This document describes various methods for collecting parasitic invertebrates and chordates for taxonomic research. It details hand collection, dust ruffling, internasal washing, body washing, and dissolution techniques for collecting ectoparasites, and examines organs and tissues for endoparasites like trematodes, cestodes, and nematodes. Methods for collecting chordates include sieving sediment for hemichordates, using nets and knives for tunicates, sieving sand for cephalochordates, and various trapping, netting, and shooting techniques for fish, amphibians, reptiles, birds, and mammals.
2. METHODS FOR COLLECTION OF
PARASITIC INVERTEBRATES
Anderson and May (1979) divided parasitic organisms into two
broad categories that transcend taxonomic boundaries.
Microparasites (viruses, rickettsias, bacteria, protozoans and
fungi) are small organisms that increase in number by multiplying
within the definitive host.
Macroparasites, which include the helminths (i.e. members of
the Phylum Platyhelminthes, Nematoda and Acanthocephala)
annelids and arthropods, are larger and populations increase within
the definitive host by recruitment of new individuals rather than by
multiplication of existing ones.
Macroparasites may be found living on the surface of the hosts
(ectoparasites) or within the host (endoparasites). The collection
method of macroparasites is detailed as follows.
4. Hand collection: Many parasites are visible with the naked eye but a dissecting
microscope or some other magnifier is required for smaller species.
•Ectoparasites that can be removed manually from living hosts include the larger
stationary parasites like leeches, ticks and some lice.
•A mammal should be searched visually for ectoparasites, with special attention
given to the ears and face, dorsal areas of the head, neck, back and rump, oral
cavity, anal region, and for bats, the patagia.
•With appropriate magnification, smaller parasites like feather mites, can be located
on the flight and tail feathers. These can be removed by dislodging them with a
dissecting needle or some similar instrument.
•Skin and scale mites can be collected from scrapings of the microscopic lesions
they produce.
•Mammals can be brushed with a toothbrush, by holding the mammal inside the
bucket, and directing the brush strokes inside the bucket. Fine combs may also be
employed for the purpose.Anesthesia:
Dust ruffling: pyrethrum powder, combination of pyrethrin, a derivative of
pyrethrum, and the synergist piperonyl butoxide, silica aerogel powder known as
Dri-Die 67 etc. Unlike anaesthesia jars, dust-ruffling allows thorough sampling of
the head in case of live specimens, which is sometimes the most heavily infested
part of the bird (Marshall 1981).
5. Internasal washing: Nasal mites live in the nasal passages of the host and
feed on mucous, blood, and tissue.
In this procedure, the nasal cavity of a dead animal is flushed with a fine stream
of water from a hypodermic syringe or bulbed pipette.
Body/carcass washing: This is an efficient technique, but one that can only
be used on specimens that are to be preserved in alcohol, skeletonized, or
discarded (Watson and Amerson 1967). The ectoparasites are removed by
shaking the dead host in a plastic jar or tin containing a 1-2% solution of
detergent or soap.
Dissolution: Dissolution techniques involve skinning the specimen and
dissolving the skin and/or feathers.
The specimens are first incubated in an enzyme bath (trypsin) at an
appropriate pH for 24 hours and then boiled in KOH with the net result that
the feathers and skin of the host are completely dissolved in potassium
hydroxide (KOH), leaving behind the exoskeletons of arthropods, which are
made of chitinous carbohydrates that do not dissolve.
Next the specimens are washed into a gridded Petri dish with 95% alcohol
and stained with acid fuchsin. Adult arthropods collected by this method are
often in good enough shape to be identified by taxonomists after mounting on
microslides.
7. Trematodes:
Trematodes are parasitic animals found among vertebrate animals,
especially those
associated with water. Trematodes may be found on their hosts in nasal
chambers, gills and
gill chambers, in the small and large intestines, cloaca, lungs and urinary
bladder or hiding
under scales of fishes.
Gills of fishes and amphibians should be placed in a saline solution with
some chloretone crystals, set aside, and examined later under the
dissecting microscope. Trematodes hiding there become relaxed and
may be combed out of the gills with the help of a dissecting needle.
They will be found by carefully examining the gills and the bottom of the
dish.
The entire gut is removed and placed it in a dish of saline, then cut it
into short sections and each section examined for trematodes. The adult
parasites can be removed by dislodging them from suckers with the
help of a blunt scalpel. Transfer worms to the dishes of saline to clean
them prior to fixation.
Similarly search the lungs, urinary bladder and the other probable parts
of the host for trematodes. Also examine the urine drained from the
bladder. Finally, look for nodules under the scales of the fishes and
elsewhere, which may harbor adult or larval trematodes.
8. Cestodes:
The members of this class may further be grouped into:
Subclass: Cestodaria - very primitive tape worms
which are found in the digestive tracts of very
primitive cartilaginous fishes, and
Subclass: Eucestoda - highly evolved tapeworms
which are found in the digestive tracts of all higher
vertebrates.
To collect either type of tapeworm digestive tract of the
host is to be
removed and carefully cut lengthwise in a dish filled with
saline. The
gut is then to be squirted several times with a pipette to
remove food
material and then placed in the cool chamber of the
refrigerator to
9. Nematodes:
The nematodes, generally known as round worms, have
successfully
invaded most available habitats. Parasitic nematodes
may inhabit any
vertebrate host - marine and fresh water fishes, frogs,
reptiles, birds
and mammals.
The body of the vertebrates needs to be examined for
parasites as soon as the host has been killed.
Occasionally the body cavity is invaded by adult and
frequently harbors larval nematodes as well adhered
to the internal organs i.e. liver, spleen, digestive tract,
body wall and mesenteries etc.
Large worms need to be removed first and then
individual sections of the host’s digestive tract or other
11. Hemichordata –e.g. Balanoglossus
Specimens are dug from shallow waters with a shovel and sorted
by hand.
A large shovelful of mud which surrounds the worm is transferred
to a bucket of screen.
The mud should then be submerged in the water from which the
specimens are carefully picked away in order to avoid breaking
the animal.
Urochordata
The only problem in collecting sessile tunicates is
dislodging them from their substrate. With the gelatinous
forms care must be taken not to rupture the tunic. With dull
pocket knife the specimens can usually be tried away from
their substrate.
Pelagic tunicates, common in the off shore waters,
especially in the summer months, are captured with a dip net
or tow net.
Working under the night light is very productive in the
summer time. The luminescent species, Pyrosoma, are very
clear even in total darknessCephalochordata
The best collecting method is to screen sand with a
coarse, 1/8th inch collecting screen. When the habitat is
located, sand is washed through the screen, one shovelful at
a time and the animals are transferred to the bucket of
water. The dredge net can also be used for collecting.