lengths of all those branches spanned by the set. These branch lengths reflect patristic or path-length distances. This study first reviews and expands on some of the properties of PD, and develops simple modifications of the measure (δnPD and enPD) to enable capture of both the phylogenetic relatedness of species and their abundances in each sample. Then the application of PD, δnPD and enPD to a wide range of conservation and resource management issues is demonstrated using avian case studies. Supertree construction procedures (matrix representation using parsimony analysis; average consensus) were used to combine the extensive DNA-DNA hybridization tree of Sibley & Ahlquist (1990) with numerous, recently published phylogenetic reconstructions to derive a phylogenetic tree for the global avian fauna. Using this supertree as a systematic framework, the utility of PD was demonstrated in four case studies: (i) state of the environment reporting, with changes in avian faunas resulting from extinctions quantified as indicators of the state of biodiversity at Global, New Zealand and Waikato region scales, and changes in available habitat quantified as indicators of pressures on biodiversity in the Waikato region; (ii) setting priorities for threatened species management, with PD as a measure of option value integrated with information on survivorship expectations to develop a ranking among threatened New Zealand forest bird species; (iii) monitoring biotic response to management, with data from 5-minute counts used to analyse changes in forest bird communities under three management regimes in New Zealand; and (iv) selection of indicator species, with PD used to objectively identify subsets of species in the Global, New Zealand and Waikato avian faunas that comprise a high proportion of the option value in those faunas.

Soils of the Ross Sea region of Antarctica are among the least diverse ecosystems on earth. Few plants and animals have colonised these soils, but bacteria are distributed throughout. We compared the bacterial communities of soil samples from 5 locations in the Ross Sea region, representing different soil taxonomic groups, using culture-independent methods. Four mineral soils and one ornithogenic soil were analysed. Organic C, Total N, and moisture of the mineral soils were low, total P and EC were variable. In contrast, the water content, organic C, and Total N and P, and EC of the ornithogenic soil were 10–100 fold higher than the mineral soils. Soil pH was alkaline. One thousand and fourteen clones were screened by restriction fragment length polymorphisms. While the majority of the ribotypes were rare, some were dominant and occurred ≥ 3 times in the respective clone libraries. The dominant ribotypes were sequenced and shown to be phylogenetically affiliated with the phyla Acidobacteria , Actinobacteria , Bacteroidetes , Proteobacteria , Deinococcus-Thermus , Firmicutes , Cyanobacteria and Candidate TM7. The closest relatives of the clones retrieved from the mineral soils were uncultured environmental clones or bacterial isolates not assigned to recognised genera. In contrast, the clones from the ornithogenic soil were most closely related to the endospore-formers; Oceanobacillus profundus , Clostridium acidiurici and Sporosarcina aquimarina. We found no convincing evidence that the Haplorthels from Scott Base, Marble Point, and Cape Hallett, have bacterial communities structured fundamentally different from those of Anhyorthels from Bull Pass and Vanda. Nonetheless the composition of the communities did vary substantially and were readily discriminated by multivariate statistics on the basis of soil properties.

Human‐assisted spread of species poses a major challenge to border security agencies. Ideally, limited resources need to be targeted at species posing the most risk. Climate matching is an important component of assessing risk but often little or no biological information is available to enable detailed modelling. To assess if distribution records alone provide useful establishment predictions we compare the climate in New Zealand and its outlying islands to that found in the current native and introduced ranges of 12 tramp ant species, three of which are already established in New Zealand, using the climate module of BIOSECURE, a risk assessment tool. Eleven species showed a similar general pattern, with mean annual temperature being the climatic variable with the least overlap between the estimated realised niche and the predicted New Zealand niche. The twelfth species, of temperate origin, is less restricted by temperature, but much of New Zealand may have too high a rainfall. The present and ...

