Biting behaviour of medically important mosquitoes (Diptera: Culicidae) in Peninsular Malaysia

Human-landing catch (HLC) technique was undertaken in nine selected study sites within Peninsular Malaysia to determine the biting cycle of Aedes, Armigeres, Culex, and Mansonia mosquitoes. HLC was conducted 24 hours on three different nights in a duration of one week at each study site. Aedes albopictus were found in all study sites with bimodal biting cycle, whereas the biting peak of Aedes butleri was recorded between 1600 and 1900 hr. For Armigeres, five study sites demonstrated similar biting peak hour (1900 - 2000 hr) for Ar. kesseli four study sites showed biting peak at 1800 - 1900 hr for Ar. subalbatus. Culex quinquefasciatus was collected from all study sites except in Sungai Penchala with its biting activity beginning from 1900 hr. Both Mansonia annulifera and Mansonia uniformis captured in two different study sites showed similar biting peaks (1500 - 1600 hr). It is recommended that vector control activities be carried out at dusk as almost all mosquito species captured started their biting activities at that time.

Management of traumatic patellar dislocation in a regional hospital in Hong Kong

INTRODUCTION

The role of surgery for acute patellar dislocation without osteochondral fracture is controversial. The aim of this study was to report the short-term results of management of patellar dislocation in our institute.

METHODS

Patients who were seen in our institution with patella dislocation from January 2011 to April 2014 were managed according to a standardised management algorithm. Pretreatment and 1-year post-treatment International Knee Documentation Committee score, Tegner activity level scale score, and presence of apprehension sign were analysed.

RESULTS

A total of 41 patients were studied of whom 20 were first-time dislocators and 21 were recurrent dislocators. Among the first-time dislocators, there was a significant difference between patients who received conservative treatment versus surgical management. The conservative treatment group had a 33% recurrent dislocation rate, whereas there were no recurrent dislocations in the surgery group. There was no difference in Tegner activity level scale score or apprehension sign before and 1 year after treatment, however. Among the recurrent dislocators, there was a significant difference between those who received conservative treatment and those who underwent surgery. The recurrent dislocation rate was 71% in the conservative treatment group versus 0% in the surgery group. There was also significant improvement in International Knee Documentation Committee score from 67.7 to 80.0 (P=0.02), and of apprehension sign from 62% to 0% (P<0.01).

CONCLUSIONS

A management algorithm for patellar dislocation is described. Surgery is preferable to conservative treatment in patients who have recurrent patellar dislocation, and may also be preferable for those who have an acute dislocation.

Repellency effects of an ozone-producing air purifier against medically important insect vectors

An indoor ozone-producing air purifier was evaluated for its repellency effects on Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, Musca domestica and Periplaneta americana adults using a modified tunnel cage. The first set of testing consisted of both bait and the air purifier, whereas only bait was offered in the second testing set. The highest percent repellency was recorded among Cx. quinquefasciatus (83.23%) while Ae. aegypti (68.56%) was the least repelled by the air purifier tested. No mortality was observed in all testings. These results illustrated the potential use of the ozone-producing air purifier as a personal protection insect repellent device in premises. Nevertheless, in order to prevent dengue infection which is transmitted by both Ae. aegypti and Ae. albopictus, ozone-producing air purifier should be utilized concurrently with other vector control methods.

Detection of Wolbachia from field collected Aedes albopictus Skuse in Malaysia

Background & objectives:

Wolbachia-based vector control strategies have been proposed as a mean to augment the existing measures for controlling dengue vector. Prior to utilizing Wolbachia in novel vector control strategies, it is crucial to understand the Wolbachia-mosquito interactions. Many studies have only focused on the prevalence of Wolbachia in female Aedes albopictus with lack of attention on Wolbachia infection on the male Ae. albopictus which also affects the effective expression of Wolbachia induced- cytoplasmic incompatibility (CI). In this study, field surveys were conducted to screen for the infection status of Wolbachia in female and male Ae. albopictus from various habitats including housing areas, islands and seashore.

