The effect of temperature on the development and survival of the infective larvae of Strongyloides ratti Sandground, 1925

Abstract

The development of the free-living infective larvae of a homogonic strain Strongyloides ratti is described.The larvae develop only between 15 and 34 °C. Transfer experiments show the temperature block to be in the preparation for the second moult.Within the temperature range 15–34 °C, increasing the temperature speeds up the rate of development of all the larval stages equally, the Q10 for development being 2·5.The maximum percentage development occurs at 20 °C. The percentage development is highest in faeces–peat culture (95% development at 20 °C), whilst the percentage development in charcoal and vermiculite cultures is about the same (75% development at 20 °C.).Larvae grown on charcoal cultures are larger than those grown on vermiculite, which are larger than those grown on peat. No significant difference was found in the length:oesophagus and length:width ratios or in the variability of larvae grown at different temperatures or on different culture media.Different worm densities in the cultures of from 2000 to 10000 larvae per g of culture did not affect either the size of the infective larve or the percentage development.The optimum temperature for survival is 15 °C. Worms grown at 20 °C lived longer than worms grown at any other temperature. There was no evidence of temperature adaptation by the larvae.The infective larvae are positively thermotactic, and show maximum activity at 37 °C.I should like to thank my supervisor, Dr Tate, for his advice and encouragement. The work was carried out during the tenure of a Medical Research Council Scholarship.

A Critical Role for Thermosensation in Host Seeking by Skin-Penetrating Nematodes

“…Detection of a host animal likely involves both olfactory and thermosensory cues [13]. Early studies of thermosensation in skin-penetrating nematodes showed that the iL3s of many species respond to warmth [22–31]. However, the detailed thermosensory behaviors of parasitic nematodes require elucidation, and the molecular mechanisms that mediate thermosensation in these parasites have not yet been investigated.…”

Effect of temperature on the development of free-living stages of Strongyloides ratti

“…Likewise, we performed a temperature shift experiment with S. ratti and found that larval development of this parasite was determined after either a 16-h exposure period at a low temperature of 15°C or after a 6-h exposure period at a high temperature of 25°C. This suggests that larval development is committed at a relatively early stage, before the first molt (the first molt of S. ratti larvae takes place within 8-9 h at 24°C (Barrett 1968)). …”

“…In S. ratti, only about 30% of eggs had already hatched in fresh feces collected from infected rats (Barrett 1968); the developmental course of the remaining eggs is probably undetermined at this stage. This may imply a survival strategy to ensure that S. ratti flexibly adapts to the ambient environment external to the host.…”

Strongyloides ratti: thermokinesis of glycolytic enzyme- and lectin-treated third-stage infective larvae in vitro

“…Mechanical and chemical signals, light, and temperature via the amphids influence the behavior and development in animal parasitic nematodes (Africa 1931;Parker and Haley 1960;Sasa et al 1960;Gupta 1963;Barrett 1968Barrett , 1969Evans and Perry 1976;Macinnis 1976;Granzer and Haas 1991). Temperature recognition is especially important in the host-finding behavior of the skin-penetrating infective larval stages of the parasites of homeotherms.…”