PHASE I: LABORATORY STUDIES
The objective of laboratory testing is to determine the inherent
biopotency of the technical material or, in the case of formulated
larvicides, their activity. It is assumed that the compound’s mode of
action has already been established. Information on the speed of
activity is important, as this will determine the type of testing
procedures to be employed.
To evaluate the biological activity of a mosquito larvicide,
laboratory-reared mosquito larvae of known age or instar (reference
strains or F1 of field-collected mosquitoes) are exposed for 24 h to
48 h or longer in water treated with the larvicide at various
concentrations within its activity range, and mortality is recorded.
For IGRs and other materials with delayed activity, mortality
should be assessed until the emergence of adults. It is important to
use homogenous populations of mosquito larvae or a given instar.
These are obtained using standardized rearing methods (see
Annex 1).
The aims of the tests are:
• to establish dose–response line(s) against susceptible vector
species;
• to determine the lethal concentration (LC) of the larvicide for
50% and 90% mortality (LC50 and LC90) or for 50% and 90%
inhibition of adult emergence (IE50 and IE90);
• to establish a diagnostic concentration for monitoring
susceptibility to the mosquito larvicide in the field; and
• to assess cross-resistance with commonly used insecticides.