The Mosquito/Copepod Kit
  A resource for Florida teachers and students.

Instructions for Rearing the Copepods

Start-up cultures

To start your culture, set up several small containers (disposable food containers work well) about ¾ full of de-chlorinated water and introduce several dozen copepods in each. Water containing chlorine can be de-chlorinated by letting it sit in open containers for several days, by passing through an industrial charcoal filter, or by treating with chemicals (e.g. sodium thiosulfate) available at most aquarium stores.

For long-term cultures, copepods can be reared in pools (plastic kiddie pools) garbage cans or other suitable containers. We have found that aquaria and similar vessels with glass (clear) sides are not very good for rearing copepods. Below we will describe the procedure using plastic pools, but the steps are the same regardless of the container used.

Once you are satisfied that the water that you are using will sustain the copepods, introduce at least 200 adults from the startup dishes into each of the rearing pools and place a standard aquarium aerator in each pool. Add approximately 1000 ml of Paramecium culture (see below) and 100 grains of wheat grain. The copepods will readily feed on the Paramecia, and the Paramecia on the wheat grain. Place the pools so that they receive light (natural or artificial) for at least part of the day, but away from direct sun. Do not use all of your copepods to start the pools cultures so that you can repeat the procedure if the initial attempt fails

Copepods are very hard to see at the beginning of the set up due to the low density. Monitor the pools regularly (every one or two days) until you are satisfied that the cultures are viable, that immatures are being produced and that copepod numbers are increasing. One way to do this is to take several 500-1000ml water samples from the pools and check for nauplii, gravid females, and overall copepod density. When density increases copepods can be seen with the naked eye throughout the pool, swimming & resting. At this point, monitoring the cultures every 1-2 weeks should be sufficient.

Pool Maintenance

As the wheat seed decomposes, some will start floating to the surface of the water and should be removed. This can be done by scooping with an 800μm sieve and discarding. Add wheat grain as needed to replace the grain removed. Sieves can be made by cutting a large hole on a plastic lid and gluing the desired size mesh tightly to cover the hole, by cutting the bottom of a plastic jar and gluing the mesh on one end, or by gluing the desired mesh to short PVC pipe sections (see examples). Every three weeks, add approximately one gallon of dense Paramecium culture (2-3 weeks old) to each pool.

Pools should be emptied and cleaned at least once yearly. This is typically done in late spring to avoid extreme temperatures which could possible increase the chance of mortality. Water is siphoned out of the pool and through a 200μm mesh screen. The contents collected (adult copepods, copepodites, nauplii, Paramecium, and wheat seed) are then separated using a 800μm mesh sieve to eliminate the wheat seed. The reduced volume of water containing the copepods is placed in the pool per the "initial set-up" instructions. Do not clean all of your pools at once. Make sure that the cultures are thriving after cleaning a pool, before your clean the next one.

Paramecium Cultures

Stock material for Paremecium cultures is included in the kit. Add 25ml of the Paramecium caudatum start culture to 1 gallon of spring water (acclimate the Paramecia to the spring water temperature before adding). Then add approximately 12 grains of wheat seed per gallon of culture and a small pinch of yeast. Plastic milk cartons (1 gallon or ½ gallon) work well for culturing Paramecium, as well as 5 gallon water jugs. Wait about two weeks (at room temperature) before using. Save about 500 ml of each jug, refill with water and add wheat seed and yeast as before to start a new culture. Once a year, purchase new start-up cultures and process as before, cultures are inexpensive and can be purchased from any biological supply store (e.g., Carolina Biological - http://www.carolina.com/).

Notes

• If copepods are cultured outside, they need to be covered and at least 3 ft. off of the ground; ostracods and other organisms will invade and dominate copepod population.
• Aquaria or similar vessels are not ideal for copepod rearing.
• It is a good idea to set up several pools and to maintain additional cultures in smaller containers at a separate location so that new cultures can be started in case of loss of original cultures.