Although there has been much recent interest in the effect of litter mixing on decomposition processes, much remains unknown about how litter mixing and diversity affects the abundance and diversity of decomposer organisms. We conducted a litter mixing experiment using litterbags in a New Zealand rainforest, in which treatments consisted of litter monocultures of each of 8 forest canopy and understory plant species, as well as mixtures of 2, 4 and 8 species. We found litter mixing to have little effect on net decomposition rates after either 279 or 658 days, and for each species decomposition rates in mixture treatments were the same as in monoculture. Litter species identity had important effects on litter microfauna, mesofauna and macrofauna, with different litter types promoting different subsets of the fauna. Litter mixing had few effects on densities of mesofauna and macrofauna, but did have some important effects on components of the microfauna, notably microbe-feeding and predatory nematodes. At day 279, litter mixing also consistently reduced the ratio of bacterial-feeding to microbe-feeding (bacterial-feeding+fungal-feeding) nematodes, pointing to mixing causing a significant switch from the bacterial-based to the fungal-based energy channel. Litter mixing sometimes influenced the community composition and diversity of nematodes and macrofauna, but effects of litter mixing on diversity were not necessarily positive, and were much weaker than effects of litter species identity on diversity. We conclude that litter mixing effects on the abundance and diversity of decomposer biota, when they occur, are likely to be of secondary and generally minor significance when compared to the effects of litter species identity and composition.

Five experiments investigated the importance of herbivory by Sminthurus viridis in structuring botanical composition in developing grasslands, and how these effects may be modified by diversity in collembolan and plant species. Differential susceptibility to S. viridis feeding was demonstrated in 23 dicotyledonous and three monocotyledonous plants assayed as seedlings at the first true leaf stage. The composition of seedling communities developing from natural and artificially constructed soil seed banks varied with the level of S. viridis infestation, with plant species least susceptible to herbivory making the greatest contribution to plant biomass. The combined effect of herbivory by S. viridis and Bourletiella hortensis on Trifolium repens biomass was shown to be less than the effect of S. viridis alone, indicating competitive interference. The adverse effects of herbivory by S. viridis on T. repens biomass was reduced by increased diversity of plants growing in association with the legume, and the presence of four non-herbivorous arthropleonan Collembola. S. viridis was shown to reduce seedling numbers, species diversity and biomass in communities developing from the soil seed bank, but the presence of non-herbivorous arthropleonan species reduced the effect of S. viridis. The experiments demonstrate the potential for herbivory by S. viridis to significantly alter species composition in developing grassland communities. However, interactions with collembolan and plant species profoundly modified S. viridis herbivory impacts, either by reducing feeding intensity or enhancing plant growth. These results highlight the fact that data from simple, synthetic systems may be poor predictors of herbivory impacts under field conditions where more complex species interactions occur.

The parasitoid Microctonus hyperodae Loan (Hymenoptera: Braconidae) was introduced into New Zealand to control the weevil Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae), a major pest of graminaceous plants. Four experiments were conducted to investigate the effects of various pesticides that are commonly used in the pastoral environments of L. bonariensis and M. hyperodae . To pical applications of aqueous solutions prepared from commercial formulations of five herbicides were not toxic, but the surfactant Silwett L-77 increased M. hyperodae mortality relative to the watertreated controls. Laboratory assays showed that M. hyperodae adults were susceptible to chlorpyrifos residues on pasture foliage following application of the insecticide to field plots at ≥ 5 g a.i. ha − 1 . Maintenance of L. bonariensis on ryegrass in the laboratory showed that treatment of the food plants with chlorpyrifos at ≥ 96 g a.i. ha − 1 reduced L. bonariensis survivorship and ultimately reduced M. hyperodae prepupal emergence from those hosts. Initially, mortalities of non-parasitized L. bonariensis were significantly greater than for parasitized L. bonariensis . Maintenance of parasitized L. bonariensis on diflubenzuron-treated ryegrass plants arrested M. hyperodae larval development in the host and ultimately reduced prepupal emergence of M . hyperodae from those hosts. Despite the arrested development of M. hyperodae , the mortality of L. bonariensis hosts was increased. Adult M. hyperodae successfully reared from hosts maintained on diflubenzuron (12.5 g a.i. ha − 1 ) treated food plants had reduced reproductive potential. The consequences of pasture management strategies that employ pesticides are discussed in relation to biocontrol of L. bonariensis by M . hyperodae .

Although island attributes such as size and accessibility to colonizing organisms can influence community structure, the consequences of these for ecosystem functioning are little understood. A study of the suspended soils of spatially discrete epiphytes or treetop “islands” in the canopies of New Zealand rainforest trees revealed that different components of the decomposer community responded either positively or negatively to island size, as well as to the tree species that the islands occurred in. This in turn led to important differences between islands in the rates of ecosystem processes driven by the decomposer biota. This system serves as a model for better understanding how attributes of both real and habitat islands may affect key ecosystem functions through determining the community structure of organisms that drive these functions.

