The tropical bed bug, Cimex hemipterus (F.), has now emerged as an important public health pest in the tropics. Despite its alarming infestation rate, the information on its population genetics remains scarce. Here, we described the infestation structure and population dynamics of C. hemipterus in the tropics, especially Malaysia and Singapore, based on eight novel microsatellites and two mtDNA markers, including cytochrome c oxidase I (COI) and 16S rRNA genes. Across populations, microsatellite data revealed high genetic diversity with significant genetic differentiation and restricted gene flow. Analysis within populations revealed evidence of a recent bottleneck. Nonetheless, elevated genetic diversity in nearly all populations suggests that the propagule in C. hemipterus populations were much diverse, distantly related (mean r = 0.373), and not significantly inbred (mean FIS = 0.24) than that observed in Cimex lectularius from previous studies. We observed seven mtDNA haplotypes across the 18 populations studied (Hd = 0.593) and several populations displayed more than one matrilineal descent. The two markers were generally congruent in suggesting a common, genetically diverse (especially at the nuclear region) source population with possibilities of multiple introductions for the bed bug populations in the present study.
A survey on termite species composition was conducted in Samunsam Wildlife Sanctuary, Sarawak in February 2015. Overall 19 species of termite belonging to 13 genera and 8 subfamilies was found in the sanctuary. It was recorded the subfamily of Termitinae had the highest number of species (6 species, equal to 31.58% of total species), followed by Nasutermitinae (3 species, 15.79%), Macrotermitinae, Amitermitinae, Rhinotermitinae, Coptotermitinae, (2 species, 10.53% respectively), and Heterotermitinae, Termitogetoninae (1 species, 5.26% respectively). Since this rapid survey is the first termite assemblage representation in Samunsam Wildlife Sanctuary, the preliminary result may serve as the baseline data for termite composition in the area. Therefore, a whole coverage for the area within this sanctuary would definitely increase the number of termite species found in the sanctuary.
Field survey of gastrointestinal helminths on rodents from family Muridae were conducted at five localities inWestern Sarawak from June 2013 until April 2014. A total of 31 host individuals comprising six species ofmurids were examined for gastrointestinal helminths using opportunistic necropsy. The hosts examined wereLeopoldamys sabanus, Maxomys rajah, M. surifer, M. whiteheadi, Niviventer cremoriventer and Sundamysmuelleri. Of these host species, 186 individuals consisting of two taxonomic groups of helminths wererecovered, namely Nematoda and Cestoda. This study contributes to the growing literature on the infestation ofendoparasites in rodents especially in Sarawak.
The yellow rice stem borer, Scirpophaga incertulas (Walker) is a prevalent pest in paddy fields worldwide. In Sarawak, a survey on pest of paddy carried out from 2009 to 2011 covering 166 paddy fields revealed that rice stem borers caused 11.4% of total paddy damage. In order to reduce the damage, identifying resistance paddy variety is crucial. The objective of this study was to screen Sarawak paddy landraces with resistance to S. incertulas. Twelve Sarawak paddy landraces were selected randomly for this study. Antixenosis resistance screening was performed in aquariums (60 x 28 x 33 cm). Three replications of one-month-old seedlings were randomly arranged in aquarium and exposed to adult S. incertulas. The number and position of egg mass on each plant were recorded. Egg mass abnormalities were also observed. For antibiosis, rice culms of two-month old seedlings from each landrace were infested with larvae. The length of surviving larvae from five rice culms was measured. The experiment revealed variations in landrace of preference for ovipositing. Among the twelve Sarawak paddy landraces, Kanowit was more preferred by S. incertulas for ovipositing in comparison to other paddy landraces suggesting susceptibility towards the pest. Abaxial leaf surface was the preferred oviposition site. There was no clear antibiosis response of the paddy landraces towards S. incertulas larvae in this study.
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