SECOND GENERATION PESTICIDES 
AND CRAB DEVELOPMENT 
John D. Costlow and C. G. Bookhout 
Duke University Marine Laboratory 
Beaufort, North Carolina 28516 
ABSTRACT 
A number of compounds have been introduced recently as potential 
substitutes for the traditional “hard” pesticides in the control of insect 
populations. Some of these compounds, juvenile hormone mimics or analogs, 
are intended to simulate the activity of naturally occurring juvenile hormones 
and prevent metamorphosis or, in the case of insect growth regulators, control 
differentiation or specific physiological processes at specific stages of 
development. Because of the phylogenetic relationship between insects and 
crustaceans, one might legitimately expect that those compounds which alter 
or interfere with the developmental pattern of insects could also have similar 
effects on the developmental stages of marine crustaceans. 
In salinities of 20 and 35 ppt, 100 percent mortality of megalopa of C. 
sapidus occurred when exposed to 10 ppm MONO-585 while 1 ppm reduced 
survival from 100 percent to 40 percent. 100 percent mortality in the zoeal 
stages of R. harrisii was observed with a dilution of 1.0 ppm in reduced 
salinities but at 20 and 35 ppt, survival was unaffected. The concentration of 
10 ppm MONO-585 was lethal in all experimental salinities. Exposure of C. 
sapidus megalopa to 0.1 ppm Methoprene resulted in reduced survival only 
when lower temperatures (20-25°C) were used. Juvenile crab stages I through 
IV were unaffected by the concentrations of Methoprene used. 
The findings of these experiments and their possible significance to normal 
development of larvae of these two species within the natural environment are 
considered. 
INTRODUCTION 
A number of compounds have been introduced recently as potential 
substitutes for the traditional, “hard” pesticides (DDT, Malathion, Dieldrin, 
etc.) in the control of insect populations. Some of these compounds, juvenile 
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