Carnivorous Plants and Their Prey

tissue. This gives the pitcher an open, lighted appearance which, once inside, confuses insect
visitors and causes them to move towards the digestive fluid thinking it the route to escape (12).
Pitchers may be very straightforward in their construction simply consisting of vegetative
cups filled with fluid. Most pitchers, however, are modified to hinder the escape of insects and
thereby increase the efficiency of prey capture (12, 27, 49). A lip or ledge may protrude inward
from the top edge of the pitcher requiring insects to attempt an upside-down walk in order to free
themselves from the trap. This often results in the prey falling down into the fluid-filled pitcher
(11, 12). Some Sarracenia have hoods over the pitchers to inhibit prey from flying out as well as
prevent rainfall from filling the pitfall trap (10). Nepenthes albomarginata, an Indonesian pitcher
plant, has a unique lure to entice termite prey. These plants have trichomes around the rim of the
pitchers that attract scouting Hospitalitermes bicolor termites. Scouts, in turn, signal their cohorts
to feed on the living plant tissue. The termites feed on the hairs and gradually move into the
pitcher in search of more of the apparently tasty trichomes. Once inside the pitcher, the termites
slip into the fluid-filled traps en masse and are ultimately digested by the plant. The attractive
zone may also be covered with downward pointing hairs that prevent exit and guide insects
towards the digestive fluid (25, 50). Within about one hour of the start of termite activity, the
insects succeed in completely grazing away the rim hairs, which ends the feeding. Pitchers are,
by this time, filled with termites (51).
Below the attractive zone in many pitfall traps lies a second zone often lined with
nectaries to attract insects further into the pitcher (1, 25). The second zone as well as the third are
typically covered with slippery secretions that cause prey to lose their grasp on the trap walls and
plummet into the digestive zone below (1, 12, 25, 50). Aldehyde-based wax crystals secreted by
the plant cover these zones and may either break away as insects move about or prove to be too
slick for prey to gain a foothold (25, 43, 47). An insect’s weight and its appendage design helps
determine what insects get caught, too. As an example, larger insects without adhesive pads on
their legs may easily slip from the waxy pitcher surface (50).
18