2.1. Animals
Studies were performed with adult male and female grasshoppers
of the species Ch. biguttulus (Orthoptera: Acrididae; L.
1758). All females used in this study were reared from eggs that
derived from grasshoppers collected in the vicinity of Go¨ ttingen,
Germany in the previous summer (the summers of 2007 and 2008).
Mixed populations of these grasshoppers were kept for up to 3
weeks in the laboratory enabling females to lay eggs into dishes
filled with moistened vermiculite. Male grasshoppers used in our
study either derived from the same clutches or were caught as subadults
in grassland areas around Go¨ ttingen. Eggs were kept at 4 8C
for at least 4months. Hatching occurred after approximately 1 week
at 26 8C and the nymphswere fed with grass and supplemental food
for crickets (Nekton, Pforzheim, Germany) ad libitum. After
moulting into the fourth nymphal instar, fully intact females were
randomly selected fromthe rearing cages and separated frommales.
The grasshoppers were reared and maintained at 20–26 8C and
photoperiods of 16 h light and 8 h darkness.