If testing an insecticide is not easy, repellents are even more difficult because the behaviour of the insect is involved. Much more than a killing product, the efficacy of a repellent is strongly affected by environmental parameters and the stories of the insects on which it is used (age, nutritional state, sex, etc.).
Olfactometer
Olfactometers can be used for screening purposes in the development of a new product in order to save money and time. They verify the activity of a product (one-way olfactometer) or make direct comparisons with a competitor’s products.
Arm-in-cage
This is a classic and widely accepted way of testing topical repellents. Results can be affected by choice of species as well as strain within the same species. It is important to change the air in the test room in order to prevent smells from accumulating and a correct breeding procedure has to be followed in order to obtain data which are as consistent as possible.
2 Room test
Two rooms are put into communication by a window which can be opened and closed with a remote control. The insects are released into one room while the bait with the repellent product is in the other. The movements of the insects are recorded. Remote control of all the parameters enables a high level of standardisation to be attained. The insects are released into the first room through a slot without entering the test rooms and the test is recorded on CCTV.
Field test
Some insects cannot be reared, or it is very expensive to do so. For these, the best place to test a product is the field, which also presents reality, so that you can be sure that if a product works in field, it really works. But field tests are never easy and even a slight change in conditions (wind, sunshine, variations in humidity or temperature, the time of the day and so on) may strongly affect results. Field tests, however, are still the only completely reliable protocol for testing ambient repellents for outdoor use.
