Tropical bed bug (Cimex hemipterus) is a nocturnal ectoparasite of the family Cimicidae that is commonly distributed in the tropical and subtropical regions of the world . Like in many other developing nations, high prevalence of bedbugs’ infestation has been reported in homes and school dormitories across Nigeria  with high frequency in untidy and congested households . Bedbug infestation rates of above 50 % have been reported in most studied communities across the country [4, 5, 6]. In such households, C. hemipterus usually hide in dry, dark places like in mattresses/pillows, carpets, furniture, abandoned appliances and walls/floors cracks  where they lay hundreds of eggs that hatch into the adult form.
The account of human-bedbug relationship is long dated before the Second World War. C. hemipterus constitutes a public health nuisance to mankind, their bites bring about considerable discomfort, social stigmatization and psychological distress (7). Although C. hemipterus are not directly associated with diseases transmission, they have been somewhat shown to aid in mechanical transmission of plague, hepatitis B virus and tularemia [2, 8].
Following the invention of dichloro-diphenyl trichloroethane (DDT) among other insecticides, elimination of bedbug was considered successful especially in the developed world with sudden decline experienced in their population . In Nigeria, chemical control using permethrin, DDT, bendiocarb and malathion remains a vital measure in the management of most insect pests . Regrettably, resurgence of bedbugs’ resistance to insecticides has been reported in the last two decades due to indiscriminate and repeated overuse of insecticides. Moreover, dissemination of mutant bedbugs as a result of unsupervised international travel has been on the increase . Furthermore, cimicid insects have been documented to be highly resistant against organochlorines, organophosphates (OPs), carbamates and pyrethroids worldwide [9, 10], thereby leaving pyrethroids as the most widely used class of insecticide for bedbug control .
Diverse resistance mechanisms such as penetration resistance through thickening of the cuticle, metabolic resistance by increased activities of detoxification enzymes and knockdown resistance by kdr mutations have been demonstrated to be responsible for the conferment of resistance statue displayed by bedbug [1, 11].
Although, reported resistance activities of bedbug to chemical treatment is evident in major high income countries, equivalent of such is scanty or non-available in the tropics especially Nigeria. Understanding their rate of survival, fecundity and resistance to chemical treatment is paramount if C. hemipterus are to be effectively managed in this part of the world. It is based on this fact that, we evaluated the susceptibility status of field collected bedbugs to four classes of selected insecticides (permethrin, dichloro-diphenyl trichloroethane (DDT), bendiocarb and malathion) using WHO standard test kits. This finding will provide useful information for those attempting to manage bedbug infestations, such as pest management professionals and homeowners in developing an informed control strategies aimed at current and future infestations.
Bedbug samples were collected from seven randomly selected buildings (four classrooms: Civil Engineering, New building, Mechanical Engineering and Multipurpose building) and (three hostels: Akata, New hall and PGD hall) in Yaba College of Technology (Yabatech), Yaba, Lagos State, Nigeria.
Yaba College of Technology (Yabatech) is a higher institution based in Yaba, located on longitude 030 22E and latitude 060 30N, surrounded by Fadeyi, Shomolu, Herbert Macauley way and Fola Agoro. The student population is about 16,000 with majority from typical Nigerian average homes, that is, children of middle-low income earners. The school has six hostel accommodations for the students which are always almost packed beyond capacity, a condition that favours bedbug infestation
A total of two hundred and seventy (270) bedbugs were harvested. Collections were done between 8pm − 10pm daily from May to August 2019 following the methods previously described by Punchihewa et al. (2019). The collected bedbugs were transferred to the Yabatech Environmental Biology Laboratory in well labelled containers and they were maintained in aerated clean plastic containers at a temperature of 25 ± 2oC and relative humidity of 75 ± 10%. The samples were maintained for 24hours before exposure to insecticides.
Insecticide susceptibility bioassay were conducted using insecticide impregnated filter paper with 0.75% permethrin, 4% DDT, 0.1% bendiocarb and 5% malathion. The bioassays were carried out using WHO insecticides test kit and were covered with cloth having very tiny mesh at both ends enough to prevent the bedbugs from escaping during exposure and supply the optimum air. Each bioassay contains fifteen bedbugs exposed to the insecticide-impregnated papers, the assay was carried in four replicates and accompanied by a control. During the exposure, the test tubes were constantly agitated to ensure the bedbug were on the insecticides impregnated papers. The insecticides exposure was carried out for 90 minutes, and the bedbugs were transferred to another aerated container with non-treated paper. Mortality and number of eggs produced were recorded at 90 minutes, 24, 48 and 72 hours.
Percentage mortality and egg production were computed per assay.
Egg production rate = number of eggs produced/ total number of bedbugs present at the beginning of every 24hrs X 100
Percentage mortality = number of dead bedbugs/ total number of bedbugs present at the beginning of every 24hrs X 100
The mortality of bedbugs in relation to exposure to insecticides and time was determined using univariate analysis of variance and Duncan multiple range test used for post hoc at 95% confidence interval and 0.05 p-value.
All analyses were done in IBM SPSS version 23.