Abstract: Background and Objective: Culicoides spp. compose the most studied vector genera and contain the species that is a vector of Leucocytozoon, the parasite that causes leucocytozoonosis. One hundred species of Culicoides spp. inhabit Indonesia and are scattered among 19 provinces, with great diversity in each region. The aim of this research was to study the species diversity and the dominance of Culicoides on layer farms. Methodology: Midges were obtained from layer farms in Sentolo, Kulon Progo (altitude ±78 m); Pakem, Sleman (altitude ±371 m) and Cangkringan, Sleman (altitude ±745 m). Midges were collected using a light trap (New Jersey Standard #2858) for 12 h, from 6 pm-6 am. Identification was performed using dissecting microscope and classified using the identification key of Wirth and Hubert. Results: Eight species were found in this study: Culicoides arakawae, C. huffi, C. oxystoma, C. guttifer, C. sumatrae, C. peregrinus, C. palpifer and C. fulvus. There was diversity in the species collected from the three research areas. Culicoides arakawae was the dominant species found in Sentolo; in Pakem, the most collected species was C. huffi and in Cangkringan, it was C. fulvus. Conclusion: There was a difference in the number of midges collected from the areas with differing topography. The largest collection of Culicoides (270 midges) was obtained from Sentolo subdistrict, Kulon Progo Regency.
INTRODUCTION
Culicoides spp. are vectors of some pathogenic diseases. While only a small portion of Culicoides spp. are vectors, Culicoides have a significant adverse impact through the transmission of arboviruses, bacteria, protozoa and parasitic worms between humans and animals. Culicoides is the group most studied, one species of which is a vector of Leucocytozoon, the organism that causes leucocytozoonosis1,2. Leucocytozoonosis is a parasitic disease in poultry that can cause loss in productivity, such as a decline in egg production, loss of up to 30% of body weight and eventually, death3,4.
Approximately 1400 species of this genus have been recorded throughout the world5. Only females of some Culicoides species, however, act as vectors of pathogens (viruses, protozoa and filarial nematodes) of medical and veterinary importance6,7. Some Culicoides spp. are vectors or suspected vectors of leucocytozoonosis in Indonesia, including C. arakawae, C. oxystoma, C. guttifer, C. huffi, C. hegneri, C. oxystoma, C. peregrinus and C. humeralis. There are one hundred species of Culicoides spp. spread over 19 provinces in Indonesia8. There are different species in different areas. The diversity of species may be caused by differences in the climatic conditions in each region. Tropical areas are generally characterized by almost uniform climatic conditions, however, topography can cause overall weather and climate differences, especially in temperature, humidity and rainfall. Weather and climate elements are heavily influenced by latitude, altitude, distance from sea, topography, soil type and vegetation. These elements affect the breeding sites of Culicoides spp. according to sites of each species9-11.
The aim of this study was to provide information on the diversity of Culicoides spp., especially on egg-layer farms in different topographic areas. This information can be used as a reference to understand the risk of Culicoides-borne diseases in an area and aid in determining the development of effective control strategies specific to farm location.
MATERIALS AND METHODS
Sample sites: During this study, insect trapping was performed in locations where previous Leucocytozoonosis occurred. Culicoides were collected from 2 different sources in Sleman and Kulon Progo district in Daerah Istimewa Yogyakarta, Indonesia. The "Special Region" (province) of Daerah Istimewa Yogyakarta comprises 4 districts and 1 city: Kulon Progo district, Gunung kidul district, Bantul district, Sleman district and Yogyakarta city. Culicoides were collected from poultry farms in Sleman (107°15’ 03" 107°29’ 30" E, 7°47’ 51" and 7°47’ 30" S) and Kulon Progo (110°1’37"-110°16’26" E 7°38’42"-7°59’3" S) (Fig. 1).
| Fig. 1: | Survey sites for Culicoides spp. collected in Yogyakarta, Indonesia |
A: Sentolo subdistrict, Kulon Progo regency, B: Pakem subdistrict, Sleman regency and C: Cangkringan subdistrict, Sleman regency |
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Sampling and identification of Culicoides: Two traps were placed in each farm to collect specimens. The light traps were activated from 6 pm-8 am to coincide with dusk/dawn and night-time activity of most Culicoides species. Light traps were placed 1.5-2 m above ground and sheltered from wind and any source of artificial light. Culicoides specimens collected in the light traps were recovered in the morning and strained to separate the insects into appropriately labeled jars. All Culicoides specimens were subsequently separated and identified according to their wing pattern. Samples were preserved in 70% alcohol and stored at room temperature until identified.
