8
No. 57 September/October 1999 Notes from the Editor Tropical Topics An interpretive newsletter for the tourism industry The importance of the living dead Although a dead tree, in a living forest, is viewed as a loss of life, nothing could be further from the truth. The decaying wood is seething with life as insects, together with fungi, work on breaking it down. These insects — termed saproxylic — contribute to the health of forests and their inhabitants in many ways: They recycle the nutrients once gathered by the trees, eventually making them accessible to the next generation of forest growth. By converting wood into protein (themselves) in both adult and larval forms they provide food for numerous birds and other animals. They provide homes. Around the world, woodpeckers play an important role in creating holes in trees but in Australia, a continent with more hole- nesting birds and mammals than anywhere else, there are none of these wood-drilling birds. Our possums and parrots would have great difficulty excavating their nest and den holes if it were not for wood-boring insects. To maintain numbers of these useful creatures, their habitat — ‘overmature’ trees and dead logs — needs to be protected. Studies in temperate forests have shown that logged forests have significantly fewer saproxylic insects than less disturbed forests, because trees have been removed before they are old enough to produce dead wood. Without noticing, Europeans were losing these insects to the point where a disproportionately high number of them now feature on the endangered lists. Little is known of how logging has affected saproxylic insects in tropical forests. However, Rainforest CRC researcher, Simon Grove, is keen to redress the balance. He is currently studying the saproxylic insects — specifically beetles, the main group — which munch on dead wood in the lowland Daintree rainforests. To date Simon has collected 450 different species but anticipates finding many more. He hopes to discover whether there are differences between what beetles are found in logged and unlogged areas of the Wet Tropics. His ultimate aim is to work out a standard, or indicator, which forest managers could use to measure sustainable rainforest management. Rather than looking at large animals, when evaluating whether a logging operation is causing long-term harm to a forest system, it may be more useful to look at the amount or variety of dead wood or overmature trees which would be needed to sustain the myriad insects that live there. The greatest loss of biodiversity is probably at the micro level — but these little creatures are no less important for being small. Instead, they are a vital part of the whole. This beetle (Kaveinga frontalis) is a common beetle of old-growth forests in the Daintree where it depends on a continuous supply of well-rotted logs. Simon has found this and two closely related species in his study sites. The only European species of this family is almost completely extinct, presumably because of the way forests have been cleared or intensively managed over the centuries. Hopefully, the same fate does not await Kaveinga. Beetles Please note that you are welcome to photocopy Tropical Topics. However, if the text is reproduced separately it must not be altered and must acknowledge the Environmental Protection Agency as the source. Illustrations must not be reused separately without permission. Please contact the editor (details on the back page) if in doubt. There is not much that beetles will not eat and few places, apart from the sea, where they do not live. They feed on almost every animal and vegetable material (including strychnine) and some inorganic materials as well. Given the phenomenal number of beetle species in the world (see p2) it is amazing that we see so little of them. In fact, they are generally hidden away, many of themlivingjustbeneaththesurface of things. This Tropical Topics takes a closer look. I'd like to thank Simon Grove and Nigel Stork, Rainforest CRC, and Geoff Monteith, Queensland Museum, for their valuable help with this issue. Illustration James Gilbert

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Page 1: Tropical Topics - wettropics.gov.auTropical Topics An interpretive newsletter for the tourism industry The importance of the living dead Although a dead tree, in a living forest, is

No. 57 September/October 1999

Notes from theEditor

Tropical TopicsAn interpretive newsletter for the tourism industry

The importance of the living deadAlthough a dead tree, in a living forest, is viewed as a loss of life, nothing couldbe further from the truth. The decaying wood is seething with life as insects,together with fungi, work on breaking it down.

These insects — termed saproxylic —contribute to the health of forests andtheir inhabitants in many ways:• They recycle the nutrients oncegathered by the trees, eventuallymaking them accessible to the nextgeneration of forest growth.• By converting wood into protein(themselves) in both adult and larvalforms they provide food for numerousbirds and other animals.• They provide homes. Around theworld, woodpeckers play an importantrole in creating holes in trees but inAustralia, a continent with more hole-nesting birds and mammals thananywhere else, there are none of thesewood-drilling birds. Our possums andparrots would have great difficultyexcavating their nest and den holes ifit were not for wood-boring insects.

To maintain numbers of these usefulcreatures, their habitat — ‘overmature’trees and dead logs — needs to beprotected. Studies in temperate forestshave shown that loggedforests have significantlyfewer saproxylic insects thanless disturbed forests, becausetrees have been removed beforethey are old enough to producedead wood. Without noticing,Europeans were losing theseinsects to the point where adisproportionately high numberof them now feature on theendangered lists.

