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African pit latrines produce prodigious numbers of the latrine fly, Chrysomya putoria, a putative vector of diarrhoeal pathogens. We set out to develop a simple, low-cost odour-baited trap for collecting C. putoria in the field. A series of field experiments was carried out in The Gambia to assess the catching-efficiency of different trap designs....
Context in source publication
Context 1
... given by the local institutional review board. Verbal consent for fly trapping was provided by household heads in Kundam Demba village. The field studies did not involve endangered or protected species. The trap development studies were carried out inside and close to the Medical Research Council’s (MRC) field station on the outskirts of Basse Santa Su (13 u 18 9 37.48 99 N, 14 u 13 9 24.46 99 W), a rural town in the Upper River Region of The Gambia. Trap comparisons were performed in Kundam Demba village (13 u 20 9 13.51 99 N, 14 u 7 9 3.43 99 W) between June and December in 2011. This is an area of open Sudanian savannah with a rainy season from May to October followed by a long dry season. Most people live in small rural villages in houses with mud or cement walls and thatched or metal roofs. Houses are mainly grouped in compounds and toilets are usually pit latrines shared by several members of a compound, although open defaecation also occurs. The trap development site close to the MRC was a communal open-defaecation area used by local farmers. Experiments were based on a Latin Square design that is used to adjust for variation in fly numbers due to trap, position and day. If a design feature significantly increased the catch sizes, it was incorporated into the basic fly trap design and tested in successive experiments. Traps were positioned in a straight line, 2 m apart, and fly collections made between 09:00 and 17:00 h, when fly numbers were greatest. Collections were normally made after 4 hours, but were extended to 6 hours when fly numbers were low in order to stabilise the variance. Flies were killed by freezing at 2 20 u C for 2 hours, identified to species and sex and then counted. A pilot 6 6 6 Latin Square comparison study was carried out, with three treatments duplicated, to estimate the variation in fly numbers between traps on different days. The mean natural logarithm of total C. putoria collected in each trap was 1.5 (SD = 1.4) for the small holes, 2.7 (SD = 1.5) for the medium holes and 3.4 (SD = 1.3) for the large holes. Fly counts were log transformed to stabilise the variance. Since the large holes caught most flies, this became our reference trap. We were interested in detecting only large differences in catching efficiency between different trap designs, so we designed our experiments to detect a 50% increase or decrease in fly numbers relative to the reference trap, at the 5% level of significance and with 80% power. Using the information above in a web-based sample size calculator ( , rollin/stats/ssize/n2.html, accessed June 2011) we required a sample size of 10. Thus we adopted a 6 6 6 Latin Square design with repeats of each trap on each trapping occasion, so that at the end of each experiment each trap design was tested 12 times (i.e. 2 6 6 days). Treatments A to E in the Latin Square were randomly allocated a number from 1 to 6 for each experiment. Flytraps were then randomly allocated to one of these numbers. The Latin Square allowed each treatment to be allocated a different position each day, so that at the end of each experiment each trap had been in each position and was never continuously next to the same neighbouring trap. Thus, at the end of each experiment the number of flies caught in each trap type will be independent of their neighbour. The basic trap used to collect flies was a 3L volume (17 cm ), transparent polypropylene box with a snap-top white opaque lid (Whitefurze, Coventry UK), perforated with 10, 1.6 cm diameter holes. The bait was 50 g of raw common catfish, Synodontis batensoda , since this was shown to be attractive to C. putoria in earlier studies [5]. The fish was placed in a white plastic pot 250 cm 3 in volume (6 cm in height and 9 cm diameter; W. K. Thomas, Chessington UK), covered with a cotton-netting lid, secured by an elastic band and placed in the centre of the floor of the trap. Preliminary experiments used traps with adhesives, but they were relatively ineffective at trapping large, strong flies, so this was abandoned. We also tested traps painted entirely in blue, white or brown paint, but these caught very few flies. Each experiment tested two or three variations of the basic trap including the diameter, number, position and shape of the entrance holes, whether or not the trap was left out overnight, the height above ground, degree of transparency of the trap walls, shape of trap (cubic or cylindrical), volume, colour and the attractiveness of gridded surfaces on the trap. The precise details of these experiments and the rationale for testing them is summarised in table 1. Our final trap consisted of 10, 1.6 cm diameter entrance holes in a white snap-top opaque lid of a 3 L polypropylene box, with transparent sides (Figure 1). The entrance holes had conical collars inserted in the trap each 1 cm in length and 0.6 cm in diameter at the smallest opening and pointing into the trap chamber. We tested this trap against several other traps (Figure 2) used for collecting flies including (1) the baited-cone trap [12], (2) Emerson and co-workers trap [18], (3) Agrilure (Agrimin Ltd, Brigg UK) and (4) LuciTrap (Bioglobal Ltd, Eight Mile Plains Australia). Baited-cone traps were 40 cm 3 mosquito exit traps with the entrance 10 cm above the ground, supported by 5 cm diameter grey plastic piping at each corner. Emerson traps were 40 cm 3 mosquito exit traps with the entrance pointed down into blue plastic buckets (diameter 24 cm, 20 cm at the base) which had three 5 cm 2 holes on the sides near the base. Agrilure traps were 30 cm 3 white corrugated-plastic cubes with horizontal entrance slits and within the trap were four vertical black adhesive strips to trap the flies. LuciTraps were UV stabilised, semi-transparent plastic buckets with flat yellow lids, 23.1 cm in diameter, perforated with 50 conical entrance holes, 1.5 cm diameter on entry, 1.5 cm deep and 0.5 cm diameter on exit. All traps were baited using 50 g of fish placed as indicated above. This final experiment used a 10 6 10 Latin Square design since there were 5 trap designs, two of each, to test. Fly counts were transformed using natural logarithms to normalize the data. General linear modelling was used to account for the variation in fly numbers between different trap designs, position of trap, day and replicate. Comparisons of traps within each experiment were made using Bonferonni Statistical analysis using SPSS version 19.0. In total, the traps caught 9,200 flies: 52.6% were Chrysomya putoria (n = 4,840), 25.4% were Chrysomya marginalis (n = 2,336), 8.1% were Musca spp. (n = 745), 7.2% were Lucilia cuprina (n = 663), 5.4% were Sarcophaga spp. (n = 497) and 1.3% were classed as ‘other’ species (n = 119). Several features of the trap influenced the number of flies collected (Figure 3a and 3b) including; the entrance hole size (F = 34.70, df = 2, p , 0.001), whether the entrance holes had conical collars of not (F = 9.39, df = 2, p = 0.01), the position of the entry holes (F = 9.74, df = 2, p , 0.001), the height of the trap (F = 26.38, df = 2, p , 0.001), the opacity of the walls (F = 34.26, df = 2, p , 0.001) and the presence or absence of a gridded surface (F = 7.47, df = 2, p = 0.03). Some features did not alter the trap catch size, including changing the diameter of the entrance holes, whilst adjusting the number of holes, so that the total area of entrance holes was the same for each trap (F = 3.25, df = 2, p = 0.06), if traps had cones or not and were left overnight (F = 0.843, df = 2, p = 0.37), the shape of the trap (F = 3.16, df = 2, p = 0.09), the volume of the trap (F = 1.55, df = 2, p = 0.23), the lid colour (F = 1.45, df = 2, p = 0.26) and slab colour (F = 1.36, df = 2, p = 0.28). Details of each trap feature tested are provided in table 1. Although larger holes caught more flies than smaller holes, the catch size to surface area ratio for 0.6 cm diameter holes (1:13) was similar to the ratio for 1.6 cm diameter holes (1:18). When we adjusted the number of holes in the lid so that the surface area of entry holes was similar, we found no significant difference between catch size, confirming our hypothesis that hole size diameter between 0.6 and 1.6 cm is not a critical feature of the trap, rather it is the total surface area of holes that is important. Whilst the number of flies collected differed significantly between the traps (F = 5.321, df = 4, p = 0.001), our trap was not significantly better than the Emerson, baited-cone trap, LuciTrap and Agrilure (p = 1.000, 1.000, 1.000, 0.583 respectively). In terms of cost per unit, the LuciTrap cost $31.53, the Agrilure cost $15.63, the Emerson Trap cost $9.66, the baited-cone trap cost $8.80 and our box trap cost $3.92. Both the LuciTrap and Agrilure included bait in the cost of the trap. We developed a simple and cheap fly trap for collecting C. putoria by incorporating the most effective design features identified from a series of simple experiments. Raw fish as a bait was used successfully for collecting C. putoria in a range of different traps, although occasionally local cats looking for food upturned the traps. Fish-baited traps have also been used successfully for collecting Chrysomya spp. in other studies in The Gambia [5,10]. Fly catch size increased as the entrance hole size increased from 0.6 cm to 1.6 cm diameter. However, since we used the same number of holes in each trap, the total hole area also increased with hole size. When we controlled for this by varying the number and size of hole, while maintaining an equal hole area, in this case we found that each trap variant collected similar numbers of flies. Thus the size of individual holes is less important than total hole area. Of the three individual hole sizes tested, we found holes 1.6 cm in diameter collected most flies. The position of the entrance holes on the trap was important, with highest fly catches obtained when the holes were on the top of the ...
