Leisnham: Relationship between male head size & mating opp in Hemideina maori

Leisnham, P. T., & Jamieson, I. G. (2004). Relationship between male head size and mating opportunity in the harem-defence, polygynous tree weta Hemideina maori (Orthoptera: Anostostomatidae). New Zealand Journal of Ecology, 28(1), 49-54. (3 copies)

Objectives of study were to determine whether males with larger heads have access to great #s of females, and whether male head size has an effect on male survival and longevity. Results suggested that small males intermittently retreat to small cracks or cavities within tor columns, where there are unlikely to be large female groups. So, larger males had access to more females than smaller males. Larger males also had no detectable disadvantage in terms of daily survival and longevity. Evidence that larger male tree weta do associate with larger harems in the wild.

Morgan-Richards: Taxonomic status of tree weta from Stephens Is.

Morgan-Richards, M., Daugherty, C.H. and Gibbs, G.W. 1995 Taxonomic status of tree weta from Stephens Island, Mt. Holdsworth and Mt. Arthur, based on allozyme variation. Journal of the Royal Society of New Zealand Vol 25(2) June 1995: 301-312. (3 copies)

Sort of a tedious account of genetic relationships. Researchers undertook an analysis of allozyme variation of tree weta from 13 sites including Stephens Island to find out whether the tree weta on that island should be viewed as a separate species. They came to the conclusion that the population is sufficiently different to warrant taxonomic recognition.

Morgan-Richards (1995): New species of tree weta from North Island

Morgan-Richards, M 1995 A new species of tree weta from the North Island of new Zealand (Hemideina: Stenopelmatidae: Orthoptera). New Zealand Entomologist, 1995, Vol 18: 15-23 (3 copies)

New discovery from Hawkes Bay. Differs from Wellington tree weta only in the colouration of the pronotum (upper surface of the protorax; the foremost section of thorax) – it is light yellow/orange. It also differs in two different allozyme loci and karyotype. I don’t really think this is of much use to Team Weta.

Beakly: Design & use of artificial refuges for monitoring adult tree weta

Beakly, C., Stringer, I., Robertson, A., & Hedderly, D. (2006). Design and use of artificial refuges for monitoring adult tree weta, Hemideina crassidens and H. thoracica. DoC Research and Development Series 233, Department of Conservation, Science and Technical publishing, Wellington. (1 copy)

Artificial refuges were constructed in order to find out tree weta dwelling preferences. Tree weta were found to prefer refuges made of fresh pine, galleries with tapering terminations, holes 16-25mm diameter, et cetera...# of weta positively correlated wth # of weta in natural cavities; no diff in results between refuge locations. This article can give us some pretty decent insight into understanding ideal weta holes.

Trewick: Weta roost proj Mohi Bush Scenic Reserve

Trewick, S.A. 1995 Interim Report on weta roost project at Mohi Bush Scenic Reserve, Hawkes Bay Regional Conservancy. Unpublished report. School of Biological Sciences, Victoria University, Wellington. (1 copy)

Six artificial weta roosts were constructed and occupancy recorded. The researchers speculate on what habitat characteristics are ideal or nonideal for inhabitation. Both tree weta and cave weta appear to have a tendency to use holes that have been previously occupied by a weta. Recommendation to continue the study using larger holes to allow harems.

Gibbs New Zealand Weta

Gibbs, G. (1998). New Zealand Weta .Reed Books (NZ)

·         Weta droppings can be distringuished from possum and rat dropings by their neatly rounded ends, not pointed as in mamals. 

·         There Cerci are accessory sense organs on the rear end of the abdomen.  These detect sound waves and other vibrations that warn the weta of something approaching from behind.  Males have longer Cerci then females.  At dusk tree weta sit with their ass out of the hold monitoring weather it is safe conditions.  Sometimes they will sit there for an hour or two before going outside. 

·         Ground weta have sharp teeth and the small species are very alert and active, certainly more suited to predation then the clumsy tree weta. Ground weta as well as tusked weta are almost entirely carnivorous.

·         Cave weta are omnivorous scavengers.  Those that live inside caves forage for dead insects, spiders, and debris that is washed into the cave by streams.  They can adapt to human modifications of caves by foraging on the mosses and liverworts that grouw around electric lights in the Waitomo caves.

·         Tree and giant weta are described as omnivorous but they are largely vegetarians.

·         Once male tree weta are about half grown they take up residence in holes or galleries.  Weta do not make their own tunnels but rely on finding holes made by large wood-boring insects or formed by some other agency.  They always enter head first and back out.

·         Any number of females will be allowed in the gallery but the dominant male will not allow any other males, they must fight for possession of the gallery if challenged. 

·         Large headed males are the species that fight over gallery occupation.  They are more aggressive

·         Sexually mature adult males will have varying head sizes from enormous “oversized” (roughly 1/3 of a colony)down to smaller then female heads.  Once insects like weta are sexually mature they cannot grow any larger.

·         Males have different instar numbers (molting cycles). Small headed have 8, medium headed have 9 and large headed have 10.  All species have mating success, while large headed individuals are protecting their galleries smaller headed are cruising around looking for chicks. Only in tree and possible tusked but not sure due to lack of research.

·         Weta are tone-deaf, meaning that they caould never enjoy music, but they can hear your approach, especially if you tread on dry stick.

·         Weta call is generated by rubbing tiny pegs (like sandpaper0 over a compb.  Biologists call it stridulation (tree weta).

·         Cave and ground weta do not have ears, cave produce no sound but ground can produce a low intensity sound.

·         Native weta predators: lizards, tuatara, birds and short-tailed bats.  Morepork is most common native predator that attachs weta at nights.  All weta natural predators are rare or nearly extinct today.

·         Invasive predators (rats, stoats, weasels and cats) have a large hunting advantage in that their sense of smell is much sharper than that of birds so they can track down weta by smell.

Tags: tree weta, ground weta, cave weta, giant weta, habitat type/use, behavior, food

Moller H. Tree Wetas

Moller, H. 1984 Tree wetas (Hemideina crassicruris) (Orthoptera: Stenopelmatidae) of Stephens Island, Cook Strait. New Zealand Journal of Zoology: 1985 Vol 12: 55-69.

·         Talks about two separate island restoration projects with tree weta populations, stephens island and

·         Tuataras important native predator of weta on these island reserves and they probably stop the tree weta from moving to the forest floor. Very well outlined in this article

·         This article is good because it is all about another experiment and goes into several monitoring methods as well as results.  However, it is very old (1984) and some of the claims that Mr. Moller makes have been disproven.  If you use something from this article make sure to fact check it with current information.

Tags: tree weta, monitoring method, food, behavior, habitat type, introduced species, island restoration

Rate, S.R. Does rat control...

Rate, S.R. (2009). Does rat control benefit forest invertebrates at Moehau, Coromandel Peninsula? DOC Research & Development Series 316. Department of Conservation, Wellington, New Zealand.

·         This is a scientific research paper put out by DOC: it looks to monitor if invertebrate populations would react positively to rat eradication on Moehau in the corremandel.

·         The conclusions of this study were that rat control had no effect on the relative abundance, diversity andbody length of pitfall-trapped invertebrates, except for a significant reduction in the numbers of ants (Formicidae).

·         They hypothesize that invertebrates that are susceptible to predation by rats were not adequately sampled, the predatory pest mammals were not reduced to low enough levels to elict a measurable invertebrate response.

·         This goes over several recommendation for the improvement of further studies

Tags: Tree weta, mainland restoration, monitoring method

Gibbs, G. Why are some Weta

Gibbs, G. W. (1998). Why are some weta (Orthoptera: Stenopelmatidae) vulnerable yet others are common? Journal of Insect Conservation, 2, 161-166.

·         Examines why some types of weta have thrived in the presence of key predators (rats), while others only exist on predator-free island refuges.  Paper addresses the question of what aspects of their bilology enable some of the “demon grasshoppers” to survive while others became extinct.

·         New Zealand lacked large mammals which made it a paradise for invertebrates, birds and reptiles.  A consequese is the high proportion of large-bodied, flightless forms of birds and insects in the fauna

·         The real impact of mammal invasions came with the Norway rat (Rattus norvegicus), which is active on the ground and the ship rat (Rattus rattus), an agile tree-climbing rate, introduced by European vessels over the last 200 years (King, 1990).

·         Lists 10 reasons why weta are so vulnerable to mammal predation: 1.Their large size 2. Flightlessness 3. They are distinctly “smelly” 4. All species are nocturnally active and relatively slow moving 5.By day they retreat into a sheltered refuge 6. They may be solitary or distinctly gregarious 7. An acoustic communication system is developed and is used also as part of their defense mechanism. 8. Long development (18-36 months) from egg-adult, they are considered K selected species unlike most insects9. Oviposition is in soil or soft rotten wood 10. Omnivores

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Ordish, R.G. 1992 Aggregation and communication of the Wellington weta Hemideina crassidens (Blanchard) (Orthoptera: Stenopelmatidae). New Zealand Entomologist 1992 Vol 15:1-8. (2 copies)

• Discusses aggregation of tree weta: their interactions with each other and whether they form clusters

• Also discusses stridulation (noise makin’!) and talks a little about how their morphology contributes to this ability. I

• Stridulation is their principal means of communication and is used primarily for defense, territorial, and eviction calls. The article describes these calls.

Rufaut, C. G., & Gibbs, G. W. (2003). Responses of a Tree Weta Population (Hemideina crassidens) After Eradication of the Polynesian Rat from a New Zealand Island. Restoration Ecology, 11(1), 13-19. (3 copies)

• Measures changes in a population of tree weta on an offshore island after removal of rats. 
• Found that weta density didn’t change, but proportion of adults changed, and weta spent more time closer to the ground and less time in tree refuges. 
• The study concludes that weta are able to withstand rat predation, but live a more relaxed lifestyle in their absence.

 

Watts, C., Stringer, I., Sherley, G., Gibbs, G., & Green, C. (2008). History of weta (Orthoptera: Anostostomatidae) translocation in New Zealand: lessons learned, islands as sanctuaries and the future. J Insect Conserv, 12, 359-370. (2 copies)

                         

• A review of weta translocations in NZ. 
• Provides case studies of past successes and failures in weta translocations to both offshore and mainland islands. 
• Also reviews various monitoring and transfer techniques.

Griffin, MJ: the case of weta as small mammals

Griffin, M.J., Trewick, S.A., Wehi, P. M. and Morgan-Richards, M. 2011 Exploring the concept of niche convergence in a land without rodents: the case of weta as small mammals. New Zealand Journal of Ecology (2011) 35(3):0-0 (3 copies)

A discussion of the use of the metaphor of weta as ecologically equivalent to rodents in other countries. This article takes an opposing stance, explaining how they are different in ecology and characteristics. This article shows that the reproductive potential and scale of change in population size differ greatly between mice and tree weta.

Watts, C., Stringer, I., Sherley, G., Gibbs, G., & Green, C. (2008). History of weta (Orthoptera: Anostostomatidae) translocation in New Zealand: lessons learned, islands as sanctuaries and the future. J Insect Conserv, 12, 359-370. (2 copies)

                         

A review of weta translocations in NZ. Provides case studies of past successes and failures in weta translocations to both offshore and mainland islands. Also reviews various monitoring and transfer techniques.