Berlese Funnel Extraction Protocol

Purpose: Assess the diversity and abundance of meso- and micro-arthropods in the soil (springtails, mites, microspiders, small insects, worms).

 

Purpose: Assess the diversity and abundance of meso- and micro-arthropods in the soil (springtails, mites, microspiders, small insects, worms).

 

Procedure: (A) Overview

(1) remove soil core from field into ziplock plastic bag

(2) place soil core in Berlese extractor (extractor pre-made)

(3) remove sample from extractor and enumerate specimens

(4) archive samples

(5) analyze data

 

(B) Precise Methods

(1) remove a 25cm x 25cm x 5cm deep (10" x 10" x 2") sample of soil (including any plant litter on surface - plant litter NOT included in the 5cm depth) and gently place in plastic bag.

 

In order to minimize crushing of soil fauna, extract the soil sample by:

(a) marking out the 25cm x 25cm margins on the soil with the end of a trowel

(b) digging a trench 25cm long by 30cm deep along one edge

(c) cut the 4 edges vertically of the 25 x 25 markings to a 10-15cm depth

(d) insert the trowel horizontally under the 25 x 25 markings at a 5cm depth

(e) lift the sample (usually more-or-less in a single piece) into a ziplock bag

 

(2) remove sample from bag and place in Berlese extractor (see appendix for construction details). As the dirt is placed in extractor, break up any clods so that the arthropods can emigrate properly from a sample of even consistency. Remove any earthworms to a separate specimen vial (worm skinmucus is terribly sticky and if the worms are not removed all of the little critters will get stuck on the worm skin). Break the clods apart without squashing the soil.

(3) Turn on 25 watt light bulb, extract for 48 hours. (Larger samples will require higher wattage and longer extraction times) Place a jar (see H in illustration) containing a small amount of antifreeze under the Berlese funnel. Antifreeze has the benefit that it does not evaporate. (Thebest way to test extraction efficiency is to replace the jar with a new one for an additional 24 hours, or until nothing else emigrates from the soil sample.)

Place extracted sample (critters, dirt, and alcohol or glycol) into one (or more as needed) labeled small vials. Add a few drops of cooking

oil to top of vial, enough to form a thin meniscus. Replace cap, agitate the mixture to force the oil intomicrodrops throughout the solution. Let the oil slowly (10 minutes) rise to the top carrying nearly all the arthropods with it. Pipette the critters from the oil layer into a petri plate; remove the excess oil and glycol from the petri plate. Sort the critters into piles of similar species. For example: place all individuals of springtail A into one pile, all of springtail B into a second pile, and so forth.  The number of piles denotes the number of species while the number of individuals within each pile denote the richness of that species.  Continue this process for mites, beetles, etc. and record the number of species into spreadsheet.

 

(4a) Draw a grid on the outside bottom of a new clean petri-plate with a marking pen. Label edges A,B,C, 1,2,3,4. Pick up each identified species and store it in a microdrop of cooking oil; one species per little square x record which species went where on archive spreadsheet.

(These will dry out and then shift around a bit after several weeks; therefore this will work for a short time but not year to year storage.)

or

(4b) Obtain a 24- or 48-depression well-plate and store each species in a different cell. Fill each well 2/3 of the way with rubbing alcohol and cover with about a 1mm thickness of cooking oil. Seal top onto well-plate and store in a tight-fitting Tupperware container with a quantity (5mm) of alcohol added to the tupperware bottom to retard evaporation from the well-plate.

 

(5) Analysis-see analysis page (sorting, identification, and statistical analysis)

 

Quick and easy Berlese Extractor Construction:

1) Obtain a 2-liter plastic soda bottle

2) Carefully and evenly cut 4" off of bottle with either a straight-edge for opening cardboard boxes, or scissors.

3) Obtain a circular piece of hardware-cloth or metal mesh (like screening) equal in size to the diameter of the bottle. Place inside cylindrical part of inverted bottle so that it comes to rest horizontally where bottle starts to contract to form neck.

4) Construct a platform out of thick cardboard or plywood with holes large enough to permit the inverted bottle to nest within them (easiest to use a ¾" or 1" circular drill bit).

5) Place the removed bottom 4" of the bottle underneath the holes to serve as a specimen collector. Fill the "cup" with about ¼" of non-poisonous anti-freeze.

6) Place soil sample in inverted bottle (the Berlese extractor) and place bottle neck through hole in platform.

7) Suspend a 25 or 40 watt bulb over the top of the extractor (see pictures).

 

 

Professional or Long-term Set-up:

 

Abiotic Factors: