Barber trap

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Barber trap with tin roof

The barber trap , also known as a ground trap , is a vessel buried in the ground, the upper edge of which is flush with the surrounding area. Articulated animals living on the ground , especially insects , but also snails and smaller vertebrates such as shrews , depending on their type, are caught . Barber traps are automatic traps and do not select very well. Therefore, they may only be used in a controlled manner and must be serviced regularly.

Naming

The trap type was named after Herbert Spencer Barber (1882–1950). He described these traps for the first time in 1931 and used them to catch cave beetles of the genera Neaphaenops and Pseudanophthalmus in the eastern United States .

construction

Essential parts of his traps were:

  • a glass vessel dug up to the edge in the mud of the cave floor, about a quarter of which is filled with a preservative liquid,
  • a smaller container with an attractant that hangs in the vessel over the preservation liquid,
  • a grid as a cover for the vessel to prevent unwanted large animals, but also vertebrates, from falling in,
  • a large stone lying on supporting stones as a roof against water from above, to prevent larger animals from accessing the trap and to concentrate the scent of the attractant on the ground, as well
  • a marker to help you find the trap again.

Depending on the catch liquid you have to pay attention to the choice of the container. If you want to carry out several evacuations, you should construct an insert in the floor so that changing the floor trap can be carried out more quickly. This can be a slightly thicker piece of pipe into which the container is inserted.

Catching liquid

Barber has found out in experiments that preserving liquids are particularly suitable for long control intervals:

Barber also recommended Zenker's solution without acetic acid, but found in his experiments no useful means of removing the crystals that formed on the surface of the capture material after a long period of time. The omission of acetic acid and ethanol in the preservation liquids was necessary so that they do not have a deterrent effect ( repellant ). The addition of ethylene glycol or glycerine resulted in the traps having a service life of up to six months without maintenance.

The additives commonly used today to reduce surface tension were also discussed back then. They cause the trapped insects to perish in the preservation liquid as quickly as possible. Important points when choosing the solution were the least possible change in the animals and the simplest possible cleaning and drying of the preparations. Benzoic acid is often used to catch ground beetles . Also, formaldehyde or saturated saline are used as a preservative.

For the capture of beetles, which are then to be prepared as evidence for scientific collections, the capture liquid developed by Renner from ethanol, water, glycerine and acetic acid in a ratio of 4: 3: 2: 1 has proven to be very effective. The ethanol (denatured alcohol can also be used) acts as an attractant and killer, the glycerine prevents the trap from drying out, and the acetic acid removes the hardening effect of the alcohol, so that the animals remain easy to prepare.

The use of floor traps as live traps, without preservation liquid, is not infrequently practiced for catches for scientific purposes, e.g. B. to catch small mammals or to obtain live animal material. Live traps have to be serviced very frequently, usually on a daily basis, which greatly increases the processing effort.

commitment

Floor trap with benzoic acid to catch ground beetles

Plastic barber traps are also used today. However, depending on the type of plastic, many insects can climb out again, but this is usually only relevant for live traps. Apart from exceptional cases, the current standard use of floor traps omits attractants , often also grids. All modifications change the number and the range of species of the captured animals considerably. For example, the preservation liquid, the color, the size and the emptying interval affect the efficiency and selectivity of the trap. No influence was z. B. determined by roofs or covers.

Due to the comparatively low processing effort and the high collection efficiency for some animal groups, ground traps are used as a standard collection method both in basic ecological research and for applied issues, e.g. B. routinely used for ecological reports and for monitoring ( environmental observation). The traps only give a reliable picture of the biodiversity of a habitat in the case of ("epigeic") species living on the ground surface . Neither real soil organisms (endogean species) nor species living in the vegetation can be reliably detected, apart from incidental discoveries. For many species, the evidence is linked to special periods of high walking activity, often the reproductive period. The detection of ground beetles (carabids) is based almost entirely on this method. Other frequently examined groups of animals are z. B. ground- dwelling rothouse beetles and some other groups of beetles as well as spiders and harvestmen . With other animal groups, the traps are very selective, but can offer valuable additions in the context of extensive investigations through the detection of species that are difficult to detect with other methods, e.g. B. with land lice , hymenoptera such. B. ants , bugs and cicadas . The rest of the catch, including small mammals and amphibians caught during the processing of invertebrates, are usually not systematically evaluated, but the (slightly euphemistic) expression "bycatch" has become established. Bycatch of vertebrates or z. B. nudibranchs can also act as an unintentional attractant, which selectively attracts scavenging species , through the gases produced here, which are usually only incomplete .

