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Nelson, New Zealand

Harper G.A.,Nelson Lakes Area Office | Harper G.A.,Biodiversity Restoration Specialists Ltd | Joice N.,Nelson Lakes Area Office | Kelly D.,University of Canterbury | And 2 more authors.
New Zealand Journal of Ecology

Poison baiting from fixed bait stations is currently the most effective method to reduce the ecological impacts of invasive Vespula vulgaris wasps in New Zealand. Maintaining extensive bait lines or grids and later removal of unused baits within forest habitats is, however, difficult and time-consuming. To improve costeffectiveness and to make use of wasps’ ability to forage at long distances from the nest, we tested the efficacy of using clusters of bait stations. We set up three clusters around Lake Rotoiti within Nelson Lakes National Park, each containing eight stations baited with Xtinguish™ (active ingredient 0.1% fipronil) for 3–4 days in early February, 2010 and recorded the traffic rates of 144 V. vulgaris nests, at varying distances from bait clusters, before and after treatment. The distance from a bait station cluster significantly affected the change in traffic rates, with a GLM model predicting an 80% reduction in average colony size within 113 m of a cluster, and a 50% reduction within 250 m but no reduction at 470 m. The efficacy of the poison baiting was affected by initial colony size – large colonies had greater reductions in traffic than small colonies. Nests up to 150 m higher in elevation than the clusters were as likely to be destroyed as those at the same elevation as the clusters. While overall this baiting strategy did not produce the 80–90% average traffic reductions achieved by more intensive grid baiting systems, it suggests that spacing grouped bait stations approximately 250 m apart has the potential to reduce wasp densities to below an ecologically damaging level with considerably less effort. © New Zealand Ecological Society. Source

Kelly M.,University of Auckland | Toft R.,Entecol Ltd | Gaskett A.,University of Auckland
New Zealand Journal of Botany

Deceptive orchids typically employ food or sexual deception of male insects. Brood-site deception, when flowers are pollinated by female flies fooled into attempting oviposition, is less well characterized for orchids but is probably common among New Zealand terrestrial orchid species. Helmet orchids (Corybas, Nematoceras and related genera) are considered specialist brood-site deceivers that mimic mushrooms and are pollinated by ovipositing female fungus gnats (Mycetophilidae). We monitored pollination in the endemic spurred helmet orchid, Corybas cheesemanii, and trapped insects visiting orchids and sympatric mushrooms. Flowering occurred from mid-May to early July, each flower lasted 23.14 d, 78.5% of the population flowered (147/194 plants), and c.25% of these set seed naturally (50% of bagged orchids set seed via autonomous self-pollination). Traps caught mostly flies (Mycetophilidae, Anisopodidae and Lauxaniidae), but orchid, mushroom and control traps did not attract significantly different fauna. Seven mycetophilids (of both sexes) visited both orchids and mushrooms, but we found no compelling evidence that C. cheesemanii was pollinated by these. Only some mycetophilid individuals caught above orchids were small enough to enter orchids, but none carried orchid pollinia. If C. cheesemanii is fungus gnat-pollinated, the range of species and sexes attracted suggests a more generalist pollination strategy than assumed. © 2013 The Royal Society of New Zealand. Source

Osawa N.,Kyoto University | Toft R.,Entecol Ltd | Tuno N.,Kanazawa University | Kadowaki K.,University of Auckland | And 3 more authors.
New Zealand Entomologist

The toxic ectomycorhizal fungi Amanita muscaria (Agaricales: Amanitaceae) was first recorded in New Zealand in 1937, and it is now widespread throughout the country. We collected decaying fruiting bodies of the mushroom in 2005 and 2006 and placed them in enclosed emergence traps to determine use by fungivorous insects. This study clarified that the endemic species Mycetophila fagi, M. flicornis (Diptera: Mycetophilidae) and Zedura curtisi (Diptera: Trichoceridae), as well as exotic Drosophila busckii (Diptera: Drosophilidae), utilised the exotic A. muscaria in various vegetation types in the North and South Islands of New Zealand. A signifcant difference was observed in the number of fungivorous insects found on the mushrooms between North and South Islands; the endemic M. fagi was dominant in South Island, while Psychodidae sp. dominated North Island. A significant difference was observed in the number of fungivorous insects between the exotic and endemic vegetation inhabited by A. muscaria. Furthermore, the biodiversity of fungivorous insects on A. muscaria within endemic Nothofagus vegetation was more than three times greater than that within the exotic Betula, Pinus, Pseudotsuga and tsuga vegetation. These observations suggest that the greater diversity of fungivorous insects on A. muscaria in natural Nothofagus forests may reflect the higher diversity found in natural forests compared with plantation forests. Source

Bodley E.J.,University of Auckland | Beggs J.R.,University of Auckland | Toft R.,Entecol Ltd | Gaskett A.C.,University of Auckland
New Zealand Journal of Botany

Greenhood orchids are most diverse in New Zealand and Australia, with at least some species pollinated by sexual deception of male fungus gnats. Preliminary investigation of endemic New Zealand Pterostylis brumalis via field phenology, hand-pollination and insect trapping revealed P. brumalis is self-compatible but relies on insects for cross pollination. Natural fruit-set was low, averaging 2.6% across two populations. High fruit-set in hand-pollinated flowers (66.7%) indicates severe pollinator limitation. In comparison, only one collected insect, a female Mycetophila vulgaris, bore orchid pollinia. Potential pollinator attractants (colour and scent) were analysed. UV reflectance may enhance pollinator detection of the flower against the background, but visual modelling generated conflicting results: a categorical fly vision model indicated excellent camouflage against herbivory, but a generic tetrachromat vision model suggested flowers are easily distinguishable against the background. Both models have flaws that create issues with drawing conclusions, and identification of the pollinator is required to understand their visual system further. Scanning electron microscopy (SEM) revealed putative scent-releasing osmophores (lateral sepals) and uniform papillate trichomes (labellum) that may mechanically direct pollinators into the floral trap. The trap is a pressure sensitive labellum that temporarily traps the visitor inside the flower. © 2016 The Royal Society of New Zealand Source

Mathieson M.,Victoria University of Wellington | Mathieson M.,Entecol Ltd | Toft R.,Entecol Ltd | Lester P.J.,Victoria University of Wellington
Journal of Economic Entomology

The efficacy of toxic baits should be judged by their ability to kill entire ant colonies, including the colony queen or queens. We studied the efficacy of four toxic baits to the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae). These baits were Xstinguish that has the toxicant fipronil, Exterm-an-Ant that contains both boric acid and sodium borate, and Advion ant gel and Advion ant bait arena that both have indoxacarb. Experimental nests contained 300 workers and 10 queen ants that were starved for either 24 or 48 h before toxic bait exposure. The efficacy of the toxic baits was strongly influenced by starvation. In no treatment with 24-h starvation did we observe 100% worker death. After 24-h starvation three of the baits did not result in any queen deaths, with only Exterm-an-Ant producing an average of 25% mortality. In contrast, 100% queen and worker mortality was observed in colonies starved for 48 h and given Xstinguish or Exterm-an-Ant. The baits Advion ant gel and Advion ant bait arena were not effective against Argentine ants in these trials, resulting in <60% mortality in all treatments. Because of the strong influence of starvation on bait uptake, control efficacy may be maximized by applying bait when ants are likely to be starved. Our results suggest queen mortality must be assessed in tests for toxic bait efficacy. Our data indicate that of these four baits, Xstinguish and Exterm-an-Ant are the best options for control of Argentine ants in New Zealand. © 2012 Entomological Society of America. Source

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