A preliminary survey of altitudinal variation in two ground wētā species,Hemiandrus maculifrons(Walker) andHemiandrus pallitarsis(Walker) (Orthoptera: Anostostomatidae)

Chappell, Esta Monique; Webb, DG; Brown, Allison J.; Tonkin, Jonathan D.

doi:10.1080/00779962.2014.922234

“…The habitat preference of some of these ground wētā is partially separated by elevation. For example, H. pallitarsis Walker, 1869 is found at lower altitudes than H. maculifrons (Walker, 1869) (Chappell et al 2015). Studies involving other wētā species, for example Hemideina maori (Pictet & Saussure, 1891), H. thoracica (White, 1842) and H. crassidens (Blanchard, 1851), have also shown that wētā occupying particular habitat ranges are physiologically adapted to those microclimates (Ramlov 1999;Bulgarella et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Ground wētā in vines of the Awatere Valley, Marlborough: biology, density and distribution

Nboyine

¹

,

Boyer

²

,

Saville

³

et al. 2016

New Zealand Journal of Zoology

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The endemic New Zealand ground wētā (Hemiandrus sp. 'promontorius') has a Naturally Uncommon conservation status. This is because of the paucity of information on its density and distribution. Here, the biology, density and distribution of a population of this wētā found in and around vineyards in the Awatere Valley, Marlborough was studied. Wētā density was assessed in vineyards, paddocks and shrublands in this valley. Soil moisture, penetration resistance, pH and organic matter were recorded at locations with and without wētā. Wētā density in vineyards was significantly higher than in either paddocks or shrub habitats. In vineyards, the density of this insect was significantly higher under-vines than in the inter-rows. Higher numbers of this wētā were found in moist soils that required lower force to burrow. Females laid an average of 55 eggs between March and April, which hatched in September. These findings highlight the intersection between agriculture and conservation.

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“…They are nocturnal, flightless, relatively abundant across New Zealand, and occupy holes in the ground during the day and emerge at night to forage and mate (Johns 2001). Their body size distributions differ between sexes as females tend to be larger than males (Taylor-Smith et al 2013, Chappell et al 2014, Chappell et al 2015. Ground weta are components of the diet of introduced rodents (Rattus spp.…”

Section: Body Size Of Ground-dwelling Invertebrates and Time (Both Forests)mentioning

confidence: 99%

Macroinvertebrate community responses to mammal control - Evidence for top-down trophic effects

Parra¹

0

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New Zealand’s invertebrates are characterised by extraordinary levels of endemism and a tendency toward gigantism, flightlessness and longevity. These characteristics have resulted in a high vulnerability to introduced mammals (i.e. possums, rats, mice, and stoats) which are not only a serious threat to these invertebrates, but have also altered food web interactions over the past two-hundred years. The establishment of fenced reserves and the aerial application of 1080 toxin are two methods of mammal control used in New Zealand to exclude and reduce introduced mammals, respectively. Responses of ground-dwelling invertebrates to mammal control, including a consideration of trophic cascades and their interactions, remain unclear. However, in this thesis, I aimed to investigate how changes in mammal communities inside and outside a fenced reserve (ZEALANDIA, Wellington) and before-and-after the application of 1080 in Aorangi Forest, influence the taxonomic and trophic abundance, body size and other traits of ground-dwelling invertebrates on the mainland of New Zealand. I also tested for effects of habitat variables (i.e. vegetation and elevation), fluctuations in predator populations (i.e. mice, rats and birds) and environmental variables (i.e. temperature). Additionally, I investigated how squid-bait suspended over pitfall traps influenced the sampling of ground weta and other invertebrates in Aorangi and Remutaka Forests. Contrary to my expectations, there were no differences in abundance or body size of invertebrates within ZEALANDIA (which excludes introduced mammals except mice) relative to the outside, except for Staphylinidae which were more abundant outside the fence. Differences in the agents of predation pressure from mainly mammals, outside the reserve, to mostly birds within ZEALANDIA, but potentially little change in net predation pressure, may explain this apparent similarity in ground-invertebrates. No differences in invertebrate communities were also recorded in the 1080-treated area (Aorangi Forest) after one year of the aerial application of 1080. It could imply that the use of this toxin does not produce any apparent detriment to invertebrates at a population level. The application of 1080 usually leads to changes in insectivorous predator (birds and introduced mammals) dynamics in the short-term mainly due to meso-predator release, which may affect invertebrate communities as a result. Temporal and spatial variation of different components of the ecosystem appear to be more significant drivers of invertebrate dynamics, than 1080 mammal control. For example, rats (Rattus spp.) limited the abundance and body size of large invertebrates (i.e. ground weta, cave weta and spiders) in Aorangi and Remutaka Forests. Smaller invertebrates such as gastropods, weevils and springtails were affected directly by spatial factors such as vegetation, while dung beetles responded to an increase in mouse density. Based on a comparison of pitfall trapping methods, I suggest the use of squid baiting as an effective method for sampling ground weta (Hemiandrus spp.) in New Zealand, as they responded positively to these baits. Finally, I propose ground weta and spiders as suitable indicators of rat predation, as they are abundant in forests and easily recognised by non-specialists, and they respond negatively to rat densities. This thesis underlines the importance of studying the effect of introduced mammal dynamics derived from mammal control in an ecosystem approach, to achieve conservation goals both in the short- and long-term, especially considering the New Zealand Government’s ambitious goal of eradicating three of the most prevalent mammal predators (rats, possums and stoats) by 2050.

