Protocols:
The following are the main protocols selected by the Diptera TWIG for the present project.
Protocol for Setting Up Malaise Traps and Handling Samples
Protocols for Culicidae (Darlene Judd)
Protocols for Ceratopogonidae (Art Borkent)
Protocols for Dolichopodidae (Daniel Bickel)
Protocols for Asilidae (Eric Fisher)
Protocols for Sarcophagidae (Thomas Pape)
Protocol for Acalyptratae (Stephen Marshall and Matthias Buck)
Protocols for Dolichopodidae (Daniel Bickel)
This family is very abundant in moist habitats and is easily collected by a variety of methods. Dolichopodids are often taken as non-target organisms while collecting something else.
A. Collecting method: Apart from sweeping, the following trapping methods are effective.
1. Pan or water traps: a number of taxa are attracted to yellow and white water traps and are often collected in large numbers. Pan traps should not be set out for more than a day in the tropics unless salt or a preservative is added). They have the advantage of being light weight, easy to use, and can target microhabitats. They are ideal for short term visits to remote regions.
2. Malaise traps are also very effective, although they tend to capture many more females than males. Ideally, they are best placed at an ecotone (e.g. edge of forest), or across (perpendicular to) a first order creek or gully.
3. Sticky traps on tree trunks catch a large number of trunk-associated taxa, such as Medeterinae, Neurigoninae, etc. Simply tack a sheet of clear plastic on a tree trunk, paint it with a dilute mixture of Tangletrap or other sticky product, and leave the trap for a day or two. The Tangletrap can be dissolved with mineral-turps or other solvents, and the specimens transferred to alcohol. Although there is some damage on some specimens, usually enough are collected to get a good series. Many "rare" taxa of other groups are taken this way as well.
B. Habitats: Dolichopodids are particularly abundant in moist habitats, and during wet periods can be found almost anywhere. However, creeks, swamps, lagoons, etc. are particularly rich, especially during dry periods.
C. Mounting techniques: Dry pointed material is easiest to work with. However, most modern trapping techniques result in alcohol specimens, often in large number. It is best to sort material while in alcohol, to isolate those specimens worth mounting (large numbers of common species and females of little taxonomic value are NOT worth dry-mounting). To dry mount, critical point drying is time consuming and not always necessary. Chemical methods such as transfer to 100% alcohol, then to chloroform, work well to produce dry specimens, if the technique is done properly.
D. Data required for study: In most cases standard label data is all that is needed, associated habitats, elevation, etc.
E. Products: An expected product is an illustrated key to species of the readily collected taxa. The production of illustrations such as good line drawings, or SEM for more complex structures, are necessary.
Preparation of Dolichopodidae in 75% alcohol.
Regarding preparation of specimens, traps often produce large numbers of specimens and I prefer to dry mount as many as possible in a time-efficient manner. If the specimens are in 75% alcohol (i.e., from yellow pan or malaise samples), I usually extract them for dry mounting by the following method:
1. 75% ethanol > 100% ethanol (two changes) so that all water is removed from the specimens. Leave specimens overnight in 100% alcohol.
2. 100% alcohol > chloroform and leave in chloroform for 2-3 hours (always use chloroform in a fume hood to avoid inhaling the fumes). Pour the specimens and chloroform onto a piece of filter paper in a glass petri dish. When the specimens are still moist with chloroform, arrange the specimens so that the wings are fully extended and dry straight. This must be done in a short time because the chloroform will vaporize quickly, leaving the specimens dry. (ALWAYS WORK IN A FUME HOOD).
The above method is quick, easy and fairly inexpensive. Large numbers of specimens (100-150) can be with a processed in a short time. As long as the specimens are clean, well preserved in alcohol, and all the water is extracted from them using 100% ethanol and chloroform, they should provide good specimens. The specimens can then be mounted using cardboard points in the usual manner (right lateral side of thorax as usual) or glued to the side of the pin (a la Ottawa). Dolichopodidae are rarely large enough to pin directly and even # 1 pins tend to destroy the thoracic chaetotaxy. Double mounting with minutin pins is too slow and there are too many specimens. In entomology, quantity is important!
Diptera TWIG / Sampling site selection /
Taxa selection / Products / Protocols