|
|
 |
 |
 |
|
|
| 1. Yellow pan traps.
The small size of scelionids requires the use of a variety of trapping methods in order to capture them.
Yellow pan traps, a modification of the Moericke traps designed to collect aphids, are extremely effective.
Individual pans catch a relatively small number, but large numbers of them can be deployed.
Typically, we set out 100-200 traps at a time.
The pans should be set out in areas where they are relatively free of obscuring vegetation.
In dry areas, pans set near sources of permanent water are especially effective.
The traps shown here are small, commercial picnic bowls (Solo brand), approximately 15cm in diameter and 5cm high.
Each pan is filled with water and a few drops of a surfactant are added.
Simple liquid dish soap may work, or an odor-free chemical may be preferred.
The traps must be emptied every 24 hours to minimize decomposition.
If collecting specimens for the purpose of DNA extraction, the traps should be emptied more often.
Small, fine-meshed aquarium nets are ideal for scooping the contents out of the pan with minimal disturbance.
After the catch has been removed from the pans, it is critically important to wash the specimens thoroughly
in order to remove any soap or material voided from the digestive tract.
Specimens are then placed in a solution of at least 75% ethanol.
|
Click on an image to enlarge.
|
|
2. Flight intercept traps.
The idea behind the FIT is to place a barrier in the flight path of an insect.
For most FITs a piece of fine netting is used; a window trap is an alternative that uses a sheet of clear plastic or glass.
On hitting this barrier, insects may land or fall directly to the ground.
A container with a killing and preservative solution is placed below the net to capture those that fall or drop down.
One common preservative is a 50-50 propylene glycol/water solution.
FITs are particularly effective devices for collecting Coleoptera.
|
|
|
3. Malaise traps.
In contrast to an FIT, the Malaise trap takes advantage of the tendency for some insects to fly up and toward light when
they encounter a barrier.
At the top of the trap is a collecting bottle filled with an ethanol solution.
Proper placement of the Malaise is important for it to be effective.
The trap should be placed across a natural flight path (such as a forest path), with the collecting end facing toward the sun
(toward the south in the Northern Hemisphere).
Malaise traps are particularly effective for larger Hymenoptera (Ichneumonoidea, Aculeata) and Diptera.
Large-bodied or arboreal scelionids, such as Macroteleia and Baryconus are commonly captured using this technique.
|
|
|
4. Sweeping.
Sweeping can be an effective method of capturing scelionids.
A net with a very fine mesh is absolutely essential.
Covering the mouth of the net with a piece of hardware cloth (about 1cm mesh) will keep out sticks and large pieces of vegetation.
This is called screen-sweeping.
The method being demonstrated in the image by Dr. Andrey Sharkov uses a very large net, the maxi-net, to sift the "aerial plankton."
|
|
|
5. Rearing.
None of the methods described so far provides any biological information other than a general indication of the habitat in which a species may be found.
Scelionid host relationships can only be deciphered by finding naturally parasitized host eggs in the field.
The wasps are usually easy to rear out by simply placing the eggs in a vial.
Care should be taken to keep a moderate level of humidity, avoiding both desiccation and fungal growth.
The eggs shown here, those of Malacosoma neustrium (L.) (Lepidoptera: Lasiocampidae), are host to Telenomus laeviusculus (Ratzeburg).
(Photo © Roger Lacroix.)
|
|
Last updated: 17 February, 2004
|
 |
|
|
|
|
;)
;)
;)
;)
;)
;)
