The Effects of Roundup® on Eisenia fetida Nathan Brownrigg Senior Capstone Spring 2005

Topics to be Discussed  Background Information  Materials and Methods  Results  Discussion of Results  Questions

Background Information  Roundup® is a common herbicide.  Glyphosate is the active chemical. It is also used in many other herbicides.  Ingredients: Glyphosate 18%, Diquat Dibromide 0.73%, Others 81.27%.

Background Information  Generally used to kill weeds and grasses. Tree stumps can also be killed by drilling holes into a fresh stump and applying the concentrated herbicide into the holes.  The herbicide is applied to the foliage of the plant and it systemically moves to the roots.  The chemical works by preventing the plant from producing certain amino acids.  This inhibits protein synthesis in the plant and eventually kills it.

Background Information  Glyphosate is generally not active in the soil (it is applied to foliage).  Strongly absorbed by the soil.  Half-life can range from days.  Eventually broken down by soil microorganisms.  Effects on soil invertebrates not known.

Background Information  Eisenia fetida  Known as redworms.  Very important compost organism.  Commonly bred for use in compost heaps.

Background information  Earthworms in general are important soil invertebrates. Their burrowing and feeding activities enhance soil fertility by incorporating thatch throughout the soil.  Because so much soil passes through their bodies and they are in constant contact with the soil, there is a significant possibility of toxins becoming concentrated within them.

Background Information  Because of possible toxin build up, earthworms can be used as bioindicators of pollution in the soil.

Topics to be Discussed   Background Information  Materials and Methods  Results  Discussion of Results  Questions

Materials and Methods  Roundup® superconcentrate was obtained from local lawn and garden center.  Enough to treat 3,000 sq ft. (using recommended amount).

Materials and Methods  Containers were prepared by adding approximately 1,000 grams of soil.  Soil depth was about 3 cm, which was recommended by the Carolina Biological Supply Co.

Materials and Methods  In all, 12 containers were prepared this way.  One other container was filled with a little more soil to maintain the earthworms not to be used in the experiment.

Materials and Methods  Earthworms were then counted into groups of 50 and weighed using an electronic balance and placed in one of the 12 containers.  These numbers later serve as the initial biomass of the earthworms.

Materials and Methods  The recommended concentration for Roundup®:  6.0 fl oz. per gallon of water.  Converted for experimental use; the recommended concentration:  14.1 ml Roundup® per 300 ml solution (distilled H 2 O + herbicide.) (4.7%)

Materials and Methods  Concentrations were then determined for experimental use:  Control: 0.00 (distilled H 2 O)  Experimental groups: 7.05(2.4%), 14.1(4.7%), 28.2(9.4%), 42.3(14.1%), and 70.5(23.5%) ml Roundup® per 300 ml solution.

Materials and Methods  The concentrations were applied to each container.  One concentration per container, 6 concentrations, 12 containers = two experiments running concurrently.

Materials and Methods  The containers were then left to incubate for 30 days.  Day 14: Moist corn meal was applied to the soil for food (as instructed by Carolina Biological Supply Co. manual).

Materials and Methods  Worms removed and reweighed after 30 days.  Weight was compared to original biomass.  Number of dead worms was also recorded.

Topics to be Discussed   Background Information   Materials and Methods  Results  Discussion of Results  Questions

Results  Too many earthworms from trial 1 died to collect data.  Due to dehydration (no mortality was observed in other three trials).  The following tables and graphs show the results from trials 2-4.

Results Biomass of Earthworms Before and After Exposure to Roundup® (Trial 2) Concentration (%) Original Biomass (g) Biomass Following Exposure (g) Difference (g) (+) (-) (-) (-) (-) 0.3

Results Biomass of Earthworms Before and After Exposure to Roundup® (Trial 3) Concentration (%) Original Biomass (g) Biomass Following Exposure (g) Difference (g) (+) (-) (-) (-) (-) (-) 0.5

Results Biomass of Earthworms Before and After Exposure to Roundup® (Trial 4) Concentration (%) Original Biomass (g) Biomass Following Exposure (g) Difference (g) (+) (-) (-) (-) (-) (-) 0.4

Topics to be Discussed   Background Information   Materials and Methods   Results  Discussion of Results  Questions

Discussion of Results  These numbers indicate that Roundup® has a negative effect on the biomass of Eisenia fetida. However, the herbicide is not fatal to the earthworms at these concentrations.

Discussion of Results  Concentrations above the recommended did not consistently decrease the biomass of the earthworms.  Experimental error may have had an effect on trial 2. However, this was corrected and results of trials 3 and 4 were relatively consistent.

Questions????????

References  Bauer C., Rombke J Factors influencing the toxicity of two pesticides on three lumbricid species in laboratory tests. Soil Biol. Biochem. 29,  Callahan C.A Earthworms as ecotoxicological assessment tools. United States Environmental Protection Agency, EPA-600/D  Mosleh Y.Y., Paris-Palacios S., Couderchet M., Vernet G Acute and sublethal effects of two insecticides on earthworm (Lumbricus terrestris L.) under laboratory conditions. Environ. Toxicol. 18(1), 1-8.  Mosleh Y.Y., Paris-Palacios S., Couderchet M., Vernet G Effects of the herbicide isoproturon on survival, growth rate, and protein content of mature earthworms (Lumbricus terrestris L.) and its fate in the soil. Applied Soil Ecology 23,  Pendergrass W Carolina Protozoa and Invertebrates Manual. Carolina Biological Supply Company. Burlington, NC. 34

Acknowledgements  Dr. McShaffrey  Dr. Pate