Methods:

Adult Ae. albopictus (n=104) were collected using human landing catches and hand aspirator. Standard ovitraps were also set in the selected areas for five days and the larvae were identified to species level. All the collected Ae. albopictus were screened for the presence of Wolbachia using multiplex polymerase chain reaction (PCR) and gene sequencing of Wolbachia surface protein (wsp) gene.

Results:

A 100 per cent positivity of Wolbachia infection was observed for individual Ae. albopictus screened. For pooled mosquitoes, 73 of the 76 pools (female) and 83 of the 87 pools (male) were positive with Wolbachia infection. The wsp gene sequence of the Wolbachia strain isolated from individual and pooled mosquitoes showed a 100 per cent homology with Wolbachia sp. of Ae. albopictus isolated from various geographical regions. Phylogenetic analysis based on wsp gene fragments showed that the isolates were clustered into groups A and B, respectively.

Interpretation & conclusions:

The results indicated that Wolbachia infection was widespread in Ae. albopictus population both in female and male Ae. albopictus. All the infected females were superinfected with both A and B strains while the infected males showed a combination of superinfection of A and B strains and single infection of B strain.

Effects of vitamin B fortified sucrose solution on the longevity and reproductive potentials of laboratory-bred Culex quinquefasciatus Say adult

Laboratory colonised mosquitoes are usually maintained on vitamin B complex fortified sucrose solution, however only few studies were conducted to evaluate the effects of such practice. This study aimed to determine the effects of different concentrations of sucrose solution fortified with and without 1% vitamin B complex on the longevity and reproductive potential of adult female of a local strain of Culex quinquefasciatus Say. Two arms of studies were carried out separately and each arm was triplicated. In one arm, concentrations of sucrose solution at 0%, 1%, 3%, 5% and 10% fortified with 1% Vitamin B complex were fed to the mosquitoes, while in the other arm, similar sucrose concentrations were used but without 1% vitamin B complex. Adult Cx. quinquefasciatus maintained on 5% sucrose solution fortified with 1% vitamin B complex exhibited significant extended vitality and longevity in stimulating ovarian development, compared with other vitamin fortified sucrose concentrations (p<0.05). The vitality and longevity of F0 and F1 males were 76.67±2.19 days and 57.67±8.19 days respectively. The F0 females survived the longest duration of 107.67±5.61 days and the F1 females survived 90.67±12.47 days with higher number of eggs laid, i.e. 1427.67±62.89 eggs at a higher hatchability rate of 57.05±8.39% or 814.49 eggs hatched. Thus, 5% sucrose solution fortified with 1% Vitamin B complex should be used to produce colonies of homogenous mosquitoes as this exerts positive biological effects on laboratory-bred Cx. quinquefasciatus.

Similar vertical transmission rates of dengue and chikungunya viruses in a transgenic and a non-transformed Aedes aegypti (L.) laboratory strain

The increase of the burden of dengue and chikungunya and the relative failure of traditional vector control strategies have highlighted the need to develop new control methods. RIDL-SIT, a vector control method based on the release of engineered male mosquitoes, has shown promising results from field trials conducted in the Cayman Islands and Brazil. In large scale use, a small proportion of females might be released along with the males. Such females are potential virus vectors; here we investigate the vertical transmission of dengue and chikungunya of homozygous OX513A females.We provided females of OX513A-My1 and a wild type comparator strain with blood meals artificially infected with dengue serotype 1, 2, 3, 4 or chikungunya viruses. For 14 days post-feeding, eggs laid by females were collected. Larvae and their mothers were first tested by qRT-PCR, then by inoculation on cell cultures to search for infectious viral particles. We found no significant difference between the minimum infection rate of OX513A-My1 and wild type females. We also discussed the potential number of females being released, a fraction of the female wild population. Consequently, we conclude that there are no evidence that OX513A-My females, if released into the environment, would cause more harm than their wild counterparts.

