ecology of phasmids - KLUEDO - Universität Kaiserslautern

Adult female feeding preference & nymph performance 60
Total Total phenol phenol content [% TAE]
10
8
6
4
2
0
c
d
Pmarg
b
e
Paequ
c c
d
Parbo
Pcord
c
f
Pcule
Pdari
a a
Pdila
e
Pgran
a
b
Philinae
d
Philsp
a
f
Phisp
a a a a
b b b
Figure 4-5: Total phenol content of leaves from 15 food plant species of M. diocles. Total phenol content differed
significantly among species (ANOVA, F = 44.60, df = 14, P < 0.01). Identical letters below boxes indicate no
difference (Tukeys HSD unequal N, P > 0.05). Box-Whiskers show mean, standard deviation and 95 % confidence
intervals of standard deviation.
4.4.2 Preference of M. diocles adult females
Feeding preference of adult M. diocles females differed significantly indicating that they differentiated
among food plant species (Figure 4-6). The assessed preference pattern at the same time revealed broad
interspecific similarities. P. marginatum seemed to represent a food source of high value within the
range of species tested. P. peltatum was most similarly accepted as food compared to P. marginatum as
its median MAI was closest to 0.5. As preferences for six more plant species were not different to
P. peltatum they also seemed to range on a similar preference level with P. marginatum as M. diocles
foods. Only four out of 14 species were preferred to P. marginatum, i.e. the MAI resulting from dual-
choice feeding trials was significantly above 0.5 (as compared to MAI of P. peltatum). Three plant
species were clearly avoided by adult females: presented with P. aequale, P. grande and P. perlascense
the insects strongly preferred the reference P. marginatum.
The measured leaf characters seemed not to function as defenses against herbivory by M. diocles.
Preference for host species neither correlated with structural and physical parameters tested nor with
total phenol contents of leaves (Figure 4-7). Likewise tannin contents of leaves seemed not to account
for the observed preference pattern of M. diocles adult females (correlation analysis was dismissed due
to rare presence of tannins). Assuming a defensive function of tannins the animals should have preferred
the leaves of plant species missing tannins. This could not be confirmed (compare Figure 4-6 and
Pimpe
Ppelt
Pperla
Preti