Towards an odour-baited trap to control Musca sorbens, the putative vector of trachoma

Ailie Robinson,Wondu Alemayehu,Oumer Abdurahman Shafi,Gebreyes Hordofa,Muluadam Abraham Aga,Gemeda Shuka,James G Logan,Anna Last,Dereje Debela,David Macleod,Matthew J Burton,Virginia Sarah,Jack Bickford-Smith

doi:10.1038/s41598-021-91609-1

Ailie Robinson, Wondu Alemayehu + Show 11 more

Open Access

https://doi.org/10.1038/s41598-021-91609-1

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Abstract

Musca sorbens is a synanthropic filth fly that aggressively attacks people to feed from mucous membranes of the eyes, nose or mouth, from open sores, or from sweat. It has long been suspected that this fly contributes to the transmission of eye infections, particularly trachoma, and recent work has added to the evidence base that M. sorbens is a trachoma vector in Ethiopia. There are few options to control M. sorbens, largely due to a lack of evidence. Space spraying with insecticides is effective, but an environmentally sound and long-term sustainable solution would be better, for example, mass trapping. We tested commercially available and homemade trap types in a pilot (laboratory) study and three field studies. A homemade design, built from a bucket and two empty water bottles, baited with a commercially available lure, The Buzz, was found to be most effective. This trap caught 3848 M. sorbens over 26 trap ‘events’ (3- or 4-day periods); mean/median per 24 h 43.6 (standard deviation 137.10)/2.25 (IQR 0.25–12.67). The Buzz lure is cheap and effective for 4 weeks, and trap components cheap and locally available. Further studies are needed to understand the impact of this trap on local fly populations and the local transmission of trachoma.

Highlights

Musca sorbens is a synanthropic filth fly that aggressively attacks people to feed from mucous membranes of the eyes, nose or mouth, from open sores, or from sweat
We found 64 female and 31 male M. sorbens, and there was no evidence that there was a difference in sex ratio in the other three traps that caught M. sorbens (Buzz/L, Buzz/F and Bickford Bucket (BB)/F; P = 0.87)
In the positive control (Bristow trap; human faeces bait), a total of 388 (69.03%) female and 152 (27.05%) male M. sorbens were caught over 27 trap events; we found no evidence that there was a difference in sex ratio in the other traps that caught M. sorbens (BB/faeces, BB/buzzlure, Bristow/neg; P = 0.98)

Summary

Introduction

Musca sorbens is a synanthropic filth fly that aggressively attacks people to feed from mucous membranes of the eyes, nose or mouth, from open sores, or from sweat. The Bazaar fly, is thought to contribute to transmission of the blinding eye disease trachoma in certain regions of the w orld[1,2,3,4,5]. This species of ‘filth fly’ persistently attacks people, feeding on sweat, mucous secretions ( ocular and nasal), and any type of skin lesions including wounds, ulcers and even tiny breaks in the s kin[1,6]. Some trapping methods have been used to monitor M. sorbens populations, including WHO exit traps attached to plastic buckets and baited with fish[2] or b eef[20], sticky traps (sheeting of some type coated with adhesive but not baited)[2,8,12], and sticky pots (bait-containing pots with sticky lids, ‘Bristow traps’)[12,17]

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