An entomopathogenic fungus (Beauveria bassiana) has been recently proposed to control bed bugs (Cimex lectularius) as a residual spray. However, the presence of bed bug aldehydes in bed bug harborage sites and their potential antifungal action raise the question whether these aldehydes can impact the effectiveness of the entomopathogenic fungus if the exposed bed bugs return to their harborages. Experiments conducted in culture showed that bed bug aldehydes can inhibit the growth of B. bassiana at high concentrations. Next, bed bugs were exposed to B. bassiana deposits (BotaniGard 22WP and Aprehend), and subsequently placed in a vial containing a source of aldehydes (exuviae or synthetic) and their mortality was monitored for 15 days. For the bed bugs exposed to BotaniGard deposits, the day 15 mortality was 62.2% when there were exuviae in the vial, compared to 97.7% without exuviae. When exposed to Aprehend deposits, bed bugs with exuviae reached 100% mortality by day 7, compared with day 6 for those without exuviae. Bed bugs exposed to a synthetic aldehyde reached 95% mortality after 15 days. The implications of the study on bed bug control will be discussed.
.jpg "Mark Donald Paul Dery photo")
