|
Activity: Arthropod Collecting Using Tree Belts, Bands, and Wraps
Tree belts, bands, and wraps are simple devices that allow you to capture a wide range of arthropods that live in or on tree bark. Because arthropods often seek shelter and hide in cracks and crevices, these devices
that are placed around tree trunks provide such a refuge. The tree belt consists of corrugated cardboard, bubble plastic, burlap, and/or peat moss. The tree belt should be wrapped around the entire diameter of
the tree and secured with string, tape, nails, or staples.
How does it work? The answer is very simple. The insects think that they have found a nice hiding place whereupon they encounter little nooks and sloped ridges.
When collecting, make sure you have a white bed sheet to shake the hiding insects onto, so you can easily see them for collecting and identification purposes.
Materials
- Corrugated paper or plastic or burlap strips
- Nails, staples, string or tape
- Plastic bags and twist ties
- Collecting vials
- 70% ethanol
- Paintbrush
- Aspirator
Procedure
A strip of cardboard approximately 30 cm wide is wrapped around the tree trunk and held in place with string and tape. The trap is left in place for about one week, then removed and all arthropods are collected
and placed in alcohol. Arthropods found on the surfaces of the cardboard should be removed in the field. Then the cardboard can be wrapped in a sheet and brought to the lab where the layers of cardboard
can be peeled apart. Many arthropods will have crawled into the spaces between the layers. An aspirator and a paintbrush dipped in alcohol may be helpful in collecting the still living and active
arthropods.
The Berlese funnel is the most commonly used method for separating arthropods from soil and litter. The components of these extractors are a sample funnel with wire mesh or screening on the bottom, a collecting
container, a bucket and a hood containing a light bulb. The sample funnel is placed in the bucket with the collecting container directly underneath, which usually contains a 70-80% ethanol preservative. A source of
heat (light bulb) is placed above the sample. The objective is to create a steep gradient of temperature and moisture throughout the sample. Arthropods react to the heat by moving downward (away from the heat) and
eventually fall to the bottom into the preservative. Cheesecloth below the sample in the funnel can reduce debris from the sample falling into the preservative as the sample dries out or is agitated by the
movement of larger organisms. The wattage of light bulb used in the Berlese funnel depends on the size and water content of the sample and on the distance of the bulb from the sample surface
 .
Methods: Leaf Litter Sampling
Litter is the decaying plant and animal material that accumulates on the soil surface. The quantity and quality of litter and the associated arthropod species
assemblages vary with the plant community, time of year, precipitation, temperature, and humidity.
- The litter is raked to the level of the soil surface and put through the sifter (condenser) to remove large fragments of debris and to concentrate the arthropods.
- The sifted litter is placed in a pillowcase, labeled and tied.
- Four such samples are taken for each selected sampling period in that habitat or microhabitat.
- Samples can be kept in the pillowcases in the laboratory for up to 4-5 days as long as they are turned frequently and not exposed to excess moisture or extreme temperatures.
Sample labels must be placed inside the bag with the specimens. Change the alcohol in about 7 days, and if possible, refrigerate or freeze the samples to await
further processing. Samples in storage should be double bagged.
 |
