Travis Marsh:- invertebrate inventory and analysis R.P. Macfarlane Buzzuniversal 43 Amyes Road, Hornby Christchurch B.H. Patrick P.O. Box 6202, Great King Street, Otago Museum, Dunedin P.M. Johns Zoology Department, Canterbury University, Christchurch C.J. Vink Entomology and animal ecology Department, Lincoln University, Lincoln May 1998 Page CONTENTS 1 SUMMARY 2 INTRODUCTION 5 The marsh 5 Lowland invertebrate communities 7 Terrestrial invertebrate survey objectives 9 METHODS 10 Sampling procedure and site features 10 Fauna investigation and identification 13 RESULTS AND DISCUSSION 14 Invertebrate biodiversity and mobility 14 Habitat and ecological relationships 16 Foliage, seed herbivores and their parasites 17 Insects on invasive weeds of Travis Marsh 20 Parasites and their distribution on the marsh 21 Flower visitors 21 The predators 22 Ground, litter and tree trunk dwellers 23 Drainage, seepage and wet bare spot inhabitants 24 Cattle and pukeko dung 25 Pukeko diet and feeding 25 Skinks 26 Sampling methods and imput needs for an invertebrate community study 26 ANALYSIS AND CONCLUSIONS 27 Biodiversity 27 Localized species loss 28 Characteristic marsh and native woodland species 29 Research and education prospects 29 Recreational value and restoration potential 30 ACKNOWLEDGMENTS 31 REFERENCES 32 Table 1 Biodiversity and habitat surveys of New Zealand grasslands to marshes (arranged by geographic and habitat proximity to Travis Marsh) 8 Table 2 Invertebrate collection:- duration, composition and habitats sampled 13 Table 3 Comparison of relative abundance of insect groups from a malaise trap at shrub/tree and the tall marsh plant sites 16 Appendix 1 Invertebrates found at Travis Marsh (467 insect species, 88 ‘introduced’ species) 39 Appendix 2 Site, plant and method details for the survey 59 Appendix 3 Selected invertebrate species: simplified keys, informal family characters and some reasons to consider species are undescribed 60 Figure 1 Travis Marsh with location of sample sites 11 Figure 2 Vegetation and east ditch boundary of the Long I. raupo-tussock sedge community 12 1 SUMMARY • Renaming the enlarged wetland of Travis swamp to a marsh would improve the perception of its value, so we use marsh in our report. The biodiversity of endemic invertebrate (confined to New Zealand) species from this marsh compares favourably to other herb to shrub communities investigated in lowland New Zealand. There are 467 insect species recorded from Travis Marsh and 81 % of these species are endemic and only 3 % were clearly vagrants. Of these species 40-70 % of the species are likely to be characteristic of marshes and wet pastures. The great reduction in manuka and raupo and loss of toetoe has probably lead to a loss of at least 10 insect species with beetles being among the more prominent possible examples. A further 55 species of the other larger invertebrates (spiders, centipedes, millipedes, landhoppers, slaters, snails, slugs, earthworms, flatworms) were found at Travis Marsh. • From four independent extrapolations there are probably 700 (650-800) resident insect species and 85-155 species of non microscopic other invertebrates at the marsh. Of these a provisional 22-25 species could well be at least regionally rare and 1.7 % were flightless. The Christchurch endemic crane fly Gynoplistia pedestris (flightless) is the best researched case. One undescribed Oxyserphus seems to be an uncommon endemic to Banks Peninsula. Any orchid flower thrip Dicromothrips maori present may be regionally rare. Other less mobile insect species with shortened wings include: - four parasitic wasps (a pteromalid, an encyrtid, an undescribed scelionid, the introduced eupelmid Macroneura vesicularis), a fungus gnat, and the common bagworm moth (female) Liothula omnivora. These seven species will have much more limited mobility than winged insects and so continuation of vegetative patches that provide their environment is more critical to them. An outline is presented on the variable ability of insect species to colonise new areas (possibly less than 0.2 km to 30 or more km) and their normal foraging range (less than 30 m to 1.5 km) to provide some insight into the need to avoid producing small isolated patches of the charateristic native wetland plant species in Travis swamp. • An estimated 66-85 insect (14-19%), 8-9 spider (30-32%) and one land snail (25%) species collected at Travis Marsh are undescribed. Certain undescribed insect species include an uncommon but widespread Elasmus species and probably three Oxyserphus wasp species, the tussock sedge moth Megacraspedus and a mirid. There are six undescribed muscid fly species and apparently a single undescribed fly species in both Caligeria and Neolimnia. Other probable undescribed species include:- Psychoda - moth flies (2-3 species), 2-4 sciariid fly species, a ‘Gaurax’ fly species, Ichneumonidae wasps (25-30 species), Braconidae wasps (2-6 species), Chalcoidea wasps (7-15 species) and 14 Diapriidae wasp species and perhaps a longhorn beetle. For marsh communities a revision of Scirtidae (marsh beetles) is needed to allow for repeatable species identification. Naming of species is impossible with the latest 110 year old, synonym plagued, and keyless last taxonomic study of this family. This may involve a more moderate number of species than the literature indicates based on the diversity at Travis Marsh and two North island wetland studies. Our survey provides a valued insight into which insect families need systematic work most for lowland marshes in New Zealand and opportunities for Canterbury research. When new species are described then Travis Marsh should be a favoured ‘type locality’ provided the essential wetland areas are retained in a protected reserve. The marsh would be well suited to this vital scientific and educational function, because of 1. an extended ecosystem that buffers invertebrates from contamination from surrounding housing 2. the few alternative and smaller safe sites 3. the ready accessibility to a population centre with a range of researchers and schools. Hence any more specimens can readily be recollected and the natural history studied in situ. In a similar way the smaller Riccarton bush is already an important preserved type locality for lowland bush in New Zealand. • Few losses of species were clearly demonstrated. There is a provisional indication that beetle species may be among the insect orders more severely affected. The reduction manuka to a minimum of a few plants has almost certainly lead to the loss of the small sap sucking Psyllidae Ctenarytaina pollicaris and the plant hoppers Novothymbris notata. Four wetland moth species, Elachista pumila, the geometrid Asaphodes abrogata and the leaf rollers Parienia mochloporana and Protithona fugitivana are apparent missing from this wetland, after being recorded previously in or near Christchurch. More thorough night light sampling including earlier and later in the season and collection and extraction of insects from the litter and moss is likely to see the moth and rove beetle species lists increase about two fold. 2 • The most acute threats of localized extinction of invertebrate species apply to those in raupo, orchid flowers, tussock sedge and perhaps native reed, spiked sedge, swamp willow weed, mosses, New Zealand milfoil and New Zealand cudweed. The diversity of native insect hosts that these native plant species support is mostly unkonown or at best poorly recorded in New Zealand. The single host specialised parasitic wasp species (about half the parasitic wasp species) and flightless larger predators (e.g ground beetles, spiders) with low reproductive capacity are likely to be more vulnerable than their herbivore hosts. Most carefully studied species from genera of herbivores or detrivores have several parasitic species of insects, because different parasites affect the various stages - eggs, larvae or pupae. For the marsh, with insects there was a ratio of 5.4 herbivore/detrivore/omnivore species to 2.5 parasite species to 1 predator species. Raupo, tussock sedge, native rushes and perhaps cogeneric sedges and rushes support at least 10 species of herbivorous invertebrates that rely on them. Any parasitoids from raupo could be vulnerable to localized extinction either with added drainage which could prevent flowering or if a proposed expressway largely obliterates or fragments the current bigger raupo patches. Other families of invertebrates that could have one or two regionally rare species include crane flies (Tipulidae), various spiders and the undescribed land snail species. The parasitoid wasps (Hymenoptera), which are poorly known taxonomically, and other rarer parasitoids and snails would needed more targeted collection to assess their distribution and abundance within the marsh. In the south west destruction of moss, swamp willow weed could well lead to local extinction for 5-10 species of moths, beetles, plant sucking bugs, spider parasites and perhaps spiders. The losses of two native rush, two low growing native sedge species, New Zealand milfoil and New Zealand cudweed could well lead to further local losses of moth and other insect species partly known from Otago/Southland studies of moths. Hence a reasonably broad eastern band of land that incorporates all the wetland and some seasonally wet area as a buffer and further plant reservoir is the most vital area for invertebrate conservation. Consequently plans for modification of adjacent wetland areas to the south and north of Travis swamp