A 14-months survey was carried out to identify the species composition of Anopheles mosquitoes from Kampung Bongor, Grik, Perak. Adding to that, a preliminary one month mosquito population screening was done at Kampung Tepin, Serian, Sarawak. Consequently, the insecticide susceptibility status of a pyrethroid was tested against two selected species of Anopheles collected from these two locations in Malaysia. A total of 4,497 Anopheles from 11 species were identified from collections in Kampung Bongor, whereas 2,654 An. letifer were collected from Kampung Tepin. The An. maculatus of Kampung Bongor and An. letifer of Kampung Tepin were then selected and tested using WHO standard diagnostic test kits and impregnated papers with 0.75% permethrin. The response values of KT50 and KT95 for An. maculatus were recorded at 28.09 minutes and 62.98 minutes respectively. Anopheles letifer recorded much slower response values of KT50 and KT95, which was at 35.09 minutes and 73.03 minutes respectively. Both An. maculatus and An. letifer showed 100% mortality after 24 hours holding period. The results indicate that both species were still susceptible to the tested pyrethroid. For effective vector control and resistance management, accurate and periodic insecticide resistance monitoring should be undertaken especially in rural areas with agricultural usage of insecticides.
Dengue is a disease propagated by vectors namely Aedes spp. mosquitoes. One of the effective approaches to control dengue is through integrated vector management and intervention programs. COMBI or Communication for Behavioral Impact is a strategic approach to control the Aedes population as well as dengue cases. This study was conducted at Taman Desa Kolej, Nilai, Negeri Sembilan, an suburban residential area to determine the effectiveness of COMBI, by using questionnaire and entomological survey as well as implementation of an intervention program. We carried out activities such as the establishment of COMBI promoter team, clean up events, talk shows with the residential community and distributed pamphlets containing information about dengue. Results indicated significant difference (p
The aim of this study is to investigate the feasibility and outcomes of using Gravid Oviposition Sticky (GOS) trap and dengue NS1 antigen tests for indoor and outdoor dengue/Aedes surveillance in the field. A one-year community-based study was carried out at Sungai Buloh Hospital Quarters, Selangor, Malaysia. GOS traps were first placed outdoors in three apartment blocks (Anggerik, Bunga Raya and Mawar). Beginning 29th week of the study, indoor traps were set in two apartment units on every floor in Anggerik. All female Aedes mosquitoes caught were tested for the presence of dengue NS1 antigen. Dengue seroprevalence and knowledge, attitude and practices on dengue prevention of the community and their reception to the surveillance approach were also assessed. Dengue-positive mosquitoes were detected at least 1 week before a dengue onset. More mosquitoes were caught indoors than outdoors in block Anggerik, but the total number of mosquitoes caught in all 3 blocks were similar. There was a significant difference in distribution of Ae. aegypti and Ae. albopictus between the 3 blocks. 66.1% and 3.4% of the community were positive for dengue IgG and IgM, respectively. Most respondents think that this surveillance method is Good (89%) and support its use nationwide. Dengue case ratio in the study apartment blocks decreased from year 2018 to 2019. This study demonstrated the practicality of performing proactive dengue/Aedes surveillance inside apartment units using the GOS traps. This surveillance method can be performed with immediate result output in the field.
Megaselia scalaris (Loew) (Diptera: Phoridae) provides great evidential value in estimating the postmortem interval (PMI) compared with other dipterans due to its common occurrence on human corpses both indoors and in concealed environments. Studies have focused on the effect of temperature, larval diet, and photoperiod on the development of the species; however, knowledge of M. scalaris development at different moisture levels is insufficient. This study aimed to investigate the effects of substrate moisture on the larval development time, pupal recovery, pupal weight, adult emergence, and adult head width of M. scalaris. The larvae were reared in five replicates on substrates with six moisture levels ranging from 50 to 90%. Larvae and puparia were sampled daily, and the collection time, number, and weight were recorded, measured, and then compared using multivariate analysis of variance with a post hoc least significant difference test. Larvae developed most quickly (3.75 ± 0.04 d) at 50% substrate moisture; the larvae were able to survive in extremely wet substrates (90% moisture), but the development time was significantly longer (6.48 ± 0.19 d). Moisture greatly influenced the pupation rate and adult emergence but showed a weak effect on the pupae weight and adult head width. Due to the significance of moisture on the development of M. scalaris, PMI estimation using M. scalaris with cadavers of different moisture content must be carefully conducted to avoid inaccuracy.
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.
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.
