Effect of temperature on the development of the free-living stages of horse cyathostomins.

Abstract

Cyathostomins are considered as the most prevalent and pathogenic parasites of grazing horses. The development on pastures of the free-living stages of these gastrointestinal worms is particularly influenced by outdoor temperature. Understanding the bionomics of free-living stages is an important prerequisite to implement mathematical models designed to assess the parasitic risk for grazing equids. The aim of this study was to assess the effect of 3 constant temperatures under laboratory conditions (10±1°C, 23±2°C, 30±2°C) and one fluctuating temperature under outdoor conditions (mean: 17±4°C) on the minimum time taken by cyathostomin eggs to develop into first/second stage larvae (L1/L2) then into infective third stage larvae (L3) in horse faeces. According to the temperatures, the minimum time taken by eggs to develop into L1/L2 was between 1 and 3days and into L3 between 4 and 22days. At 10°C, the development time of eggs into L3 was the longest and at 30°C the fastest. The results were consistent with historically available data and their compilation should lead to the improvement of parameterised models assessing the parasitic risk period in grazing equids.