insects Article Predicting Geographic Distribution of Forensically Significant Blow Flies of Subfamily Chrysomyinae (Diptera: Calliphoridae) in Northern Thailand Tunwadee Klong-klaew 1, Ratchadawan Ngoen-klan 2, Kittikhun Moophayak 3, Kom Sukontason 1, Kim N. Irvine 4, Jeffery K. Tomberlin 5 ID , Pradya Somboon 1, Theeraphap Chareonviriyaphap 2, Hiromu Kurahashi 6 and Kabkaew L. Sukontason 1,* 1 Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand; [email protected] (T.K.); [email protected] (K.S.); [email protected] (P.S.) 2 Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand; [email protected] (R.N.); [email protected] (T.C.) 3 Nakhonsawan Campus, Mahidol University, Nakhonsawan 60130, Thailand; [email protected] 4 National Institute of Education, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore; [email protected] 5 Department of Entomology, Texas A&M University, 2475 TAMU, College Station, TX 77843, USA; [email protected] 6 Department of Medical Entomology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan; [email protected] * Correspondence: [email protected] Received: 11 July 2018; Accepted: 17 August 2018; Published: 21 August 2018 Abstract: Blow flies (Diptera: Calliphoridae) are carrion-breeding flies that are commonly used as evidence in forensic investigation. An adequate knowledge of ecological and geographical data of blow fly has a direct application in forensic science, as far as estimating time of colonization or corpse relocation. The aim of this study was to evaluate the occurrence of four species of Chrysomyinae (Chrysomya pinguis, Chrysomya chani, Chrysomya villeneuvi, and Ceylonomyia nigripes) across six land use types in central Chiang Mai, northern Thailand. Eighteen study sites were selected for sampling across three districts of Chiang Mai province (Mueang Chiang Mai, Mae Rim, and Hang Dong). Adult flies were collected every two weeks using a funnel trap baited with 1-day tainted beef offal. The predicted geographic distributions of forensically important blow fly species were modeled using the computer program ArcGIS, based on selected climatic variables (temperature, relative humidity, and light intensity) recorded at study sites. During the study period, 1298 adult flies were collected, with peak fly occurrence during summer (April–May). Seasonal fluctuation patterns varied depending on fly species. Climatic factors displayed diverse impact on associated fly populations. Identified species were restricted mainly to mixed deciduous forests (MDF) especially in the mountainous area. None of these flies were trapped in an urban area. Keywords: spatial distribution; predictive distribution; GIS; forensic entomology 1. Introduction Many blow flies (Diptera: Calliphoridae) species are carrion-breeding and have veterinary, medical, and forensic importance [1,2]. They play a prominent role as vectors of human as well as livestock, pathogens [1,2]. Additionally, they are currently the most commonly used arthropod group in forensic entomology research to determine time of colonization as related to the post-mortem interval (PMImin) as they are commonly associated with decomposing human remains [3,4]. The presence and abundance Insects 2018, 9, 106; doi:10.3390/insects9030106 www.mdpi.com/journal/insects Insects 2018, 9, x FOR PEER REVIEW 2 of 15 presence and abundance of such species are useful for reconstructing crime scenes, as particular carrion-associatedInsects 2018, 9, 106 species have different environmental requirements, therefore they colonize2 of 15 carcasses in different habitats [5]. of suchIn Thailand, species are the useful vast majority for reconstructing of forensic crime import scenes,ant species as particular investigations carrion-associated have been speciesfocused have on speciesdifferent identification environmental [6–8], requirements, developmental therefore rate they of colonize immature carcasses stage in [9,10], different and habitats insect [5 ].succession [11,12].In Furthermore, Thailand, the fly vast surveys majority have of forensicbeen conducted important on speciesa local scale investigations or limited have to only been specific focused land on usespecies types, identification for instance, [6 –in8], forest developmental or in mountainous rate of immature area [13,14]. stage [Knowledge9,10], and insect about succession the spatial [11 and,12]. temporalFurthermore, distributions fly surveys is still have lacking. been conductedThere is very on little a local literature scale or on limited the geographic to only specific distribution land use of forensicallytypes, for instance, important in forest flies in or Thailand, in mountainous and published area [13, 14studies]. Knowledge focused