Sex-Linked Genetic Influence on Caste Determination in a Termite
Yoshinobu Hayashi,1
Nathan Lo,2
Hitoshi Miyata,1
Osamu Kitade1*
The most ecologically successful and destructive termite species
are those with both a nymph caste and an irreversibly wingless
worker caste. The early developmental bifurcation separating
these castes is widely accepted to be strictly environmentally
determined. We present evidence that genotype also influences
this process. Offspring from four different crosses of nymph-
and worker-derived secondary reproductive individuals had strongly
differentiated caste and sex ratios, despite uniform rearing
conditions. These data fit an X-linked, one-locus-two-allele
model. Of five possible genotypes, one was lethal, two resulted
in workers, and two resulted in either nymphs or environmentally
determined workers. Caste is thus controlled both by environment
and by a complex genetic inheritance pattern.
2 Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia.
* To whom correspondence should be addressed. E-mail: kitade{at}mx.ibaraki.ac.jp
