Ancylostoma duodenale and Necator americanus: effect of temperature on egg development and mortality

The development and mortality of the eggs of Ancylostoma duodenale and Necator americanus in distilled water were monitored over a range of temperatures between 15 and 35 degrees C. Egg demography was examined within the context of a four-parameter mathematical model of development and mortality. Over the range of temperatures studied, egg mortality (mu) was an increasing exponential function of temperature (T) measured in degrees Celsius. A single model adequately described the mortality of both species (In [mu] = 0.41*T-6.87). The minimum time (tau) to hatching was consistently less for A. duodenale (In [1/tau] = -(0.79 + 53.05*[1/T]) than N. americanus (In [1/tau] = -(0.99 + 53.05*[1/T]]. The hatching rate (sigma when t greater than tau) was an increasing function of time and temperature in both cases, but the precise functional relationship was species specific.