Little is known of how logginghas affected saproxylic insects intropical forests. However,Rainforest CRC researcher, SimonGrove, is keen to redress the

balance. He is currently studying thesaproxylic insects — specificallybeetles, the main group — whichmunch on dead wood in the lowlandDaintree rainforests. To date Simonhas collected 450 different species butanticipates finding many more. Hehopes to discover whether there aredifferences between what beetles arefound in logged and unlogged areas ofthe Wet Tropics. His ultimate aim is towork out a standard, or indicator,which forest managers could use tomeasure sustainable rainforestmanagement. Rather than looking atlarge animals, when evaluatingwhether a logging operation is causinglong-term harm to a forest system, itmay be more useful to look at theamount or variety of dead wood orovermature trees which would beneeded to sustain the myriad insectsthat live there.

The greatest loss of biodiversity isprobably at the micro level — butthese little creatures are no lessimportant for being small. Instead,

they are a vital part of thewhole.

This beetle (Kaveinga frontalis) is acommon beetle of old-growthforests in the Daintree where itdepends on a continuous supply ofwell-rotted logs. Simon has foundthis and two closely related speciesin his study sites. The onlyEuropean species of this family isalmost completely extinct,presumably because of the wayforests have been cleared orintensively managed over thecenturies. Hopefully, the same fatedoes not await Kaveinga.

Beetles

Please notethat you are welcome to photocopyTropical Topics. However, if thetext is reproduced separately it mustnot be altered and mustacknowledge the EnvironmentalProtection Agency as the source.Illustrations must not be reusedseparately without permission.Please contact the editor (details onthe back page) if in doubt.

There is not much that beetles willnot eat and few places, apartfrom the sea, where they do notlive. They feed on almost everyanimal and vegetable material(including strychnine) and someinorganic materials as well.

Given the phenomenal number ofbeetle species in the world (seep2) it is amazing that we see solittle of them. In fact, they aregenerally hidden away, many ofthem living just beneath the surfaceof things. This Tropical Topicstakes a closer look.

I'd like to thank Simon Grove andNigel Stork, Rainforest CRC, andGeoff Monteith, QueenslandMuseum, for their valuable helpwith this issue.

Illu

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Jam

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Page 2: Tropical Topics - wettropics.gov.auTropical Topics An interpretive newsletter for the tourism industry The importance of the living dead Although a dead tree, in a living forest, is

2

Life in a rotten log“There is nothing more alive than a dead tree (Il n’y a rien plus vivant qu’un arbre mort).” Jeannine Petit, Frenchenvironmentalist.

Big on numbers, small on volume “The number of minute and obscurely-coloured beetles is exceedingly great. It is sufficient to disturb the composure of anentomologist’s mind, to look forward to the future dimensions of a complete catalogue.” Charles Darwin, The Voyage ofthe Beagle (1839)

Darwin, whose interest in the natural world began with abeetle collection, had an inkling of how many beetles therewere, but it is unlikely that he had any real idea of theenormity of their numbers. It is now estimated that theymake up fully one quarter of all species on earth —including plants, mammals, fish, birds and all the otherinsects put together. In just one hectare of forest inSulawesi (Indonesia) researchers found more than 4000while, even in the less beetle-rich temperate zone, it ispossible to collect over 1000 species from a single Britishback garden. Worldwide, about 350 000 beetle species havereceived names, but many, many more remain unnamed. Thetotal number is a matter for wild guesswork (see Howmany?, this page). As far as Australia is concerned, a totalof 30 000 beetle specieshas been suggested —but this figure is bound tobe an underestimate.

While the mostspectacularly large and colourful specimens are the onesoften put out for public display, the collections hidden awayin entomologists’ cabinets give a more realistic idea ofbeetle dimensions. Tray upon tray, at first glance, appear tocontain empty labels — long names without anyaccompanying specimens. Then you realise that thoselabels also carry little specks, no larger than full stops, andthat those misplaced punctuation points are actually thebeetles. The vast majority of beetles are under 2mm inlength and many are less than half a mm.

It will be a long time — if ever — before a complete beetlecatalogue is finalised, but, sadly, it will be a much smallerpublication than it would have been in Darwin’s time. Therate at which natural habitat is being destroyed has ledscientists to estimate that anywhere between 2000 and 30000 animal and plant species are being made extinct eachyear. A large proportion of these are likely to be beetles.

How many?The systematic cataloguing of plants and animals beganwith the Swedish biologist, Linnaeus, about 240 yearsago. Since then roughly one and a half million differentspecies* have been described and named — but that isonly the tip of the iceberg.

The question which now perplexes scientists is not howmany more species there are, but, simply, how big is theiceberg? One thing they do know is that most of it ismade up of insects. Relatively few mammals, birds andother large animals remain to be discovered but the morework which is done on insects, the more reluctantscientists become about putting a figure on how manythere are. The greatest unknown is the insect fauna of theworld’s tropical rainforests. Trees experimentally foggedwith insecticides have provided a rain of specimens and itis not unusual for 90 percent of them to be new toscience. For example, in a set of 65 different speciesbelonging to one minor family of beetles collected inSulawesi, only three had previously been described.

