Protect against bites by land leeches

[Psyche]

What a detailed research, Teo.

I noticed the common land leech( H. zeylanica) goes as high as 4000m in some countries, as well as being found in Japan.

I am curious about the situation here in Sundaland. I recalled a botanist who wrote in his book about the relief from leeches after 3000 feet.
My own experience is that as you go past 2500 feet, where the air is distinctly cooler the leeches are rather rare.
For example, walking through the montane forest (above 3000ft.)of Gunong Ledang (Mount Ophir, at the border of Malacca & Johor, approx.4100ft.) where slipper orchids start to appear, I did not encounter any leech.
I also do not remember seeing leechs in Cameron Highlands(5000ft.).
Admittedly my experiences are rather limited.

BC members go regularly to Fraser's Hill and often are prone on the ground to get the best shots. This is at risk of inviting an ardent smoocher in the netherland.The town area is 1300m.(4000ft.), and the Jeriau Fall is 630m.(1900ft.)
Do any member noticed any difference in the number of these slimey vampires between the two spots?

The presence of leeches is of course dependent on the vertebrate hosts .
Forest trails with signs of wild pigs are likely to be swarmed with these crawlies.
Even in bright open areas, the banks of streams and canals in rural areas, where the ground is moist, are leech-infested because of cattles.
The steep trail up the side of waterfalls are leech-free (as far as I know)despite their foreboding looks.Since hardly any animal pass up the trail, any leech there could die of hunger.

TL Seow

[Silverstreak]

BC members go regularly to Fraser's Hill and often are prone on the ground to get the best shots. This is at risk of inviting an ardent smoocher in the netherland.The town area is 1300m.(4000ft.), and the Jeriau Fall is 630m.(1900ft.)
Do any member noticed any difference in the number of these slimey vampires between the two spots?

One of the trail we dropped by last year within the town area was full of leeches. I had 5-6 of them on the boots within a few minutes of stoping by to shoot a skipper. Khew also experienced same in one of the jungle trails in the town area on one of his trip.

At Jerai waterfall , the puddling ground is too hot for leeches , but no idea about the forested area, I do not think any of us explore the trail in that area.

I think you are right on these suckers depend on the resident wild boars for their regular meals. wherever I see wild boar foot prints in an area they are always around.

During our Langkawi trip we stop near the top of Gunung Raya and I went just 30 meters into a trail, saw wild boar footprints, without stopping I turned back out and I had close to 10 on my shoes !

[teotp]

What a detailed research, Teo.

I noticed the common land leech( H. zeylanica) goes as high as 4000m in some countries, as well as being found in Japan.

I am curious about the situation here in Sundaland. I recalled a botanist who wrote in his book about the relief from leeches after 3000 feet.
My own experience is that as you go past 2500 feet, where the air is distinctly cooler the leeches are rather rare.
For example, walking through the montane forest (above 3000ft.)of Gunong Ledang (Mount Ophir, at the border of Malacca & Johor, approx.4100ft.) where slipper orchids start to appear, I did not encounter any leech.
I also do not remember seeing leechs in Cameron Highlands(5000ft.).
Admittedly my experiences are rather limited.

BC members go regularly to Fraser's Hill and often are prone on the ground to get the best shots. This is at risk of inviting an ardent smoocher in the netherland.The town area is 1300m.(4000ft.), and the Jeriau Fall is 630m.(1900ft.)
Do any member noticed any difference in the number of these slimey vampires between the two spots?

The presence of leeches is of course dependent on the vertebrate hosts .
Forest trails with signs of wild pigs are likely to be swarmed with these crawlies.
Even in bright open areas, the banks of streams and canals in rural areas, where the ground is moist, are leech-infested because of cattles.
The steep trail up the side of waterfalls are leech-free (as far as I know)despite their foreboding looks.Since hardly any animal pass up the trail, any leech there could die of hunger.

TL Seow

Researchers like R. T. Sawyer, J. P. Moore and J. R. Harrison are specialists working only on leeches. They explored many countries looking for these blood sucking animals and also received specimens from museum workers (e.g. A. S. Pearse from Siam Museum, M. W. F. Tweedie and Prof. W.A. Young from Singapore, H. M. Pendlebury from Federated Malay States Museum, Dr. W. L. Schmitt from U. S. National Museum...etc) contributing samples to them for research purposes for many years. Numerous field trips, experiments and publications about leeches were carried out and also documented by them. My write-up is just a small abstract based from their comprehensive publications.

