AXENIZING AND CULTURING ENDOMIGRATORY PLANT-PARASITIC NEMATODES USINGPLURONIC F127, INCLUDING ITS EFFECTS ON POPULATION-DYNAMICS OF PRATYLENCHUS PENETRANS

A non-chemical technique for surface sterilizing plant-parasitic nemat odes for aseptic cultures is described. The method is most applicable to nematodes with active migratory infective stages and requires only a felv starting specimens. Rate of achieving a primary aseptic culture with the technique ranged from 60%-100% depending on the conditions o f the specimens collected for culturing. Aseptic cultures of species o f Meloidogyne, Rotylenchulus, Pratylenchus, and Radopholus initiated w ith the method remained contamination-free after 12 months of maintena nce in tomato root explant or alfalfa callus cultures. Further studies of Pluronic F127, a polyol gel medium employed in the technique to co nfine the spread of contaminating bacteria or fungi associated with th e nematodes, showed that the polyol gel was a suitable support medium for culturing corn root explant, alfalfa callus tissues, and consequen tly Pratylenchus species including P. agilis, P. brachyurus, P. scribn eri, and P. penetrans. During the course of 10 months, P. penetrans re ared in polyol-base medium followed a standard biological growth curve , multiplied to a higher population density, maintained a similar fema le-to-male ratio, and possessed a similar tendency to reside inside or outside host tissues as did P. penetrans reared in agar-base medium. The percentages of P. penetrans juveniles in the sub-populations resid ing outside or inside the host tissues reared in polyol-base medium al so were similar to and fluctuated temporally in like manner as those r eared in agar-base medium. Members of these sub-populations from the p olyol- or agar-base were equally infective and reproductive after 9 mo nths of culturing.