Evaluation of insect growth regulators, temephos and Bacillus thuringiensis israelensis against Aedes aegypti (L) in plastic containers

The residual activities of 5 insect growth regulators (IGRs) were studied and compared to operational dosage of temephos (1 mg/L) and Bacillus thuringiensis israelensis (Bti) (0.008 mg/L). The IGRs, temephos and Bti were applied into plastic containers containing 5 litres of water. Thirty Aedes aegypti larvae were added into each container weekly. Efficacy of these IGRs were evaluated for effective duration of each dosage and the percentage of emergence inhibition (EI). An end-point of EI/mortality ≥ 50% was considered to be effective. Pyriproxyfen possessed the longest residual activity in both indoor (43 weeks) and outdoor (26 weeks) conditions, followed by temephos (26 weeks in indoor and 16 weeks in outdoor). Although the residual activity of Bti in indoor lasted 8 weeks which was longer than cyromazine and diflubenzuron; however, it was least effective in outdoor which only lasted 2 weeks. This study revealed that pyriproxyfen possessed good residual effect among test IGRs compared to temephos and Bti. The use of IGRs can be an alternative long-term control measure in stagnant water body.

ABSENCE OF AEDES AEGYPTI (L.) ON AN ECOLOGICAL ISLAND: COMPETITIVE EXCLUSION?

Ovitrap surveillance was conducted in 2012 and 2006 in Malay and Aboriginal Villages on Carey Island. In each village, standard ovitraps were placed indoors and outdoors at randomly selected houses/locations. All L3 larvae recovered were identified up to species level. Results demonstrated that only larvae of Aedes albopictus were found in all the positive ovitraps placed indoors and outdoors. In 2012, a high ovitrap index (OI) of 66.7% indoor and 84.0% outdoor in the Malay Village; and 62.5% indoor and 88.0% outdoor in Aboriginal Village with an apparent absence of Aedes aegypti. In 2006, a 100% OI was recorded in all ovitraps set indoors and outdoors in both villages.

TEMPORAL CHANGES OF AEDES AND ARMIGERES POPULATIONS IN SUBURBAN AND FORESTED AREAS IN MALAYSIA

Surveillance of mosquitoes and their distribution in association with rainfall, relative humidity, and temperature were conducted in selected suburban and forested areas, namely, Sungai Penchala (Kuala Lumpur) and Taman Alam (Selangor) for 12 months. Armigeres kesseli was the most abundant species in Sungai Penchala while Aedes butleri was the most dominant species in Taman Alam. A positive correlation between mosquito distribution and rainfall was observed in selected mosquito species in Sungai Penchala (Armigeres kesseli, r = 0.75; Armigeres subalbatus, r = 0.62; and Aedes albopictus, r = 0.65) and Taman Alam (Armigeres sp, r = 0.59; Ae. butleri, r = 0.85; and Ae. albopictus, r = 0.62). However, no significant cor- relation was found either between selected mosquito species in both study areas and relative humidity or temperature. Results obtained suggested that vector control programs to be conducted based on temporal distribution of vectors in order to achieve beneficial outcomes with effective costing.

Evaluation of Sumithion L-40 against Aedes aegypti (L.) and Aedes albopictus Skuse

