ecology of phasmids - KLUEDO - Universität Kaiserslautern

Adult female feeding preference & nymph performance 65
Survival and growth of nymphs as key demographic traits in insect herbivores were expected to
decrease with increasing defensive leaf characters. Correlation analysis of performance with leaf
toughness, specific leaf weight, water and total phenol content showed no relationship to nymph growth
(Figure 4-10) and survival (Figure 4-11). Considering tannin contents of leaves their effects on nymph
performance remained unclear. (Leaf tannin content could not be correlated to nymph performance due
to rare presence of tannins.) If tannins influenced survival plant species containing tannins should have
ranged on the upper end considering nymph mortality. In contrast to this prediction 47.5 % of nymphs
survived on P. marginatum (1.58 % TAE) only exceeded by survival on two other tannin-free plant
species (P. dilatatum, Phil. inaequilaterum; cf. Table 4-2 and Table 4-3). Similarly survival of nymphs
feeding on tannin containing leaves of P. cordulatum and P. hispidum ranged on mid levels. While
tannins seemed not to be related to nymph survival there is a clear pattern in terms of growth rates of
nymphs. Growth rates on all three Piper species containing tannins and fed to nymphs (P. cordulatum,
P. hispidum, P. marginatum; cf. Figure 4-9 and Table 4-2) were only exceeded by nymph growth on
P. peltatum (tannin-free).
relative growth rate of nymphs
0.20
0.15
0.10
0.05
0.00
f
g
Dlong
Mean
±StDev.
±1.96*StDev.
c
d
e
f
Paequ
a
b
Pcord
b
c
Pcule
e
f
Pdari
c
d
e
Pdil
g
Pgran
b
c
d
Philinae
d
e
f
g
Philsp
a
b
Phisp
a a
Figure 4-9: Relative growth rates of M. diocles nymphs on single food plant species (measurements after two
weeks, one week later too many nymphs had died). Growth rates differed significantly depending on food source
(ANOVA, F = 34.2, df = 12, P < 0.01). Identical letters indicate no significant difference (Tukeys HSD unequal N,
P > 0.05).
Pmarg
Ppelt
c
d
e
f
Preti