H. ephippiger nymphs were collected from ponds and lakes
in the Abou-Roash area, Giza Governorate, Egypt. They were
kept in a glass aquarium (50, 30 and 20 cm in length, width and
height), respectively. Collected nymphs were reared in an
aquarium in the laboratory and fed daily to satiation on different
sizes of L. natalensis. Nymphs were starved for a period of 24 h
before they were used in experiments. Fully grown nymphs (the
last two instars) with sizes ranging from 3.2 to 4.5 cm in length
were used in the experiments.