Feeding assay deterrence

Feeding assays Assays were performed with diets placed between two layers of Parafilm M (23). The diet was as described (24). When young aphids were used (survival and feeding deterrence assays) they were 3rd and 4th-instar nymphs. 

Recent studies have examined the chemical basis of sea hare response to attack and have identified amino acid constituents in the opaline glands and ink secretions of A. californica that stimulate a false feeding response ( phagomimicry ) as well as confused behavior in the shiny lobster (Panulirus interruptus) 194-195 Both ink and opaline secretions are acidic, believed to enhance behavioral responses.196 The importance of inking as a deterrent mechanism is revealed by feeding assays in which reef fish consumed frozen mollusks but did not eat live specimens.43... 

From Table 7 it can be seen that ajugasterone C is more than 10-fold more potent than 8-ecdysone, and more than 30-fold more potent than cyasterone, as a feeding deterrent to S- grcaninum when Incorporated into the artlflcal diet of this behavioral bio-assay. 

As with sessile animals and plants (see other chapters, this volume), the chemical deterrence of mobile invertebrates is best assessed using an approach in which ecologically relevant consumers are offered palatable food items with chemical extracts coated on, or embedded within, them.7 Assays in which the toxicity of compounds is assessed by dissolving them in the water containing the assay organisms have been repeatedly shown to bear no relation to the effects of compounds when ingested with prey.1 8,9 Most feeding deterrents of mobile invertebrates appear to be lipid-soluble, thus these... 

A second example of an activated chemical defense concerns the Indo Pacific sponge Aplysinella rhax, in which tissue damage results in the rapid enzymatic transformation of psammaplin A sulfate 63 into psammaplin A 64 exposure of 63 to tissue from other sponges does not result in any conversion. Compound 63 deters feeding by reef fish, but when offered a choice between psammaplin A and its sulfate, both foods were avoided. In aquarium assays with C. solandri, extracts of damaged tissue were more deterrent than extracts from intact tissue, but both treatments were less palatable than control foods. In choice experiments, C. solandri preferred food treated with 63 over 64.104... 

A series of 14 synthetic pyrroles, furans, thiophenes, and prolines were assayed using X. bifasciatum, the presence of bromine was important for activity, replacement of the pyrrolic N by either O or S did not affect activity, while the prolines tested were inactive.107 A later study compared the feeding deterrency of 65 and 66... 

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