Bed bug deterrence

A global resurgence of bed bugs, a once common household pest that had nearly disappeared for 50 years, has renewed scientific interest in these fascinating insects. Pest control companies from every part of the world are reporting many more encounters now than 10 years ago [1]. Undoubtedly, many factors have led to this outbreak, but evolved resistance to some of the most commonly used insecticides is a contributor [2]. Unlike many other blood-feeding arthropods, such as mosquitoes, tstetse flies, ticks, and sand flies, bed bugs are not known to effectively vector any human pathogen. However, bed bugs inhabit our beds, and return repeatedly at night [3] for blood meals required to complete each stage of development (five immature stages) and each cycle of egg production. Recent research by Harraca and colleagues presented in BMC Biology provides new insights into the reproduction of bed bugs that may offer an untapped opportunity for pest control [4].

Harraca and colleagues have demonstrated that bed bug nymphs (Cimex lectularius) produce a chemical signal that interrupts the attempts of adult males to mate with them [4]. Because adult males, females, nymphs and eggs are found in aggregations around where the host sleeps (in the case of humans, our beds), encounters between males and nymphs are common. Copulation between an adult and a nymph is reproductively ineffective, but can be very costly to the nymph and the male; rupture of the cuticle for the nymph, and loss of sperm and other components of the ejaculate for males. As a result the reproductive fitness of the male and survival of the nymphs are parallel interests. These are exactly the circumstances that should favour the evolution of communication, because both signaller and receiver benefit from the information transfer. Two complementary manipulative experiments conducted by Harraca et al. [4] provide convincing evidence of effective communication between nymphs and males. When the glandular source of the scent that is unique to nymphs is blocked, males will copulate with them. When a nymph-specific compound or nymph-specific ratio of compounds were puffed on male-female pairs, mating was disrupted. Furthermore, males have sensory neurons that respond to the nymph odours. Thus, the chemical signal translates into the simple received message that the source nymph is not a reproductive female. The nature of copulation, known as traumatic or hypodermic insemination, may help to explain the evolution of communication between nymphs and males.

It remains to be seen if the newer thrusts of basic science research, such as that reported by Harraca and colleagues in BMC Biology, will contribute new approaches to pest control, but certainly the reliance of bed bugs on chemical signalling [13–15] is one avenue that needs to be explored further. Interfering with mating behaviour is an attractive idea, which has shown success with many agricultural pest species, but the longevity of bed bugs (months to a year or more) and our lack of tolerance of their repeated biting, makes the concept much more challenging. Whether interfering with sexual reproduction with 'anti-aphrodiasiac' pheromones is of practical significance or not, ongoing research on bed bug biology is likely to have an impact on the way that we manage this tough pest.