Summary 1There is increasing awareness that similar suites of plant traits may govern foliage palatability and litter decomposability, but whether there is an association between the response of vegetation to herbivory and litter decomposition rates across plant species remains unexplored. 2We collected 141 samples of litter from 59 understorey and 18 canopy tree species from a total of 28 sites under natural forest throughout New Zealand. We assessed whether variables related to decomposition and quality of litter of the understorey species showed a statistical relationship with the response of vegetation density (assessed using a pole-intercept method) of the same species at the same locations to browsing by deer and goats. Decomposition and nutrient-loss data from litter were obtained using standardized laboratory bioassays. 3There was a significant positive correlation between litter decomposition rate and the extent to which vegetation density was reduced by browsing mammals (r = 0·488, P

Several invasive European slug species are thriving in New Zealand and have become important pests of many crops. In pasture, they are particularly damaging to white clover during renovation and the problem may be exacerbated by direct drilling. Slug feeding causes both lethal and sublethal damage that reduces clover establishment and thus pasture quality. Much less is known about slug damage to established pastures and the degree to which slugs limit pasture persistence. Established pastures frequently support large slug populations that feed on clover and the application of molluscicides can reduce slug numbers and increase the proportion and yields of clover. Future research on these pests should concentrate on determining damage thresholds, breeding resistant clover varieties and developing agronomic practices that favour natural enemies. In the long term, there is much potential for developing microbiological pesticides that target slugs. Keywords: molluscs, slugs, clover

Forest dwelling browsing mammals, notably feral goats and deer, have been introduced to New Zealand over the past 220 years; prior to this such mammals were absent from New Zealand. The New Zealand forested landscape, therefore, presents an almost unique opportunity to determine the impacts of introduction of an entire functional group of alien animals to a habitat from which that group was previously absent. We sampled 30 long-term fenced exclosure plots in indigenous forests throughout New Zealand to evaluate community- and ecosystem-level impacts of introduced browsing mammals, emphasizing the decomposer subsystem. Browsing mammals often significantly altered plant community composition, reducing palatable broad-leaved species and promoting other less palatable types. Vegetation density in the browse layer was also usually reduced. Although there were some small but statis- tically significant effects of browsing on some measures of soil quality across the 30 locations, there were no consistent effects on components of the soil microfood web (com- prising microflora and nematodes, and spanning three consumer trophic levels); while there were clear multitrophic effects of browsing on this food web for several locations, com- parable numbers of locations showed stimulation and inhibition of biomasses or populations of food web components. In contrast, all microarthropod and macrofaunal groups were consistently adversely affected by browsing, irrespective of trophic position. Across the 30 locations, the magnitude of response of the dominant soil biotic groups to browsing mammals (and hence their resistance to browsers) was not correlated with the magnitude of vegetation response to browsing but was often strongly related to a range of other variables, including macroclimatic, soil nutrient, and tree stand properties. There were often strong significant effects of browsing mammals on species composition of the plant community, species composition of leaf litter in the litter layer, and composition of various litter-dwelling faunal groups. Across the 30 locations, the magnitude of browsing mammal effects on faunal community composition was often correlated with browser effects on litter layer leaf species composition but never with browser effects on plant community composition. Browsing mammals usually reduced browse layer plant diversity and often also altered habitat diversity in the litter layer and diversity of various soil faunal groups. Across the 30 locations, the magnitude of browser effects on diversity of only one faunal group, humus-dwelling nematodes, was correlated with browser effects on plant diversity. However, browser effects on diversity of diplopods and gastropods were correlated with browser effects on habitat diversity of the litter layer. Reasons for the lack of unidirectional relationships across locations between effects of browsers on vegetation community attri- butes and on soil invertebrate community attributes are discussed. Browsing mammals generally did not have strong effects on C mineralization but did significantly influence soil C and N storage on an areal basis for several locations. However the direction of these effects was idiosyncratic and presumably reflects different mechanisms by which browsers affect soil processes. While our study did not support hypotheses predicting consistent negative effects of browsing mammals on the decomposer subsystem through promotion of plant species with poorer litter quality, our results still show that the introduction of these mammals to New Zealand has caused far-ranging effects at both the community and ecosystem levels of resolution, with particularly adverse effects for indigenous plant com- munities and populations of most groups of litter-dwelling mesofauna and macrofauna.