A study on insect succession of monkey carcass in a forested area in Ulu Gombak, Selangor, Malaysia was conducted from 9 May to 18 June 2007. The third instar of the housefly, Musca domestica (Linnaeus) (Diptera: Muscidae) were only found on dry stage of a decomposed (Day-33) monkey carcass (Macaca fascicularis Raffles). This observation revealed that M. domestica maggots were found together with other muscid fly maggots, Hydrotaea (=Ophyra) spinigera (Stein) (Diptera: Muscidae) on dry stage of a carcass. However, the role of M. domestica on forensic entomological study remains unknown. This study recorded the first finding of M. domestica maggots on primate carcass in Malaysia.
Signal fly, Scholastes sp. (Diptera: Platystomatidae) was observed associated with animal carcasses in Malaysia. The first observation was on a monkey carcass, which was killed by using a handgun and immediately placed in a forested area in Gombak, Selangor while the second observation was on a pig that died of natural causes and whose carcass was placed in an oil palm plantation in Tanjung Sepat, Selangor. Both animal carcasses were visited by Scholastes sp. flies during the fresh decomposition period. However, the role Scholastes flies in the decomposition process remains unknown. In this paper, we report the occurrence of Scholastes sp. on animal carcasses in Malaysia for the first time.
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.
In estimating the postmortem interval (PMI) using maggots obtained during autopsy, the forensic entomologist makes decisions regarding the effects of low-temperature storage of the body on the insects. In this case report, a corpse was found in an abandoned house in the residential area of Bukit Mertajam, Penang, Malaysia. The maggots were found to be alive inside the mouth of the deceased although the corpse had been in the morgue cooler for 12 days. The maggots were reared and identified as Chrysomya megacephala (Fabricius). The emerged adult flies were kept as a stock colony, and the duration of development under the indoor fluctuating temperature regime was studied. The total duration of developmental process of this species was 9.5 ± 0.5 days, and the PMI estimated was 3.2 ± 0.6 days. This case report demonstrates the survival of Ch. megacephala maggots for 12 days and their growth inside the morgue cooler.
The distributions of flies are not only confined to ground level but can also be at higher altitudes. Here, we report three forensic cases involving dipterans in high-rise buildings in Kuala Lumpur, Malaysia. Case 1 involved a corpse of adult female found at the top floor of a fifteen-story apartment. Case 2 dealt with a body of a 75-year-old female discovered in a bedroom on the eleventh floor of an eighteen-story building, while Case 3 was a 52-year-old male found in his fifth floor shop house. Interestingly, entomological analysis revealed that all corpses were infested with similar Dipterans: Megaselia scalaris (Loew) (Diptera: Phoridae), Synthesiomyia nudiseta (Wulp) (Diptera: Muscidae) and sarcophagid (Diptera: Sarcophagidae). The first two species were commonly associated with corpses found indoors at ground level. We noted the additional occurrence of blowflies Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) and Chrysomya rufifacies Macquart (Diptera: Calliphoridae) larvae in Case 2 and Case 3, respectively. Findings from this study are significant as they demonstrate that certain groups of fly can locate dead bodies even in high-rise buildings. Forensic entomofauna research on corpses found at high elevation is scarce and our study has highlighted the peculiarity of the fly species involved in Malaysia.
Forensic entomology refers to the science of collection and analysis of insect evidence in order to determine the minimum time period since death. This study aimed to investigate the occurrence of forensically important flies on 34 human remains referred to Universiti Kebangsaan Malaysia Medical Centre over a period of three years. Entomological specimens were collected at the death scenes and/or during autopsies. Live specimens were reared into adults while preserved specimens were processed for species identification. Five families, seven genera and nine species of flies were identified from human remains. The results of the study showed Chrysomya megacephala (Calliphoridae) maggots occurred on corpses with the highest frequency (70.6%), followed by Ch. rufifacies (Calliphoridae) (44.1%), sarcophagid fly (Sarcophagidae) (38.2%), Synthesiomya nudiseta (Muscidae) (20.6%), Megaselia scalaris (Phoridae) (14.7%), Lucilia cuprina (Calliphoridae) (5.9%), Ch. nigripes (Calliphoridae) (5.9%), Eristalis spp. (Syrphidae) (5.9%) and Hydrotaea spinigera (Muscidae) (2.9%). The greatest fly diversity occurred on remains recovered indoors (eight species) compared to outdoors (three species). Whilst, single and double infestations were common for both indoor and outdoor cases, multiple infestation of up to six species was observed in one of the indoor cases. Although large numbers of fly species were found on human remains, the predominant species were still those of Chrysomya, while S. nudiseta was found only on human remains recovered from indoors. The present study provides additional knowledge in the context of Malaysian forensic entomology and the distribution of forensically important flies which is of relevance to forensic science.
