Intercastes obtained in Kalotermes flavicollis and Reticulitermes lucifugus (Isoptera) by treatment with the IGR fenoxycarb.

Groups of the two Italian termites Kalotermes flavicollis and Reticulitermes lucifugus were exposed to different concentrations of the Insect Growth Regulator fenoxycarb. Results showed a marked juvenile hormone analogue activity, since the substance induced, on both species, an abnormal appearance of intercastes. SEM observations confirmed that fenoxycarb-induced individuals show morphological features intermediate between the ones of the initial-previous caste and the ones of soldiers. On K. flavicollis, fenoxycarb inhibited the differentiation to neotenic reproductives, but did not prevent larval moults. Caste unbalances induced by this IGR can cause a progressive weakening of termite colonies until extinction.