If leeches rely only on cattle and wild pigs to survive by now they became extinction and why they have so many species and "so" abundance at certain localities (of cause I do not know much about their ecology)? Beside the mentioned two hosts, many domestic and wild mammals, birds, reptiles, amphibians including fishes (marine and fresh water), turtles (fresh and sea water) are their hosts (some leeches also attach to fresh water crabs).

Just referred to a paper (title: Leeches from Borneo and the Malay Peninsula: Bulletin of Raffles Museum 10: 67-79, 1935) by J. P. Moore: He stated that H. picta, H. zeylanica sumatrana and H. zeylanica subagilis and two species of burrowing Erpobdellidae Gastrostomobdella monticola and Mimobdella buttikoferi were collected at elevations from 3,300 to 10,000 ft at Mount Kinabalu (if leeches like H. picta and H. zeylanica can survived as high as 10,000ft why can't they lives at 4,000 or 5,000ft). Another example: Mr. Tweedie found H. sylvestris interrupta and Gastrostomobdella vagabunde from hills of Perak.

We didn't searched (dig into the ground, overturn the soil and stones, tracking their hosts and collect samples...) for these creatures when we visited Cameron Highlands (I did not encountered leeches there too), Bukit Fraser (leeches encountered from few locations), Genting Highlands (No leeches too).. and other places like Kuala Kubu Bharu (none) and Langkawi (few locations). We are looking for butterflies and other insects up there. BC members went outing during sunny days (dry and hot) and these animals are retreated to their safe places, who went out to butterflying during rainy days? Leeches will have their favourite localities and time (at night?) and we may not there when they are active. Regarding how long leeches can survive after their last blood meal? I read somewhere in Sawyer's book, will find out when I visit the library again.

Teo T P

(Note: May I know which book written by the botanist about the relief of leeches after 3,000ft? If you can remember the title and author).

[Psyche]

Hi Teo,

I do not doubt the veracity of the papers you quote.
I was referring to the common land leech which I did not say feed only on cattles & wild pigs, but vertebrate hosts.
Neither did I say they are not found at high elevations, but that I have not seen them.
I have asked if the number seen at Fraser's Hill at 4000ft aree different than at lower down.
My intention is to see whether the cooler temperature have affected their number.

TL Seow

[teotp]

Hi Teo,

I do not doubt the veracity of the papers you quote.
I was referring to the common land leech which I did not say feed only on cattles & wild pigs, but vertebrate hosts.
Neither did I say they are not found at high elevations, but that I have not seen them.
I have asked if the number seen at Fraser's Hill at 4000ft aree different than at lower down.
My intention is to see whether the cooler temperature have affected their number.

TL Seow

Sorry, I misunderstand your intention, Seow.

I will find out whether any research papers discuss about the effect of temperatures on leech numbers at different altitudes, and also the survival time of leech under starvation. Cheers!

Teo T P

[teotp]

J. L. Harrison wrote in his paper (Leeches : Medical Journal of Malaya 8: no. 2, page164, Dec 1953) : "They can tolerate a considerable amount of drying, leeches which had become hard dry and motionless have been revived, but much needs to be done on this subject. Laboratory experiments suggested that they can tolerate up to about five months starvation."

Teo T P

More notes about food intake of leeches:

Generally, blood sucking leeches feed infrequently but take in large quantities of blood at one time. Hirudo species normally takes two to five times its own weight of blood and Haemadipsa species may take ten times its own weight. These large meals are digested slowly over a period of many months. Researcher carried out experiments and drew up detailed balance sheets for Hirudo species: A Hirudo leech of 128 mg took in 640 mg during one meal. The digestion of the meal took about 200 days and during that time there was a loss in weight by excretion of 524 mg. The balance of 116 mg had been incorporated into their tissues and as no further meal was taken the leech lived on its reserves for another 100 days. From this it is apparent that a leech will grow steadily if it obtains a meal every six months and it will not die of starvation (Reference: Leeches (Hirudinea) - their structure, physiology, ecology and embryology 1962, 201pp, edited by K. H. Mann; chapter 4 - nutrition: 36-43).

[teotp]

[QUOTE=teotp;112577] Land leeches including H. zeylanica appear to be capable of transmitting trypanosomes to their host. Similarly, active trypanosomes are known to live in the crops of Chtonobdella bilineata and H. zeylanica for at least 52 and 44 days after the last meal respectively. The latter species has been implicated as a possible vector for Trypanosoma evansi, causative agent for surra, an often fatal disease for domestic animals (Sawyer et al, 1982).

Trypanosoma evansi infections are quite common among horses, cattle and camels and normally does not infect humans. A case of T. evansi infection was reported by Joshi et al (2005) in a chronic patient in Maharastra state of India.

