Susceptibility of Human Bed Bugs (Cimex hemipterus)to Selected Insecticide Products in Three Educational Institutions in Accra Metropolis, Ghana

ABSTRACT

The rapid increase in bed bug resistance to pyrethroids call for the development of novel control strategies. Products combining pyrethroids and neonicotinoids have become very popular for bed bug control in Ghana and around the world. However, concerns about evolution of resistance to these compounds have been scantly reported in Ghana. Over the years, various control measures have been employed to control bed bug populations of which chemical insecticides are the most common method used. This study was aimed at identifying commonly used methods/approaches in bed bugs control, determining the lethal dose (LD50) and lethal time (LT50) of some of the frequently used insecticides in some selected educational institutions. Two bed bug populations were collected from Presbyterian Boys’ Senior High School (Presec) and Mensah Sarbah Hall by handpicking and brushing method. Questioner-Interviewer response method was used to identify insecticides and commonly used bed bug control methodsin the study. Mass-reared adult bed bugs (Cimex hemipterus) (10, 1:1 sex ratio) were treated with the selected insecticides. Each treatment was replicated four times resulting in 40 bed bugs per treatment. Laboratory bioassays were used to measure the toxicity of insecticides after topical application and mortality rate was recorded at 24, 48 and 72 hours post-treatment. Chlorpyrifos (99.5 % purity) and Lambda-cyhalothrin (98.7 % purity) were used as standards for this study. Fumigation was the most commonly used method in bed bug control for both study sites. Dursban 4E emulsifiable concentrate (480g/L Chlorpyrifos) and K- Othrine Super (Lambda-cyhalothrin 30 g/L and Acetamiprid 30 g/L EC) were observed as the most frequently used products. The highest percentage mortality after 24 hours post-treatment, was recorded to be 100% and 95% for Chlorpyrifos (125 µg/µl). However, K-Othrine Super exhibited a significantly stronger insecticidal activity with LD50 values of 4.35 µg/µl and 4.34 µg/µl against bed bugs collected from Presec and xiii Mensah Sarbah, respectively. K-Othrine Super was the only insecticide that was uniformly fastacting and ultimately effective. Lambda-cyhalothrin insecticide showed the least potent insecticidal activity with LD50 values of 23.26 µg/µl and 20.52 µg/µl against bed bugs collected from Presec and Mensah Sarbah, respectively. Results from one-way ANOVA revealed that, there was no significant difference between the insecticidal activities of the two bed bug populations (p=0.473). The shortest LT50 value recorded was 1 hour and 45 minutes for K-Othrine Super against bed bugs collected from Mensah Sarbah whilst the longest LT50 value recorded was 82.16 hours (3 days 10 hours and 9 minutes) for Lambda-cyhalothrin against bed bugs collected from Presec. This study revealed that population of bed bugs from the two study sites showed different levels of susceptibility to the insecticides.