Differentiating species is not simple. In some cases, thesame species may be accidentally described several times— different scientists may have ‘discovered’ and namedit, males and females may look like different species or theinsect may have several quite distinct forms. On the otherhand, different species may have been given the samename. The definition of a species is that it is not able tointerbreed with any other species — but this is verydifficult to prove with dead insects which are categorisedon form alone.

The harder scientists try to answer the question “Howmany?”, the more likely they are to simply say, “A lot”.

*This refers to ‘higher’ organisms; an appropriateclassification system has not been discovered forbacteria, viruses and the like.

“The Creator, if He exists, musthave an inordinate fondnessfor beetles.” J.B.S.Haldane.

Striped possums are particularlyadept at locating and teasing beetlelarvae out of dead wood, using theirelongated fourth fingers. Logs prisedapart by striped possums are acommon sight in the lowland WetTropics.

Beetles comprise the main group ofwood-eating insects. Indeed, it hasbeen calculated that the number ofbeetle species which live in dead anddying wood outnumber all the world’sspecies of mammals, birds, reptiles andamphibians by at least two to one.

Beetles living in a rotten log mayinclude some which feed directly onthe dead wood (borers) as well asspecies which feed on thedecomposing fungi. Yet others feed onthe waste from these beetles — orsimply prey on all the others. Somelive there only as larvae, others spendtheir entire lives in the rotting wood.

Large numbers of jewel, stag andlongicorn (longhorn) beetles as well asthe celebrated rhinoceros beetle feedon dead wood.

Mueller’s stag beetleis completely dependent, in the larvalstage, on dead wood which has beeninfected with fungus. Found only inthe Wet Tropics this magnificentbeetle, which gleams with metallicred and green highlights, has beencalled the most beautiful insect in theworld. Only the males have 'antlers'which are used as levers duringconflict. Each tries to to pass themunder the rival's body and, by raisingthem, to dislodge their opponent.

A note to tour guides: Next time you find yourself in a quiet forest, bear in mindhow much can be said about dead wood (see also pages 1, 4 and 5).

Page 3: Tropical Topics - wettropics.gov.auTropical Topics An interpretive newsletter for the tourism industry The importance of the living dead Although a dead tree, in a living forest, is

Out and about

3

Channel-billedcuckoos havesimilar migratoryhabits, arrivingfrom New Guineato breed aboutthe same timeas the PIPs.Known by birdwatchers as ‘flyingT-squares’, because of their ratherT-shaped form in flight, they lay theireggs in the nests of crows,currawongs, magpies and magpie-larks(pee-wees) — birds which might seemtoo clever and aggressive to allowsuch an imposition. The cuckoos donot attract much attention until thefirst storms which prompt them to emitloud racous calls — a habit which hasearned them the name ‘storm-bird’.These birds eat figs and sometimesgather on the trees in small feedingparties when they have finishedbreeding.

As spring progresses, birdsong isincreasing and many pairs are gettingbusy with nesting. Listen for williewagtails singing their ‘sweet prettylittle creature’ song in the dead ofnight. Is this stimulated by moonlight— or perhaps by artificial streetlights?Certainly September and October are

good times to hear this.

Pied imperial-pigeons (PIPs) were firstspotted on Low Isles and in Cairns inmid-August this year. There is ageneral impression on the mainlandthat they seem to have arrived earlythis year, but this is not borne out bythe survey on Low Isles where belowaverage numbers (451) were countedat the beginning of September. Groupscan be seen feeding on Alexanderpalm berries, a very important fruitearly in the breeding season.

A Handbook for tour guides in theDaintree River to Cape Tribulation areawas published by the Wet TropicsManagement Authority recently. Alarge part of the Handbook is a sectiondevoted to Talking Points, whichrelate to 18 sections of the trip north.Items of interest, such as history, localplants and animals, frequently askedquestions and general facts are givenfor each point. Other sections dealwith ecotourism, local Aboriginalcustodians, special features of thearea, maps and reading lists.

Thoroughly researched and written,largely by Juliana Ledger and EllenTerrell, the Handbook contains awealth of information and is of interestand relevance for tour guidesthroughout the Wet Tropics.

Update note (2006):This handbook is still available as aCD. Contact the Wet TropicsManagement Authority, Ph: 4052 0555.

Some items, past their 'use-bydate', have been removed fromthe web version of the newsletter.

