Kajian Predasi Catfish terhadap Larva Nyamuk Aedes aegypti Sebagai Upaya Pencegahan Penyebaran Demam Berdarah Dengue

Aedes aegypti acts as a primary vector of the dengue virus which causes Indonesia to become a dengue-endemic country. Chemical and physical vector control methods to prevent the spread of DHF are considered less effective so that additional biological vector control is needed. The purpose of this paper is to examine the potential ability of catfish predation as Ae. aegypti vector controller. This paper was prepared by reviewing eight Indonesian research journals, eight international research journals, reports and regulations of the Ministry of Health of the Republic of Indonesia, the website of the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC), the University of Florida Entomology and Nematology, and one textbook. The results showed that the predation ability of African sharptooth catfish (Clarias garipenus) was 80.3% greater on average than Cyprinus carpio, Ctenopharyngodon idella, and Oreochromis niloticus as well as the predation ability of Walking catfish (Clarias batrachus) with an average of 79.6%. larger than Anabas testudineus, Oreochromis niloticus, and Poecilia reticulata. Further experimental research to deepen scientific information on the predation ability of various catfish species against Ae. aegypti mosquito larvae are still needed. Cooperation between fields and communities is also needed to prevent the spread of dengue disease properly. Mosquito larvae eating fish belonging to catfish species, namely African sharptooth catfish (Clarias garipenus) and walking catfish (Clarias batrachus) have the potential to be a new biological vector controller because they have very high predation power compared to other mosquito larvae eating fish.

Isolation and Characterization of Mosquito-Associated Spiroplasma cantharicola from Aedes japonicus Collected in Hokkaido, Japan

Species of the genus Spiroplasma are common within arthropods and plants worldwide. Mosquito-associated Spiroplasma spp. have been reported to show pathogenicity toward mosquitoes, which serve as vectors of several infectious diseases that have detrimental effects on public health. Although Spiroplasma spp. are expected to have potential use as biological vector-control tools, characteristics such as their distribution, host species, and cytopathogenic effects (CPEs) are not well understood. In this study, we isolated a Spiroplasma sp. from a female Aedes japonicus collected in Hokkaido, northern Japan. Phylogenetic analysis based on the 16S rRNA gene sequence indicated our isolate was closely related to S. cantharicola. We screened 103 mosquito pools consisting of 3 genera and 9 species, but only detected S. cantharicola in the first isolation. In an in vitro assay, our isolate grew well at 28 °C, but no propagation was observed at 37 °C. Furthermore, the isolate showed strong CPE on a mosquito-derived cultured cell line (C6/36), and its propagation slightly increased when co-cultured with C6/36 cells. To our knowledge, this is the third report of the isolation of S. cantharicola from mosquitoes and the first case in Asia. Our findings provide epidemiological data on S. cantharicola distribution in the region.

First molecular-based detection of SARS-CoV-2 virus in the field-collected houseflies

This is the first report of SARS-CoV-2 detection on field-collected Musca domestica housefly surface and tissue samples using the high-sensitive PCR assay which suggests the possible insect-borne transmission. The study was conducted in Shiraz city, southern Iran, in May and Jun 2020. Adult flies were sampled at the outdoor areas of two hospitals treating COVID-19 patients. Fly samples were first washed twice to remove the insect surface attached to SARS-CoV-2 virions. After that, the disinfected fly samples were homogenized. Fly surface washout and homogenate samples were tested using Taq Man real-time PCR assay for the SARS-CoV-2 virus. In a total of 156 houseflies, 75% of samples from the body washout samples were positive for SARS-CoV-2. Strikingly, 37% of the homogenized specimens were positive for the SARS-CoV-2, suggesting the possible infection of the insects or uptake of the virion to the insect metabolism. The other possibility is the houseflies up took the blood or blood fluids of the patients and the RNA of the SARS-CoV-2 survived in the insect body without replicating. Our preliminary findings suggest that the houseflies could transmit SARS-CoV-2 as a mechanical or biological vector especially during the warm seasons while increasing the population and activity of houseflies.