Citations
... Calliphora vicina [25] Lucilia caesar [26] Lucilia illustris [27] L. sericata [24,[28][29][30] L. cuprina [20,[31][32][33] Phormia regina [26,29,34] Protophormia terraenovae [35] Chrysomya megacephala [36] Ch. putoria [23] Co. macellaria [21,22,37] S. magellanica [24] Wohlfahrtia nuba [38] Musca domestica [39] Collecting Wild Flies Several options are available to the collector of live flies for the establishment of laboratory colonies. Female flies can be encouraged to lay eggs on decomposing meat or other suitable bait [40], maggots may be hand-collected from wild carcasses and cadavers [7,41,42], and adult flies can be trapped [6,[43][44][45]. Common choices of bait include minced ovine (sheep), porcine (pork), or bovine (cattle) meat, but a wide range of other mammal and bird meats will attract medicinal fly species. ...
... A variant of this trap mechanism utilises the same inability of flies to escape through an inverted, funnel-shaped opening. Inexpensive plastic storage containers may be baited with meat or other attractants and furnished with inward-pointing cones [44]. Commercial traps exploit this approach to capture sheep blowflies that can cause significant stock loss and animal suffering [51]. ...
... The numbers of flies collected during the present experiments were lower than previous studies conducted in animal farms in the USA [10,16,37] but comparable to similar field studies conducted in small rural villages in Africa and Asia [38,39]. Unlike experiments conducted on farms in the USA, where the only breeding, resting, mating sites and source of food is the farm; in Asia and Africa there are many alternative sites that can compete with the baited and sticky traps, such as open defecation sites and rubbish deposits, which may reduce the numbers of flies caught. ...
Background
There are many different traps available for studying fly populations. The aim of this study was to find the most suitable trap to collect synanthropic fly populations to assess the impact of increased latrine coverage in the state of Odisha, India.
Methods
Different baits were assessed for use in sticky pot traps (60% sucrose solution, 60 g dry sucrose, half a tomato and an non-baited control), followed by different colours of trap (blue versus yellow) and finally different types of trap (baited sticky pot trap versus sticky card traps). The experiments were undertaken in a semi-urban slum area of Bhubaneswar, the capital of Odisha. The first experiment was conducted in 16 households over 30 nights while experiments 2 and 3 were conducted in 5 households over 30 nights.
Results
The traps predominantly caught adult Musca domestica and M. sorbens (78.4, 62.6, 83.8% combined total in experiments 1–3 respectively). Non-baited traps did not catch more flies (median 7.0, interquartile range, IQR: 0.0–24.0) compared with baited traps (sucrose solution: 6.5, 1.0–27.0; dry sucrose: 5.0, 0.5–14.5; tomato: 5.0, 1.5–17.5). However, there were significantly more flies collected on blue sticky pot traps, which caught nearly three times as many flies as yellow sticky pot traps (Incidence Rate Ratio, IRR = 2.91; 95% CI: 1.77–4.79); P < 0.001). Sticky card traps (27, 8–58) collected significantly more flies than the non-baited sticky pot traps (10, 1.5–30.5).
Conclusions
Blue sticky card traps can be recommended for the capture of synanthropic fly species as they are non-intrusive to residents, easy to use, readily allow for species identification, and collect sufficient quantities of flies over 12 hours for use in monitoring and control programmes.
... A study in pitfall trap found that more insects were caught as trap size increased (Koivula et al., 2003). Lindsay et al. (2012) conversely suggested that the volume of trap was not a significant feature affecting trap catch of odor-baited flytrap. Differences of experimental design between the present study and other studies, particularly the time of traps were left in the field and the different study sites, make data comparisons impractical. ...
