ecology of phasmids - KLUEDO - Universität Kaiserslautern

Community structure & host range 19
Absolute abundance [ind.]
40
35
30
25
20
15
10
5
0
Nymphs Adults
May-00
Jun-00
Jul-00
Aug-00
Sep-00
Oct-00
Nov-00
Dec-00
Jan-01
Feb-01
Mar-01
Apr-01
May-01
Jun-01
Jul-01
Figure 2-3: Temporal fluctuations of absolute phasmid abundances along forest edges on BCI for phasmid
nymphs (black bars) and phasmid adults (white bars). Each bar represents the cumulative catch per month along
three line-transects (N = 286). Please note that Oct. 2000 and Jul. 201 were excluded from GOF tests.
2.3.3 Food niche
Single phasmid species showed a highly aggregated distribution on particular host plant families
resulting in narrow resource niches with values for Levin’s standardized niche breadth BA ranging from
0 (Otocrania sp.) to 0.40 (Bacteria ploiaria) (Table 2-2). For example, the low niche breadth of 0.10 for
I. dentipes (the second most abundant species in forest edge habitats; cf. Figure 2-1) resulted from 68
specimens recorded on two plant families, and 91 % of these specimens were found on two individuals
of Vismia baccifera (Clusiaceae). All three individuals of Otocrania sp. were found on Sapindaceae.
Niche breadth was larger in the other three species because they were recorded on more plant families
and individuals were less aggregated (major proportion of individuals per plant family: O. martini, 55 %
on Clusiaceae, 18 % on Euphorbiaceae; B. ploiaria, 34 % on Rhamnaceae; M. diocles, 49 % on
Piperaceae,and one third of these on P. marginatum, 25 % on Araceae).
Generally, resource niches of phasmid species were separated as demonstrated by Pianka’s index of
niche overlap Ojk, usually ranging from 0 to 0.19. In contrast, niche overlap between O. martini and
I. dentipes was high (Ojk = 0.91) because 55 % of the O. martini and 91 % of the I. dentipes individuals
shared 2 individuals of Vismia baccifera as food resource (cf. Table 2-2).