Since catching with barber traps, like in principle all recording methods, is more or less selective depending on the animal group and species, the species spectrum is influenced by the method, but to an even greater extent the frequency (abundance) of the species in the catch. It is known that some species do not get caught in ground traps at all, even if they are active on the ground surface. As a rule of thumb, more large species than small, more imagines than larvae or immature, and more predators than herbivores are captured. An interpretation of the catch numbers is possible if z. B. several floor trap investigations can be compared. As a rule, however, the method does not allow the absolute frequency (individuals per area) of a species to be determined, and the relative abundance (common and rare species) cannot be determined in all cases. It is often assumed that the method registers an averaged product of the absolute abundance and running activity of a species, which, especially in the case of predatory species, could possibly be a measure of its importance in the habitat. If this assumption is followed, the catch frequency is often referred to as the "activity density" of the species. Often the catch is also roughly standardized to "trap days", i. H. the total yield divided by the number of traps and by the exposure time in days, whether these are really equivalent, is controversial.

literature

  • Barber HS: Traps for cave-inhabiting insects. Journal of the Elisha Mitchell Scientific Society. Volume 46 (1931): 259-266.
  • BA Woodcock: Pitfall trapping in ecological studies. In: Simon Leather (editor) (2005): Insect sampling in forest ecosystems. (Methods in Ecology). (Blackwell Publishing).

Individual evidence

  1. ↑ Klaus Renner (1980): Faunistic-ecological studies of the beetle fauna of different biotopes in terms of plant sociology in the Evessell book near Bielefeld-Sennestadt. Ber.Naturw.V.Bielefeld: special issue 2, pp. 145–176.
  2. ↑ Björn Erling Waage (1985): Trapping efficiency of carabid beetles in glass and plastic pitfall traps containing different solutions. Fauna norvegica, Series B, 32: 33-36.
  3. ↑ Martin H. Schmidt, Yann Clough, Wenke Schulz, Anne Westphalen, Teja Tscharntke (2006): Capture efficiency and preservation attributes of different fluids in pitfall traps. Journal of Arachnology 34: 159-162.
  4. ↑ Neucir Szinwelski, Verônica S. Fialho, Karla SC Yotoko, Léon R. Seleme, Carlos F. Sperber (2012): Ethanol fuel improves arthropod capture in pitfall traps and preserves DNA. Zookeys 196: 11-22. doi : 10.3897 / zookeys.196.3130
  5. ↑ Sascha Buchholz, Anna-Marie Jess, Florian Hertenstein, Jens Schirmel (2010): Effect of the color of pitfall traps on their capture efficiency of carabid beetles (Coleoptera: Carabidae), spiders (Araneae) and other arthropods. European Journal of Entomology 107: 277-280.
  6. ↑ Karl EC Brennan, Jonathan D. Majer, Nicholas Reygaert (1999): Determination of an Optimal Pitfall Trap Size for Sampling Spiders in a Western Australian Jarrah Forest. Journal of Insect Conservation Volume 3, Number 4: 297-307. doi : 10.1023 / A: 1009682527012
  7. ↑ Jens Schirmel, Sarah Lenze, Daniel Katzmann, Sascha Buchholz (2010): Capture efficiency of pitfall traps is highly affected by sampling interval. Entomologia Experimentalis et Applicata, 136: 206-210. doi : 10.1111 / j.1570-7458.2010.01020.x
  8. ↑ Sascha Buchholz & Carsten Hannig (2009): Do covers influence the capture efficiency of pitfall traps? European Journal of Entomology 106: 667-671.
  9. ↑ GL Lövei & T. Magura (2011): Can carabidologists spot a pitfall? The non-equivalence of two components of sampling effort in pitfall-trapped ground beetles (Carabidae). Community Ecology Volume 12, Number 1: 18-22. doi : 10.1556 / ComEc.12.2011.1.3

Web links

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