ecology of phasmids - KLUEDO - Universität Kaiserslautern

Community structure & host range 12
see Figure 1-2). Transects were monitored at night every two weeks. The vegetation was scanned with
headlamps up to 2 m heights and in a one-sided width of about 2 m from the line center (to both sides in
the understory and to one side at the forest edge). Phasmids were classified to morphotypes, and
released again after body length was measured.
2.2.2 No-choice feeding trials
To estimate breadth and overlap of the realized niches of phasmid species I recorded all plants on which
phasmids were found along line-transects. As observations of feeding in the field were rare, all plant
records were treated as potential host plants. These plant species were then tested in subsequent nochoice
feeding trials.
To determine diet breadth (sensu absolute food niche) phasmid adults and nymphs were presented with
leaves from alternative plant species in a no-choice design. Adult leaves were harvested in the forest,
placed in a sealed plastic zip log bag and brought back to the laboratory. Within 2 hours of being
collected leaves or leaf discs were presented to phasmids. Feeding trials were conducted in a screened
room subject to ambient conditions. According to the size of the animals, plastic containers of different
sizes were used as trial arenas. The lid of such arenas was screened to allow for ambient conditions.
Each plant species was tested with a minimum of three M. diocles individuals. Adult phasmids and large
nymphs (instars five and six) were presented with whole leaves. Leaves were offered with water supply
by sticking the petiole in a water-filled vial and fastening it with Cotton. Small nymphs (instars one to
four) were offered leaf discs (punch of 13 mm diameter) that were stuck into a piece of cardboard to
assure free access for the nymph. A piece of humid paper towel helped minimizing desiccation. Feeding
trials began in the late afternoon and lasted 24 hours. In cases where the leaf received only a few bites or
was not eaten at all, it was considered inedible (see for comparison Barone 1998). As soon as one
phasmid individual obviously had fed on a leaf, the according plant species was recorded as edible. In
general, phasmids fed on leaves in a measurable way. If a leaf was left untouched while a nymph had
moulted, the trial was discarded.
Four different groups of plants were offered to the four phasmid species maintained in the laboratory:
(1) potential host plants, i.e. plant species where phasmids were found on in the field; (2) congeners and
confamilials of the plant species that were proven edible; (3) a selection of 10 of the most abundant tree
species on BCI (>1000 ind.*50 ha -1 ; Condit et al. 1998); (4) a random selection of plant species from
forest understory and forest edge. For the latter, I asked field botanists on BCI to bring leaves of a
random plant species back to the lab.
2.2.3 Data analysis
2.2.3.1 Estimating phasmid community parameters
A list of phasmid species on BCI was achieved by means of all available field records (i.e. line-transect
and collection records). Field records besides line-transect data have not been used for analysis of