Daya Predasi Ikan Lemon (Labidochromis caeruleus) dan Ikan Kapiat (Barbonymus schwanenfeldii) Terhadap Larva Nyamuk Aedes aegypti

Dengue hemorrhagic fever (DHF) is a vector-borne disease that still happens every year in Indonesia. This disease is caused by the dengue virus and transmitted by the Aedes aegypti as its vector. One of the biological vector controls that can be implemented is using fish as a predator of mosquito larvae, such as using Electric Yellow Cichlid fish (Labidochromis caeruleus) and Tinfoil Barb fish (Barbonymus schwanenfeldii). This study aimed to determine the difference in predation capacities of Electric Yellow Cichlid and Tinfoil Barb on Ae. aegypti larvae. This research is quasiexperimental with a completely randomized design (CRD) with Post Test Only research design. One aquarium with three liters of water containing one fish is given 25 Ae. aegypti larvae. Testing of each fish species is carried out in five replications. Fish predation was observed every 30 seconds until all larvae were eaten. The result showed that Electric Yellow Cichlid could prey on 25 larvae in an averagetime of 5.7 minutes, while Tinfoil Barb spent 11.6 minutes. The results of the Friedman test showed that there was a significant time difference in preying time of Electric Yellow Cichlid and Tinfoil Barb. It’s concluded that Electric Yellow Cichlid was more effective as an Ae. aegypti larvae predator.

Manipulating vector transmission reveals local processes in bacterial communities of bats

Infectious diseases result from multiple interactions among microbes and hosts, but community ecology approaches are rarely applied. Manipulation of vector populations provides a unique opportunity to test the importance of vectors in infection cycles while also observing changes in pathogen community diversity and species interactions. Yet for many vector-borne infections in wildlife, a biological vector has not been experimentally verified and few manipulative studies have been performed. Using a captive colony of fruit bats in Ghana, we observed changes in the community of Bartonella bacteria over time after the decline and subsequent reintroduction of bat flies. With reduced transmission, community changes were attributed to ecological drift and potential selection through interspecies competition mediated by host immunity. This work demonstrated that forces maintaining diversity in communities of free-living macroorganisms act in similar ways in communities of symbiotic microorganisms, both within and among hosts. Additionally, this study is the first to experimentally test the role of bat flies as vectors of Bartonella species.

Identification of bacteria and parasites with medical importance present in common fly (Musca domestica), captured in a highly marginated community

The common fly (Musca domestica L.) is a mechanical vector and can be a biological vector through ingestion and regurgitation. In rural communities is common to observe numerous populations of this, consequence of multiple unsanitary sites. The present study was carried out in order to identify the species of bacteria and parasites with medical importance present in the common fly, captured in homes and microhabitats (chicken coops, pigsty and backyards) in homes of the community of Cholul, Cantamayec. 20 species of bacteria were identified: E. coli (41.78%) was the most frequent species in all processed flies. In turn, households (45.20%) were the place where the greatest amount of bacterial species was isolated, being E. coli (42.42%), the frequent species, in the same way in pigsty (45.65%), chicken coops (38.09%) and backyards (30.76%). Regarding the enteroparasites identified from the digestive cavity of flies, Endolimax nana (38.46%) was the frequent cyst and Ascaris lumbricoides (15.38%), the only nematode found. In turn, the pigsty (n = 5) was the site with the highest number of isolated enteroparasites. The results obtained show that flies carry pathogens that could be involved in human infections ofcommunity origin.

Direct Evidence for Infection of Varroa destructor Mites with the Bee-Pathogenic Deformed Wing Virus Variant B - but Not Variant A - via Fluorescence-in situ-Hybridization Analysis.