Identification of Culicoides spp.: The collected samples were sorted to separate Culicoides spp. from other insects. Morphological identification of Culicoides species was conducted by examining the wing pigmentation pattern using a stereo microscope. Species identification was performed on the wing patterns of Culicoides spp. according to Wirth and Hubert12 and Uslu and Dik13.
RESULTS
In this study, 405 Culicoides specimens were collected (270 from Sentolo, 54 from Pakem and 81 from Cangkringan) (Table 1). The captured specimens were classified into 8 species. The most abundant species was C. huffi (32.59%), which was collected in all of the locations. C. huffi, representing 32.59% of Culicoides collected, was the dominant species. Culicoides arakawae, C. huffi and C. peregrinus each contributed more than 10% to the species composition.
A total of 405 Culicoides midges comprising eight species collected from three areas of Yogyakarta. A total of 270 (66.67%) midges were recovered from Sentolo, 54 (13.33%) midges were recovered from Pakem, 81 (20%) midges were recovered from Cangkringan. Eight Culicoides species; C. arakawae (31.11%), C. huffi (32.59%), C. oxystoma (1.48%), C. guttifer (8.64%), C. sumatrae (0.74%), C. peregrinus (4.1%), C. palpifer (0.74%) and C. fulvus (15.31%) were identified (Table 2).
DISCUSSION
Midges were collected from commercial layer chicken farms in Sentolo sub-district, Kulon Progo regency; Pakem sub-district, Sleman regency and Cangkringan sub-district, Sleman regency. Climate data for each location can be seen in Table 1.
| Table 1: | Climate data |
| Source: BMKG Yogyakarta (2017) | |
| Table 2: | Culicoides spp. collected from three areas |
The farm located in Sentolo was at an altitude ±78 masl with a temperature of 26.5°C, humidity of 87%, 395 mm of rainfall and wind velocity of 7.4 km h–1. The farm located in Pakem is situated under the slopes of Mount Merapi, at an altitude ±371 masl with a temperature of 26.7°C, almost the same temperature as Sentolo. Humidity in Pakem is similar to Sentolo (87%), but the rainfall is only 343 mm, which is less than Sentolo. The farm in Pakem has the highest wind velocity (25.9 km h–1). Mellor et al.6 showed that wind speed most significantly affects populations of Culicoides. Wind speed affects flying activity and the incidence of insect bites. Culicoides that entered the trap were assumed to be adult midges. High wind speeds make it difficult for Culicoides to target hosts.
Cangkringan is located on the slopes of Mount Merapi and the farm in Cangkringan is located at an altitude of 745 masl. It has the lowest temperature of all the collection locations. The temperature is 24.8°C and the humidity is 88%. Rainfall in Cangkringan is the lowest (308 mm). The wind velocity in Cangkringan is 12.2 km h–1, higher than the wind velocity in Sentolo and lower than the wind velocity in Pakem. The tropics are generally characterized by almost uniform climatic conditions. However, the difference in altitude above sea level (masl) can cause differences in weather and climate as a whole, but especially in temperature, humidity and rainfall. These weather and climate elements are heavily influenced by latitude, altitude, distance to the sea, topography, soil type and vegetation. Low altitudes are characterized by ambient temperature, high air and oxygen pressures and increased rainfall. The rate of temperature change is due to having different variations for each place9.
Puddles and bushy plants were found around the farms in each area. The research location in Sentolo was dominated by teak plants with rice fields surrounding the farm.
| Fig. 2(a-c): | Commercial egg-layer farms of survey sites |
(a) Sentolo subdistrict, Kulon Progo regency, (b) Pakem subdistrict, Sleman regency and (c) Cangkringan subdistrict, Sleman regency |
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The Pakem site was dominated by shrubs with many puddles around the farm. The Cangkringan region was dominated by bamboo plants. The types of plants in each region varied and can be seen in Fig. 2. Many studies have shown that abiotic environmental factors, such as topographic parameters, can be important sources of variation of plant diversity14-16.
A total of 405 Culicoides midges comprising eight species were collected from the three areas of Yogyakarta. A total of 270 (66.67%) midges were recovered from Sentolo, 54 (13.33%) midges were recovered from Pakem and 81 (20%) midges were recovered from Cangkringan. Eight Culicoides species were identified: C. arakawae (31.11%), C. huffi (32.59%), C. oxystoma (1.48%), C. guttifer (8.64%), C. sumatrae (0.74%), C. peregrinus (4.1%), C. palpifer (0.74%) and C. fulvus (15.31%) (Table 2). Site differences caused by climate differences affect habitats and can result in different numbers of midges17,18.