We established a greenhouse experiment based on replicated mini-ecosystems to evaluate the effects of defoliation intensity on soil food-web properties in grasslands. Plant communities, composed of white clover (Trifolium repens), perennial ryegrass (Lolium perenne) and plantain (Plantago lanceolata) with well-established root and shoot systems, were subjected to five defoliation intensity treatments: no trimming (defoliation intensity 0, or DI 0), and trimming of all plant material to 35 cm (Dl 1), 25 cm (DI 2), 15 cm (DI 3) and 10 cm (Dl 4) above soil surface every second week for 14 weeks. Intensification of defoliation reduced shoot production and standing shoot and root mass of plant communities but increased their root to shoot ratio. Soil microbial activity and biomass decreased with intensification of defoliation. Concentrations of NO 3 -N in soil steadily increased with intensifying defoliation, whereas NH 4 -N concentrations did not vary between treatments. Numbers of microbi-detritivorous enchytraeids, bacterial-feeding rotifers and bacterial-feeding nematodes steadily increased with intensifying defoliation, while the abundance of fungal-feeding nematodes was significantly enhanced only in Dl 3 and DI 4 relative to DI 0. The abundance of herbivorous nematodes per unit soil mass was lower in DI 3 and DI 4 than in DI 0, Dl I and DI 2. but when calculated per unit root mass, their abundance tended to increase with defoliation intensity, The abundance of omnivorous and predatory nematodes appeared to be highest in the most intensely defoliated systems The ratio of abundance of fungal-feeding nematodes to that of bacterial-feeding nematodes was not significantly affected by defoliation intensity. The results s infer that defoliation intensity may significantly alter the structure of soil food webs in grasslands, and that defoliation per se is able to induce patterns observed in grazing studies in the field. The results did not support hypotheses that defoliation per se would cause a shift between the bacterial-based and fungal-based energy channels in the decomposer food web, or that herbivore and detritivore densities in soil would be highest under intermediate defoliation. Furthermore, our data for microbes and microbial feeders implies that the effects of defoliation intensity on soil food-web structure may depend on the duration of defoliation and are therefore likely to be dynamic rather than constant in nature.

We established a greenhouse experiment based on replicated mini-ecosystems to evaluate the effects of defoliation of different plant species combinations on soil food-web structure in grasslands. Plant communities, composed of white clover (Trifolium repens), perennial ryegrass (Lolium perenne) and plantain (Plantago lanceolata), were subjected to the following defoliation treatments: no defoliation of any species (control) and selective trimming of all possible one-, two- and three-way combinations of the species either to 27 cm height (weak defoliation) or to 15 cm height (strong defoliation) above the soil surface three times over a 10-week period. Successive defoliations removed the largest amounts of shoot mass from systems in which T. repens was included among the defoliated species because T. repens dominated aboveground plant biomass. At the final harvest shoot mass was lowest in treatments that included defoliation of T. repens, while total root mass was on average lower in strongly than in weakly defoliated systems and did not differ between the control and defoliation treatments. Total shoot production was not affected by defoliation. Microbial basal respiration and soil NO3-N concentration differed between the combinations of defoliated species; e.g. microbial respiration was on average 32% lower in systems in which only L. perenne was defoliated than in systems in which only T. repens was defoliated. Microbial biomass and soil NH4‐N concentration were not significantly affected by defoliation treatments. Enchytraeid abundance differed significantly between the combinations of defoliated species: in systems in which only L. perenne was defoliated enchytraeid abundance was on average 88% lower than in systems in which all species or only T. repens were defoliated. Enchytraeid abundance was also positively associated with total defoliated shoot mass. Abundances of both bacterial-feeding and fungal-feeding nematodes were affected by the combination of defoliated species; e.g. the abundance of bacterial feeders was on average 52% lower in systems in which only T. repens was defoliated than in systems in which both P. lanceolata and T. repens were defoliated. Fungal-feeding nematodes were also more numerous in strongly than in weakly defoliated systems and positively associated with total defoliated shoot mass. Herbivorous nematode abundance was not significantly affected by defoliation treatments. The results show that the response of soil food webs to defoliation can be affected by which combination of species in a plant community is defoliated. Further, it seems that the role of the combination of species that are defoliated may for some components of the soil biota (e.g. fungal-feeding nematodes) be explicable simply in terms of the total mass of foliage removed. However, for other components of the soil biota (e.g. bacterial-feeding nematodes and enchytraeids) species-specific properties of different plant species in the combination of defoliated species are also clearly important, over and above simple mass removal effects of defoliation. q 2001 Elsevier Science Ltd. All rights reserved.

