Super- or single infection : Wolbachia supergrouping of wild mosquito populations from varied location types in Peninsular Malaysia

Wolbachia has the ability to cause reproductive abnormalities in infected hosts including cytoplasmic incompatibility (CI). CI is activated when there are multiple Wolbachia supergroups or strains infection present in insect populations. Wolbachia-transinfected mosquitoes have been used widely in some countries as a biological control agent. In order to ensure a successful Wolbachia establishment, it is important to determine the diversity of natural Wolbachia present in the wild mosquito populations. The adults and immature stages of mosquitoes were collected from urban, suburban and rural areas and were reared into adults and identified to species before being subjected to molecular analysis. We found that 22% out of 222 males and 34.6% of 543 females tested were carrying Wolbachia based on PCR amplification of the Wolbachia 16S rDNA genes technique. PCR digestion for Wolbachia supergrouping showed that most of the Ae. albopictus were superinfected with Wolbachia (52.41%), whereas 21% and 28% of the positive samples were singly infected with supergroup A and B, respectively. There is an indication that prevalence of Wolbachia varies between mosquito populations in different areas. However, further studies to incorporate both PCR amplication of the Wolbachia 16S rDNA and wsp genes with bigger sample size should be performed to measure exact infection of Wolbachia in Malaysia. The baseline data on diversity of Wolbachia supergroups is expected to facilitate Wolbachia strategy by helping us to better understand the patterns and impact of the bacteria’s transmission in the environment

A scoping review on the use of different blood sources and components in the artificial membrane feeding system and its effects on blood-feeding and fecundity rate of Aedes aegypti.

In some laboratories, mosquitoes' direct blood-feeding on live animals has been replaced with various membrane blood-feeding systems. The selection of blood meal sources used in membrane feeding is crucial in vector mass rearing as it influences the mosquitoes' development and reproductive fitness. Therefore, this scoping review aimed to evaluate the existing literature on the use of different blood sources and components in artificial membrane feeding systems and their effects on blood-feeding and the fecundity rate of Ae. aegypti. A literature review search was conducted by using PubMed, Scopus, and Web of Science databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA-ScR). The EndNote version 20 software was used to import all searched articles. Relevant information was retrieved for analysis into a Microsoft Excel Spreadsheet. A total of 104 full-text articles were assessed for eligibility criteria, whereby the articles should include the comparison between different types of blood source by using the membrane feeding systems. Only 16 articles were finally included in the analysis. Several studies had reported that human blood was superior in blood-feeding Ae. aegypti as compared to sheep blood which resulted in lower fecundity due to accumulation of free fatty acids (FFA) in the cuticles. In contrast, cattle whole blood and pig whole blood showed no significant differences in the blood-feeding and fecundity rate as compared to human blood. This review also indicated that bovine whole blood and pig whole blood enhanced Ae. aegypti's vitellogenesis and egg production as compared to plasma and blood cells. In addition, human blood of up to 10 days after the expiration date could still be used to establish Ae. aegypti colonies with good blood-feeding rates and number of eggs produced. Thus, future studies must consider the importance of selecting suitable blood sources and components for membrane blood feeding especially in mosquito colonisation and control measure studies

Should we bother doing dengue vector surveillance, and if so, how should we do it?

There is an enduring disconnect between the routine surveillance of mosquitoes that transmit dengue viruses and control activities to limit disease spread. A great variety of methods used to collect vector surveillance data exists globally, with program design typically influenced by historical, socio-cultural and cost factors. Surveillance data can be expensive to collect, meaning that without demonstration of its usefulness in directing mosquito control it may be deprioritized or even abandoned. Given that universally prescribed surveillance methods are unlikely to be sustainable and successful, we propose that strategies be designed according to the local terroir of dengue transmission. Strategy design should consider not only costs, but the amenability of workers and the public to various methods, the utility of methods for directing control and reducing disease, and the underlying spatial structure of the vector populations locally. A process of evaluating each of these factors should precede strategy design and be part of on-going review processes. In the case that the usefulness of vector surveillance cannot be demonstrated, then it may be argued that resources could be allocated to other aspects of disease control

Fear towards insects and other arthropods: a cross sectional study in a Malaysian university

Insects and other arthropods can elicit fear and disgust in certain individuals and communities which is yet to be explored in Malaysia. Therefore, we aimed to determine the prevalence of fear and disgust toward varied arthropods and compare the level of emotions between female and male respondents and the different arthropod types. A cross-sectional survey using a new designed arthropods survey was performed among 224 undergraduate students in Universiti Kebangsaan Malaysia. Based on our study, more than half of the respondents feared scorpion, wasp, centipede, bee, blister beetle and cockroach. Meanwhile, more than half of the respondents reported disgust toward maggot, cockroach, caterpillar, centipede, sago larvae and head lice. Female students who formed the majority of respondents reported higher fear and disgust toward the top-fifteen chosen insects. The most feared arthropod is the scorpion, while maggot (i.e. fly larvae) is the most disgusted arthropod. Statistically significant differences of fear were found between female and male respondents toward most arthropods, whereas no significant differences were found between genders for disgust toward most arthropods. In addition, previous history of spider bite is significantly associated with fear of spiders. This study revealed fear of arthropods is prevalent among university students in Malaysia. Persistent fear toward arthropods can lead to entomophobia, a specific phobia that may require intervention by health professionals