Space spraying of chemical insecticides is still an important mean of controlling Aedes mosquitoes and dengue transmission. For this purpose, the bioefficacy of space-sprayed chemical insecticide should be evaluated from time to time. A simulation field trial was conducted outdoor in an open field and indoor in unoccupied flat units in Kuala Lumpur, to evaluate the adulticidal and larvicidal effects of Sumithion L-40, a ULV formulation of fenitrothion. A thermal fogger with a discharge rate of 240 ml/min was used to disperse Sumithion L-40 at 3 different dosages (350 ml/ha, 500 ml/ha, 750 ml/ha) against lab-bred larvae and adult female Aedes aegypti and Aedes albopictus. An average of more than 80% adult mortality was achieved for outdoor space spray, and 100% adult mortality for indoor space spray, in all tested dosages. Outdoor larvicidal effect was noted up to 14 days and 7 days at a dosage of 500 and 750 ml/ha for Ae. aegypti and Ae. albopictus, respectively. Indoor larvicidal effect was up to 21 days (500 ml/ha) and 14 days (750 ml/ha), respectively, after spraying with larval mortality > 50% against Ae. aegypti. This study concluded that the effective dosage of Sumithion L-40 thermally applied against adult Ae. aegypti and Ae. albopictus indoor and outdoor is 500 and 750 ml/ha. Based on these dosages, effective indoor spray volume is 0.4 - 0.6 ml/m³. Additional indoor and outdoor larvicidal effect will be observed at these application dosages, in addition to adult mortality.

Surveillance of Aedes albopictus Skuse breeding preference in selected dengue outbreak localities, peninsular Malaysia

Entomological surveillance was conducted in order to determine the abundance and to evaluate any changes of biological vectors or ecology, especially in the dengue outbreak areas. The abundance and breeding preference of Aedes albopictus and Aedes aegypti were conducted in selected dengue outbreak localities in three states of peninsular Malaysia namely Selangor, Federal Territory of Kuala Lumpur, and Penang Island using ovitraps and larval survey method. It was determined that Ae. albopictus was predominant in most of the localities and found to breed more outdoor than indoor. A wide range of breeding foci were recorded in this study. It was also determined that ovitrap method was more effective to detect the presence of Aedes mosquitoes when the larval survey was at low rate of infestation. The abundance of Ae. albopictus in dengue outbreak localities emphasis that the vector control programme should also target this species together with the primary dengue vector, Ae. aegypti.

Eco-virological survey of Aedes mosquito larvae in selected dengue outbreak areas in Malaysia

BACKGROUND & OBJECTIVESI: Transovarial transmission of dengue virus in the Aedes vectors is now a well-documented phenomenon reported from many parts of the endemic areas in the world, which played an important role in initiating and maintaining the outbreak in human populations. This study investigated the factors affecting breeding habitats and the relationship with transovarial dengue virus in larvae of Aedes aegypti and Ae. albopictus.

METHODS

Larval surveillance was conducted in dengue outbreak areas in Malaysia from 2008 until 2009. Sampling was carried out based on habitat type, water condition (substrate type), canopy coverage, temperature and pH at breeding habitats. RT-PCR was performed to detect presence of transovarial dengue virus in larvae collected in the study areas.

RESULTS

A total of 789 breeding habitats were identified during this study and the majority of these breeding sites were plastic containers (57.46%). Aedes albopictus dominated most of the water condition surveyed, while Ae. aegypti indicated preference toward habitats with clear water. Aedes aegypti was selective in selecting ovipositional sites compared to Ae. albopictus where shaded areas were shown to be the most preferred. From a total of 363 mosquito larvae pools, 23 (6.3%) pools were positive for dengue virus where 18 of them were from Ae. albopictus and five were from Ae. aegypti mosquito larvae pools.

INTERPRETATION & CONCLUSION

This study indicated the presence of transovarial transmission of dengue virus in immature Ae. aegypti and Ae. albopictus in the field. This study also showed that combination of water conditions, canopy coverage, temperature and pH of breeding habitats were the factors affecting the larval population. The study suggested that larval survey programme could serve as a tool not only to monitor the local dengue vector distribution but also to provide objective information for taking appropriate action by the community against dengue vectors.

