MCKENNEY, JR., C.L.; USEPA, NHEERL, Gulf Ecology Division: The influence of insect juvenile hormone agonists on metamorphosis and reproduction in estuarine crustaceans

Comparative developmental and reproductive studies were performed on several species of estuarine crustaceans in response to three juvenile hormone agonists (JHAs). Larval development of the grass shrimp, Palaemonetes pugio, was greater than two orders of magnitude more sensitive to disruption by JHAs than was embryonic development. For 2 JHAs, developing larvae of the mud crab, Rhithropanopeus harrisii, exhibited reduced metamorphic success at lower concentrations than grass shrimp larvae. These responses suggest that the more rigidly controlled metamorphic process in crabs is more sensitive to compounds acting as endocrine disruptors than is the more plastic metamorphic pattern in shrimp. The final crab larval stage, the megalopa, was more sensitive to JHA exposure than earlier zoeal stages. Mud crab larvae exposed to fenoxycarb had reduced biomass and lipid content, particularly triglycerides and sterols. Concentrations of fenoxycarb which reduced the reproductive capacity in single life-cycle exposures of the estuarine mysid, Americamysis bahia, were similar to those concentrations which inhibited metamorphosis in grass shrimp. Juvenile mysids released by exposed adults and reared through maturation without further exposure produced fewer young and had altered sex ratios (lower percentages of males) at lower parental-exposure concentrations than directly impacted parental reproduction. Since the endocrine glands responsible for regulating mysid sexual differentiation and reproduction develop during larval stages, these transgenerational responses may well be a product of irreversible effects during developmental exposures which become apparent following maturation and initiation of reproduction.