This study was conducted to examine the effect of malathion on the development of Chrysomya megacephala. A total of 12 adult Sprague-Dawley rats was divided into 4 groups. Each animal in the 4 groups was given orally 0 (control), 10, 25 and 50ml/kg body weight of malathion, respectively. Chrysomya megacephala larvae were then allowed to grow on the liver of carcass. Larvae development was estimated by means of weight and length, time of adult emergence and survival rate. Results indicated that for the first 6 to 30 hours, larvae from control group developed more rapidly than larvae feeding on tissue containing malathion. However, the 3 doses of malathion did not exhibit significant impact on larvae length and weight. The time required for adult emergence was significantly greater for malathion-treated colony which was 10 days compared to 7 days in control colony. Control larvae of C. megacephala had higher survival rate compared to larvae exposed to the three different doses of malathion. Analysis of the tissues indicated that all rats and fly samples were positive for malathion. Malathion concentration was highest in liver. It was concluded that the presence of malathion altered the development rate of C. megacephala and thus disrupted normal postmortem interval estimation.
The WHO adult susceptibility test is in use for insecticide resistance monitoring. Presently, materials are being imported from the Universiti Sains Malaysia, Malaysia and sometimes it is cost prohibitive. As an alternative, we present here a method of bottle bioassay using indigenous material. Different aspects related to the assay were studied and validated in the field. Bottle assay was standardized in the laboratory by using locally sourced material and laboratory-maintained insecticide-susceptible Anopheles stephensi and Aedes aegypti strains against technical grade deltamethrin and cyfluthrin insecticides dissolved in ethanol in a range of different concentrations. The frequency of use of the deltamethrin-coated bottles and shelf-life were determined. Discriminating dose for deltamethrin and cyfluthrin was 10 μg against An. stephensi and 2 μg against Ae. aegypti females. Insecticide-coated bottles stored at 25 to 35 °C can be used for three exposures within 7 days of coating. The study carried out in the laboratory was validated on wild caught An. culicifacies in the states of Odisha and Chhattisgarh against deltamethrin-coated bottles in comparison to WHO adult susceptibility test. Results of the study indicated that deltamethrin-coated bottles were effective up to three exposures within 7 days of coating for field population and 100% mortality was recorded within 35 min as observed in laboratory studies for field collected susceptible population. Also in the WHO adult susceptibility test, 100% knock-down within 35 min and 100% mortality after 24 h holding period were observed in susceptible population, while in it was 50% knock-down in 1 h and 64% mortality after 24 h holding period for resistant population (50% mortality in bottle assay in 60 min). The bottle assay can be used as an alternative to the WHO adult susceptibility test both in the laboratory and field for monitoring insecticide resistance in mosquito vectors using locally sourced material.
Scuttle flies of genus Puliciphora Dahl (Diptera: Phoridae) are recorded for the first time in Malaysia from rabbit carcasses placed in concealed environments. They consist of Puliciphora borinquenensis Wheeler ♂♀, Puliciphora obtecta Meijere ♀ and Puliciphora beckeri Meijere ♀. All species were obtained from rabbit carcasses in used luggage and garbage bin placed at Forensic Science Simulation Site, Universiti Kebangsaan Malaysia, Bangi, Selangor. The specimens were collected from the carcasses using a modified Malaise trap, an entomological aspirator and preserved in 70% ethanol. This report expands the geographical distributions of these species and their microhabitat, suggests its possible important role in forensic entomology.
In forensic entomology, breeding of fly larvae in a controlled laboratory environment using animal tissue is a common technique to obtain insect developmental time for the estimation of postmortem interval. Previous studies on growth media are mostly on the effect of different diets on fly development. However, the interaction effects between temperature and food type used have not been explored. The objective of this study was to compare the use of cow's liver agar and raw liver on the development of a forensically important fly, Megaselia scalaris (Loew). This study also determined the interaction between different temperatures and different food types on the growth of this species. A total of 100 M. scalaris eggs were transferred into each of the two media mentioned above. Liver agar was prepared by adding dried ground liver into nutrient agar, whilst raw liver was naturally prepared from the same animal source. This experiment was conducted at 27, 30 and 33 °C in an incubator in a continuously dark condition. Length and weight of larvae, puparia and adult samples were determined. Total developmental times for larvae feeding on liver agar at each temperature were approximately 7-15 h slower than those feeding on raw liver. Survival rates were almost equal in both diets but were lower at 33 °C. Mean larva length in both diets did not differ significantly at all temperatures, but larvae feeding on liver agar had lower mean weight values than those in raw liver at 30 and 33 °C. The effect of temperature was significant in female puparia weight and male adult weight whereas the effect of diet types was significant in both male and female puparia size and weight. Interaction effects of temperature and food type on M. scalaris puparium size and adult weight were significant, indicating that puparium size and adult weight depended on both food type and temperature. This experiment highlighted the use of cow's liver agar as an alternative diet to breed M. scalaris in the laboratory and the importance of considering the interaction effect between temperatures and food types when deciding the most suitable medium in fly larva rearing.
