Antennal sensory structures of polymorphic soldiers in the termite macrotermes annandalei (Silvestri)

The caste system in social insects controls individual’s interactions and communications. Termites have two altruistic castes, the workers and soldiers, comprising of polymorphic forms. Polymorphism within caste is very common among soldiers and workers of most of the species of the genus Macrotermes. This study elucidates the antennal sensilla of polymorphic soldiers i.e., soldier major and soldier minor in termite Macrotermes annandalei (Silvestri) using the scanning electron microscope (SEM), and analyses the differences. The results revealed seven types of sensilla viz., sensilla chaetica (subtypes- I, II, III and IV), sensilla trichodea, sensilla trichodea curvata, sensilla capitula, Bohm bristles, sensilla campaniformia (subtypes-I and II) and sensilla uiniquefas in both major and minor. These suggest that these polymorphic forms exhibit no variations in the occurrence and distribution of various sensilla. The putative functions and importance of all the various types of sensilla are discussed.