Deformed wing virus (DWV) is a bee pathogenic, single- and positive-stranded RNA virus that has been involved in severe honey bee colony losses worldwide. DWV, when transmitted horizontally or vertically from bee to bee, causes mainly covert infections not associated with any visible symptoms or damage. Overt infections occur after vectorial transmission of DWV to the developing bee pupae through the ectoparasitic mite Varroa destructor. Symptoms of overt infections are pupal death, bees emerging with deformed wings and shortened abdomens, or cognitive impairment due to brain infection. So far, three variants of DWV, DWV-A, DWV-B, and DWV-C, have been described. While it is widely accepted that V. destructor acts as vector of DWV, the question of whether the mite only functions as a mechanical vector or whether DWV can infect the mite thus using it as a biological vector is hotly debated, because in the literature data can be found that support both hypotheses. In order to settle this scientific dispute, we analyzed putatively DWV-infected mites with a newly established protocol for fluorescence-in situ-hybridization of mites and demonstrated DWV-specific signals inside mite cells. We provide compelling and direct evidence that DWV-B infects the intestinal epithelium and the salivary glands of V. destructor. In contrast, no evidence for DWV-A infecting mite cells was found. Our data are key to understanding the pathobiology of DWV, the mite’s role as a biological DWV vector and the quasispecies dynamics of this RNA virus when switching between insect and arachnid host species. IMPORTANCE Deformed wing virus (DWV) is a bee pathogenic, originally rather benign, single- and positive-stranded RNA virus. Only the vectorial transmission of this virus to honey bees by the ectoparasitic mite Varroa destructor leads to fatal or symptomatic infections of individuals, usually followed by collapse of the entire colony. Studies on whether the mite only acts as a mechanical virus vector or whether DWV can infect the mite and thus use it as a biological vector have led to disparate results. In our study using fluorescence-in situ-hybridization we provide compelling and direct evidence that at least the DWV-B variant infects the gut epithelium and the salivary glands of V. destructor. Hence, the host range of DWV includes both, bees (Insecta) and mites (Arachnida). Our data contribute to a better understanding of the triangular relationship between honey bees, V. destructor and DWV and the evolution of virulence in this viral bee pathogen.

First Report of Spirocerca Lupi Larva in Dung Beetles (Scarabaeus Armeniacus) in Iran: A Morphological and Molecular Identification

Background: Dung beetles are detritivores insects. They naturally use feces of vertebrates as foods and reproduction beds. This leads to frequent contacts between dung beetles and parasitic helminths. The current study was carried out to assess infections of dung beetles with larval stages of helminths in rural areas of Taleqan County, Alborz Province, Iran. In total, 200 dung beetles were randomly collected in June 2017 from the highlands of Taleqan County. Beetles were dissected in normal saline and carefully studied using stereomicroscopy. Morphological characteristics of the recovered larvae were drawn using camera lucida equipped microscope at 400× magnification. Furthermore, genomic DNAs of the recovered larvae were extracted and PCR amplifications of the mitochondrial cytochrome c oxidase subunit 1 (cox1) genes were carried out and the amplicons were sequenced. Results: All collected dung beetles were identified as Scarabaeus armeniacus from Scarabaeidae family (55.5% were male and 44.5% female). Three females of the beetles were infected with nematode larva, morphologically identified as the third-stage of Spirocerca lupi larvae. The average length and width of the larvae were 2.95 (2.81–3.15; CI 95%) and 0.12 (0.1–0.15; CI 95%) mm, respectively. The phylogenetic analysis showed that S. lupi belonged to a clade within Spirocercidae family, well separated from Onchocercidae family. Conclusions: In the current study, S. armeniacus was introduced as a potentially biological vector for the transmission of S. lupi to vertebrates in the region. To the best of the authors’ knowledge, this is the first reported on larval stages of S. lupi in S. armeniacus.