show abstract

“…They are nocturnal, flightless, relatively abundant across New Zealand, and occupy holes in the ground during the day and emerge at night to forage and mate (Johns 2001). Their body size distributions differ between sexes as females tend to be larger than males (Taylor-Smith et al 2013, Chappell et al 2014, Chappell et al 2015. Ground weta are components of the diet of introduced rodents (Rattus spp.…”

Section: Body Size Of Ground-dwelling Invertebrates and Time (Both Forests)mentioning

confidence: 99%

Macroinvertebrate community responses to mammal control - Evidence for top-down trophic effects

Parra¹

0

View full text Add to dashboard Cite

New Zealand’s invertebrates are characterised by extraordinary levels of endemism and a tendency toward gigantism, flightlessness and longevity. These characteristics have resulted in a high vulnerability to introduced mammals (i.e. possums, rats, mice, and stoats) which are not only a serious threat to these invertebrates, but have also altered food web interactions over the past two-hundred years. The establishment of fenced reserves and the aerial application of 1080 toxin are two methods of mammal control used in New Zealand to exclude and reduce introduced mammals, respectively. Responses of ground-dwelling invertebrates to mammal control, including a consideration of trophic cascades and their interactions, remain unclear. However, in this thesis, I aimed to investigate how changes in mammal communities inside and outside a fenced reserve (ZEALANDIA, Wellington) and before-and-after the application of 1080 in Aorangi Forest, influence the taxonomic and trophic abundance, body size and other traits of ground-dwelling invertebrates on the mainland of New Zealand. I also tested for effects of habitat variables (i.e. vegetation and elevation), fluctuations in predator populations (i.e. mice, rats and birds) and environmental variables (i.e. temperature). Additionally, I investigated how squid-bait suspended over pitfall traps influenced the sampling of ground weta and other invertebrates in Aorangi and Remutaka Forests. Contrary to my expectations, there were no differences in abundance or body size of invertebrates within ZEALANDIA (which excludes introduced mammals except mice) relative to the outside, except for Staphylinidae which were more abundant outside the fence. Differences in the agents of predation pressure from mainly mammals, outside the reserve, to mostly birds within ZEALANDIA, but potentially little change in net predation pressure, may explain this apparent similarity in ground-invertebrates. No differences in invertebrate communities were also recorded in the 1080-treated area (Aorangi Forest) after one year of the aerial application of 1080. It could imply that the use of this toxin does not produce any apparent detriment to invertebrates at a population level. The application of 1080 usually leads to changes in insectivorous predator (birds and introduced mammals) dynamics in the short-term mainly due to meso-predator release, which may affect invertebrate communities as a result. Temporal and spatial variation of different components of the ecosystem appear to be more significant drivers of invertebrate dynamics, than 1080 mammal control. For example, rats (Rattus spp.) limited the abundance and body size of large invertebrates (i.e. ground weta, cave weta and spiders) in Aorangi and Remutaka Forests. Smaller invertebrates such as gastropods, weevils and springtails were affected directly by spatial factors such as vegetation, while dung beetles responded to an increase in mouse density. Based on a comparison of pitfall trapping methods, I suggest the use of squid baiting as an effective method for sampling ground weta (Hemiandrus spp.) in New Zealand, as they responded positively to these baits. Finally, I propose ground weta and spiders as suitable indicators of rat predation, as they are abundant in forests and easily recognised by non-specialists, and they respond negatively to rat densities. This thesis underlines the importance of studying the effect of introduced mammal dynamics derived from mammal control in an ecosystem approach, to achieve conservation goals both in the short- and long-term, especially considering the New Zealand Government’s ambitious goal of eradicating three of the most prevalent mammal predators (rats, possums and stoats) by 2050.

show abstract

A preliminary survey of altitudinal variation in two ground wētā species,Hemiandrus maculifrons(Walker) andHemiandrus pallitarsis(Walker) (Orthoptera: Anostostomatidae)

Cited by 5 publications

References 17 publications

Ground wētā in vines of the Awatere Valley, Marlborough: biology, density and distribution

Ground wētā in vines of the Awatere Valley, Marlborough: biology, density and distribution

Macroinvertebrate community responses to mammal control - Evidence for top-down trophic effects

Macroinvertebrate community responses to mammal control - Evidence for top-down trophic effects

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