Fruit-eating birds are attracted tocorky bark (Carallia brachiata) trees atthis time of year, as the orange fruitbegin to ripen. This tree is a member ofthe Rhizophoraceae family ofmangroves but is one which hasadapted to rainforest habitats. Abushy tree, with glossy leaves, itmakes a good addition to the gardenor resort. It also attracts the attractiveblack, white and yellow day-flyingfour-o’clock moths, whose caterpillarsfeed on the foliage.

Page 4: Tropical Topics - wettropics.gov.auTropical Topics An interpretive newsletter for the tourism industry The importance of the living dead Although a dead tree, in a living forest, is

Holy rollersThe sacred scarab beetles of AncientEgypt were actually lowly dung beetles.They were thought to produce life fromdeath because the balls of decayedmatter which they rolled and buried(along with their eggs) produced newlife. Similarly, the sun god was seen asa great scarab which rolled the ball ofthe sun across the heavens. Every daythe sun was ‘reborn’ — so scarabs becamethe symbol of rebirth. Likewise, any good ecologist alsoappreciates the worth of these insects since they do indeedpromote life by recycling nutrients from waste. Apart fromfeeding on it themselves, adult beetles use dung to providefood for their larvae. The ball rollers (there are also burrowers)do this by rotating a piece of dung with their hind legs andplastering with the front legs until the ball is the correct size.The female then hollows out a cavity and, after reversing in,lays an egg. When the egg hatches, the larva remains withinthe ball feeding on the dung until it pupates and emerges as anadult.

Some native dung beetles save themselves the trouble ofsearching for dung by clinging to the fur of wallabies, near tothe anus. They are thus able to jump on to the faecal pellets asthey are produced and fall to the ground with them. Others are‘cuckoos’, laying their eggs in the dung balls collected by otherspecies.

Scarab beetles (Scarabaeidae)One of the largest Australian beetle families, this group contains at least 3000 species. Adults tend to have front legs adapted forburrowing, since their larvae often feed in the soil. Cane beetles, whose larvae feed on the roots of sugar cane plants, are scarabs.

Also included in the scarab group are thenectar-feeding, day-flying, brightly-coloured flower scarabs, which buzz loudlyin flight because they are able to fly withoutlifting their elytra — the hard wing covers(see p7). Flower beetles include the brightgreen ‘grasshopper’ beetles, and thefiddleback beetles, named for the violin-likepattern on their backs. Furrowed rosechafers, which have attractively lined blackand tan backs, are fairly common in thetropics.

Christmas beetles also buzz loudly in flight.There are many types, a fact whichsometimes leads to arguments betweenpeople with a fixed idea of their appearance.As larvae, these beetles feed on grass rootsbut as adults they can seriously defoliatetrees, particularly eucalypts, during summer.The aptly-named golden scarab, found inthe Wet Tropics, is a Christmas beetle.

This new species of largeflightless dung beetle,

Aulacopris matthewsi,was discovered byQueensland Museumresearchers on thesummit of MtSorrow, behind Cape

Tribulation — the onlyplace it has ever beencollected.

Ladybirds (Coccinellidae)A favourite among beetles, the standard ladybird iswelcomed by gardeners for its, and its larva’s, habitof feeding on garden pests such as aphids,

mealybugs, mites and scale insects. In fact, anumber of Australian species have been used tocombat agricultural pests overseas. However,some species, such as the twenty-eight spottedladybird, feed on foliage of tomato, pumpkin andpotato plants. The bright colours of many ofthese beetles warn potential predators that theyare poisonous — toxins are exuded from theirknees. There are over 300 species of ladybirds inAustralia, most of them small and easilyoverlooked.

Fireflies (Lampyridae)Fireflies are beetles. In Australiamost are found in the wetter areas,favouring rainforests andmangroves. The blinking light,which comes from segments onthe underside of the tip of theabdomen (far right), is created by achemical process. This is triggeredwhen the beetle opens smallapertures to allow air in. The chemicalsreact to the presence of oxygen with a blaze of light, but are soonexhausted. However, they quickly recharge in time for the nextburst — hence the flashing effect. Males are the main flashers,cruising at night in search of a mate. With enormous eyes and avisor to keep his attention focused, he is on the lookout for ananswering blink which indicates a suitably impressed, butflightless, female.

Firefly larvae, and pupae, are also slightly luminous. The larvaefeed on snails, which they are able to paralyse, but it is thoughtthat the adults (like some other beetles) do not feed at all. Theirshort lives add a certain urgency to their flashy courtingbehaviour.

Passalid beetles (Passalidae)Passalid beetles are found particularly in wettropical and subtropical forests where they feed ondecaying wood. Many are large and shiny black with‘waists’ between front and back sections. They are ofparticular interest because they live in semi-social familygroups, with parents caring for and feeding their young.The young larva lets its parents know where it is byrubbing hind and mid legs together to produce a sound.The adults (which rub hind wings against abdomens inreply) then chew up wood for the larva to feed on.Their presence in a log can often be detected by thepresence of large piles of sawdust collecting beneath the log.

