M.F.S. TAWFIK, K.T. AWADALLAH, F. YOUSIF* AND K.M. AZZAM*.
Biological Control Laboratory, Faculty of Agriculture, Cairo University , Giza , Egypt .
* Medical Malacology Department, Theodor Bilharz Research Institute, Embaba , Egypt .

ABSTRACT

Feeding capacity of the various feeding stages of the belostomatid Limiwgeronfieben upon the two snails, Biomphalarta alexandrina and Ilelisoma duryi was estimated. During the nymphal stage of the predator, this capacity increased progressively in the successive instars, while in the adult stage it appeared higher on II. duryi than on, Balexandrina and in the female than in the male. Observations of the factors affecting rate of consumption upon the last snail showed that this rate increased as temperature increased from 15CC to 30'C. It also increased, but at a decreasing rate with the increase of prey-density. On the other hand, the depth of water did not affect consumption that increased as the size of water decreased.The prey preferability of L. fieberi towards the different snail species living on its natural habitat could be arranged descendingly as follows: Bulinus Iruncatus, Ilelisoma duryi and physa acuta, Biomphalaria alexandrina, Lymnaea cailliaudi, Planorbis planorbis and lastly G. ehrenbergi. The most preferable species was B. truncarus; the intermediate host of Schistosoma haematobium.

Key Words: Predator, Limnogeton fiebeni, Snails, Consumption.