Dave et al., I've been using both pitfall trap and Berlese sampling methods to survey leaf litter arthropods in Costa Rica for the last year. For the pitfall traps I'm using small, ~150ml cups in which I put ~30ml of 75% ethanol alcohol with a few drops of liquid soap, to break the surface tension. I place the trap at least 4-7 days prior to the first use (to minimize disturbance, e.g., to ant colonies) and check them after 4 days of sampling. The alcohol does attract bark beetles (Coleoptera:Curculionidae:Scolytinae), but I've never caught any small mammals, though I did once catch a small anole. Pitfall traps are good for capturing larger and more active organisms in the leaf litter, but it will capture very few sessile organisms (including many insect larvae) or organisms living within the soil itself, as the cup is placed with the top aligned with the soil surface.
Berlese sampling involves collecting leaf litter and/or soil - typically either a predefined volume or area - then placing it into a Tullgren/Berlese funnel (see, e.g., http://www.emanco.ca/eman/ecotools/protocols/terrestrial/arthropods/soil-litt.html). The litter is placed into a funnel with an inset piece of mesh, and suspended over a jar of 75-95% ethanol, with a light source just above the litter. As the litter dries, the arthropods move away from the heat and fall into the ethanol. This method also captures fairly active organisms, but will capture more sessile organisms than the pitfall traps. To fully sample leaf litter and/or soil, and capture the sessile organisms, I'd recommend using the Winkler method (see, e.g., http://viceroy.eeb.uconn.edu/ALAS/winkler00.html), where litter is chopped up and sifted then suspended in a bag over a container of ethanol with a light source at the top of the bag. Here are a few good survey papers and a brief from the Biological Survey of Canada which discuss the merits of various methods: Cooper, R.J., and R.C. Whitmore. 1990. Arthropod sampling methods in ornithology. Studies in Avian Biology 13:29-37. Delabie, J.H., B.L. Fisher, J. Majer, J., and I.W. Wright. 2000. Sampling effort and choice of methods, pp. 145-154. In: Agosti, D., J.D. Majer, L. Alonso, and T. Schultz [eds.], Measuring and monitoring biodiversity: standard methods for ground-dwelling ants. Smithsonian Institution Press, Washington D.C. Edwards, C.A. 1991. The assessment of populations of soil-inhabiting invertebrates. Agriculture, Ecosystems and Environment 34:145-176. Parr, C.L., and S.L. Chown. 2001. Inventory and bioindicator sampling: testing pitfall and Winkler methods with ants in a South African savanna. Journal of Insect Conservation 5:27-36. TERRESTRIAL ARTHROPOD BIODIVERSITY: PLANNING A STUDY AND RECOMMENDED SAMPLING TECHNIQUES A Brief Prepared by the Biological Survey of Canada (Terrestrial Arthropods) 1994\ http://www.biology.ualberta.ca/bsc/briefs/brterrestrial.htm Cheers, Nicole Michel ************************************************** Nicole Michel Dept. of Ecology and Evolutionary Biology 400 Boggs Hall Tulane University New Orleans, LA 70118 Fax: 504-862-8706 Phone: 360-606-5631 ************************************************** ************************************************** Nicole Michel Dept. of Ecology and Evolutionary Biology 400 Boggs Hall Tulane University New Orleans, LA 70118 Fax: 504-862-8706 Phone: 360-606-5631 ************************************************** -----Original Message----- From: Ecological Society of America: grants, jobs, news on behalf of Jordan M. Marshall Sent: Mon 5/26/2008 8:13 AM To: ECOLOG-L@LISTSERV.UMD.EDU Subject: Re: [ECOLOG-L] Catching soil invertebrates Dave In my experiences with pitfall traps, I don't recall capturing many earthworms. I have captured occasional snails, slugs, and some larvae, more likely to capture insect nymphs. If you do use pitfall traps, I have always used propylene glycol as the killing agent/preservative, 2-4 cm deep, since it isn't too attractive to insects or mammals. This is the main ingredient in low toxicity antifreeze and most boat/RV antifreeze. The labels are pretty clear regarding the ingredients. I wouldn't use ethylene glycol, main ingredient in most other antifreeze. This is attractive to insects and mammals. Since pitfall traps are usually passive, an attractant isn't usually wanted. Even using propylene glycol, you will capture some mammals in pitfall traps; shrews and voles are the most common in my experience. Checking traps every week or 2 weeks is acceptable, I have done both for different studies. For sampling earthworms, I would think soil cores (10-15 x 25 cm?) or small soil pits (25 x 25 x 25 cm?) would be the most effective technique. Sieve the soil and remove the earthworms. Jordan -- Jordan M. Marshall, Ph.D. School of Forest Resources and Environmental Science Michigan Technological University Cooperative Emerald Ash Borer Project 5936 Ford Ct. Suite 200 Brighton, MI 48116 Ph (810) 844-2701 Fax (810) 844-0583 www.jordanmarshall.com > "David H. Byman" <[EMAIL PROTECTED]> > Sent by: "Ecological Society of America: grants, jobs, news" > <ECOLOG-L@LISTSERV.UMD.EDU> > 05/23/2008 10:54 PM > Please respond to > "David H. Byman" <[EMAIL PROTECTED]> > > > To > ECOLOG-L@LISTSERV.UMD.EDU > cc > > Subject > [ECOLOG-L] Catching soil invertebrates > > > > > > > Dear All: I would like to do a comparative study of soil > macroinvertebrates inside and outside a deer exclosure. As I am > interested in evaluating the available of shrew food as affected by heavy > deer browsing, I would like to census the populations of snails, slugs, > earthworms and insect larvae inside and outside the exclosure fence. > Are pitfall traps the best technique for all these invertebrate > groups? If pitfalls are a good technique, should I put a layer of > glycerol or some other preservative to preserve the animals in the bottom > of the can in case I can't visit the traps more than once a week? Thanks > for your help. > Dave Byman > > > > David Byman > Asst. Prof. Biology > Penn State University > Worthington Scranton Campus > 120 Ridge View Drive > Dunmore PA 18512-1699 > 570-963-2586 > mailto:[EMAIL PROTECTED] >