Effects of preservatives and killing methods on morphological features of a forensic fly, Chrysomya megacephala (Fabricius, 1794) larva

Preservation of larvae retrieved from cadavers is important in ensuring the quality and integrity of entomological specimens used for the estimation of post-mortem interval (PMI). The process of killing and preserving larvae could distort the larvae leading to inaccurate estimation of PMI. In this study, the effects of killing Chrysomya megacephala larvae with hot water at different temperatures and subsequent maintenance in various preservatives were determined. Larvae not killed by hot water but preserved directly were used as control. The types of preservative used were 10% formalin, 70% ethanol and Kahle's solution. The morphological features examined were length, turgidity, curvature and coloration of larvae. Larvae killed in 80ºC hot water have shorter mean length (12.47 ± 2.86 mm) compared to those in 60ºC hot water (12.95 ± 2.69 mm). Increasing the duration of preservation in all types of preservative caused elongations of larvae treated or untreated with hot water. There were no significant changes in larval turgidity preserved in Kahle's solution compared to other two preservatives and were unaffected by the duration of storage. Larvae preserved in Kahle's solution experienced the least changes in coloration and shape compared to other preserved larvae in 70% ethanol or 10% formalin. Larvae directly immersed alive in 70% ethanol experienced the most changes in curvature, coloration and turgidity. This study suggested that killing larvae with hot water at 80ºC and preservation in Kahle's solution is the optimum method resulting in least changes in morphological features of Ch. megacephala larvae.

Prognostic factors associated with clear cell sarcoma in 14 Chinese patients

PURPOSE. To identify prognostic factors associated with clear cell sarcomas in 14 Chinese patients. METHODS. Medical records of 7 men and 7 women (mean age, 36 years) with histologically confirmed clear cell sarcoma of tendons and aponeuroses were reviewed. Patient demographics, tumour characteristics, and treatment modalities were retrieved. Prognostic factors associated with favourable 5-year survival were determined. RESULTS. The most affected sites were the thigh (n=5) and the foot (n=4); the mean time from symptom onset to diagnosis was 9.5 months. The tumour stage at diagnosis was IIA in 8 patients, IIB in 2, and III in 4. The mean tumour size was 4.5 cm in diameter. One patient was lost to follow-up. For the remaining 13 patients, the mean time to disease-related mortality was 2.5 years. Nine patients had distant metastases; the most common sites were lungs and pleura (n=7), followed by distant lymph nodes (n=4), bone (n=2), pericardium (n=2), and brain (n=1). All patients underwent surgical excision. Three women and one man (mean age, 27 years) attained 5-year disease-free survival. All had stage IIA tumours at diagnosis. Their mean tumour size was 1.75 cm in diameter, which was significantly smaller than that of all patients (4.5 cm). Tumour size of ≤ 2.5 cm in diameter (p=0.004) and stage IIA tumour at diagnosis (p=0.04) were significant prognostic factors for 5-year survival. CONCLUSION. Tumour size of ≤ 2.5 cm and early stage tumour are associated with 5-year disease-free survival. Early detection is crucial for the prognosis of clear cell sarcomas.

A preliminary report on ants (Hymenoptera: Formicidae) recovered from forensic entomological studies conducted in different ecological habitats in Malaysia

This study reported the ant species that were recovered from monkey carcasses in three different ecological habitats in Malaysia. The study was conducted from 9 May - 10 October 2007, 6 May - 6 August 2008 and 26 May - 14 July 2009 in forested area (Gombak, Selangor), coastal area (Tanjong Sepat, Selangor) and highland area (Bukit Cincin, Pahang), respectively. Monkey carcass was used as a model for human decomposition in this study. A total of 4 replicates were used in each of the study sites. Ants were observed to prey on eggs, larvae, pupae and newly emerged flies. This study found that ant species could be found at all stages of decomposition, indicating that ants were not a significant indicator for faunal succession. However, different species of ants were obtained from monkey carcasses placed in different ecological habitats. Cardiocondyla sp. was only found on carcasses placed in the coastal area; while Pheidole longipes, Hypoponera sp. and Pachycondyla sp. were solely found on carcasses placed in the highland area. On the other hand, Pheidologeton diversus and Paratrechina longicornis were found in several ecological habitats. These data suggests that specific ant species can act as geographic indicators for different ecological habitats in forensic entomology cases in Malaysia.