This is the first published invertebrate survey focusing on a low‐altitude shrubland community in New Zealand. Invertebrates were collected from a remnant native shrubland (450 m) protected by the Brookdale Conservation Covenant, Rock and Pillar Range, Otago, New Zealand in late summer/autumn 1999. Sampling was carried out by beating 30 randomly chosen shrubs of each of two native species: Olearia bullata H. D. Wilson & Garnock‐Jones (Asteraceae) and Coprosma propinqua A. Cunn. (Rubiaceae). Fifty pitfall traps were also set under the same shrubs and on nearby open patches of exotic grassland. Three Phyla, six Classes, 25 Orders and approximately 280 species were recorded. An annotated list of taxa is presented, and plant/host associations plus other observations on the fauna are discussed. Approximately 90% of the identified species were endemic, emphasising the importance of such remnant habitats for the protection of New Zealand's biodiversity.

Although factors affecting plant growth and plant carbon/nutrient balance – e.g., light availability and defoliation by herbivores – may also propagate changes in below-ground food webs, few studies have aimed at linking the above-ground and below-ground effects. We established a 29-week laboratory experiment (∼one growing season) using autotrophic microcosms to study the effects of light and defoliation on plant growth, plant carbon/nutrient balance, soil inorganic N content, and microbial activity and biomass in soil. Each microcosm contained three substrate layers – mineral soil, humus and plant litter – and one Nothofagus solandri var. cliffortioides seedling. The experiment constituted of the presence or absence of two treatments in a full factorial design: shading (50% decrease in light) and artificial defoliation (approximately 50% decrease in leaf area in the beginning of the growing season). At the end of the experiment a range of above-ground and below-ground properties were measured. The shading treatment reduced root and shoot mass, root/shoot ratio and leaf production of the seedlings, while the defoliation treatment significantly decreased leaf mass only. Leaf C and N content were not affected by either treatment. Shading increased NO 3–N concentration and decreased microbial biomass in humus, while defoliation did not significantly affect inorganic N or microbes in humus. The results show that plant responses to above-ground treatments have effects which propagate below ground, and that rather straightforward mechanisms may link above-ground and below-ground effects. The shading treatment, which reduced overall seedling growth and thus below-ground N use and C allocation, also led to changes in humus N content and microbial biomass, whereas defoliation, which did not affect overall growth, did not influence these below-ground properties. The study also shows the carbon/nutrient balance of N. solandri var. cliffortioides seedlings to be highly invariant to both shading and defoliation.

While there has been a rapidly increasing research effort focused on understanding whether and how composition and richness of species and functional groups may determine ecosystem properties, much remains unknown about how these community attributes affect the dynamic properties of ecosystems. We conducted an experiment in 540 mini-ecosystems in glasshouse conditions, using an experimental design previously shown to be appropriate for testing for functional group richness and composition effects in ecosystems. Artificial communities representing 12 different above-ground community structures were assembled. These included treatments consisting of monoculture and two- and four-species mixtures from a pool of four plant species; each plant species represented a different functional group. Additional treatments included two herbivore species, either singly or in mixture, and with or without top predators. These experimental units were then either subjected to an experimentally imposed disturbance (drought) for 40 d or left undisturbed. Community composition and drought both had important effects on plant productivity and biomass, and on several below-ground chemical and biological properties, including those linked to the functioning of the decomposer subsystem. Many of these compositional effects were due to effects both of plant and of herbivore species. Plant functional group richness also exerted positive effects on plant biomass and productivity, but not on any of the below-ground properties. Above-ground composition also had important effects on the response of below-ground properties to drought and thus influenced ecosystem stability (resistance); effects of composition on drought resistance of above-ground plant response variables and soil chemical properties were weaker and less consistent. Despite the positive effects of plant functional group richness on some ecosystem properties, there was no effect of richness on the resistance of any of the ecosystem properties we considered. Although herbivores had detectable effects on the resistance of some ecosystem properties, there were no effects of the mixed herbivore species treatment on resistance relative to the single species herbivore treatments. Increasing above-ground food chain length from zero to three trophic levels did not have any consistent effect on the stability of ecosystem properties. There was no evidence of either above-ground composition or functional group richness affecting the recovery rate of ecosystem properties from drought and hence ecosystem resilience. Our data collectively point to the role of composition (identity of functional group), but not functional group richness, in determining the stability (resistance to disturbance) of ecosystem properties, and indicates that the nature of the above-ground community can be an important determinant of the consistency of delivery of ecosystem services.

