Research Article

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

G. Smitha1 and G. A. Schada2

a1 Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, New Bolton Center, 382 W. Street Road, Kennett Square, PA 19348, USA

a2 Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA


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°C. Egg demography was examined within the context of a fourparameter mathematical model of development and mortality. Over the range of temperatures studied, egg mortality (μ) was an increasing exponential function of temperature (T) measured in degrees Celsius. A single model adequately described the mortality of both species (ln [μ] = 0·041*T − 6·87). The minimum time (τ) to hatching was consistently less for A. duodenale (ln [1/T] = −(0·79+53·05*[l/T]) than N. americanus (ln [1/T] = −(0·99 + 53·05*[l/T])). The hatching rate [σ when t > τ) was an increasing function of time and temperature in both cases, but the precise functional relationship was species specific.

(Accepted January 14 1989)

Key words

  • Ancylostoma duodenale;
  • Necator americanus;
  • egg development;
  • mortality;
  • temperature.