The common bed bug, Cimex lectularius and the related tropical bed bug Cimex hemipterus are cosmopolitan pests of human habitation, with documented infestations dating back to ancient Greece and Pharaonic Egypt. With the advent of DDT and other synthetic insecticides during WWII, bed bugs became a rarity in industrialized countries. As bed bugs are not known to transmit human disease, scientific interest in them waned along with their prevalence. Since the 1990s, however, many countries including the United States have experienced exponential increases in bed bug populations. This widespread resurgence is attributed to a combination of insecticide resistance, changes in control strategies for other urban pests, and an increase in travel both within and between countries. The problem is exacerbated by a reduction in the number available efficacious pesticides, either through product cancellations or regulatory restrictions.
Bed bugs are difficult to find and identify because of their small size and cryptic habits. Their bodies, which are 1-7 mm long and dorso-ventrally flattened, allow them to hide in narrow cracks. They are generally nocturnal, with maximum activity between midnight and 6:00 am. Under ideal laboratory conditions, bed bugs will go through five nymphal stages, each lasting 4-8 days before a final molt to an adult stage. Depending on the strain of bed bug, their level of resistance to pesticides, activity level, the ambient temperature and humidity, and host availability, adult bed bugs may live for anywhere from three months to four years.
A variety of techniques and devices may be used to monitor or trap bed bugs for surveying, monitoring, mitigation and management purposes. Visual inspections are commonly used to detect bed bugs, but are time and labor-intensive; even trained individuals can miss large numbers of insects. Bed bug-sniffing dogs are an increasingly common survey method, especially for detecting low-level infestations, but dogs are expensive to train and employ, are not available in all areas, and their accuracy can vary widely between dog-and-handler teams. Recent studies have demonstrated the potential for trapping as a viable alternative to visual or canine inspections in confirming the presence and size of an infestation (Wang et al. J. Econ. Entomol. 2010, 103:172-177).
Current bed bug mitigation devices range from unbaited, passive sticky traps of various designs, pitfall traps, heating units with either a sticky means or a pitfall means, carbon dioxide generators with either a sticky means or a pitfall means, and combinations that include insect-mediated compounds and/or host mediated compounds with a sticky means, pitfall means or a monitoring or other insect detection system. These devices are of limited utility as they can fail to mitigate bed bugs either in the presence or absence of a host. These traps are not able to efficiently attract, trap, and kill an adequate number of bed bugs, thus resulting in scenarios that necessitate additional efforts for surveying, monitoring, mitigation and management purposes.
Bed bug attractants fall into two discrete categories: insect-mediated compounds or host-mediated compounds. Insects use a set of compounds in their chemical ecology, which are commonly present in harborage areas and involve mating, aggregation, alarm or arresting pheromones (i.e. Siljander et al. U.S. Pat. No. 7,892,528). Primary host-mediated factors are carbon dioxide, and heat, and are involved in host location by bed bugs. Few effective host-produced chemicals have been discovered. Many such compounds have been hypothesized from the host cues used by mosquitoes and other blood-feeding insects, such as lactic acid and butyric acid.
The currently-accepted threshold of attraction for bed bugs using carbon-dioxide is a release rate of 50 milliliters (mL) per minute (Anderson et al. Med. Vet. Ent., 2009, 23:99-105). This rate necessitates that large quantities of compressed gas, dry ice, or acid/mineral mixture is required to generate a sufficient quantity of carbon-dioxide. This limits the portability, duration of release and size of attractant device available, and makes said devices expensive. It is known carbon dioxide can be generated by microbial means, but no method has been shown to attract bed bugs at a low release rate, over a period longer than 1 to 7 days. Thus, an improved method of generating carbon dioxide in quantities sufficient to attract bed bugs is desired.
In addition, there is a need for a method which includes both a short-term, low cost, disposable monitoring system, but which can also be economically used over a term longer than 10 days.
Thus, there is a need in the bed bug detection field to create new and improved bed bug attractant compositions and new and improved methods to enable their use to attract, monitor or trap bed bugs for surveying, monitoring, mitigation and management purposes. This invention provides such improvements.