Bionomics of the oriental latrine fly Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae): temporal fluctuation and reproductive potential

Abstract

BackgroundChrysomya megacephala is a blow fly species of medical and forensic importance worldwide. Understanding its bionomics is essential for both designing effective fly control programs and its use in forensic investigations.MethodsThe daily flight activity, seasonal abundance related to abiotic factors (temperature, relative humidity and rainfall) and reproductive potential of this species was investigated. Adult flies were sampled twice a month for one year from July 2013 to June 2014 in three different ecotypes (forest area, longan orchard and palm plantation) of Chiang Mai Province, northern Thailand, using semi-automatic funnel traps. One-day tainted beef offal was used as bait.ResultsA total of 88,273 flies were sampled, of which 82,800 flies (93.8%) were caught during the day (from 06:00 to 18:00 h); while 5473 flies (6.2%) were caught at night (from 18:00 to 06:00 h). Concurrently, the abundance of C. megacephala was higher in the forest area (n = 31,873; 36.1%) and palm plantation (n = 31,347; 35.5%), compared to the longan orchard (n = 25,053; 28.4%). The number of females was significantly higher than that of males, exhibiting a female to male sex ratio of 2.36:1. Seasonal fluctuation revealed the highest abundance of C. megacephala in summer, but low numbers in the rainy season and winter. Fly density was significantly positively correlated with temperature, but negatively correlated with relative humidity. No correlation between numbers of C. megacephala with rainfall was found. Activity occurred throughout the daytime with high numbers from 06:00 to 18:00 h in summer and 12:00 to 18:00 h in the rainy season and winter. As for the nocturnal flight activity, a small number of flies were collected in summer and the rainy season, while none were collected in the winter. Dissection of the females indicated that fecundity was highest during the rainy season, followed by winter and summer.ConclusionsSince the assessment of daily, seasonal activity and the reproductive potential of C. megacephala remains a crucial point to be elucidated, this extensive study offers insights into bionomics, which may be considered for integrated fly control strategies and forensic entomology issues.

Population dynamics of an invasive bird parasite, Philornis downsi (Diptera: Muscidae), in the Galapagos Islands

“…A second hypothesis is that males become less attracted to papaya bait between bird breeding seasons. Although field studies in Galapagos have confirmed that young and old males are attracted to yeasts and fermenting fruits [18,26], it is possible that males outside the bird breeding season need less food or seek a different food than females, as occurs with some muscid, calliphorid and tephritid fruit flies [27,28,29].…”

Small Bait Traps May Not Accurately Reflect the Composition of Necrophagous Diptera Associated to Remains

“…Additionally, some authors have demonstrated the importance of biases associated with small bait traps, such as those caused by weather factors, height of traps, and position, as well as biased sex ratios and age-classes of captured Diptera [ 11 , 39 , 40 ]. Furthermore, the flight patterns of Calliphoridae are known to vary throughout the day [ 41 , 42 ]. As such, from an experimental standpoint, small bait traps which sample constantly are more likely to capture taxa which may not be active when the carcasses are being sampled.…”

Time Flies—Age Grading of Adult Flies for the Estimation of the Post-Mortem Interval

“…The authors recommend that the isotope signatures for the body in question should also be determined so that they can be compared with the signatures from the entomological specimens from the crime scene. [25,27,31] easy to do preparation mainly just for females rough classification into categories 3…”

“…This kind of staging is also established for forensically relevant Muscidae or blow flies like Chrysomya spp. [28][29][30][31] The dependence on protein sources for egg formation and the absence of oviposition sites, which could delay the egg formation, but also the numbers of ovarian cycles in female flies, are a disadvantage of these methods, as they are the source of significant variation [12]. Moreover, Gillies and Wilkes [32] highlighted the lack of reproducibility of this technique across species and between technicians during their work on Anopheles spp.…”