The impact of climate on the abundance of Musca sorbens, the vector of trachoma

Abstract

Background: To assess the extent to which climate may affect the abundance of Musca sorbens, a putative vector of trachoma.

Data sources: Studies were identified by systematically searching online databases including CAB abstracts, Embase, Global Health, Medline, Web of Science and BIOS Online, references from key articles, and the websites of relevant international agencies.

Methods: A systematic literature review was conducted of field and laboratory studies that reported the impact of climate factors (e.g., temperature, humidity) on the synanthropic fly Musca sorbens. Data were systematically extracted and studies assessed for quality by two readers. Study results were reported narratively.

Results: A total of 16 studies met the inclusion criteria but only three evaluated associations between climatic/abiotic factors and M. sorbens. Limited evidence indicates that M. sorbens abundance has an optimal temperature and humidity range. Thirteen studies reported seasonal patterns but no consistent pattern was found between season and the abundance of M. sorbens.

Conclusions: The evidence base regarding the effect of climatic factors on M. sorbens is limited, so it is difficult to construct a biological model driven by climate for this species. A multivariate statistical approach based on the climate of sites where M. sorbens is found may better capture its complex relationship with climatic factors as well as aid in mapping the global range of M. sorbens.

Fig. 1

Prevalence of Active Trachoma in Africa, Asia, and the Pacific Islands (Trachoma Atlas, Accessed August 2015)

Fig. 2

The Life Cycle Of Musca sorbens, the Eye-Seeking Fly Implicated in Trachoma Transmission. (Rothamsted Research Visual Communications Unit, Reproduced with Permission)

Fig. 3

Potential Effects of Climatic Factors and Mediators on Fly Abundance, Fitness, and Trachoma Transmission (Factors Found to be Associated with M. Sorbens from Retrieved Papers Marked in Bold)

Fig. 4

PRISMA Process of Paper Selection

Fig. 5

Temperature Optima for Different Life Stages of M. sorbens, High and Moderate Quality Studies. 1. Shortest egg hatching time, Hafez & Attia 1958 [21, 22]. 2. Highest percentage egg hatching, Hafez & Attia 1958 [21, 22]. 3. Shortest larval period, Hafez & Attia 1958 [21, 22]. 4. Shortest duration of pupal period, Hafez & Attia 1958 [21, 22]. 5. Highest percentage of pupal hatching, Hafex & Attia 1958 [21, 22]

Fig. 6

Humidity Optima for Different Life Stages of M. sorbens, High and Moderate Quality Studies. 1. Shortest egg hatching time, Hafez & Attia 1958 [21, 22]. 2. Highest percentage egg hatching, Hafez & Attia 1958 [21, 22]. 3. Pupal phase duration was independent of humidity at humidities studied by Hafez & Attia 1958 [21, 22]