Bait-trapping is a useful approach for monitoring fly population dynamics, and it is an effective tool for physical control of pest species. The aim of this study was to test a newly developed semi-automatic funnel fly trap with some modifications of the former prototype fly trap to study medically important fly population density. The efficacy of the semi-automatic funnel trap was assessed by field sampling during July 2013-June 2014 using 1-day tainted beef offal as bait. The modified semi-automatic funnel traps were able to capture a total of 151,141 adult flies, belonging to the families: Calliphoridae (n = 147,248; 97.4%), Muscidae (n = 3,124; 2.1%) and Sarcophagidae (n = 769; 0.5%), which are the medically important fly species. Among the total of 35 species collected, Chrysomya megacephala (Diptera: Calliphoridae) (n = 88,273; 59.95%), Musca domestica (Diptera: Muscidae) (n = 1,324; 42.38%) and Boettcherisca perigrina (Diptera: Sarcophagidae) (n = 68; 33.01%) were the predominant species of each family. High number of flies was captured in forest area, representing 42.47% (n = 64,197) of total specimens. Female flies were trapped more than male with total sex ratio of 0.37 male/female. Flies were trapped throughout the year with peak population in summer. Peak activity was recorded in the afternoon (12.00–18.00 h). In summary, the modified semi-automatic funnel fly trap can be used for field collection of the adult fly. By setting the timer, population dynamics, diversity, and periodic activity of adult flies were determined.
... Others fly trap raw fish baited for flies routine sampling used in Gambia (8), and India (9, 10), and in Iran (11). The fish bait used about 50gm fresh fish, the common and different flytraps utilized for catching blow flies are seen in the following illustrating diagram (12). This study had been determined to collect and identify Calliphoridae ...
Fauna of Iraq-Diyala’s Calliphoridae and other Diptera flies of medically and veterinary importance was assessed by collection with hanging up modified baited flytrap. In this survey sex (6) genera and nine (9) species affiliated to Calliphoridae, Muscidae, Sarcophagidae and Fanniidae families. The species identified were Calliphora vicina (Robineau-Desvoidy 1830), C. vomitoria (Linnaeus 1758), Pollenia spp. (Robineau-Desvoidy 1830), Lucilia cuprina (Wiedemann 1830), L. sericata (Meigen 1826), Musca domestica (Linnaeus1758), M. sorbens (Wiedemann 1830), Muscina stabulans (Fallen 1817), Fannia canicularis (Linnaeus) and Sarcophaga Africa (Wiedemann 1824). The modified fish baited adult flytrap used in this study was serviceable and could be profitable for animals protection and field routine flies sampling to study Calliphoridae and other flies diversity and population dynamics.
... Unlike smell, studies characterising insects in pit latrines have been undertaken. Adult and larvae of Chrysomya putoria, Chrysomya marginalis, Musca spp, Lucilia cuprina, Sarcophaga spp have been reported [80][81][82]. S Irish, et al. [83] identified members of Psychodidae, Culicidae, Calliphoridae, Syrphidae, Stratiomyidae, Sarcophagidae families from pit latrines in central Tanzania. Some types of mosquitoes especially Culex quinquefasciatus and species of Anopheles are known to breed in wet pits [84,85]. ...
... Laboratory and field experiments on the use of expanded and shredded waste polystyrene beads to eliminate mosquitoes in pit latrines have been very successful [91]. Traps placed over the squatting plate hole have also been developed and experimented with success at controlling insects in pit latrines [82]. Pyriproxyfen, an insect juvenile hormone, and local soap have been found to reduce flies in pit latrines [92]. ...
BackgroundA pit latrine is the most basic form of improved sanitation which is currently used by a number of people around the globe. In spite of the wide spread use, known successes and advantages associated with pit latrines, they have received little attention in form of research and development. This review focuses on the usage and performance (filling, smell and insect nuisance) of pit latrines in urban areas of sub-Saharan Africa (SSA) and proposes approaches for their improvements and sustainability. Methods
Current pit latrine usage within urban SSA was calculated from Joint Monitoring Programme (JMP) water and sanitation country-files. We conducted a literature search and review of documents on pit latrine usage, filling, smell and insect nuisances in urban areas of SSA. Findings of the review are presented and discussed in this paper. Results and DiscussionPit latrines are in use by more than half the urban population in SSA and especially among low income earners. An additional 36 million people in urban areas of SSA have adopted the pit latrine since 2007. However, their performance is unsatisfactory. Available literature shows that contributions have been made to address shortfalls related to pit latrine use in terms of science and technological innovations. However, further research is still needed. Conclusion
Any technology and process management innovations to pit latrines should involve scientifically guided approaches. In addition, development, dissemination and enforcement of minimum pit latrine design standards are important while the importance of hygienic latrines should also be emphasized.
... The traps were constructed of the same type of materials and were prepared in the same way, however, they were different colours. The colour of the lid of a fly trap was not shown to significantly affect the number of Chrysomya putoria collected in traps in The Gambia, however, the opacity of traps did affect the trap catch [31]. In future studies, the same colour of exit trap should be used to avoid any variation due to this factor. ...