abouton the the common spatial andspecies temporal (e.g., C.distributions megacephala is, C. still rufifacies lacking., and There M. isdomestica very little) [15,16]. literature on the geographic distribution of forensically importantThe objective flies in Thailand, of this andstudy published was to studies evaluate focused the onoccurrence the common of speciesChrysomyinae (e.g., C. megacephala (Diptera: , Calliphoridae)C. rufifacies, and acrossM. domestica a variety)[15 of,16 land]. use types in central Chiang Mai, northern Thailand. Four speciesThe of objective blow fly of in this the study subfamily was to Chrysomyinae evaluate the occurrence were chosen of Chrysomyinae because they (Diptera: are among Calliphoridae) the most prominentacross a variety groups of of land insects use typesassociated in central with Chiang corpses Mai, and northerncarrion, and Thailand. are therefore Four species important of blow forensic fly in indicators.the subfamily Furthermore, Chrysomyinae they were have chosen been reported because theyfrom are human among corpses the most in many prominent countries groups [17–20]. of insects To utilizeassociated these with flies corpses as evidence and carrion, in forensic and are investigations, therefore important one forensicneeds to indicators. know where Furthermore, they occur. they Blow have fliesbeen are reported ectotherms, from human temperature corpses heavily in many influenc countrieses [ 17their–20]. development, To utilize these behavior, flies as evidence and physiology in forensic [21].investigations, But the influence one needs of temperatur to know wheree and other they climatic occur. Blow factors flies (relative are ectotherms, humidity temperatureand light intensity) heavily oninfluences their geographic their development, distribution behavior, is unknown. and physiology In this study, [21]. But the the relationship influence of of temperature fly abundance and with other climaticclimatic factors (relativewas studied. humidity Maps and of light predicted intensity) distributions on their geographic for four distributionspecies of carrion-associated is unknown. In this Chrysomyinaestudy, the relationship were constructed of fly abundance using withArcGIS climatic program. factors was studied. Maps of predicted distributions for four species of carrion-associated Chrysomyinae were constructed using ArcGIS program. 2. Materials and Methods 2. Materials and Methods 2.1. Study Areas 2.1. Study Areas This study was conducted in three districts: Urban Mueang Chiang Mai (MU), suburban Hang DongThis (HD), study and was Mae conducted Rim (MR) in in three the central districts: part Urban of Chiang Mueang Mai Chiang province Mai (MU),(Figure suburban 1). The Hangentire Dongarea of(HD), each and of the Mae three Rim districts (MR) in thewas central stratified part initia of Chianglly based Mai provinceon a systematic (Figure 1random). The entire sampling area of method each of [22].the three The contour districts wasmaps stratified of Chiang initially Mai basedprovince on a (MapMagic systematic randomTM scale sampling1:150,000 methodwith a UTM [22]. The projection contour type,maps Everest of Chiang Spheroid Mai province and (MapMagicthe Indian TM1975scale Datu 1:150,000m) were with used a UTM for projectionplotting type,the study Everest area. Spheroid The descriptionand the Indian of study 1975 Datum) sites selection were used and for land plotting use ca thetegories study area.was provided The description in the ofprevious study sites study selection [16]. Sixand different land use land categories uses were was providedclassified: in disturbed the previous mixed study deciduous [16]. Sixdifferent forest (DDF), land uses mixed were deciduous classified: forestdisturbed (MDF), mixed mixed deciduous orchard forest (MO), (DDF), paddy mixed field deciduous (PF), lowland forest (MDF), village mixed (LLV), orchard and (MO), city town paddy (CT) field [15,16].(PF), lowland village (LLV), and city town (CT) [15,16]. FigureFigure 1. 1. MapMap of of Thailand Thailand showing showing three three sample sample distri districtscts (Mueang (Mueang Chiang Chiang Mai, Mai, MU; MU; Mae Mae Rim, Rim, MR; MR; andand Hang Hang Dong, Dong, HD) HD) and and 18 18 sampling sampling locations. locations. Green Green shade shade represents represents a a mountainous mountainous area. area. Insects 2018, 9, 106 3 of 15 2.2. Fly Collection Sampling was conducted at 18 sites, representing six land uses and covers three districts of the central part of Chiang Mai province, Thailand [16]. The collection was performed from May 2009 to May 2010. Adult fly collection was carried out every two weeks using an in-house prototype reconstructable