The efficacy testing of Diatomaceous Earth to the Common Bed Bug,

26/Jun/2006

Stephen Doggett, Department of Medical Entomology, ICPMR, Westmead Hospital , Westmead NSW 2145.

Ph: 02 9845 7265 Fax: 02 9893 8659 Email: stephend@icpmr.wsahs.nsw.gov.au

Background

Over the last five years within Australia (& elsewhere in the world) there has been a major increase in the number of infestations of bed bugs, both of the Common (Cimex lectularius) and Tropical (Cimex hemipterus) species (Doggett et al. 2003, 2004). Some pest control companies are now reporting a 1,000% increase in the number of treatments for bed bugs over the last four years (Doggett 2005). Numerous suggestions have been offered to explain this rise; however it is generally thought that modern pest management procedures are largely responsible along with the development of insecticide resistance. One particular problem for the pest manager in Australia is the lack of insecticides that have high efficacy and long residual activity. This ensures that control is a major challenge with the result that treatment failures are all too common. Thus there is an urgent need for new insecticides to become available for the control of bed bugs. In light of the major bed bug resurgence, an insecticide that has been independently accessed and demonstrated to be efficacious is likely to offer excellent returns to the manufacturer. As Diatomaceous Earth (DE) has an extremely long residual action (and tends to nullified only by the built up of dust, dirt and other debris) and as its mode of action limits the possibility of resistance developing, there is a strong potential for DE to be employed as a preventative insecticide, which further enhances the prospect for strong financial returns.

Aim

To test the susceptibility of the Common bed bug, Cimex lectularius, to Diatomaceous Earth.

Methods

The methods are loosely based on Fletcher & Axtell (1993).

Test Animal

The bed bugs used are the Common bed bug, Cimex lectularius, from a colony established by the Department of Medical Entomology during 2004. The founder specimens were sourced from various infestations within the Sydney metropolitan area and have not been tested for insecticide susceptibility. The colony is maintained within 1L containers, provided with a blood meal once per week via anesthetised rats, and held at 25 oC, with 80%RH. Two days after feeding, active partially engorged adults are removed and used for the insecticide tests. Sex of the bed bug is not determined.

Experiment

The bed bugs are exposed to residues of the DE dust on filter paper within Petri dishes. The DE will be applied at the dose rate as currently registered for other insect pests; the surface area of the filter paper will be determined and the amount of DE required to treat the area calculated. The dust will be applied to the filter paper and spread evenly over the surface via a small paint brush. The Petri dish and filter paper sans DE and with DE will be weighed, to accurately measure the amount of DE added. For the test DE, ten bed bugs will be exposed, with a total of four replicates (i.e. 40 bugs in total exposed). The controls will consist of four replicates of ten bugs on filter paper in Petri dishes not exposed to the DE (a further 40 bed bugs and thus 80 used in total). Mortality is determined after 24 hours by counting bed bugs that do not move after the dish is tapped. Statistical analysis of the results will be made via one way ANOVAR.

References

Doggett S.L. (2005). Bed bug ecology and control . Chapter 7, Pests of Disease & Unease.Synopsis of Papers of the Symposium ‘Pests of Disease & Unease’, held 22 April 2005 , Westmead Hospital .

Doggett S.L, Geary M.J., Crowe W.J., Wilson P. and Russell R.C. (2003). Has the Tropical Bed Bug, Cimex hemipterus (Hemiptera: Cimicidae), invaded Australia ?Environmental Health, 3: 80-82.

Doggett S.L, Geary M.J. and Russell R.C. (2004). The resurgence of bed bugs in Australia , with notes on their ecology and control . Environmental Health, 4: 30-38.

Fletcher M.G. & Axtell R.C. (1993). Susceptibility of the bed bug, Cimex lectularius, to selected insecticides and various treated surfaces . Medical and Veterinary Entomology, 7: 69-72.