An improved Method for testing Liquid Contact Insecticides in the Laboratory

Abstract

1. Methods for laboratory testing of contact insecticides are reviewed, and some of the disadvantages of these methods are discussed. Reasons are given for preferring an immersion to a spraying method, and the necessity for a supply of “ standardised ” insects is stressed.2. An improved immersion method for laboratory testing of contact insecticides is described, and the rigid technique necessary is detailed.3. The effect on the resistance ofAhasverus advenato a derris insecticide of varying the time of immersion, the age of the insects, the temperature and the humidity before, during, and after immersion is illustrated and shows the necessity of controlling all these factors.4. Results with a standard derris insecticide are given to show the great accuracy that can be obtained by the new method ; that the same result with the same insecticide can be repeated from day to day; and that two workers using the same insecticide have obtained identical results.5. The reaction to starvation is correlated with variations in age, temperature, and humidity, to show that the starvation death rate is a measure of the insects' powers of resistance to an insecticide.6. Statistical analysis and discussion of methods of expressing mortality is reserved for a later communication.