The consequences of permanent loss of species or species groups from plant communities are poorly understood, although there is increasing evidence that individual species effects are important in modifying ecosystem properties. We conducted a field experiment in a New Zealand perennial grassland ecosystem, creating artificial vegetation gaps and imposing manipulation treatments on the reestablishing vegetation. Treatments consisted of continual removal of different subsets or “functional groups” of the flora. We monitored vegetation and soil biotic and chemical properties over a 3-yr period. Plant competitive effects were clear: removal of the C3 grass Lolium perenne L. enhanced vegetative cover, biomass, and species richness of both the C4 grass and dicotyledonous weed functional groups and had either positive or negative effects on the legume Trifolium repens L., depending on season. Treatments significantly affected total plant cover and biomass; in particular, C4 grass removal reduced total plant biomass in summer, because no other species had appropriate phenology. Removal of C3 grasses reduced total root biomass and drastically enhanced overall shoot-to-root biomass ratios. Aboveground net primary productivity (NPP) was not strongly affected by any treatment, indicating strong compensatory effects between different functional components of the flora. Removing all plants often negatively affected three further trophic levels of the decomposer functional food web: microflora, microbe-feeding nematodes, and predaceous nematodes. However, as long as plants were present, we did not find strong effects of removal treatments, NPP, or plant biomass on these trophic groupings, which instead were most closely related to spatial variation in soil chemical properties across all trophic levels, soil N in particular. Larger decomposer organisms, i.e., Collembola and earthworms, were unresponsive to any factor other than removal of all plants, which reduced their populations. We also considered five functional components of the soil biota at finer taxonomic levels: three decomposer components (microflora, microbe-feeding nematodes, predaceous nematodes) and two herbivore groups (nematodes and arthropods). Taxa within these five groups responded to removal treatments, indicating that plant community composition has multitrophic effects at higher levels of taxonomic resolution. The principal ordination axes summarizing community-level data for different trophic groups in the soil food web were related to each other in several instances, but the plant ordination axes were only significantly related to those of the soil microfloral community. There were time lag effects, with ordination axes of soil-associated herbivorous arthropods and microbial-feeding nematodes being related to ordination axes representing plant community structure at earlier measurement dates. Taxonomic diversity of some soil organism groups was linked to plant removals or to plant diversity. For herbivorous arthropods, removal of C4 grasses enhanced diversity; there were negative correlations between plant and arthropod diversity, presumably because of negative influences of C4 species in the most diverse treatments. There was evidence of lag relationships between diversity of plants and that of the three decomposer groups, indicating multitrophic effects of altering plant diversity. Relatively small effects of plant removal on the decomposer food web were also apparent in soil processes regulated by this food web. Decomposition rates of substrates added to soils showed no relationship with treatment, and rates of CO2 evolution from the soil were only adversely affected when all plants were removed. Few plant functional-group effects on soil nutrient dynamics were identified. Although some treatments affected temporal variability (and thus stability) of soil biotic properties (particularly CO2 release) throughout the experiment, there was no evidence of destabilizing effects of plant removals. Our data provide evidence that permanent exclusion of plant species from the species pool can have important consequences for overall vegetation composition in addition to the direct effects of vegetation removal, and various potential effects on both the above- and belowground subsystems. The nature of many of these effects is driven by which plant species are lost from the system, which depends on the various attributes or traits of these species.

