Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: July 6, 1999
Publication Date: N/A
Petri dishes containing 0.8% water-phytagel medium were seeded with root- knot nematode (Meloidogyne incognita) egg masses obtained from monoxenic nematode cultures on excised tomato roots or with suspensions of separated eggs obtained from similar egg masses by dissolving the gelatinous matrix with sodium hypochlorite solution. Natural garden soil (500 mg) was placed around each egg mass and the separated eggs. Each treatment was replicated 12 times; the Petri dishes were kept in the dark at 25C, and microscopic observations were made daily for a period of three weeks. Forty-eight hours following the onset of the experiment, various species of bacteria, fungi, nematodes and mites were near both the egg masses and the separated eggs. Within 7 to 10 days, after experimental set-up, all the separated eggs were destroyed by the soil microorganisms whereas the egg masses remained intact. When separated eggs were placed on pieces of a gelatinous matrix exposed to soil as described above, the eggs survived possibly because of protection by the gelatinous matrix. Light microscopic observations of egg masses placed in Petri dishes and exposed to various bacteria and fungi typical of soils showed that although the microorganisms were in close contact with the egg mass surface, they could not penetrate the egg masses. It is concluded that the gelatinous matrix has antimicrobial properties that may enable root-knot nematode eggs to survive in the soil in spite of its hostile microbial flora.