Assessing repellency in a modified avian LC50 procedure removes the need for additional tests

The purposes of this article are to present a method that takes into account avoidance behavior in the evaluation of LC50 studies with birds and to provide a concept for the use of food avoidance behavior in the environmental hazard/risk assessment of pesticides used in agriculture for birds. An analysis is made of the standard LC50 test and of three types of food avoidance tests. It is concluded that the standard dietary LC50 test provides most of the information necessary to understand the repellent properties of a pesticide. It is recommended that food consumption be measured daily and that information be provided about the learning abilities of the species tested (when does food avoidance appear). A method is proposed to calculate the no-repellent concentration (NoRC). The NoRC is the concentration in the treated food at which the birds in the test will eat the same amount of treated food as the control group eats untreated food. These small alterations of the standard LC50 test make other repellency tests with birds superfluous. Those repellency tests can be used to provide information about the edibility of the granules and seeds (coated or pillorized, but not treated with a substance), which results in less suffering for test animals.