This study reviews forensic entomological specimens analysed by the Department of Parasitology & Medical Entomology, Universiti Kebangsaan Malaysia for the year 2004. A total of 10 cases (6 males and 4 females) were observed for the entomological specimens. Various types of death scenes were obtained including indoor and outdoor area such as bushes field, rubbish dumping site, and aquatic areas. Identified fly species collected from the death sites were blow flies, Chrysomya megacephala, Chrysomya rufifacies and Lucilia cuprina and unknown sarcophagid larvae, with Ch. megacephala being the most common species found in the ecologically varied death scene habitats. The post-mortem interval (PMI) estimation ranged from one to five days, based on the entomological specimens collected.
In forensic entomology, larval rearing usually includes the presence of biological contaminants including scuttle flies (Diptera: Phoridae). Scuttle flies are recognized as forensically important insects and have been reported causing nuisance and contamination in laboratory environments. This paper reports for the first time the finding of multiple scuttle fly species affecting colonies of third instar larvae of the Oriental latrine blowfly, Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae), reared indoors at the Forensic Science Simulation Site, Universiti Kebangsaan Malaysia. Adult scuttle flies were discovered inside a rearing container after the emergence of adult C. megacephala., The scuttle fly species are Megaselia scalaris (Loew), M. spiracularis Schmitz and Puliciphora borinquenensis (Wheeler). Notes on the life history and biology of these species are discussed herein.
Decomposing carrion provides a temporary microhabitat and food source for a distinct community of organisms. Arthropods constitute a major part of this community and can be utilized to estimate the postmortem interval (PMI) of cadavers during criminal investigations. However, in Malaysia, knowledge of carrion arthropod assemblages and their succession is superficial. Therefore, a study on three types of forensic entomology animal model was conducted from 27 September 2010 to 28 October 2010 in a tropical rainforest at National University of Malaysia, Bangi, Selangor, Malaysia. Over one month collections of arthropods were made on nine animal carcasses: three laboratory rats (Rattus norvegicus, mean weight: 0.508 ± 0.027 kg), three rabbits (Oryctolagus cuniculus, mean weight: 2.538 ± 0.109 kg) and three long tailed macaque (Macaca fascicularis, mean weight: 5.750 ± 0.551 kg). A total of 31,433 arthropods belonging to eight orders and twenty-eight families were collected from all carcasses. Among 2924 of adults flies collected, approximately 19% were calliphorids with Chrysomya megacephala (Fabricius, 1794) being the most abundant. Arthropod taxon richness was lower on rat carcasses compared to that of rabbit and monkey carcasses, and this was more apparent during the first week of decomposition. However, there were no significant differences in Shannon-Weiner index (H'), Simpson dominance index (C) and Pielou's Evenness index (J) between different animal model. The arthropod assemblages associated to animal model were different significantly (p<0.05) while decomposition stage was a significant factor influencing insect assemblages (p<0.05). Analysis on the arthropods succession indicated that some taxa have a clear visitation period while the others, particularly Coleoptera, did not show a clear successional pattern thus require futher insect succession study. Although human bodies were not possible for the succession study, most of the arthropods collected are necrophagous, and will also possibly colonize human cadaver, and potentially be useful in assisting in estimates of PMI in future forensic cases in Malaysia.
Isomyia paurogonita Fang & Fan, 1986 (Diptera: Calliphoridae), a rare species of the subfamily Rhiniinae (tribe Cosminini) was recorded for the first time in Malaysia. We collected one male and two females during a field trip conducted at Genting Highland, Pahang, peninsular Malaysia in May 2011. A 3-day old cow liver was offered as attractant and dipterans collected were transferred to the laboratory for specimens processing and identification. The adults of I. paurogonita were attracted to the odour and then captured by using a sweep net. Isomyia paurogonita was also recorded from two other localities in Peninsular and Malaysian Borneo, namely Gombak Utara, Selangor and Sibu, Sarawak.