Kangaroo Island Fires: Effects on Endemic Orthopteroid Insects

Kangaroo Island Fires:  Effect on Orthopteroid Insects

A great deal of attention has been focused on the over 1 billion “animals” that have been lost to the recent bushfires in Australia. However, little attention has been paid to the insects that have been lost. To a large extent the reason is simply that so little is known of the distributions of the insect fauna that it is hard make reliable generalisations. In over 40 years of study of the Australian orthopterofauna (grasshoppers, katydids, crickets, stick insects, mantids and their allies), I have discovered a number of Kangaroo Island endemics that deserve attention at this important time. With more than half the island consumed by very "hot" fires, it is likely that some endemic insects are extinct.

Kangaroo Island is Australia’s third largest island and is positioned 112 km southwest of Adelaide. The closest point to the mainland is Snapper Point, about 14 km from the Fleurieu Peninsula. In addition to endemic insects, the island shares species with the adjacent mainland of South Australia as well as distant Western Australia.


Vertebrate Highlights


A distinct species of Emu once lived on Kangaroo Island but was extinct by 1836. Kangaroo Island is the last South Australian refuge of the Glossy Black Cockatoo. Six bats and a number of frogs are endemic there. The Kangaroo Island Dunnart is an endemic marsupial mammal. Koalas were introduced and thrived due to the presence of Manna Gum trees, many of which are now gone due to the fires. The Koala population may survive but in very reduced and regulated numbers. These animals plus seals, Little Penguins and beautiful blue ocean bays and gorgeous vistas make Kangaroo Island a haven for Australian and foreign visitors alike.



Vivonne Bay, the most beautiful landscapes on Kangaroo Island. It is the home of several katydids including one species of the genus Metaballus.


Continual destruction of the native vegetation occurs mostly due to agriculture. Clearing for vineyards, grazing and bee-keeping, grain production and commercial development all have contributed to the reduction of the native habitat. The recent fires probably have been the death knell for a number of species.




Near Mt McDonnell, Kangaroo Island, 1977. Kawanaphila katydids can be expected in the grassy areas and an assortment of other katydids are to be found in the adjacent shrubby vegetation. A "hot" fire might wipe them out for good.



My research interests focus on the orthopteroid insects—the grasshoppers, katydids, crickets, stick insects mantids and cockroaches. I have visited Kangaroo Island once, in November-December 1977. I was aware that a distinctive orthopteran fauna existed there based on specimens in the Australian National Insect Collection, Canberra and the South Australian Museum.

The trip in 1977 was most rewarding. Not only did I find examples of the specimens I had seen in the museum collections but I encountered with several new and peculiar species.


A few examples:

Kangaroo Island Micro Katydid


The world’s smallest known katydids occur in the genus Microtettigonia. Microtettigonia kangaroo Rentz with males measuring about 5 mm in length with females slightly larger occurs on the island and adjacent mainland. An adult male of a related species, M. tachys Rentz, the first known species is seen on the Australian 2 cent coin. The minute wings, used solely in sound production, are mostly concealed beneath the pronotum (thoracic shield). This little katydid lives mostly on the ground where it feeds on a variety of vegetation. Forbs, herbs and grasses comprise its diet. It is diurnal. After dark it retreats to the safety of dense grasses and clumps of lomandra.




Microtettigonia tachys, a species very similar to M. kangaroo Rentz, adult male.






Microtettigonia tachys, a female perched on a piece of lettuce.
When studied (Rentz, 1979) this tiny katydid was deemed to be so different that it was placed in its own subfamily. Subsequently additional species were discovered in South Australia and Western Australia all in similar habitats and very threatened by habitat destruction, especially by fire.

Kangaroo Island Robust Fan-winged Katydid


Psacadonotus insulanus Rentz is known only from Kangaroo Island where it is rare and very wary and difficult to find. It is one of eight species in the genus all of which are southern in their distribution. They occur in heath habitats on both sides of the Australian continent. This katydid lives on or near the ground with the daytime hours spent in leaf litter or amongst dead twigs. Activity commences in late afternoon just before sunset. Males perch in dead branches within a 50 cm of the ground and have a short but distinctive call. The katydids are so secretive that they cannot be coaxed to move when disturbed. Females of all species are rarely seen because of this habit.


Fan-winged katydids are so-called because the hind wing of both sexes is fan-like and black. When the katydid is threatened it is produced and is rubbed against special spines on on the internal ridge of the hind leg causing a scratchy sound. The jaws of this katydid are powerful and probably used to crack seeds and fruits. Captive specimens also ate grasshoppers so that suggests they may be at least partially predaceous.



Psacadonotus insulanus Rentz, Kangaroo Island Robust Fan-winged Katydid, adult male.






Ben Lexcen's Vernal Katydid

Imagine a katydid with a "winged keel". Well one does exist. It is a member of an Australian endemic subfamily, Zaprochilinae, of the katydid family, Tettigoniidae. All known members of the subfamily feed on pollen and nectar. The species of concern here is Kawanaphila lexceni Rentz. It is one of 11 known species in the genus that occur in heath habitats in the southern part of the Australian continent.

