Survival Rates of Eggs of Trichuris myocastoris (Nematoda, Trichuridae) under Different Temperature Regimes

Abstract

The environmental temperature is one of the most important abiotic factors that significantly affects the development and survival of exogenous stages of development of parasitic nematodes, especially geohelminths. This study aimed to evaluate the effect of temperature on the survival and development of eggs isolated from the gonads of female nematodes Trichuris myocastoris Enigk, 1933, under laboratory conditions in vitro. Experimental studies demonstrated that at a temperature regime from 15°C to 35 °C, the duration of formation of motile larvae in egg cultures ranged from 35 to 170 days, and their survival rates ranged from 61.0 to 87.7 %. At a temperature regime of 25 °C the largest number of viable eggs of T. myocastoris was formed, 87.7 %. The shortest period of larval formation in eggs was 35 days at a temperature of 35 °C, with 73.7 % of viable eggs. The period of embryogenesis lasted 35 days at 35 °C, 55 days at 25 °C, and 170 days at 15 °C. The lethality rate of eggs of T. myocastoris, depending on the cultivation temperature, varied significantly and was 26.3 % at a temperature of 35 °C, 12.3 % at 25 °C, and 39.0 % at 15 °C. The growth and development of eggs during embryogenesis is accompanied by changes in their morphometric indicators. Depending on the temperature regime, we observed an increase of egg length by 2.2–4.5 %, a decrease in egg width and shell thickness by 4.7–6.9 % and 19.2–28.0 %, respectively.