Summary Aim The New Zealand terrestrial mollusc fauna is among the most speciose in the world, with often remarkably high richness at lowland forest sites. We sought to elucidate general explanations for patterns of richness in terrestrial mollusc communities by analysis of species coexistence and habitat relationships within a New Zealand district fauna. Location Pukeamaru Ecological District, eastern North Island, New Zealand. Methods We sampled molluscs using qualitative methods at twenty-three sites and quantitatively by frame sampling of scrubland-forest floor litter at sixteen of these sites and analysed patterns of species richness and turnover in relation to regional species pools and local habitat attributes. We then tested for nonrandom assemblage of taxa along diversity and habitat gradients. Results Ninety-four indigenous mollusc species were recorded from a district fauna estimated at 102 indigenous species: only two species were endemic. From the presumptive geological history of the district, the low endemism, and Brooks parsimony and indicator species analyses of faunal relationships, the communities were indicated to have resulted by accumulation of colonists from other New Zealand districts since the Miocene. Richness ranged from two or three indigenous species in dune habitats to fifty-nine species in a floristically rich forest. Beta diversity was high and site occupancy per species was low, indicating communities structured by successive replacement of ecological equivalents. Sites differing in vegetation had characteristic species assemblages, indicating a degree of habitat specialization. Canonical correspondence analysis indicated that canopy tree species, canopy height, floristic diversity, altitude, litter mass, and litter pH were important determinants of species assemblage in scrubland and forest. Richness was strongly associated with site floristic diversity and, for litter-dwelling species, the pH of litter substrate. High richness occurred at those sites supporting molluscs in high abundance. Shell-shape distributions were essentially Cainian unimodal, with communities dominated by snail species with subglobose to discoidal shells. Mean and variance of shell size increased with mollusc species richness and floristic diversity at sites, indicating dominance of communities by small-shelled species at early successional or floristically poor sites, and increased richness resulting from addition of larger snails into vacant niches. Shifts in shell form were associated with sympatry in several congeneric taxa. Main conclusions The underdispersion of shell shape, relative to faunas elsewhere in the world, indicates that community structure in New Zealand land snail faunas has been constrained by limited phylogenetic diversity and/or by convergence upon successful adaptations. The remarkably high richness that characterizes these communities indicates special conditions allow coexistence of numerous species. The relationship between floristic diversity at sites and the richness, diversity, and shell-size distributions of the molluscs suggests assemblages structured around niche partitioning among competing species. While there is an element of congruence between vegetation and mollusc pattern, this study indicates that assembly rules will be defined, and spatial pattern predicted, only through a better understanding of the linkage between regional species pool, organism traits, environment, and local community assemblage.

1 The development of general principles regarding biotic interactions involving plants, or plant species effects in ecosystems, is best achieved through simultaneous evaluation of several species. We utilized a comparative approach involving 20 dicotyledonous herbaceous species, to explore possible relationships between several plant ecophysiological traits and plant litter decomposition, interactions involving competition and herbivory, and plant species effects on soil properties. 2 Decomposition rates of plant stem and leaf litter were negatively related to plant mass, time until flowering and vegetative growth rate, and positively related to stem nitrogen content. Root decomposition was also related to several traits. Multiple regression relationships showed that 74% and 84% of the variation across species for stem and root litter decomposition, respectively, could be predicted by plant traits; this suggests that plant traits may be powerful predictors of decomposition and have potential as alternative predictors to the litter quality characteristics that previous studies have concentrated on. 3 Palatability of both seedlings and leaf discs by the invertebrate herbivores Deroceras reticulatum and Listronotus bonariensis were frequently related to plant traits. Those traits that showed the strongest relationships with the palatability data included various vegetative growth characteristics and (for the leaf disc data) nitrogen concentrations of flowering plant stems. 4 Competitive effects of the dicotyledonous species against a phytometer species, the grass Lolium perenne, were negatively related to leaf nitrogen concentration, and multiple regression relationships involving this trait in combination with others explained over 50% of the variation across species. The competitive response of both plant mass and total seed production to L. perenne was poorly related to plant traits. 5 The effects of plant species on soil properties including microbial biomass and activity, pH, nitrate concentration and total nitrogen were often closely related to various plant traits. Multiple regression relationships revealed that combinations of several traits were often important in determining these effects; the strongest relationships found were for effects of senescent plants on soil respiration and for the effects of flowering plants on soil nitrate. Plant traits were therefore clearly important in determining plant species effects on soils. 6 Our study emphasizes the importance of plant traits in understanding (and predicting) species interactions and effects in communities and ecosystems, and shows that properties considered at the whole plant level have the potential to manifest themselves over much larger scales. We therefore conclude that there are clear linkages between plant ecophysiological traits, biotic interactions involving plants, and ecosystem level properties and processes.