The disposal of human excreta in latrines is an important step in reducing the transmission of diarrhoeal diseases. However, in latrines, flies can access the latrine contents and serve as a mechanical transmitter of diarrhoeal pathogens. Furthermore, the latrine contents can be used as a breeding site for flies, which may further contribute to disease transmission. Latrines do not all produce flies, and there are some which produce only a few, while others can produce thousands. In order to understand the role of the latrine in determining this productivity, a pilot study was conducted, in which fifty latrines were observed in and around Ifakara, Tanzania. The characteristics of the latrine superstructure, use of the latrine, and chemical characteristics of pit latrine contents were compared to the numbers of flies collected in an exit trap placed over the drop hole in the latrine. Absence of a roof was found to have a significant positive association (t=3.17, p=0.003) with the total number of flies collected, and temporary superstructures, particularly as opposed to brick superstructures (z=4.26, p<0.001), and increased total solids in pit latrines (z=2.57, p=0.01) were significantly associated with increased numbers of blowflies leaving the latrine. The number of larvae per gram was significantly associated with the village from which samples were taken, with the largest difference between two villages outside Ifakara (z=2.12, p=0.03). The effect of latrine superstructure (roof, walls) on fly production may indicate that improvements in latrine construction could result in decreases in fly populations in areas where they transmit diarrhoeal pathogens.
... Our previous fieldwork demonstrated that C. putoria was attracted strongly to human faeces (Lindsay et al. 2012) and that they could be trapped using a simple plastic box trap (Lindsay et al. in press). We therefore tried a proof-of-principle experiment to test whether we could use the odours generated from a latrine to attract flies and trap them there. ...
Objective
To explore ways of controlling Chrysomya putoria, the African latrine fly, in pit latrines. As pit latrines are a major source of these flies, eliminating these important breeding sites is likely to reduce village fly populations, and may reduce the spread of diarrhoeal pathogens.
Methods
We treated 24 latrines in a Gambian village: six each with (i) pyriproxyfen, an insect juvenile hormone mimic formulated as Sumilarv® 0.5G, a 0.5% pyriproxyfen granule, (ii) expanded polystyrene beads (EPB), (iii) local soap or (iv) no treatment as controls. Flies were collected using exit traps placed over the drop holes, weekly for five weeks. In a separate study, we tested whether latrines also function as efficient flytraps using the faecal odours as attractants. We constructed six pit latrines each with a built-in flytrap and tested their catching efficiency compared to six fish-baited box traps positioned 10 m from the latrine. Focus group discussions conducted afterwards assessed the acceptability of the flytrap latrines.
Results
Numbers of emerging C. putoria were reduced by 96.0% (95% CIs: 94.5–97.2%) 4–5 weeks after treatment with pyriproxyfen; by 64.2% (95% CIs: 51.8–73.5%) after treatment with local soap; by 41.3% (95% CIs = 24.0–54.7%) after treatment with EPB 3–5 weeks after treatment. Flytraps placed on latrines collected C. putoria and were deemed acceptable to local communities.
Conclusions
Sumilarv 0.5G shows promise as a chemical control agent, whilst odour-baited latrine traps may prove a useful method of non-chemical fly control. Both methods warrant further development to reduce fly production from pit latrines. A combination of interventions may prove effective for the control of latrine flies and the diseases they transmit.
Musca flies (Diptera: Muscidae) have been found culpable in the mechanical transmission of several infectious agents, including viruses, bacteria, protozoans, and helminths, particularly in low-income settings in tropical regions. In large numbers, these flies can negatively impact the health of communities and their livestock through the transmission of pathogens. In some parts of the world, Musca sorbens is of particular importance because it has been linked with the transmission of trachoma, a leading cause of preventable and irreversible blindness or visual impairment caused by Chlamydia trachomatis, but the contribution these flies make to trachoma transmission has not been quantified and even less is known for other pathogens. Current tools for control and monitoring of house flies remain fairly rudimentary and have focused on the use of environmental management, insecticides, traps, and sticky papers. Given that the behaviors of flies are triggered by chemical cues from their environment, monitoring approaches may be improved by focusing on those activities that are associated with nuisance behaviors or with potential pathogen transmission, and there are opportunities to improve fly control by exploiting behaviors toward semiochemicals that act as attractants or repellents. We review current knowledge on the odor and visual cues that affect the behavior of M. sorbens and Musca domestica, with the aim of better understanding how these can be exploited to support disease monitoring and guide the development of more effective control strategies.