Reference:

Joshi, P.P., V.R. Shegokar, R.M. Power, S. Herder, R. Katti, H.R. Salkar, V.S. Dani, A. Bhargava, J. Jannin & P. True. (2005). Human trypanosomiasis caused by Trypanosoma evansi in India: The first case report. American Journal of Tropical Medicine & Hygiene 73: 491-495.

[teotp]

Hi Teo,
I have asked if the number seen at Fraser's Hill at 4000ft aree different than at lower down.
My intention is to see whether the cooler temperature have affected their number. TL Seow

Population ecology of leeches is affected by factors of the environment, both living and non-living.

I. Inanimate environment:
Many factors under this category affect the distribution and abundant of leeches including H. zeylanica and H. picta. These factors include light, temperature, gravity and water.

Sunlight is a highly complex physical factor in the environment and also influences the temperature. On one hand it is harmful to leeches but on the other yields much information of condiserable usefulness to them. The useful aspects of environmental light are primarily those give information on the time of the year (photoperiodism: use as cues for leech reproductive maturation), time of day (diurnal rhythms: H. zeylanica is most active in the mornings and early evenings) and proximity of potential host (shadow reflex: see below). But light is not an essential factor for survival (this is demostrated in nature by species which lives in two sorts of continuously dark environments like caves (e.g. Dina absoloni) and ocean depths (e.g. Bathybdella sawyeri). Leeches are responsive to sudden decrease in light intensity (shadow reflex), especially in "hungry" individuals, the blood sucking H. zeylanica and H. picta both display these searching responses to an attraction toward a potential host (Sawyer, 1986a).

Many leeches spend all or part of their lives exposed to cold water. In most cases the rate of feeding decreases with water temperature, with some species more greatly affected than others. Some species are remarkablely active at low temperatures. The predaceous species Erpobdella octoculata stops feeding at very low temperature (1.5 degree C). In most cases rates of expression of elementary behaviours is directly dependent on ambient temperature. For example, the rate of inchworm crawling sequences of Hemiclepsis marginata correlates linearly with temperatures in the ecological meaningful range 5 - 25 degree C. At abnormally high temperatures there is a rapid decrease in the rate of crawling (34 - 37 degree C) leading to disorientation (37 - 41 degree C) and death (over 41 degree C). Thermoreception plays some role in host recognition in those groups with warm blood hosts (e.g. Hirodo medicinalis, H. zeylanica, Theromyzon tessulatum..). Unfed Hirudo medicinalis are strongly attracted to warm objects and display a behavioural preferrence to bite those warmed to 37 - 40 degree C objects. Specific thermoreceptors have not been identified but certain identified neurous reportedly have increases impulse frequencies when warm (35 - 45 degree C)(Mann, 1962; Sawyer, 1986a).

Some leeches give the appearance of responding to gravity. The most remarkable example of apparent negative geotaxis is that displayed by the land leech H. picta. This species has a behavioural proclivity for climbing low-lying bushes and if put into a jar they will repeatedly climb upward as the jar turned upside down. Gravity and geotaxis experiments carried out to test Hirudo medicinalis and Theromyzon tessulatum by placing them in tall glass cylinders (125 cm), both H. medicinalis (88%) and Theromyzon tessulatum (84%) showed repeatedly climb upward to the top of the cylinders. Haemadipsa zeylanica also has climbing habit, but up hills rather than bushes. Some species display positive geotaxis (e.g. Piscicola geometra and Hclobdella stagnalis). The precise cues involved on responding to gravity and geotaxis are uncertain, for some species probably oxygen plays a role on the behaviour (Mann, 1962; Bhatia & Bora, 1973; Sawyer, 1986a).

Water plays a very important role in determining the ecological distribution of leeches. In general leehces are most abundant in stagnant water and become less frequent as water current increases. Land leeches like H. zeylanica and H. picta need to keep thier entire animal moist, so their distal 17 pairs of nephridia are modified, the urinary bladder is relatively very large and opening of the terminal excretory duct (nephridiopore - instead of being in the typical ventral position) is lateral or actually dorsal to lateral margins. In addition, the last pairs of nephridia open onto a tri-lobed phlange-like structure called auricle. The middle lobe, which contains the nephridiopore, is triangular and the outer two have prolonged membranous margins which project caudally. These auricles act as damp brushes which distribute moisture over the surface and margins of sucker. This is to keep the sucker free of adhering debris on the surface. This is why land leeches are most active during or soon after rain when the substrate is moist. The differences between foraging in H. zeylanica and H. picta and their aquatic counterparts can be attributed to specialized adaptions to live on land. Both species display the behaviour of cleaning the oral and caudal suckers by rubbing the sucker against its own body or the substrate (auricles). Sucker cleaning is clearly a behavioural adaption to the sucker mode of locomotion (inchworm crawling and rarely vermiform crawling) on land and increases in frequency as the substrate become drier. Difficulty in manoeuvring on a dry substrate explains scarcity on land leeches after several days without rain, and also the distribution of these blood sucking animals on certain locations (Mann, 1962; Cameron, 1962; Sawyer, 1986a, 1986b & 1986c).

