Microhabitats of larval stages searched and collecting methods
In the field, larvae are searched and collected in holes of
trees (Fig. 2).In holes
found in trees, larvae and pupae are collected by suction with
a 2 meter-long hose. It is used to suck the water and organic
material contained in the hole and to deposit them in a plastic
container. After extracting initial contents, clean water is used
to wash the walls of the hole and extract again new contents.
In this way, it makes sure that larvae and pupae are not longer
stuck to the walls and bottom.
In the chamber of the bamboo (Fig.
3) ), larvae and pupae are collected by suction with a 30
ml pipette. Similarly, the walls of chambers are washed to obtain
all possible larvae and pupae.
In concavities of rocks along rivers (Fig.
4) ), larvae and pupae are obtained by using a small red for
fishes or a strainer.
In puddles (Fig. 5)
and pools with aquatic plants (Fig
6) a plain net covered with glass nylon is run over the surface
and spanning 10 cm of depth. In some cases, this net is tied to
extension poles or branches increasing the sampling surface. Sieves
covered with glass nylon are also used. To search for larvae associated
to aquatic plants (those obtaining O2 by perforating tissues of
the plants) are transferred to big containers with clean water,
then shaken energetically in order to release larvae from the
roots. Next, the water in the container is sieved, transferring
larvae, together with organic matter and some aquatic plants,
into a plastic bag with clean water. This allows transporting
larvae to the lab.
When using bromeliads (Fig.
7) ) and florescence of helicons, water is rapidly poured
into a container placed under the plant or flowers. Sometimes,
it is necessary to cut bromeliads and the florescence to check
carefully because larvae normally stick near the base of the leaves
and flowers. It is recommended to wash all these plant structures
over a sieve or a net, and to shake them slightly to obtain the
detachment of any larva stuck to the plant matter.
The water accumulated in the base of the petioles of the Araceae
(Fig. 8) plants
is a habitat preferred by some species of the genera Sabethes
and Wyeomyia among others. It is difficult to extract larvae located
between the petioles because they are thick and close to the stem.
One appropriate technique is to cut some centimeters above and
below of the union of the petiole and the stem. The stem section
with the petiole is rapidly reversed on a container with clean
water. Then, larvae are extracted with a pipette and placed into
a collecting bag with clean water. This last step needs to be
done fast to avoid mixing water with the plant fluids, which can
affect larva survival.
Other habitats for searching larvae and pupaes are bracteas of
palms; fallen fruit containing water (Figs.9
y 10); artificial
containers such as tires, cans, bottles, flowerpots and others;
holes made by crabs; and in general any michohabitat where water
can be accumulated.
