Feeding assay choice tests

We will perform the Leaf disk test, also known as leaf disk assay or leaf disk choice test, the second of two bioassays of tannins in the diet of insects in this book. In this often used bioassay, leaf sections of a standard size are treated with the compound(s) in question. Several circular leaf sections ( leaf disks ) (Ali et al. 1999, Filho and Mazzafera 2000, Shields et al. 2008, Wheeler and Isman 2000) or cellulose membrane filters (Hollister and Mullin 1999, Larocque et al. 1999) are presented to a caterpillar in a choice experiment. We measure how much chow the caterpillar has consumed and whether any feeding inhibition is concentration dependent. Regardless of what compounds are being tested, leaf disk tests serve as an important tool in bioassaying feeding inhibitors and stimulants in insects. The cited references are examples of such studies. (In the first tannic acid experiment - Chap. 18 - the tannic acid was mixed into diet in varying concentrations.)... 

The method of statistical analysis in many bioassays focuses on analyzing the number and pattern of choices made by subjects. In general, these assays will not involve truly continuous variables, but will involve counts, e.g., the number of times that each branch of an olfactometer was chosen, the number of times that upwind flight was observed, the number of eggs deposited on test or control substrates, or the number of times that test or control feeding substrates were selected. Such data often are distributed following a Poisson distribution and can... 

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