Nematode Root Parasite — LINFORD, et al . 
119 
through wounds as ,does this species. Even 
infusoria have been found in punctured root 
cells. There seems, accordingly, to be no sub- 
stitute for microscopic observation of the living 
nematodes in association with roots for deter- 
mination of feeding habits and host ranges of 
species found superficially associated with roots. 
Our studies raise some question concerning 
the syngonism reported for Paratylenchus 
nanus by Cobb (1923: 369) and Steiner 
(1924: 1065). Those workers regarded the 
species as syngonic because, in the absence of 
males among their specimens, the females con- 
sistently contained sperm cells in the uterus. 
Abundance of males in P. minutus makes such 
an assumption unnecessary. Furthermore, our 
experience leads us to question whether males 
may actually have occurred in the populations 
from which Cobb and Steiner drew their sam- 
ples. We first recognized the abundance of 
males after discarding sieve methods of collec- 
tion and adopting the funnel technique; and the 
inability of males to feed results in relatively 
few of them entering a root. Before syngonism 
is accepted for any paratylench there should be 
either better evidence that males do not occur 
or that the female is capable of spermatogenesis. 
SUMMARY 
A very small nematode that occurs in great 
abundance in certain pineapple fields on the 
island of Oahu, and less widely on Molokai and 
Maui, is described as Paratylenchus minutus 
Linford. Over 900 individuals have been ex- 
tracted from 1 gram of soil and over 23,000 
per gram of pineapple root with its adhering 
soil. This nematode is relatively tolerant of 
slow desiccation in soil but is essentially equal 
to Heterodera marioni in sensitivity to soil 
fumigants. It is primarily an ectoparasite of the 
root hairs and epidermal cells of the young 
mature zone of roots, but it enters the epider- 
mis and cortex through wounds made by other 
agencies. To feed, it inserts the tip of its stylet 
through a wall into a living cell. In this posi- 
tion, prolonged periods of pulsation of the 
median esophageal bulb for ingestion of food 
are preceded by and alternate with periods of 
rest. This feeding, which appears to involve 
extra-oral digestion, fails to interrupt normal 
streaming of the host protoplast. No visible 
pathology has been associated with prolonged 
feeding from a single cell. The host range of 
this paratylench evidently is wide, for limited 
observation has established 25 known host 
plants representing 13 families. 
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