Ladybird larvaeare just as usefulas adults atcontrolling pests.

Introduced rollersMore than 350 different species of dung beetles are native toAustralia but they are accustomed to utilising the dry pellets ofmarsupials and are unable to cope with the large moist pats ofintroduced cattle. Apart from providing breeding grounds for bushflies and other pests, it was discovered that cowpats were rapidlycovering up grazing land at the estimated rate of one million hectaresa year! In order to deal with the growing problem, in the 1960s anumber of European and African dung beetles were introduced. Theygot rolling and the result has been the improvement of pastures, asnutrients previously held in the pats are recycled, plus a welcomereduction in numbers of bush flies and other nuisances. Incidentally,certain mites which feed on fly and other insect larvae, use the dungbeetles as vehicles for transportation between pats.

Bits of beetle diversity**

4 **Note: It is possible to mention only a few of the 117 Australian beetle families

*

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Rhinoceros beetles, which belong to this group,attract more interest than almost any other beetlespecies. The males develop long, horn-likemouthparts which are used in jousting matches

between rivals competing for a female. The size of the‘horns’ depends entirely on how well the beetle fed, indead wood or compost, during its larval stage (see

variations, right). The fiercesome appearance of these beetles, alongwith the loud hissing sound they produce when stressed, seems to actas an effective deterrent against many predators.

Page 5: Tropical Topics - wettropics.gov.auTropical Topics An interpretive newsletter for the tourism industry The importance of the living dead Although a dead tree, in a living forest, is

Stagbeetles(Lucanidae)Named for the

sometimesantler-like

mouthparts of somemales, stag beetles are found in wet areaswhere their larvae live in decaying fungus-infested logs. Adults, however, mayfrequent the canopy feeding on nectar,young leaves, sap or fruit. Being nocturnal,stag beetles are not often seen althoughthey are sometimes attracted to lights.Australia is home to more species of stagbeetle than most parts of the world,although the majority live in the coolersouthern forests. In the Wet Tropics, theyare most diverse at higher altitudes.

Weevils (Curculionidae)The largest Australian beetle family, with 6000 known members at the last count, is the group containing weevils. No fewer than 150different species have beem collected just from the absolute summit of Mt Bellenden Ker.

Hear no weevil, see no weevil speak no weevil!

Ambrosia beetles have earned their name from the yeast-like ambrosia fungi which they cultivate for food. Knownalso as pinhole borers, they make tiny tunnels into theheartwood of dead or dying trees, lining the tunnel walls withthe fungi. They even carry it with them when they move from tree to tree. Some ambrosiabeetles also build colonies with societies not unlike those of termites or bees. The burrowsof ambrosia beetles are not a perfect refuge, since certain predatory beetles follow them intotheir tunnels for an easy meal.

Many weevils are pest species feeding onall parts of trees, vegetables, grains andornamentals. However, while we maycurse the weevils which work their wayinto our bags of flour and spaghetti,other species have proven themselves tobe very useful in the fight against weeds.Two different weevil species, both fromBrazil, are being used to control Salviniaand water hyacinth, two South Americanwater weeds which choke waterways intowhich they have been dumped.

Aquatic beetlesBeetles inhabit every part of the world except the sea. Twolarge families live in freshwater, where they are able to diveby storing air under their elytra or abdomen. Most havestreamlined bodies and modified legs which act as oars.Sometimes they crash-land on the shiny paintwork of cars inwhat is assumed to be an unfortunate case of mistakenidentity. (For more details see Tropical Topics 44.)

Longicorn beetles(Cerambycidae)Also known as longhorn beetles,members of this large family havelong antennae which measure from three-quarters to several times the length of theirbodies. This increases their sensory powers and may also help them to survive attacks —a small bit of antenna lost to an ant doesn’t matter so much if they are extra long. Larvaegenerally feed on dead and dying wood; some large ones are a favourite traditionalAboriginal food. This group contains Australia’s largest beetle, the 80mm Batrocerawallacei, from the Cape York Peninsula, and the slightly smaller and brightly coloured B.boisduvali, common in the Wet Tropics.

Rove beetles (Staphylinidae)Many rove beetles are long, with smallelytra, and flexible bodies. Lacking thesolid, hardened appearance of thestandard beetle, they are easily mistakenfor other sorts of insects, such asearwigs. Most are black or brown,although some Wet Tropics speciesare purple and green. It has beennoticed that some rove beetlesfold their wings asmany as 12times, to fitthem undertheirsmallelytra.

Weevils are distinguished by the elongated snout (rostrum) which they use to drill intoleaves and bark to feed and, in the case of females, to create egg chambers. However,bark beetles and ambrosia beetles, whose rostra are inconspicuous, are also included inthis group.

