The effects of ozone gas on the common bed bug (Cimex lectularius L.)
Ozone gas is a strong oxidizing agent that is a naturally occurring component of the stratosphere. It can be easily synthesized and is used for a variety purposes including odor and microbial remediation. This study explores the effects of ozone on the common bed bug Cimex lectularius L. Ozone gas has previously been employed for control of insects in stored grain situations. Its potential as a management option for bed bug infestations has been proposed anecdotally on-line. However, reports on the effcacy of ozone are not present. The primary advantage of ozone as an insect treatment is the ability to be produced on-site and applied as a gas with no residual concerns and/or chemical disposal issues. However, the concentrations and exposure time required for mortality in bed bugs, as well as the effects of sub-lethal ozone exposure in insects in general, are poorly understood. This research explored the use and sub-lethal impacts of ozone in several ways by: (i) determining the ozone concentration and exposure time in the form of a concentration-time equation (CT expressed in ppm-min) required to achieve >95% mortality in bed bugs held in a bench-top chamber (ii) determining antioxidant enzyme activities by assay for the specific activity of 4 known antioxidant enzymes: Superoxide dismutase (SOD), Glutathione transferase (GST), Glutathione peroxidase (GPx), Catalase (CAT) (iii) determining the baseline electrical activity of the central nervous system using electrophysiological recording equipment. The results of each of these sections showed that: (i) the CT99 for adult bed bugs was 418,301ppm-min while the CT 99 for nymphs was calculated at 294,212ppm-min. Eggs were least susceptible with a CT99 of 2,323,093 ppm-min (ii) the cytosolic enzyme activities of both SOD and CAT were significantly elevated in ozone-treated insects as compared to control insects (p<0.05). GPx and GST activities did not vary significantly in the two treatment groups (iii) neurophysiology studies indicated that baseline electrical activity in ozone treated bed bugs was significantly lower than that of controls (p=0.019). Overall, this research provides insights into putative sub-organismal level impacts of ozone-exposure in insects and also highlights the potential and challenges of ozone as a tool for bed bug control.
Gondhalekar, Purdue University.
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