THE EFFECTS OF AN ISOPOD CASTRATOR,<i>PROBOPYRUS PANDALICOLA</i>, ON THE SEX CHARACTERS OF ONE OF ITS CARIDEAN SHRIMP HOSTS,<i>PALAEMONETES PALUDOSUS</i>

Abstract

Effects of the parasitic isopod, Probopyrus pandalicola, on the sex characters of its host shrimp, Palaemonetes paludosus, are described, and possible mechanisms for these effects are discussed. P. pandalicola sterilize the female host by preventing ovarian maturation but do not affect the external sex characters. In contrast, the growth of the external sex characters of the male host was either acelerated (chela) or retarded (pleopod structures), but there was no parasitic effect on the testes. The mechanism for these castration effects appears to be some combination of a nutritional drain and/or a hormonal interference by the parasite.