Impact of abiotic factor changes in blowfly, Achoetandrus rufifacies (Diptera: Calliphoridae), in northern Thailand

Abstract

Understanding how medically important flies respond to abiotic factor changes is necessary for predicting their population dynamics. In this study, we investigated the geographical distribution of the medically important blowfly, Achoetandrus rufifacies (Macquart) (Diptera: Calliphoridae), and ascertained the response to climatic and physio-environmental factors in Chiang Mai, northern Thailand. Adult fly surveys were carried out every 2 weeks from May 2009 to May 2010 at 18 systematically randomized study sites in three districts of Chiang Mai province (Mueang Chiang Mai, Mae Rim, and Hang Dong), using reconstructable funnel traps with 1-day tainted beef offal as bait. During the study period, 8,861 adult A. rufifacies were captured, with peak densities being observed at the end of winter (i.e., late February) and throughout most of the summer (May to March). Population density had a weak but significant (α = 0.05) positive correlation with temperature (r = 0.329) and light intensity (r = 0.231), and a weak but significant (α = 0.05) negative correlation with relative humidity (r = -0.236). From the six ecological land use types (disturbed mixed deciduous forest, mixed deciduous forest, mixed orchard, lowland village, city town, and paddy field), greater fly densities were observed generally in the disturbed mixed deciduous forest and lowland village, but not in the paddy fields. In conclusion, A. rufifacies are abundant from the end of winter and throughout most of the summer in northern Thailand, with population density being weakly positively correlated with temperature and light intensity, but weakly negatively correlated with relative humidity. The greatest densities of this fly species were collected in disturbed mixed deciduous forest and lowland village land uses. The prediction of annual and season specific distributions of A. rufifacies were provided in each season and all-year patterns using a co-kriging approach (ArcGIS9.2).

Daily and Seasonal Prevalence of the Blow Fly Chrysomya Rufifacies (Diptera: Calliphoridae) as Revealed by Semiautomatic Trap Collections in Suburban Chiang Mai Province, Northern Thailand

“…Although the distribution pattern of C. rufifacies has been documented from previous investigations in Australia and Thailand (Norris 1966;Mcleod & Anderson 1992;Klong-klaew et al 2014), our study is the first to characterize the daily and seasonal activity of adult C. rufifacies using a semi-automatic trap in Chiang Mai Province, Thailand. Most of the adult C. rufifacies in traps were obtained from the forested area, which may indicate a preference by this species.…”

“…To prevent contamination, each bait was placed in a separate container at ambient temperature. Offal bait has been shown previously to be effective in attracting medically important blow flies in the field (Ngoenklan et al 2011;Klong-klaew et al 2014). All fly collections remained in the field until the trap had completed its 24 h rotation.…”

“…In Thailand, C. megacephala and C. rufifacies coexist in various ecological environments, including urban, rural, and forested areas (Ngoen-klan et al 2011;Klong-klaew et al 2014). Both flies are regarded as ecologically similar species (i.e., species that use the same resource) Ngoen-klan et al 2011;Klong-klaew et al 2014). Larvae of C. rufifacies were reported to attack C. megacephala in a forensic entomology field study and in the laboratory (Wells & Greenberg 1994;Wells & Kurahashi 1997).…”

“…Precise information on the annual activity of forensically important flies is necessary for estimation of minimum post-mortem interval (PMI min ), especially in determining the time of death. Abiotic factors such as temperature, relative humidity, light intensity, and rainfall have been reported to impact the distribution of C. rufifacies (Vogt 1988;Klong-klaew et al 2014). Furthermore, a complex interaction between the timing of the daily light-dark cycle and temperature is the principal factor influencing insect activity (Archer & Elgar 2003).…”

Forensically Important Blow Flies Chrysomya pinguis, C. villeneuvi, and Lucilia porphyrina (Diptera: Calliphoridae) in a Case of Human Remains in Thailand

“…Among seasons, blow fly collections during the winter were low when compared with summer and rainy seasons [24,25]. It is interesting that C. villeneuvi , C. pinguis , and L. porphyrina coexisted in large numbers during the winter in high mountainous areas of northern Thailand.…”