Pengaruh suhu terhadap perkembangan lalat berkepentingan forensik chrysomya villeneuvi patton (Diptera: Calliphoridae)

Entomologi forensik adalah satu bidang ilmu yang menggunakan serangga sebagai bahan bukti untuk menganggarkan selang masa kematian atau selang post mortem (PMI). Penentuan PMI tersebut berdasarkan kepada saiz dan peringkat perkembangan serangga. Chrysomya villeneuvi merupakan salah satu spesies langau yang boleh dijadikan sebagai petunjuk yang baik untuk menganggarkan PMI apabila ia ditemukan pada mayat. Kajian ini bertujuan untuk menghasilkan suatu data asas dan graf perkembangan bagi lalat Ch. villeneuvi pada suhu yang berbeza. Data yang diperoleh juga digunakan untuk membangunkan jadual jam darjah terkumpul (ADH). Justifikasi kajian dijalankan kerana data perkembangan lalat spesies ini belum dibangunkan di Malaysia. Penentuan PMI terpaksa dilakukan dengan berpandukan kepada data perkembangan Ch. megacephala. Ini akan menyebabkan pengiraan PMI menjadi kurang tepat. Kajian terdahulu juga hanya melibatkan kajian berkaitan morfologi dan tingkah laku spesies ini. Kajian perkembangan telur, larva dan pupa lalat Ch. villeneuvi dijalankan pada suhu bawah 25, 27, 30, 33 dan 37ºC di makmal dengan menggunakan kebuk pertumbuhan serangga. Sumber asal lalat dewasa diperoleh dengan meletakkan bangkai tikus di Pusat Penyelidikan Universiti Malaya, Batu 16, Gombak. Lalat dewasa dipelihara di makmal untuk dijadikan sumber koloni. Lebih kurang 150 biji telur dibiakkan dengan meletakkannya ke dalam bekas yang mengandungi 200 g hati lembu sebagai sumber makanan untuk larva yang baru menetas. Lima ekor larva diukur panjangnya setiap tiga jam untuk mendapatkan satu nilai purata untuk setiap suhu. Pemprosesan slaid dan pengambilan foto larva dilakukan untuk mengetahui peringkat perkembangan larva. Ch. villeneuvi mengambil masa selama 9.40 ± 0.02 hari pada suhu 25ºC, 9.34 ± 0.04 hari (27ºC), 9.00 ± 0.07 hari (30ºC), 7.95 ± 0.02 hari (33ºC) dan 7.51 ± 0.02 hari (37ºC) untuk melengkapkan satu kitar hidup. Pada suhu pembiakan yang berbeza, terdapat perbezaan signifikan (p<0.001) ke atas masa perkembangan kitar hidup lalat Ch. villeneuvi. Semakin tinggi suhu dan nilai ADH, semakin pendek satu kitar hidup lalat Ch. villeneuvi. Kajian ini menyatakan tentang tempoh peringkat dalam kitar hidup berdasarkan suhu membantu dalam pembangunan data ADH. Penyiasat forensik di Malaysia boleh menganggarkan PMI berdasarkan graf perkembangan dan data ADH yang diperoleh daripada kajian ini apabila Ch. villeneuvi ditemui pada mayat

Monitoring Aedes population using ovitrap index and larval abundance in an urban university residence

Autocidal ovitraps have played a significant role in surveillance and control of dengue vectors, Aedes aegypti and Aedes albopictus. Malaysia has witnessed the deployment of several types of autocidal ovitraps, which includes the Mosquito Larvae Trapping Device (MLTD) introduced by Kuala Lumpur City Hall. This study aimed to assess Aedes larval abundance and local meteorological variables in a university residence, in Cheras, Kuala Lumpur. MLTD (n=30) baited with organic NPK fertiliser (5:5:5) solutions were deployed. Larvae collection and trap servicing were performed weekly for a duration of eight weeks. Rearing and species identification for larvae were conducted in the laboratory. Out of 2,152 Aedes larvae, 85% of them were Ae. albopictus whilst the remaining were Ae. aegypti. Outdoor collection of Ae. albopictus surpassed its indoor collection (mean larvae per trap of 9.28 versus 6.08). Conversely, an indoor collection of Ae. aegypti was greater than its outdoor collection (mean larvae per trap of 1.72 versus 0.86). The highest ovitrap indices were observed in Week 5 and 6 which were 90% and 93%, respectively. Week 1 had the lowest ovitrap index, 30%. Our analyses revealed a positive correlation between Aedes larval abundance and maximum temperature (r=0.830, p=0.011) whereas minimum relative humidity was shown to have a negative correlation (r=-0.778, p=0.023), with the larval abundance. Routine monitoring of dengue vectors at its immature stages can provide information on the density and fluctuation of the local mosquito population. Coupled with concurrent meteorological variables, it can guide vector control operations as part of dengue prevention strategies