Advanced Method For Evaluation of the Residual Efficacy of Products To Control Cimex Lectularius (Hemiptera: Cimicidae)

Abstract:
In order to avoid treatment failures in bed bug control and to prevent the development of insecticide-resistant bed bug strains, laboratory efficacy tests of products for bed bug control must be adapted more to practical conditions. For our study, Cimex lectularius of the insecticide susceptible laboratory strain of the FEA served as test animals. The bed bugs were fed on rabbits once a week. Juvenile Cimex lectularius after 4 and adults after 6 blood feedings were used for the efficacy tests. For efficacy evaluation, insecticidal formulations containing pyrethroids, carbamate or pyrrol were used according to the instructions for use. The test products were applied to 3 different types of surfaces: Hornitex™ (non-sorptive surface), plywood and wallpaper (surfaces of different sorption). Test animals were exposed to treated surfaces for at minimum five different exposure times (e.g. 5, 15, 30, 60 and 180min) to simulate different exposure conditions. The efficacy of several insecticides declined at shorter exposure times. Only one pyrethroid formulation showed 100% mortality of adult and juvenile bed bugs at all tested exposure times on all test surfaces. Standard rearing conditions and defined age of test animals revealed reproducible efficacy results. The test results showed that it is important for the practical use of tested products, even if they are used according to the instructions for use, to know the range of efficacy in different application conditions, e.g. in dependence of the exposure time of bed bugs and the types of surfaces. Thus, application of a product can be optimized and treatment failures can be avoided.