Are Plant-Parasitic Nematodes Present in the Gut System and Castings of Earthworms in Cotton Fields?

Earthworms are known to be beneficial to row crops. They aerate the soil as well as move organic matter into the soil helping move nutrients throughout the soil horizon, but what else do earthworms transport? In this study the two questions that are being answered is if nematodes are found in earthworm castings and if so can nematodes survive the journey of passing through the earthworms gut system. Selected fields infested with the reniform nematode (Rotylenchulus reniformis), one located on the E.V. Smith Research Center Milstead, Alabama and the seconds is located on the Tennessee Valley Research and Extension Center near Belle Mina, Alabama. Both fields have high populations of nematodes and populations of earthworms. Earthworms and earthworm castings were collected randomly throughout the field in the early morning hours. Castings were extracted for nematodes by sucrose centrifugation, identified and enumerated using an inverted Nikon Microscope. The earthworms were dissected and the gut systems of the earthworms were then extracted in search of nematodes inside the earthworm in the field. At the E.V. Smith research field, 100% of the worm castings contained reniform nematodes with populations ranging from 1 to 7 vermiform reniform life stages in each 5 cc of worm castings. The worm casting size ranged from a combination of 2.5 ml to 7.5 ml but was standardized at 5 ml. There were also free-living nematodes found in the castings with a population range of 77 to 772 found in the castings. All nematodes observed were alive and viable.