Inhibition of polyamine biosynthesis alters oviposition behavior in female crickets

The role of polyamines in the expression of cricket oviposition, a juvenile hormone-dependent behavior, was investigated using a specific inhibitor of ornithine decarboxylase, alpha-difluoromethylornithine (alpha-DFMO). The fat body of treated female house crickets (Acheta domesticus) did not show any putrescine and presented reduced levels of spermidine, whereas spermine titres were significantly enhanced. In nervous tissue, alpha-DFMO did not affect spermine titres but induced a severe drop in spermidine levels. In polyamine depleted females, the expression of egg-laying behavior was delayed and was expressed less frequently compared with controls. As drug treatment did not seem to affect juvenile hormone titres, the data suggest that juvenile hormone might act on behavior by way of polyamine metabolism. These results support the view that, in insects, as in vertebrates, the ornithine decarboxylase-polyamine system is involved in the maturation of complex behaviors.