Effect of a potent trehalase inhibitor, validoxylamine A (VAA), on the oocyte development and ootheca formation was observed in two species of cockroaches, Blattella germanica, and Periplaneta fuliginosa. By injection with VAA to female adults of B. germanica, lethal activity was observed and the oocyte development delayed, but the ootheca was formed with hatchable oocytes in most of the surviving females. In P. fuliginosa, VAA injection suppressed oocyte development and normal ootheca formation. Oothecae deposited by VAA-injected females were dented and no nymph hatched from the oothecae as in P. americana reported previously. These effects on the reproduction seem to be caused by the inhibitory action of VAA to the trehalase, because the trehalase activity in the ovary and accessary gland was actually inhibited by the administration of VAA in both species. The inhibition of trehalase was lower in the ovary of B. germanica than in that of P. fuliginosa whose ootheca formation was affected more strongly by the administration of VAA.
