Pesticides applied to soil in order to control pests or turf diseases may severely affect earthworms. Toxicity to earthworms varies widely among the different types of pesticides classified by use- insecticides and related compounds, fungicides, herbicides, fumigants and vermicides. Two groups of pesticides have been identified as being extremely toxic to earthworms and most other soil organisms. Fumigants such as chloropicrin, dichloropropane, and methyl bromide are one such group. Vermicides, which were designed to kill earthworms, such as ammonium sulphate, lead arsenate, mercuric chloride are detrimental to worms.
Since herbicides are designed to kill or regulate plant growth, they pose very little threat to earthworm toxicity. However, fungicides and insecticides are responsible for the most extensive pesticide impact on earthworms. Insecticides with carbamate compounds such as Turcam and Baygon significantly reduce earthworm populations and cause paralysis at normal doses. Other insecticides with carbamate compounds such as Carbofuran at sublethal responses leave earthworms with delayed clitellum development, low weight, and the absence of cocoon production using only recommended doses to the insecticide. (Delahaut & Koval)
This project will allow the students to see what type of effect that pesticides have on earthworms. They will use three different types of pesticide and examine the external and internal affects that each have on earthworms. The students will maintain earthworms in habitats sprayed with various pesticides for four to six weeks. Therefore, the students will have to dissect at least twelve earthworms for this project.
Materials and Resources
4 plastic or rubber storage containers with lids
Peat moss or the same soil where the earthworms were collected (bedding materials)
Small box of cornmeal (earthworm food)
Three different types of pesticides
Dissecting pan and scope
Fill each of the tubs about halfway to the top with either topsoil or peat moss to act as a bedding material.
Place ten earthworms into each tub.
Mark each tub with the name of the pesticide added. Do not add pesticide to one of the tubs to serve as the control.
Place the tops on the tubs and allow the earthworms to get acclimated to their new environment (about 24 hours).
After approximately 24 hours, sprinkle about 1 tablespoon full of cornmeal over the surface of each tub to serve as a food supply.
Take the containers outside and apply the each of the pesticide to the appropriate tub according to the directions on the pesticide container.
After applying the pesticide, spray or sprinkle 200 ml of distilled water over the surface of each tub.
While outside, Spray or sprinkle 200 ml of water on the container marked control and replace the lid and let it set for one week.
Replace the lids on the containers and allow them to stand for one week.
After about one week, start making observations.
Wearing rubber gloves, observe the external anatomy of five of the earthworms from each of the tubs.
Record the skin color, texture of the earthworm and the overall condition of each of the worms.
Take a picture of the worm for your science fair project board.
Put them down and notice their movement. Record your observations.
Observe their heartbeat underneath a dissecting scope. Record your observtions.
Place the worms back into their respective tubs.
Find a picture of the internal structure of a normal earthworm. Use this to identify the parts of the internal structure of the earthworm.
Choose one worm from each of the tubs to dissect.
Place enough alcohol in a petri dish to fill it half way.
Place the worm into the petri dish. This will kill the worm and get it ready for dissecting.
After a few minutes, place the worm on the dissecting tray.
Dissect the earthworm, pay close attention to the digestive system, and reproductive structures such as the seminal vesicles
Take a picture of the worms for your science fair project board.
After a worm from each container have been observed, photographed and dissected, sprinkle about 1 tablespoon full of cornmeal over the surface of each tub to serve as a food supply.
Repeat steps 6 through 8. One week later, repeat steps 11 through 23.
Repeat steps 24 and 25 for 4 to 6 weeks before concluding the experiment.