DIETARY PREFERENCES OF THE OPISTHOBRANCH MOLLUSK STYLOCHEILUS LONGICAUDA FOR SECONDARY METABOLITES PRODUCED BY THE TROPICAL CYANOBACTERIUM LYNGBYA MAJUSCULA

Pure compounds isolated from the cyanobacterium Lyngbya majuscula Gomo nt were evaluated in an artificial diet for their influence on the fee ding preferences of the sea hare Stylocheilus longicauda (Quoy and Gai mard, 1824), which lives in and feeds on this filamentous cyanobacteri um (blue-green alga). Microcolin B, ypaoamide, malyngolide and other n atural products acted as feeding deterrents at natural concentrations. At lower concentrations, sea hares were indifferent to ypaoamide and malyngolide in their diets. In contrast, barbamide stimulated sea hare feeding at the concentrations normally found in L. majuscula. Malynga mides and majusculamides, the most common natural products found in sa mples of L. majuscula from Guam, increased sea hare feeding at low con centrations and inhibited feeding at the higher concentrations that oc curred in some collections of L. majuscula. Dietary selection of cyano bacteria by S. longicauda may be regulated by the concentration of spe cific chemical cues produced by L. majuscula.