hormone mimics or analogs, are intended to simulate the activity of naturally 

 occurring juvenile hormones and prevent metamorphosis or, in the case of a 

 second group, insect growth regulators, to control differentiation or specific 

 physiological processes during development. 



Several authors have reported the effects of juvenile hormone mimics on the 

 development of insects (15, 17, 19 and others). Only a fev^ studies, however, 

 are reported on the effects of these compounds on other invertebrates (9, 10, 

 13). Of these Gomez et al (9) and Ramenofsky et al (13) first described the 

 effect of two juvenile hormone mimics on development and metamorphosis of 

 the cirripede, Balanus galeatus, and Tighe-Ford (1977) subsequently reported 

 juvenile hormone analog effects on another species of barnacle, Elminius 

 modestus. Studies on representative species of other marine Crustacea are 

 limited, but do include the effect of two juvenile hormone mimics on larval 

 development of the mud-crab, Rhithropanopeus hamsii (1, 2, 4). A study by 

 Forward and Costlow (8) describes the manner in which one of these 

 compounds may affect the behavior of crab larvae, Payen and Costlow (11) 

 studied the effects of juvenile hormone mimics on gametogenesis of adult 

 Rhithropanopeus hamsii. 



Because of the phylogenetic relationships between insects and crustaceans, 

 one might legitimately expect that those compounds which would alter or 

 interfere with the developmental pattern of insects could also have similar 

 effects during the development of marine decapods. 



The present study was undertaken to further explore the effects of two 

 compounds, methoprene (Zoecon Corporation) and MONO-585 (Monsanto 

 Corporation) on the development of larvae of estuarine crabs. Specifically, 

 experiments were designed to determine if these compounds would affect 

 survival of the larvae, alter the number of larval stages, change the time 

 required for development of all stages and metamorphosis, or affect the 

 frequency of molting within the early juvenile crab stages after metamorphosis. 

 A second portion of the experiment was designed to determine if effects of 

 these compounds would be altered by changes in such environmental factors as 

 salinity and temperature. 



The two species which were selected for study were the small mud-crab, 

 Rhithropanopeus harrisii (Gould), and the megalopa of the commercial blue 

 crab, CaUinectes sapidus Rathbun. 



MATERIALS AND METHODS 



Following the general rearing procedures described by Costlow and 

 Bookhout (5) and Costlow, Bookhout and Monroe (7) ovigerous females of C 



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