Mitochondrial DNA analyses reveal low genetic diversity in Culex quinquefasciatus from residential areas in Malaysia

The present study explored the intraspecific genetic diversity, dispersal patterns and phylogeographic relationships of Culex quinquefasciatus Say (Diptera: Culicidae) in Malaysia using reference data available in GenBank in order to reveal this species' phylogenetic relationships. A statistical parsimony network of 70 taxa aligned as 624 characters of the cytochrome c oxidase subunit I (COI) gene and 685 characters of the cytochrome c oxidase subunit II (COII) gene revealed three haplotypes (A1-A3) and four haplotypes (B1-B4), respectively. The concatenated sequences of both COI and COII genes with a total of 1309 characters revealed seven haplotypes (AB1-AB7). Analysis using tcs indicated that haplotype AB1 was the common ancestor and the most widespread haplotype in Malaysia. The genetic distance based on concatenated sequences of both COI and COII genes ranged from 0.00076 to 0.00229. Sequence alignment of Cx. quinquefasciatus from Malaysia and other countries revealed four haplotypes (AA1-AA4) by the COI gene and nine haplotypes (BB1-BB9) by the COII gene. Phylogenetic analyses demonstrated that Malaysian Cx. quinquefasciatus share the same genetic lineage as East African and Asian Cx. quinquefasciatus. This study has inferred the genetic lineages, dispersal patterns and hypothetical ancestral genotypes of Cx. quinquefasciatus.

Current insecticide susceptibility status of Malaysian Anopheles maculatus Theobald to malathion, permethrin, DDT and deltamethrin

Chemical insecticides are still considered as important control agents for malaria vector control. However, prolonged use of these chemicals may select mosquito vectors for resistance. In this study, susceptibility status of adult Anopheles maculatus collected from 9 localities in peninsular Malaysia, viz., Jeli, Temerloh, Pos Banun, Senderut, Jeram Kedah, Segamat, Kota Tinggi, Kluang and Pos Lenjang were determined using the standard WHO bioassay method in which the adult mosquitoes were exposed to standard insecticide impregnated papers malathion, permethrin, DDT and deltamethrin--at pre-determined diagnostic dosage. Deltamethrin was most effective insecticide among the four insecticides tested, with the LT50 of 29.53 min, compared to malathion (31.67 min), DDT (47.76 min) and permethrin (48.01 min). The effect of all insecticides on the laboratory strain was greater (with all insecticides demonstrated LT50 < 1 hour) than the field strains (deltamethrin 32.7, malathion 53.0, permethrin 62.0, DDT 67.4 min). An. maculatus exhibited low degree of resistance to all test insecticides, indicating that these chemical insecticides are still effective in the control of malaria vector.

In vitro antibacterial activity and physicochemical properties of a crude methanol extract of the larvae of the blow fly Lucilia cuprina

The emergence of multidrug-resistant bacterial strains has prompted the reintroduction of maggot therapy in the treatment of chronic, infected wounds. Many previous studies have demonstrated the potent antibacterial activity of larval excretions/secretions of the blowfly Lucilia sericata (Meigen) (Diptera:Calliphoridae) against bacteria. However, the antibacterial activity of its sibling species, Lucilia cuprina (Wiedemann) (Diptera:Calliphoridae) against a wide range of pathogenic bacteria has never been determined. The aim of this study was to develop a new procedure to produce whole body extract of larvae of L. cuprina via methanol extraction as well as to demonstrate the in vitro antibacterial activity of this extract against seven selected wound pathogens (Staphylococcus aureus, methicillin-resistant S. aureus, S. epidermidis, Streptococcus pyogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli). The turbidimetric assay demonstrated that L. cuprina larval extract was significantly potent against all bacteria tested (P < 0.001). Additionally, colony-forming unit (CFU), agar well diffusion and minimum inhibitory concentration assays have confirmed the apparent potency of larval extract against P. aeruginosa. The reconstituted larval extract was highly robust and thermally stable. These observations substantiated the feasibility of the methanol extraction method in the production of larval extract.