Ground beetles (Carabidae)These beetles number about 2500 species inAustralia, with 500 different species being foundunder the bark of eucalypts alone. Most arepredators, both as larvae and as adults, the latterequipped with long legs for fast movement.Although many of the species which live on theground are flightless, they are swift, effectivehunters, which can often be seen by day. Oneparticularly ferocious group of species hasearned the name ‘tiger beetles’.

The ground beetle,Mecynognathus dameli(above), is a 75mmflightless scavenger andpredator from the tip of CapeYork peninsula. It is fearedthat cane toads, when theyarrive, may threaten itsexistence, as they seem tobe doing for manyground beetles in the WetTropics.

Jewel beetles (Buprestidae)This large family includes some of our most attractively-coloured beetles, many with ametallic sheen. Adults tend to feed on nectar, with some preferring leaves, while most larvaefeed under bark or bore into wood, stems or roots. Larvae which feed on hoop pine havebeen known to emerge as adults from furniture up to four years after it was made from thetimber. Smaller species are responsible for the galls formed on many trees while others areleaf miners, tunneling around in the leaf tissue. Forest-dwelling tribes in many parts of theworld use the colourful elytra in ear-rings or necklaces.

5All illustrations marked * are reproduced from The Insects of Australia, # from Australian Weevils, courtesy CSIRO.

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One particular long-snouted weevil (Ithystenushollandiae) (left) which lives on the outside of

logs has an interesting sex life. The males,which have unusually long legs, come in two sizes

— large and small. The large male stands over hischosen female, but the small male sometimes sneaks

between his legs and mates with the female instead — astrategy not unlike that of parrotfish!

Elytra

Page 6: Tropical Topics - wettropics.gov.auTropical Topics An interpretive newsletter for the tourism industry The importance of the living dead Although a dead tree, in a living forest, is

Tourist talkENGLISH GERMAN JAPANESE

6

Questions & Answers Facts and statsQ What is the current situation withpharmaceutical extracts from FarNorth Queensland rainforest plants,in particular black bean(Castanospermum australe)?

A The National Cancer Institute inUSA was interested in the chemicalproperties of black bean. Scientistshave found compounds in the seedswhich are very active againstenzymes in the HIV virus — but theycannot be used because the beansare also very toxic. However, thecompounds are used as a benchmarkagainst which other compounds canbe tested so it has become apharmaceutical tool for furtherinvestigation.

Researchers studying the seeds ofthe rare ribbonwood tree(Idiospermum australiense), foundonly in the Daintree and theBellenden Ker area, have discovereda new chemical called idiospermulinewhich may prove to be medicallyuseful. Idiospermuline affectstransmission of messages betweenindividual nerve cells and has beenresponsible for seizures in cattlewhich have eaten the seeds.However, in controlled doses it mayhave medical uses.

The Queensland PharmaceuticalResearch Institute is in the process ofinvestigating all Queensland plantsand receives about 2500 plantsamples a year. (A sample is just partof a plant, such as the flowers or the

bark; roughly 10-15

samples are derived from each plantspecies.) After seven years they nowhave about 20 000 samples and hopeto complete the job in 10. Potentiallyuseful components need to berigorously tested so the lead timebetween discovery of a compoundand its arrival in the market place isabout 10-15 years.

Q Where do march flies go whenthey are not around?A Having mated and laid eggs, theadults probably die — but the badnews is that the larvae aredeveloping in their absence. Theselarvae are aquatic and are found increeks and, to a certain extent, instanding water. That is why theadults are common in river valleyswhere they have gathered to mate.They seem to be most abundant inthe build up to the wet season —possibly the rains flush out many ofthe larvae, thus causing a drop innumbers.

Like mosquitoes, it is only the femalemarch flies which bite, requiring ablood meal for reproduction. Themales are quite rare and may frequentthe treetops. Curiously, the peskyfemales of different types may preferdifferent parts of the anatomy, onetype specialising in ankles whileanother type may be attracted to thehead. They seem to be especiallyattracted to blue, black and coloursin between.

Around the world, march flies havedifferent names. They are also calledhorse or deer flies as well as green-heads — a reference to their largeeyes which have iridescentreflections. (In males these eyesalways meet in the middle.) The name‘march’ may have originally comefrom the word ‘marsh’.

beetleforewingrottenwoodlarvafungusto borerhinocerosrhinoceros beetlestagstag beetledung

kou chumae banekusattakiyouchukabihori nukusaikabuto mushio jikakuwagata mushifun

KäferVorderflügelvermodertHolzLarvePilzbohrenNashornNashornkäferHirschHirschkäferMist

In England and the United States,foresters who are concerned about theloss of wood-inhabiting insects use ring-barking or even explosives to artificiallyage some of the trees.

