ecology of phasmids - KLUEDO - Universität Kaiserslautern

Adult female feeding preference & nymph performance 62
MAI [median]
MAI [median]
1
0.5
0
1
0.5
0
0 100 200 300 400 500
a)
Relative leaf toughness
2.5 3.5 4.5 5.5
b)
c) Specific leaf weight [mg/cm2]
d)
MAI [m edian]
MAI [median]
1
0.5
0
1
0.5
0
60 60 70 70 80 90
Water Water content content [%] [%]
0 1 2 3 4 5 6 7 8 9
Phenol content [%TAE]
Figure 4-7: Preference of M. diocles adult females (expressed as Mean Acceptability Index; MAI) in relation to
structural and chemical leaf characters of 14 food plant species. MAI showed no significant relation to any of the
measured leaf traits (Product moment correlation, df = 12, all P > 0.05): a) leaf toughness (r = 0.15), b) water
content of leaves (r = -0.38), c) specific leaf weight (r = 0.26), d) leaf phenol contents (r < 0.01).
4.4.3 Performance of M. diocles nymphs
Survival and growth seemed to be highly depending on the plant species nymphs fed on.
A comparison of survival probabilities of nymphs under different food sources revealed substantial and
significant differences (Figure 4-8 and Table 4-3). The effects of food source on nymph survival were
temporarily heterogeneous. Median survival and quartiles differed species specifically (Table 4-3). For
instance within the first day 25 % of nymphs on P. cordulatum had died while initial mortality rate was
lower on all other food sources. This effect changed over time. When mortality on P. cordulatum
decelerated (and more than 25 % of nymphs had survived at the end) it accelerated on other plant
species (D. longispatha, P. grande, P. dariense) leading to comparatively higher mortality in the long
run. Median survival time was lowest for P. grande: after six days 50 % of nymphs feeding on
P. grande had died. After day 15 no nymphs had survived. Likewise median survival time on
D. longispatha was 9 days and no nymph survived beyond day 17. Opposed to these low quality foods,
feeding on Philodendron inaequilaterum allowed high nymph survival. After six weeks 76 % of
nymphs were still alive while on all other host plant species from 50 % (P. dilatatum) up to 100 % of
nymphs had died.