Perioperative antithrombotic management in joint replacement surgeries

OBJECTIVES

To determine optimal perioperative antithrombotic management for patients with cardiac diseases undergoing joint replacement surgeries.

DATA SOURCES

MEDLINE and PubMed database search up to January 2013.

STUDY SELECTION

Those dealing with perioperative antithrombotic management of patients undergoing orthopaedic operations, especially joint replacement, and also those undergoing general surgery. Various combinations of the following key words were used in our search: "antiplatelet", "antithrombotic", "anticoagulant", "coronary stent", "perioperative", "venous thromboembolism", "cardiovascular", "surgery", "orthopaedic", "knee replacement", "hip replacement", "joint replacement", and "arthroplasty".

DATA EXTRACTION

Literature review, original articles, and best practice guidelines.

DATA SYNTHESIS

Patients should be stratified according to their risk of developing arterial thromboembolism in order to decide the most appropriate perioperative antiplatelet or anticoagulant regimen for them. After recent coronary stenting, including bare-metal stents implanted within 6 weeks and drug-eluting stents implanted within 6 months, surgery should be deferred. For venous thromboembolism prophylaxis in patients already on aspirin, the dosage should be adjusted as necessary or additional low-molecular-weight heparin administered.

CONCLUSION

The perioperative management of patients with cardiac diseases in receipt of antithrombotic agents is based upon a delicate balance between the perceived risk of arterial thromboembolism and the perceived risk of perioperative bleeding. One must exercise good judgement in deciding the most appropriate perioperative antithrombotic regimen. Venous thromboembolism is also a common problem after joint replacement surgeries. For patients already on aspirin, optimal venous thromboembolism prophylaxis is still being debated.

First molecular genotyping of voltage gated sodium channel alleles in Culex quinquefasciatus populations in Malaysia

A nationwide investigation was performed to detect the presence of 1014 mutation(s) in voltage gated sodium channel (kdr) gene of Culex quinquefasciatus from 14 residential areas across 13 states and a federal territory in Malaysia. Molecular genotyping of kdr mutation was performed via a modified three tubes allele-specific-polymerase chain reaction (AS-PCR) and direct sequencing of kdr gene. Based on the results of AS-PCR, homozygous susceptible (SS) genotype was found in nine out of 14 populations with 38 individuals from a total sample size of 140. Heterozygous (RS) genotype was most predominant (99 individuals) and distributed across all study sites. Homozygous resistance (RR) genotype was detected in Perak (one individual) and Selangor (two individuals). The resistance kdr allele frequencies ranged from 0.1 to 0.55, with the highest being detected in Cx. quinquefasciatus population from Selangor. This study has documented the first field-evolved instance of 1014F mutation in Malaysian mosquitoes and the findings of this study could be utilized in the implementation of strategic measures in vector control programs in Malaysia.

Temephos resistance in field Aedes (Stegomyia) albopictus (Skuse) from Selangor, Malaysia

Larvae of Aedes albopictus obtained from dengue endemic areas in Selangor, Malaysia were evaluated for their susceptibility to operational dosage of temephos (1 mg/L). Larval bioassays were carried out in accordance to modified WHO standard methods. Biochemical microassay of enzymes in Ae. albopictus was conducted to detect the emergence of insecticide resistance and to define the mechanisms involved in temephos resistance. The 50% mortality lethal time (LT50) for Ae. albopictus tested against temephos ranged between 58.65 to 112.50 minutes, with resistance ratio ranging from 0.75 - 1.45. This study addressed the fluctuation of time-related susceptibility status of Ae. albopictus towards insecticide. Significant difference on the weekly enzyme levels of non-specific esterases, mixed function oxidases and glutathione S-transferases was detected (p ≤ 0.05). No significant correlation was found between temephos resistance and enzyme activity (p > 0.05). Only glutathione S-transferases displayed high level of activity, indicating that Ae. albopictus may be resistant to other groups of insecticide. The insensitive acetylcholinesterase was detected in some field collected Ae. albopictus populations, indicating the possibility of emergence of carbamate or other organophosphate resistance in the field populations. Continuous resistance monitoring should be conducted regularly to confirm the efficacy of insecticides for dengue control.

