Morphological Identification and DNA Barcoding of the Tropical Bed Bug Cimex hemipterus Fabricius (Hemiptera: Cimicidae) from Thrissur, Kerala, India

Abstract

Knowledge of bed bugs is scant from Kerala due to improper identification, sparse population and better sanitation. But if an infestation begins it reaches extreme proportions because of the lack of awareness. To the best of our knowledge no detailed scientific studies on the identification of the bed bug species were carried out in Kerala. This study was aimed to perform morphological and molecular identification along with the morphometric analysis of the bed bug species from two sites—Avittappally and Mulankunnathukavu. Morphological identification was made by calculating the width to length ratios of the pronotum and hind femora. DNA barcoding was performed to identify the bed bug species accurately. A total of 21 morphological characters were used to compare bed bugs from the sample and the morphometric characters were measured and analysed using a Leica S8APO stereo microscope. The results indicated that the width-to-length ratios of pronotum and hind femora were 2.2±0.04 mm and 3.5±0.04 mm in Avittappally specimens and 2.1±0.05 mm and 3.2±0.05 mm in Mulankunnathukavu specimens. The genetic distance between the 2 COI sequence of our study were 0.027% and the intraspecific genetic distance between the 2 COI sequence of this study with 5 C. hemipterus sequences reported from other countries was found to be 0.025, 1.227, 0.058, 0.025 and 0.024% for Mulankunnathukavu specimen and 0.001, 1.280, 0.008, 0.001 and 0.001% for Avittappally specimen, respectively. The mean values of HL, HFW, HTW, MTW, FTW between the two places were significantly different. The results of PCA showed that the total percentage of variance reached 89.073% and 93.760%. Based on Morphological and morphometric characteristics along with molecular sequencing we assert that the bed bugs collected from both places were Cimex hemipterus.