2 Materials and methods
2.1 Sample collection of grasshopper [Chondracris
rosea rosea (De Geer)]
Adult grasshopper was captured in Cangzhou city,
Hebei province of China. The photograph of this species
of grasshopper is shown in Fig. 1. The sample was
narcotized by 99% ether. Then the mandibles as the
selected component were separated from the body by
scalpels, and the grasshopper was executed after the
operation. Finally, the mandibles were washed by distilled
water.
Fig. 1 Grasshopper.
2.2 Corn stalk samples
Corn (Nongda 108) was used as the test material
seed. The corn was planted on April 21, 2012 and stalk
was harvested on October 7, 2012 from the plots (location:
125.419007°W, 43.813500°N) of the Experiment
Station, Jilin, Changchun. The collected corn stover was
stored for 2 months indoors until experiments in a
laboratory with air conditions of about 18 °C – 20 °C and
relative humidity of about 35%, where the stalks naturally
dried. No degradation of the stalks was observed,
and the stalks maintained their structural integrity and
mechanical property.
Corn stalk samples were prepared as test material
by stripping of the leaves and husks. Due to the likelihood
of cutting the stalks by harvesting machinery at
internode was high, and the internodes were more uniform
than the nodes, so internodes of corn stalks were
selected for cutting experiments. The diameter of internodes
was approximate 30 mm.
2.3 Photograph taken by stereoscope
The geometrical morphology of the grasshopper
[Chondracris rosea rosea (De Geer)] was measured with
a stereoscope XTJ-30. Fig. 2 shows the digital photograph
of grasshopper mandible taken by the stereoscope.
The sharp serrated structure on top of the mandible is the
incisors of the grasshopper.