Feeding assay toxicity

Mycotoxins, toxic metaboUtes of some fungi, can be assayed by immunochemical techniques to determine concentration in animal feed and foodstuffs. Some of the analytes assayed in kits and the detection limits are Hsted in Table 4 (45). These assays are especially advantageous for routine analysis of large samples of foodstuffs (45,46). 

Fig. 6 Biomonitoring of pollution in the Ebro Delta with Daphnia magna and Corbicula fluminea. (a) Map of sampling sites. Site 1 is out of the figure limits, close to Amposta (see Fig. 1). (b) Assays for neurotoxic activity (ChE and CbE) and D. magna feeding). Note the different pattern for the microcrustacean (sensitive to insecticides), which show a maximal toxic (inhibitory) effect in May and June, and the mollusk (relatively resistant), (c) Oxidative stress markers. These markers showed a similar response for both species with maximal effects (activation) in May (month 5) and August (month 8). Data from [43] and [44], Dm and Cf identify markers from D. magna and C. fluminea, respectively...

Bitton, G. Rhodes, K. Koopman, B. Cornejo, M. Short-term toxicity assay based on daphnid feeding behavior. Water Environ. Res. 1995, 67, 290-293. 

These same two diterpenes were subjected to the tobacco hornworm assay. Brlantheln Y, 10, was quite toxic at 250 ppm, killing the exposed larvae within thirty hours. There appeared to be no inhibition of feeding. On the other hand, the less functionalized brlanthein W, 12, elicited only 50 percent mortality over five days, and the surviving larvae suffered from extremely poor weight gains (only 6J of controls) despite feeding freely on the treated diet. 

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... 

The effects of seeds of Delphinium hybrid, cv."Pacific Giant, King Arthur" were investigated in the housefly nicotinic receptor assay, and their toxicity to insects was investigated. Chloroform extracts of the Delphinium seeds were assayed for activity against a number of species of insects and mites, and the results of these tests are summarized in Table I. The extract caused mortality in a number of different species, and protected leaves from feeding damage. 

---