Culicoides arakawae was the dominant species, especially in Sentolo. Seven C. arakawae were found in Pakem. Culicoides arakawae was not found in Cangkringan. In Sentolo, there were many trees and there were rice fields around the farms. These conditions support breeding sites of C. arakawae. Culicoides huffi was also commonly found in the Sentolo area and is the dominant species found in Pakem. Around the farm in Pakem were many shrubs and nearby were trenches with small amounts of flowing water. According to Wirth and Ratanaworabhan18, breeding sites of C. arakawae include muddy puddles, which are often found in rice fields. The breeding sites of C. huffi are usually on the sides of rivers or where there are many puddles. Culicoides fulvus was the dominant species found in Cangkringan. There are many cow and sheep farms in Cangkringan. Breeding sites of C. fulvus are not known. Culicoides fulvus are usually found sucking the blood of cows, buffalo, sheep and marsupials19. Generally, hematophagous species (such as mosquitoes and Culicoides) prefer a specific host on which to feed20-23, although some species are generalists. Some Culicoides species, however, exhibit opportunistic feeding behavior with respect to host distribution and density22,24-26. Most species of the genus Culicoides are known to be either mammalophilic24,26,27 or ornithophilic21,27,28.
Culicoides guttifer, C. peregrinus, C. oxystoma and C. palpifer were found in all areas. Culicoides guttifer are commonly found in Sentolo, where the area is dominated by poultry farms. Thirty-eight C. guttifer specimens were found: 32 from Sentolo, five from Pakem and one from Cangkringan. Culicoides guttifer has a preferred host of poultry8. Culicoides peregrinus is commonly found in Cangkringan. Twenty-seven C. peregrinus specimens were recovered from Cangkringan, six from Sentolo and two from Pakem. Mean temperature and relative humidity of the capture day, mean humidity between 21 and 19 days prior to capture event, density of ruminants, percentage cover of water bodies within a 2 km radius and interaction between temperature and humidity were predictors for presence of C. oxystoma. Mean rainfall, NDVI of the capture day and percentage cover of water bodies were indicators for C. imicola presence29. Cangkringan had a mean temperature of 24.8°C and there are many tall bamboo trees blocking the sunlight. These conditions support breeding sites of C. peregrinus. Culicoides oxystoma and C. palpifer were found in every site in low numbers. Six C. oxystoma specimens were recovered; four specimens in Sentolo, one from Pakem and one from Cangkringan. Only one C. palpifer was recovered in each area. One C. sumatrae was found in Sentolo and two in Pakem. It has been previously reported that Culicoides species breed in various sites including mud rich organic matter, water reservoirs, along streams, rain puddles, mud around dams, reed sites and cow dung4.
The implication of this study is that the differing number of specimens between locations might be an indicator of the establishment and dynamics of settled Culicoides spp. The application of this study is to identify the various Culicoides species and use this information to prevent the transmission of diseases through Culicoides. The importance of this study is that the types of the Culicoides species can be one of the risk factors for the transmission of diseases transmitted by the vector Culicoides.
CONCLUSION AND FUTURE RECOMMENDATIONS
Based on the results, it can be concluded that there is a difference in the number of midges obtained from the three areas. Differences in climatic factors at sampling areas with different altitudes affect the habitat of Culicoides. The most Culicoides species (270 midges) were obtained from Sentolo subdistrict, Kulon Progo regency. This site had an altitude of 78 masl, a temperature at 26.5°C, humidity of 87%, 395 mm of rainfall and a wind velocity at 7.4 km h–1. Culicoides arakawae was the dominant species. The conditions at Sentolo support breeding sites of Culicoides.
This study can provide explanations of the risk factors of transmission of diseases transmitted by the variety of Culicoides vectors, especially in the Yogyakarta region. Further identification should be performed using PCR to more accurately reveal the Culicoides species.
SIGNIFICANCE STATEMENT
This study determined the diversity of Culicoides spp. at three locations in Yogyakarta. This article reports that Culicoides arakawae was the most common midge species found in Yogyakarta. Culicoides arakawae is a vector for leucocytozoonosis. This study is beneficial because it informs veterinarians about the risk of diseases caused by Culicoides sp. This study will help research efforts to understand the variety of Culicoides spp. in Yogyakarta that has not previously been described.
ACKNOWLEDGMENTS
We deeply thank the Directorate of Research and Community Services, Ministry of Research, Technology and Higher Education Rep. of Indonesia and Universitas Gadjah Mada for providing space and equipment. This study was funded by PUPT’s program, 2016.