Table 1 Effects of Climatic Factors on the Abundance of M. sorbens, High Quality Studies

Authors: Toyama & Ikeda, 1981 [23]

Tempera-ture: 12 mm below surface of dung pat

Adult: abundance

Method: Flies trapped for 5 min using cone traps baited with fresh cow dung pats; Frequency: Bi-weekly for 11 months then weekly for an additional 14 months.

Adult M. sorbens is significantly more abundant in summer than winter (p < 0.001).

Direct effects: Summer (i.e., higher temperature) is significantly associated with greater abundance of all life stages of Musca sorbens.

Type: Field study

Season: Summer (May - October) and winter (November – April); year unstated

Indirect effects: Crusts on dung pats at higher summer temperatures reduce breeding potential of parasites which predate developing M sorbens. Greater abundance of M sorbens in summer may therefore reflect lower predation i.e., an indirect effect of temperature.

Location: Dairy farm, Oahu, Hawaii, USA

Egg and larval abundance

Method: Dung pat infestation rates: 20 randomly selected dung pats were examined for eggs and 20 for larvae. Frequency: Weekly between 10:00–20:00 h, for 15 months.

Significantly more dung pats with eggs and larvae found in summer (p < 0.001). Dung pat temperatures were higher than ambient temperatures only in summer (ambient 29.16 ± 0.80C, dung pat 33.36 ± 1.14C; p < 0.001). Dung pats developed thick, hard crusts during summer, but were thin and softened each night from moisture during winter. There were significantly more flies in unsoftened than softened pats (p < 0.001), and higher rates of parasitism of larvae in winter than summer (14 %, ns).

Larval abundance

Method: Dung pat larval examinations: 4 dung pats more than 3 days old were collected and examined. Frequency Monthly for 13 months.

Authors: Taye et al., 2007 [9]

t, November 2003 and February

Adult abundance

Method: Human landing catches on young children: counts of fly-eye contacts over 10 min outdoors, a short break, then 10 min indoors between 8:30 and 13:00. Frequency: Bi-weekly for 11 months then weekly for an additional 14 months.

Almost all eye-seeking M. sorbens were captured outdoors at low and at medium altitudes [99.3 %; 95 % confidence interval (CI) 99.1 %–99.5 %; p < 0.001].

Direct effects: Medium altitude is significantly associated with greater abundance of adult M. sorbens.

Type: Field study

Altitude: <2000 m

2200–2500 m

>3000 m

Location: 12 villages in Gurage zone, Ethiopia.

Season: May, August, November 2003 and February 2004

Adult abundance

Method: Modified WHO-exit traps baited with beef 10 traps over 25 h, 1.5 m above ground in playground, plantation, pits, shade, and indoors Frequency: Weekly between the hours of 10:00 and 20:00, for 15 months.

M. sorbens numbers declined with increasing altitude - of the 3465 M. sorbens trapped, 55.6 % and 44.3 % were collected in the low- and mid-altitude villages, respectively, but only 0.1 % (p = 0.001) came from villages at higher altitudes.