Factors in Survival of Nematodes

Publisher Website
Google Scholar
Abstract
It is evident that some nematode species are capable of living in soil or plant debris for long periods of time in the absence of a food source, while others are not. Some are able to withstand drying, flooding, and unusually low temperatures, while other species have specialized stages for survival. It is interesting to speculate that many of the specialized features of survival have developed in conjunction with parasitism and have progressed from no specialization in most free-living nematodes and the plant ectoparasites, to the specialization of a hatching stimulus for the eggs of Heterodera and Ascaris. The author has attempted to develop the following important basic concepts in this review: (a) the varying degrees of survival are invested in the physiological stage of the individual, and its ability to function under conditions of cryobiosis, anhydrobiosis, anoxybiosis, and osmobiosis; (b) fat storage and metabolism are responsible for extended periods of survival; (c) most nematodes have the capacity for both oxidative and fermentative metabolism which enhance their survival potential in a variety of environmental conditions; (d) the physical membranes surrounding the nematode and its eggs are important factors in survival, for they form the boundaries between the physiological reactions within the nematode and its external environment; (e) the basic pattern in the life cycle provides ample avenues for specialization, adaptation, and development of timing mechanisms for survival; and (f) specializations for parasitism, or dispersal, or both have developed concurrently with the faculty for survival. The significance of survival, then, is that nematodes are enabled to inhabit environments not consistently favorable, and that a comparatively short life cycle can be extended for varying periods of time up to 30 years. The bibliography consists of 135 references.