For non-Australian readers who may be unfamiliar with the "winged keel" this refers to the 1983 sailing success of Australia wresting the America's Cup from the USA because of the invention of the winged keel by Ben Lexcen. Ben died before "his" species was described but his widow was informed and said he would have approved of the honour.







Ventral surface of the abdomen of a female of K. lexceni illustrating the "winged keel" at the base of the subgenital plate.


All Kawanaphila species are small, males measuring about 16 mm, females slightly larger. All species are elongate and hairy. They have elongate (prognathous) mouthparts that enable them to dip deep into flowers and sip nectar. To further facilitate that habit, the mandibles are grooved, supposedly forming a channel to take up the nectar. The hairy body of Kawanaphila specimens in museums is often adored with pollen indicating that these katydids may be pollinators. Males have very short wings that are used only to produced species-distinctive sounds that attract females. The ovipositor of all females is stout and heavily built suggesting it may be used to lay eggs in plant tissue.

Vernal Katydids are common where they occur but they went largely unnoticed in the taxonomic world for two reasons. They reach their peak abundance in late winter and early spring when collectors are not in the field and, to the untrained eye, they appear as nymphs of some other katydid. Vernal Katydids are very abundant and multitudes of singing males can be heard with the mini bat-detector on a winter night.

Vernal Katydids frequent thin-stemmed plants such as Lepisdosperma, a plant that is often associated with marsh habitats. However, some species can be found well of the ground feeding on Banksia flowers. All members of this subfamily are fragile insects. Drought and fires could have a devastating affect on their populations. This species was found at several localities on Kangaroo Island and on the adjacent Fleurieu Peninsula of South Australia.



Kawanphila iyouta Rentz, adult male on Lepidosperma sp. stridulating at night.



Kawanaphila nartee Rentz, adult female, the most widespread species of the genus at night.





Zaprochilus australis (Brullẻ), an Australian Twig-mimicking Katydid at night.


Z. australis (another member of the Zaprochilinae) is one of the oldest-known Australian katydids. Zaprochilus comprises four species. The narrow tegmina, concealing the fan-like hind wings, have a rolled appearance. This species is most most widespread of the genus with examples known from coast to coast in the southern half of the continent. It has a historic association with Kangaroo Island because the type specimen was collected there.


It seems that the initial specimen sent to Brullẻ in 1835 was collected by Nicholas Baudin, on an expedition authorised by Napoleon Bonaparte. Two vessels comprised the "fleet" on the expedition- Le Gẻographe and Le Naturaliste. Baudin was the captain of Le Gẻographe and sheltered around Kangaroo Island during a storm in 1802. A second trip was made with Le Gẻographe and another ship, the Casuarina, on and around the island from 27 December 1802 to 1 February 1803. It is uncertain whether the type of Z. australis was collected on the first or the second trip.


Metaballus mesopterus Rentz the Kangaroo Island Marauding Katydid



Metaballus mesopterus Rentz the Kangaroo Island Marauding Katydid at night.

Ten known species comprise Metaballus, all of which are southern in the Australian distribution. They are often common and during years of peak abundance attract public attention because of their large size and contrasting colours.

Fully-winged, very short-winged and semi fully-winged (mesopterous) species are known. M. mesopterus is active day and night. Groups of singing males can easily be heard when you walk through their habitat. All species are known to be carnivorous feeding on a variety of insects. This species is endemic to the island and has been observed at several localities in addition to the type locality of Vivonne Bay.

Conclusions


Above a few examples of the katydids (family Tettigoniidae) that are endemic to Kangaroo Island. Other orthopteroids such as grasshoppers (Monistria yeelana insulana Rehn, now Yeelanna argus (Rehn), were considered as endemic but more recent studies have concluded that they are not endemic. Kangaroo Island is the type locality for the widespread phaneropterine katydid Caedicia marginata Brunner von Wattenwyl. Apteronomus Tepper, an endemic Raspy Cricket genus (Gryllacrididae) with two species, A. bordaensis Tepper, A. tepperi Karny is known only from Kangaroo Island.




Many other insects are important occupants of Kangaroo Island. Their fate after the extensive fires remains to be determined. About 50% of the island was lost to the fires. Hopefully enough "seed area" remains to prevent the extinction of these insects.






Literature

Brullé A. G. 1835. Cinquième Ordre. Orthoptères. In Audouin & Brullé. Histoire naturelle des insectes. 9 [1] (5):1-225 [225–416 in 1836]

Rentz, D. C. F. 1985. A Monograph of the Tettigoniidae of Australia Volume 1 The Tettigoniinae, with an appendix by D. H. Colless, CSIRO Australia 384 Pp.

Rentz, D. C. F. 1993. Tettigoniidae of Australia Volume 2 The Austrosaginae, Zaprochilnae and Phasmodinae with contributions by D. H. Colless and N. Ueshima. CSIRO Australia. Pp. 386

Rentz, D. C. F. 2001. Tettigoniidae of Australia Volume 3 The Listroscelidinae, Tympanophorinae, Meconematinae and Microtettigoniinae. CSIRO PublishingCollingwood, Vic. 524 Pp.
Rentz, D. C. F. 2010. A Guide to the Katydids of Australia. CSIRO Publishing,Collingwood, Vic. 214 Pp.