Molecular identification of Malaysian Chrysomya megacephala (Fabricius) and Chrysomya rufifacies (Macquart) using life stage specific mitochondrial DNA

DNA identification of blow fly species can be a very useful tool in forensic entomology. One of the potential benefits that mitochondrial DNA (mtDNA) has offered in the field of forensic entomology is species determination. Conventional identification methods have limitations for sibling and closely related species of blow fly and stage and quality of the specimen used. This could be overcome by DNA-based identification methods using mitochondrial DNA which does not demand intact or undamaged specimens. Mitochondrial DNA is usually isolated from whole blow fly and legs. Alternate sources for mitochondrial DNA isolation namely, egg, larva, puparium and empty puparium were explored in this study. The sequence of DNA obtained for each sample for every life cycle stage was 100% identical for a particular species, indicating that the egg, 1st instar, 2nd instar, 3rd instar, pupa, empty puparium and adult from the same species and obtained from same generation will exhibit similar DNA sequences. The present study also highlighted the usefulness of collecting all life cycle stages of blow fly during crime scene investigation with proper preservation and subsequent molecular analysis. Molecular identification provides a strong basis for species identification and will prove an invaluable contribution to forensic entomology as an investigative tool in Malaysia.

DNA typing of Calliphorids collected from human corpses in Malaysia

Estimation of post-mortem interval (PMI) is crucial for time of death determination. The advent of DNA-based identification techniques forensic entomology saw the beginning of a proliferation of molecular studies into forensically important Calliphoridae (Diptera). The use of DNA to characterise morphologically indistinguishable immature calliphorids was recognised as a valuable molecular tool with enormous practical utility. The local entomofauna in most cases is important for the examination of entomological evidences. The survey of the local entomofauna has become a fundamental first step in forensic entomological studies, because different geographical distributions, seasonal and environmental factors may influence the decomposition process and the occurrence of different insect species on corpses. In this study, calliphorids were collected from 13 human corpses recovered from indoors, outdoors and aquatic conditions during the post-mortem examination by pathologists from the government hospitals in Malaysia. Only two species, Chrysomya megacephala and Chrysomya rufifacies were recovered from human corpses. DNA sequencing was performed to study the mitochondrial encoded COI gene and to evaluate the suitability of the 1300 base pairs of COI fragments for identification of blow fly species collected from real crime scene. The COI gene from blow fly specimens were sequenced and deposited in GenBank to expand local databases. The sequenced COI gene was useful in identifying calliphorids retrieved from human corpses.

Vertical distribution of Aedes mosquitoes in multiple storey buildings in Selangor and Kuala Lumpur, Malaysia

The aim of the present study was to determine the vertical distribution and abundance of Aedes mosquitoes in multiple storey buildings in Selangor and Kuala Lumpur, Malaysia. Ovitrap surveillance was conducted for 4 continuous weeks in multiple storey buildings in 4 residential areas located in Selangor [Kg. Baiduri (KB)] and Kuala Lumpur [Student Hostel of University of Malaya (UM), Kg. Kerinchi (KK) and Hang Tuah (HT)]. The results implied that Aedes mosquitoes could be found from ground floor to highest floor of multiple storey buildings and data from different elevation did not show significant difference. Ovitrap index for UM, KB, HT and KK ranged from 0 - 29.17%, 0 - 55.56%, 8.33 - 83.33% and 0 - 91.17% respectively. Aedes aegypti and Aedes albopictus were found breeding in HT, KK and KB; while only Ae. albopictus was obtained from UM. The results indicate that the invasion of Aedes mosquitoes in high-rise apartments could facilitate the transmission of dengue virus and new approaches to vector control in this type of residential area should be developed.