Zinc-mediated hatching of eggs of soybean cyst nematode,Heterodera glycines

Abstract

Egg hatching of the soybean cyst nematode,Heterodera glycines, was not affected by millimolar concentrations of calcium sulfate or calcium chloride. However, zinc chloride and zinc sulfate caused strong and moderate increases in hatching, respectively. The inhibitors of calcium transport, ruthenium red and lanthanum chloride, and calcium ionophore A23187 had no effect on hatching in the presence or absence of 3 mM zinc chloride. Selected chelators decreased the zinc-induced hatching ofH. glycines eggs. Eggs exhibited a formation constant with zinc between 5.5 and 11.2. The addition of zinc chloride after chelation with EDTA and rinsing caused expected hatching rates. Concentrations of calcium chloride, manganese chloride, and magnesium chloride had no effect on hatching of eggs in zinc chloride, but reduced hatching at higher concentrations, possibly by osmotic influences. Hatching of eggs was increased as the time of exposure to zinc chloride was increased and was maximal at 28 °C and a pH of 5.3. Picrolonic acid, a known hatching stimulant, increasedH. glycines hatching, while sodium metavanadate had no effect. Analysis of seasonal hatching during 1981-1982 in untreated control eggs indicated that hatching was most pronounced in May.