The world’s largest beetles, from SouthAmerica and Fiji, grow to a length of200mm — almost the width of this page.They are almost 800 times larger than thesmallest ones. The heaviest beetle, theAfrican goliath, weighs up to 100g.

The word ‘beetle’ comes from OldEnglish words meaning ‘little biter’.

Fossils of beetle-like insects, found inEastern Europe and Central Asia, dateback about 280 million years. They differfrom modern beetles in several ways —true beetles first turn up in the fossilrecord 40 million years later.

Males of the largest Australian jewelbeetle have an unfortunate habit of tryingto mate with discarded brown beer bottleswhich resemble the females in colour,texture and sheen.

Some beetles break the life cycle rules.Some females never develop beyond thelarval stage, some larvae give birth tolarvae, some adults do not lay eggs butproduce live young and others reproducewithout mating.

Some larvae, particularly if their foodhas a low food value, may have long lives;an American longhorn beetle larva wasrecorded as living for over 40 years indry wood. Other larvae have been keptwithout food for five years. Continuingto moult, they shrank to one six-hundredth of their original weight. Morenormally, beetles can become dormant(diapause) at any stage of their life.

Stag beetles are kept as pets in Japan andcan be bought from vending machines.Recently one measuring 80mm, whichwas 1mm longer than the previous recordholder, changed hands for the equivalentof $135 000.

The chemicals used by fireflies to emitlight do so in the presence of certainbacteria which cause urinary tractinfections, so they have been used to testfor the bacterial presence.

Woodworms are actually the larvae offurniture beetles. They can reduce a pieceof timber to a shell containing crumblingwood and powder. The deathwatch beetlealso damages timber, usually oak. Itsname comes from the belief that the tickingmating signal made by the adult beetlesbanging their heads on the floor of theirtunnels indicateded the approach ofdeath in the house.

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What is a beetle?The scientific name for the beetle group, Coleoptera, means ‘sheath winged’.This refers to their most important characteristic — forewings which havebecome hardened coverings known as elytra. These protect the folded hindwingswhen they are not in use. The elytra are not completely useless when the beetleflies, but are often turned to point forwards and upwards, probably acting likeaeroplane wings to give the beetle some lift.

Compared with many soft and vulnerable insects, the beetle is a well-armouredtank. Its hard but flexible shell (cuticle), the structure of which has been likened tofibre-glass, protects it well from predators and from infection by microorganisms,as well as against physical accident. An additional wax layer helps prevent waterloss. With this tough construction, it is perhaps not surprising that these insectshave become the most successful of all animal groups.

The majority of beetle larvae, on theother hand, are fat, soft and caterpillar-like, with or without legs — look inany compost heap and you are likelyto find them. They take many variedforms, but are most easilydistinguished fromother insect larvaeby their hardenedheads. Many alsohave strong jaws,used to bitethrough toughroots and stemsand even timber.

When the larva isready to pupate it stops feeding andmay leave the food source. Somesimply tunnel under stones, but leafand stem feeders often drop on to thesoil and burrow beneath the surface.Some ground beetles burrow down fora matter of metres — but wood borersmay head for the surface so that, asadults, they are able to escape easily.Water beetle larvae usually leave thewater and burrow into nearby soil. Thelarvae hollow out a chamber in whichto pupate, perhaps lining it with a typeof faecal cement. Some produce acocoon but this is rare in beetles.

Life on the mountain topsResearchers from the Queensland Museum have found that in the Wet Tropics many beetlespecies, notably the flightless ones, are found on just one mountain top and nowhere else.These mountains have isolated each beetle population from every other for millennia, andhave gradually enabled them to evolve into separate species.

As part of this research, the beetle faunas of 49mountain tops were assessed for species richness andrarity. When the numbers of species were counted, MtBellenden Ker came out top with 84 species, while MtElliot, south of Townsville, ranked 36th with only 17species. But, when their rarity values were compared, MtElliot came out top and Bellenden Ker dropped to fifthplace. Mt Elliot is far from other mountains so the insectfauna presumably evolved in isolation from early times,whereas those on other mountain tops were able tomove around a little more freely, leading to a morewidespread distribution.

These findings are important to managers, who need toassess the natural values of different mountain topswhen faced, for example, with requests for permission tobuild transmission towers.

This smallpredatorybeetle,Philipis

bicolor, is known only fromthe summit of Mt Demi, the1100m mountain whichlooms above the town ofMossman.It lives on thetrunks of mossy trees.Queensland Museumsurveys discovered 32 newspecies belonging to thegenus Philipis in the WetTropics, most of themrestricted to just one or twomountains.

Not beetlesCockroaches are notbeetles: Although thetoughened forewings offlying species aresomewhat similar, theyoverlap instead ofmeeting in a straight line.

Bugs are not beetles:Beetles tend to havechewing mouthparts whilethose of bugs are adaptedfor sucking.

