Methode02 Mesofauna and Megafauna extraction

Inital Concept

Compare the mesofauna of the soil between the conventional and the biodynamic agriculture. We decide to use the berlese extractor to collecte the mesofauna. We want to extract the metabolite of the entire sample without sorting the invertebrate and use this to rate the chimiodiversity of the soil. The megafauna (earthworm, centipede, spiders...) is sorted out before the berlese extraction and analyzed as individual extracts.

This experiment is replicated four times for each type of agriculture.

Methodology

Collect

A place is randomly chose in the side row of the 5m x 20m plot. To limit the crop damage, we took the soil sample right under the 20cm x 20cm cut for the methode 1. A bloc of soil of 10cm x 10cm and 5cm deep is collected and store in a zip-lock prelabelled with an unique code. The soil blocks are store in a shaded area until the end of the collection process. They are then store in the 4°C fridge to await the extraction.

Extraction

Berlese

First of all, the block of earth is gently disassembled by hand. The megafauna is set aside. Each individual is placed in a pre-labelled falcon tube and an individual observation is added to qfield (located where the soil was taken). The observation is done exactly the same as the observation of plants. Photos are taken, localisation, and, if known, the species name (If not, "unknow" will be filled in the box).

The megafauna falcon tubes are store in the -80°C and then dry-freezed during 72 hours. Those specimens will then be extracted with the dbgi process.

The mesofauna is extracted by the berlese extractor. The soil is placed in a sieve and gently compacted. The sieve is placed over a funnel and a container of ethanol is placed directly underneath. A bulb that heats up is placed above the earth and this heat dries the soil from above. The mesofauna try to escape the heat and drought by escaping from below, eventually falling into the ethanol.

After Berlese

Photos of the mesofauna are done to futur identification of the specimens with the binocular loup. Then the falcon tube are centrifuged for 5 min at 5000 rps. The pellet is removed using a pipette with a cut tip and conserve in a eppendorf tube already weighted. If necessary, centrifuge the eppendorf tube for 2 min at 13'000 rps, take out the nupernatant and put the end of the pellet (if too much for). Remove the supernatant in the eppendorft tube, after centrifugation (2 min at 13'000 rps) and dry the extract with (the azote machine ??).

Once dry, the eppendorft tube are weighted again and the mass of the specimens is add to the database. Then, a metal bead is placed on the tube and the extraction process is done as dbgi extraction process.

1700 microliter of the ethanol is collected and put in a vial tube to see if any molecule have been extracted during the berlese processus.

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