The alarm-defense system of Cimex lectularius and its implications for pest management
Ulrich, Kevin Richard
Thorne, Barbara L
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In this dissertation, I focus on the alarm-defense system of the common bed bug, Cimex lectularius, its effectiveness against pathogen attacks, and its role as a mechanism of communication for conspecifics. This dual role of an alarm-defense system is efficient and effective considering that the two functions are typically required simultaneously in times of danger; the same substance should serve both purposes. First, I surveyed the most common types of commercial bed bug treatments to determine long-term efficacy. Regardless of the treatment, chemical or heat, retreatments for bed bug infestations were required. After 3 years, 20.8% of housing units receiving a chemical treatment required additional treatments; 9.5% of units receiving heat treatments required a retreatment during the same period. Multifamily units required retreatments significantly more than all other housing types. Given these findings that emphasize the necessity for a multifaceted IPM program, I investigated whether the entomopathogenic fungus, Metarhizium anisopliae, could be used to control bed bugs. Feeding experiments demonstrated that bed bugs were innately susceptible to this fungus. However, regardless of whether bed bugs were sprayed with a fungal solution or contacted a treated surface, only at 98% humidity was mortality high. In addition, the two major aldehydes (E)-2-hexenal and (E)-2-octenal emitted as defensive secretions by bed bugs inhibited the in vitro growth of an isolate of M. anisopliae. The ability to accurately and quickly detect new infestations is a critical element to an IPM-based strategy. This detection requires an understanding of attraction behavior and cues. I show through use of video-tracking software, (E)-2-hexenal and (E)-2-octenal attract adult bed bugs. Behavioral assays determined both males and females were attracted to 0.04 ug of an aldehyde blend for up to two hours after initial treatment of filter paper disks. Results suggest that these bed bug secretions may be candidates for lures and monitors. Taken together, this research describes the chemical ecology of bed bugs, providing insight into relevant signaling and defensive behavior, which has direct implications on pest management practices.