Earwigs are not beetles:They have forceps-likestructures at the tips oftheir abdomens. Some rovebeetles, with reduced wingcovers and forceps-likemouthparts, cansuperficially resembleearwigs

Cockroaches, bugs and earwigs alldevelop their adult form gradually,developing wings (unless they arewingless species) during the last fewmoults. Beetles (like butterflies, beesand flies) start as larvae and after aperiod of pupation, emerge as fully-formed adults.

Monteithiumascetum, namedin 1998, isknown only fromthe summit zone of Mt Finnigan,near Cooktown, and Mt Sorrow,at Cape Tribulation. It lives inleaf litter and feeds on decayingwood. Its body surface, whichlooks almost like coral growth,is normally camouflaged withcongealed soil. Its namecommemorates the first collectorof the species, Geoff Monteith ofthe Queensland Museum.

Upper illustrations by Geoff Thompson, Queensland Museum. Others reproduced from The Insects of Australia, courtesy CSIRO.

Life in the coloniesA number of beetle species live insidethe colonies of termites, ants and beesfor at least part of their lives. They aretolerated and even fed and protectedby their hosts, some of them paying inthe form of a food secreted fromspecial glands — an arrangementsomewhat similar to the relationshipbetween certain caterpillars and ants(see Tropical Topics 54.) Other beetlesare less friendly, living next to antcolonies and picking off theinhabitants for dinner, or raiding theirfood stores.

Another set of beetle larvae prey onbees. The adult female lays eggs onflowers. The young larvae then attachthemselves to visiting bees to hitch alift back to the nest. There they feedon the bee larvae as well as on thehoney and nectar stores.

Some beetles have become honorarytermites. Having taken on theappearance of termites, they aretreated as colony members.

Defence strategiesThis rufous and blackbeetle is toxic — and ismimiced by numerousother non-toxic beetlespecies (and a moth) whichcopy its warning colours.

Beetles produce a variety of chemicalsto protect them from their enemies —from bacteria and fungi as well aspredators which may be tempted tomake a meal of them. One of thesechemicals is cantharidin, found in largequantities in the infamous ‘Spanishfly’, a beetle of southern Europe.Although poisonous, cantharidin hasbeen used medicinally — and as anaphrodisiac.

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BookshelfAustralian BeetlesJohn F. Lawrence and E.B.BrittonCSIROMelbourne University Press (1994)A chapter from the much bigger, 2-volume, The Insects of Australiapublished by CSIRO in 1991. Althoughmuch is the same as the original, a newIntroduction has been added withinformation on Fossil History,Australian Beetles and their Habitats.

A Field Guide to Insects in AustraliaPaul Zborowski and Ross StoreyReed Books (1996)Featuring a good section on beetles,this book is immensely useful to theamateur who is curious about insects.Both authors live in the Wet Tropics somany of our northern insects arefeatured.

The Life of BeetlesGlyn EvansGeorge Allen and Unwin Ltd. (1975)This book may be difficult to obtain now,but is a relatively easy-to-readintroduction to beetle natural history.

Wildlife Australia Vol 36 no 2 Winter1999Rolling your ownSybil MonteithShort, informative piece on dung beetles.

Wildlife Australia Vol 35 No 2 Winter1998FirefliesDr Geoff MonteithAnswer to a reader’s question aboutfirefly behaviour.

Wildlife Australia Vol 35 No 3Spring1998Weevil WonderRon HohenhausBrazilian weevils and water hyacinth.

New Scientist 11 August 1990Counting species one by oneNigel Stork and Kevin Gaston

BBC Wildlife August 1990Every little thingKevin Gaston and Nigel StorkTwo articles on the impossible task ofcounting the world’s species.

Journal of Insect Conservation, 3, 67-74 (1999)The conservation of saproxylic insectsin tropical forests: a research agendaSimon J. Grove and Nigel E. Stork

This newsletter was produced by the Queensland Department of Environment and Heritage (now The EnvironmentalProtection Agency) with funding from the Wet Tropics Management Authority.

For further information contact...

Wet Tropics Management Agency(For general infomation on the WetTropics World Heritage Area only.)PO Box 2050CAIRNS QLD 4870Ph: (07) 4052 0555Fax: (07) 4031 1364Website: www.wettropics.gov.au

Stella MartinThe EditorTropical TopicsEnvironmental Protection AgencyPO Box 2066CAIRNS QLD 4870

Ph: (07) 4046 6674Fax: (07) 4046 6751e-mail: [email protected]

Opinions expressed in TropicalTopics are not necessarily those ofthe Department of Environmentand Heritage (EPA).

While all efforts have been madeto verify facts, the Department ofEnvironment and Heritage (EPA)takes no responsibility for theaccuracy of information suppliedin Tropical Topics.

© The State of Queensland.Environmental Protection Agency