Correlation between social structure and nymphal wood-digestion ability in the xylophagous cockroaches Salganea esakii and Panesthia angustipennis (Blaberidae: Panesthiinae)

This study compares wood-digestion ability of various developmental stages, including first-instar nymphs and adults, of S. esakii and P. angustipennis by analyses of endogenous cellulase (endo-beta-1,4-glucanase: EG) gene expression. Three partial EG sequences were obtained in each species and confirmed to be expressed only in the salivary glands. In subsocial S. esakii, first-instar nymphal EG expression levels were strikingly low when compared to those of adults (10^-4-10^-3), but other nymphal stages had expression levels similar to those of adults. First-instar nymphal EG expression levels in gregarious P. angustipennis, however, were quite high compared to those of adults (10^-1). Thus, first-instar nymphs of P. angustipennis probably decompose cellulose using endogenous EGs. These results suggest that there is a correlation between social structure and first-instar nymphal wood-digestion ability in these xylophagous cockroaches.