The parasitoids Microctonus aethiopoides Loan and Microctonus hyperodae Loan (Hymenoptera: Braconidae) have been introduced into New Zealand to control the adult stage of the forage pests Sitona discoideus and Listronotus bonariensis (Coleoptera: Curculionidae), respectively. These parasitoids have been chosen to examine the environmental impact of introduced biological control agents on native and non‐target species. A survey of the Curculionoidea fauna of pasture, lucerne, and modified native grassland in parts of the southern South Island, Canterbury, and the northern North Island of New Zealand, where these parasitoids are present, was carried out in order to identify Curculionoidea with taxonomic and ecological affinities with the target hosts, and hence, potential non‐target hosts. At a total of 155 sites, 85 species of Curculionoidea were identified, of which 64 (75%) were native species. Three tribes in the subfamily Brachycerinae (broad‐nosed weevils) accounted for 61 species, and 7 trib...

Laboratory host specificity of 2 biological control agents, already introduced in New Zealand, was compared with actual field parasitism. The parasitoids were Microctonus aethiopoides Loan and Microctonus hyperodae Loan, braconids imported to control the curculionid forage pests Sitona discoideus Gyllenhal and Listronotus bonariensis (Kuschel), respectively. The nontarget weevil species tested included native, introduced, and beneficial species. M. aethiopoides oviposited in 11 of the 12 species to which it was exposed and successfully parasitized 9 species. M. hyperodae oviposited in 5 of the 11 species to which it was exposed and developed successfully in 4 species. Higher percentage parasitism was recorded with M. aethiopoides than with M. hyperodae . Field collections of weevils from Otago, Canterbury, and Waikato indicated that 10 New Zealand native species and 3 other nontarget species, including the weed biological control agent Rhinocyllus conicus (Froehlich), were parasitized by M. aethiopoides . M. hyperodae has been found parasitizing 1 native species, as well as Sitona lepidus Gyllenhal, which was accidentally introduced to New Zealand recently. In nontarget species, parasitism levels in the field of >70% have been recorded for M. aethiopoides and

Laboratory experiments were done to examine the effect of ryegrass infection by the endophytic fungus Acremonium lolii Latch, Christensen & Samuels (Ascomycetes: Clavicipitaceae) on Microctonus hyperodae Loan, a parasitoid of Listronotus bonariensis (Kuschel). Infection of ryegrass did not influence the rate of parasitism in weevils confined with naive parasitoids to individual plants and to ryegrass swards in small plots. In contrast, M. hyperodae with prior experience of hosts feeding on endophyte infected grass subsequently were more efficient in parasitizing hosts on this diet. Feeding on individual plants and small plot swards by weevil for 3–4 d increased subsequent parasitoid attack rate.

Laboratory experiments were conducted to examine the effect of ryegrass infection by the endophytic fungus Acremonium lolii Latch, Christensen and Samuels on Microctonus hyperodae Loan, a parasitoid of Listronotus bonariensis (Kuschel). Progression of parasitoids through the larval instar stages was shown to depend on adequate nutrition of the weevil host. Compared to confinement on endophyte-free ryegrass, parasitizedweevilsheldonnonpreferreddietscomprising leaf segments from endophyte-infected ryegrass and switchgrass contained parasitoid larvae with retarded development. Similarly, development of parasitoid larvae was retarded in hosts feeding on artificial diet containing diterpenes and alkaloids of A. lolii origin. Several diterpenes incorporated into the diet reduced survival of the parasitoid larvae. Attack rate of parasitoids was reduced when the quality of potential host weevils was compromised by confinement on nonpreferredA. lolii-infected ryegrass or without food for14days. r 1996 Academic Press, Inc.