II. Animate environment:
It seems that only European leech species have been studied intensively so that conclusions can be reached about their habitat preferences. Information of land leeches is mainly confined to brief notes about their food organisms, but the following data may give some ideas about their food in relation to their distribution and abundance:

Hirudidae:
Hirudo spp (blood sucking on: Mammals, birds, reptiles, amphibians and bony fish).
Macrobdella spp (blood sucking on: Mammals, amphibians and bony fish).
Philobdella spp (blooding sucking on: Mammals).
Hirudinaria spp (blood sucking on: Mammals).
Haemopis spp (devouring: Molluscs, insects, crustaceans, worms and carrion).

Erpobdellidae:
Erpobdella spp (devouring: Molluscs, insects, crustaceans, worms and carrion).
Trocheta spp (devouring: Molluscs, insects crustaceans and worms).
Nephelopsis spp (devouring: Insects, crustaceans, worms and carrion).

Haemadipsidae:
Haemadipsa spp (blood sucking on: Mammals and amphibians).

Glossiphoniidae:
Batracobdella spp (blood sucking on: Amphibians and molluscs).
Hemiclepsis spp (blood sucking on: Amphibians and bony fish).
Theromyzon spp (blood sucking on: Birds).
Haementeria spp (blood sucking on: Mammals, birds, reptiles and amphibians).

Piscicolidae:
Piscicola spp (blood sucking on: Elasmobranchs).
Pontobdella spp (blood sucking on: Molluscs).
Branchellion spp (blood sucking on: Elasmobracchs and molluscs).
Abranchus spp (blood sucking on: Elasmobranchs).

Mann (1962) pointed out that only a few leeches are restricted to one kind of host (e.g. Hemibdella soleae to Solea spp; Callobdella lophii on angler fish). Majority of leeches while disposed to attack a particular kind of host will take meal where they can find one. For example, H. zeylanica attack mainly animals like mammals and amphibians (Mann, 1962) but they have been recorded on birds and reptiles (Sharma & Fernando, 1961). In comparison, the macrophagous forms take an even wider variety of food most of them will take any kind proteinaceous material that is offered including carrion or young of thier own species (Mann, 1962).

Undoubtedly, predators of leeches play a role on their distribution and population. The most important predators of leeches are fish, birds, aquatic insects, crayfish and other leeches (at least one leech species is a predator of other leeches). One third of the overall diets of the terrestrial garter snakes (Thamnophis elegans) are specialized predators on leeches (e.g. Haemopis spp) and earthworms (Sawyer, 1986a).

Looking over the very incomplete knowledge of the ecology of land leeches, it appears that factors influencing the distribution and abundances of these creatures are complex. Other factors like oxygen and calcium content of water, the rate of water movement and their competition with other organisms are not take into consideration.

The above abstract is dedicated to Seow. Again, my apology for the misunderstanding. Cheers!

Teo T P

Literature cited:

Bhatia, M.L. & S.S. Bora (1973). Bionomics and distribution of the land leeches of Kumaon Hill, U. P. Journal of Bombay Natural History 70, no.1: 36-56.

Cameron T.W.M. (1962). Parasites and parasitism. Methuen & Co. Ltd. London. 322pp.

Mann, K.H. (1962). Leeches (Hirudinea): their structure, physiology, ecology and embryology. Pergamon Press - London. 201pp.

Sawyer, R.T. (1986a). Leech biology and behaviour volume 1: anatomy, physiology and behaviour. Clarendon Press - Oxford. 418pp.

Sawyer, R.T. (1986b). Leech biology and behaviour volume 2: feeding biology, ecology and systematics. Clarendon Press - Oxford. 374pp.

Sawyer, R.T. (1986c). Leech biology and behaviour volume 3: Bibliography. Clarendon Press - Oxford. 226pp.

Sharma, R.E. & C.H. Fernando (1961). Leeches and their ways. Malayan Nature Journal 15: 152-159.

[Psyche]

Again an awesome amount of research in the subject matter, Teo.

Thanks for all the info.

TL Seow

[Silverstreak]

Wow! I think we are the most well informed forum on leeches !!

Thank you Thiam Peng for doing all this research and sharing them with the forum!


Cheers!