A Cotton Blue-Lactophenol Technique for Mounting Plant-Parasitic Nematodes

Abstract

The lack of a rapid and reliable method of making permanent preparations of nematodes is most strongly felt in the case of the plant-parasitic forms. The method in general use for most plant- and soil-inhabiting nematodes consists in relaxing the worms by gentle heat, fixing in 5% formalin or Ditlivsen's fixative (Thorne, 1925) and then impregnating slowly with glycerine. This procedure is quite reliable for the non-plant-parasitic forms but its results with plant-parasitic worms are very uncertain. With the latter it is necessary to transfer from fixative to very dilute glycerine, usually 1.5% glycerine in 7.5% alcohol with a trace of thymol or copper sulphate to discourage moulds. The glycerine is allowed to concentrate very slowly during at least four weeks until the worms can be transferred to pure glycerine in which they are mounted. Even then the results are often disappointing for the worms very frequently collapse.In considering this general problem recently the authors called to mind the appearance of worms stained within plant tissues by the acid fuchsin-lactophenol method (Goodey, 1987: Franklin, 1949). This method causes no collapse or distortion of the worms and takes but a few minutes from living material to permanently stained preparations. The process has now been developed for use with free specimens of Anguillulina dipsaci and plant-parasitic species of Aphelenchoides, and is as follows: