Hatch inhibition of Meloidogyne incognita by aqueous extracts and exudates of five species of cyanobacteria
AbstractThe effects of extracts and exudates of the cyanobacteria, autotrophic blue green algae, Anacystis (Synechococcus) nidulans, Oscillatoria fremyii, Lyngbya sp., Phormidium molle and Westiellopsis prolifica on hatching of Meloidogyne incognita were investigated. Hatch inhibition was greater in extracts than in exudates. The rate of hatch and cumulative percentage hatch over 12 days of incubation were significantly reduced, to 66.9 and 67.6% in exudates (extracellular secretions) of A. nidulans and Lyngbya sp., respectively, compared to 91.2% hatch in nutrient medium control and 85% in water. After one day of incubation, the rate of hatch in the aqueous extracts (intracellular contents) of the species A. nidulans (2.5%), Lyngbya sp. (3%) and O. fremyii (3.2%) was significantly less that the 29.8% hatch in the control. Cumulative per cent hatch increased to only 7.0, 8.6 and 22.1% over 12 days of incubation compared to 85% in water. Replacing exudates or aqueous extracts with water did not significantly increase the rate of hatch, thus indicating that the suppression of hatch was mostly irreversible.