sapidiis and R. harrisii were brought in from the waters of the Newport Estuary 

 in the vicinity of Beaufort, North Carolina, and maintained in sahnities and 

 temperatures most closely approximating those of the experimental conditions 

 until hatching of the larvae occurred. With the experiments on 

 Rhithropanopeus harrisii, the larvae were set up in separate experimental series 

 consisting of 50 larvae per species, and maintained in temperature controlled 

 cabinets with a photoperiod of 12 hours light and 12 hours dark, until the 

 fourth juvenile crab stage was reached. 



In experiments with Callinectes sapidtis, which involved only the megalopa 

 stage, larvae were maintained through the seven zoeal stages of 30 ppt, 25^C 

 until the final zoeal molt. At that time. 20 megalopa were transferred to each 

 of the experimental salinity and temperature conditions, and maintained in a 

 photoperiod consisting of 12 hours light and 12 hours dark until the fourth 

 juvenile crab stage was reached. Within each of the experimental series a 

 control series was maintained, and at least one acetone-control series was 

 maintained, since both methoprene and MONO-585, only sUghtly soluble in 

 water, were prepared from the pure compound as an acetone stock solution of 

 1 ppt. 



D 



The two compounds used in this experiment were methoprene (Altosid : 

 ZR-515; isopropyl 1 l-methoxy-3, 7, 1 l-trimethyldodeca-2, 4-dienoate) 

 manufactured by Zoecon Corporation, Palo Alto, California, and MONO-585 

 (2, 6-di-t-butyl-4- (oa dime thy Ibenzyl) phenol) manufactured by Monsanto 

 Chemical Company, St. Louis, Missouri. 



In the experiments on Rhithropanopeus harrisii larvae involving MONO-585, 

 dilutions of 10, 1 and 0.1 ppm were used in combination with 25°C, known 

 from previous work to be the optimum temperature for development (7), and 

 salinities of 5, 20 and 35 ppt. 



In experiments with Callinectes sapidus megalopa, a variety of salinities, 

 constant temperatures, and cyclic temperatures were combined with the 

 dilutions of MONO-585 (10, 1, 0.1 ppm) or methoprene (0.1 and O.Ol ppm). 

 These included, depending on the particular series, salinities ranging from 5 to 

 35 ppt and temperatures, constant or cyclic, ranging from 20°C to 35°C. The 

 specific conditions for individual experimental series will be considered in 

 connection with the results. 



Larvae in all series were checked each day for survival and stage of 

 development, the numbers being recorded for each experimental series. 

 Individual megalopa were segregated in plastic compartmented boxes to avoid 

 cannabaiism, and also to facilitate recording the time of metamorphosis to the 

 first and subsequent crab stage for each individual. 



322 



