Mortality of Cimex lectularius L., the common bed bug, by horizontal insecticide transfer

To evaluate the efficacy of horizontal insecticide transfer, five adult Harold Harlan susceptible-strain and five adult pyrethroid-resistant, field-strain bed bugs were placed on metal panels that had been treated with one of four insecticides (or water) and aged for one week.  Bed bugs remained on panels for one hour before being transferred to petri dishes containing filter paper and five untreated bed bugs.  Mortality was recorded for two weeks for bed bugs that were exposed to insecticides directly, as well as for those that were exposed indirectly via horizontal transfer.  In general, higher mortality occurred among bed bugs that were exposed to insecticides directly or indirectly as compared to controls.  Higher mortality also occurred among bed bugs that were exposed to insecticides directly compared to those that were exposed indirectly.  Harold Harlan bed bugs were more susceptible to direct exposure and horizontal transfer when compared to pyrethroid-resistant, field-strain bed bugs.  Products exhibited significant differences in efficacy, with some approaching 100% mortality for indirect exposures, while others failed to differ from the control, even for direct exposures.  These findings demonstrate that significant differences in field performance may exist among products if horizontal transfer occurs frequently in natural settings.