The sensory setae morphology and behavior in the soldier caste of subterranean termite, Coptotermes spp. (Blattodea: Rhinotermitidae)

概要

Termites live in a colony as social insects. They are divided into three castes based on the labor
differences in the nest, reproductive caste (queen and king), worker caste (pseudergate), and
soldier caste. Each caste performs different labors and organize the role of each caste in the nest
by certain communication system. Two types of communication systems generally exist, chemical
and non-chemical communication. Chemical communication may include the works of pheromone
between individuals. Whereas non-chemical communication is established when one individual
vibrates the surroundings or structure to generate sound or vibration, which is accepted by another
individual. In order to respond chemical and non-chemical signals, termites develop sensory
receptors located on their organs or body parts. Some sensory receptors have different anatomical
characteristics to support their function, such as sensory setae on termite’s antennae. Setae can
become an olfactory sensory receptor when it has porous cuticle allowing chemical substance’s
direct contact with the sensory cells, or mechanosensory receptor when it has long or broad flexible
pegs or caps allowing the sensory cells beneath the pegs or caps to sense cuticle distortion.
In Coptotermes, setae distribution on the soldiers’ body have been usually utilized as an alternative
characteristic to diagnose species. However, the excessive use of size-correlated characteristics on
the head parts covers the importance of the body setae distribution for species discrimination.
There is also little information regarding the functional morphology of the setae, particularly setae
that are not located on the antennae, such as mouthpart, head part, and thorax part. Since soldier
caste has remarkable morphology modification to perform their defensive task, the biological
structures of setae on their body to support their defensive labors or survival has been less studied.
The thesis aimed to investigate setae characteristics and their functional morphology on the body
parts of Coptotermes spp. soldier. Firstly, the morphology analysis was illustrated by linear and
geometric morphometric analysis to explain Coptotermes spp. soldier caste morphology. ...