Identifying Spanish Areas at More Risk of Monthly BTV Transmission with a Basic Reproduction Number Approach

Bluetongue virus (BTV) causes a disease that is endemic in Spain and its two major biological vector species, C. imicola and the Obsoletus complex species, differ greatly in their ecology and distribution. Understanding the seasonality of BTV transmission in risk areas is key to improving surveillance and control programs, as well as to better understand the pathogen transmission networks between wildlife and livestock. Here, monthly risk transmission maps were generated using risk categories based on well-known BTV R0 equations and predicted abundances of the two most relevant vectors in Spain. Previously, Culicoides spp. predicted abundances in mainland Spain and the Balearic Islands were obtained using remote sensing data and random forest machine learning algorithm. Risk transmission maps were externally assessed with the estimated date of infection of BTV-1 and BTV-4 historical outbreaks. Our results highlight the differences in risk transmission during April-October, June-August being the period with higher R0 values. Likewise, a natural barrier has been identified between northern and central-southern areas at risk that may hamper BTV spread between them. Our results can be relevant to implement risk-based interventions for the prevention, control and surveillance of BTV and other diseases shared between livestock and wildlife host populations.

Field efficacy of guppies and pyriproxyfen (Sumilarv® 2MR) combined with community engagement on dengue vectors in Cambodia: a randomized controlled trial

Evidence on the effectiveness of low-cost, sustainable biological vector control tools for Aedes mosquitoes is limited. Therefore, the purpose of this trial is to estimate the impact of guppy fish, in combination with the use of the larvicide Pyriproxyfen (Sumilarv® 2MR), and Communication for Behavioral Impact (COMBI) activities to reduce entomological indices in Cambodia.In this cluster randomized, controlled superiority trial, 30 clusters comprising of one or more villages each (with approximately 170 households) will be allocated, in a 1:1:1 ratio, to receive either a) three interventions (guppies, Sumilarv® 2MR, and COMBI activities), b) two interventions (guppies and COMBI activities), or c) control (standard vector control).Households were invited to participate, and entomology surveys among 40 randomly selected households per cluster were carried out quarterly. The primary outcome was the population density of adult female Aedes mosquitoes (i.e. number per house) trapped using adult resting collections. Secondary outcome measures include the House index, Container index, Breteau index, Pupae Per House, Pupae Per Person, mosquito infection rate, guppy fish coverage, Sumilarv® 2MR coverage, and percentage of respondents with knowledge about Aedes mosquitoes causing dengue. In the primary analysis, adult female Aedes density and mosquito infection rates was aggregated over follow-up time points to give a single rate per cluster. This was analyzed by negative binomial regression, yielding density ratios.The number of Aedes females was reduced by roughly half compared to the control in both the guppy and PPF arm (Density Ratio (DR)=0.54 [95% CI 0.34-0.85], p=0.0073), and guppy arm (DR=0.49 [95% CI 0.31-0.77], p=0.0021). The extremely low cost of including guppy rearing in community-based health structures along with the effectiveness demonstrated suggest guppies should be considered as a vector control tool as long as the benefits outweigh any potential environmental concerns. PPF was also highly accepted and preferred over current vector control tools used in Cambodia, however product costs and availability are still unknown.Author SummaryDengue is one of the most rapidly spreading mosquito-borne viral diseases in the world, is caused by bites of infected Aedes mosquitoes, and can sometimes lead to death. Cambodia has one of the highest per-capita incidence rates in Asia. Without a cure or routinely available efficacious vaccine, dengue control relies largely on reduction and avoidance of mosquitoes. In Cambodia, dengue mosquito control activities are focused on larviciding with temephos and pyrethroid based adulticide sprays to which Aedes have been shown to be increasingly resistant. This study was designed to evaluate novel biological vector control tools (guppy fish and a controlled release larvicidal matrix) utilizing an integrated vector management approach with community-based methods tailored to the local context. The results indicate that the tools resulted in a statistically significant reduction in immature and adult Aedes mosquito density. The interventions were accepted by and communities were willing to pay for them. The results suggest guppies are an ideal vector control tool as long as the benefits outweigh any potential environmental concerns. PPF was also highly accepted and preferred over current vector control tools used in Cambodia, however product costs and availability are still unknown.