Systematic & Applied Acarology Special Publications
(2009) 23, 1–30.
Systematic & Applied Acarology Society
The effect of
rochelidae) phoresy on the dispersal of
D. V. BERESFORD
& J. F. SUTCLIFFE
Trent University Biology Department, 1600 West Bank Drive, Peterborough ON, Canada K9J 7B8.
Corresponding author. Phone: 705 652-7452; Email: firstname.lastname@example.org
In south-central Ontario, the stable flies disperse from their overwintering farms and re-establish populations at
neighbouring dairy and beef farms each spring. Two species of phoretic macrochelid mites commonly found on
stable flies are
. We tested the hypothesis that mite phoresy
affects the dispersal of their stable fly phorionts. At a beef farm we found a higher proportion of parous stable
flies with mite scars than expected, based on the proportion of nulliparous females carrying mites. These results
were consistent with our hypothesis, indicating that stable flies without mites may be emigrating more than flies
carrying mites. We further tested our hypothesis by comparing the mite load on dispersing stable flies sampled
with a vehicle-mounted truck trap to the mite load on resident stable flies sampled from three dairy farms and
one beef farm (May to October, 2001). Significantly, no stable flies caught in the truck trap were carrying mites,
compared to the seasonal means of 10% and 5% of female and male stable flies with mites at the four farms.
This effect of mite phoresy on stable fly populations is discussed.
, stable fly
Dispersal is one of the most important aspects of any organism's success (Andrewartha & Birch
1954). For many mites, dispersal is achieved by phoresy on insect hosts. While it is known that
ectoparasites can alter host dispersal (e.g., Wecker 1962), little is known about the effect of phoretic
mites on their host's dispersal patterns. This paper examines whether phoresy by two
mite species affects the dispersal of one of their muscid phorionts,
The stable fly is a costly (Cantigui
. 1997, Campbell
. 2001, Mullens
. 2006) and
highly dispersive pest species that annually re-colonizes dairy and beef farms in temperate climates
(Beresford & Sutcliffe 2009). Stable flies from farm populations often carry phoretic mites of
various species (Axtell 1964, Hunter & Rosario 1988, McGarry & Baker 1997). Both Williams
(1976) and Hogsette and Ruff (1985) used the presence of phoretic macrochelid mites on dispersing
stable flies to infer an agricultural origin of stable flies found on coastal areas.
Many of the Macrochelidae are voracious predators of fly eggs and first instar larvae (Doube
. 1986), and play an important role in limiting fly populations in agricultural systems (Wallace
. 1979, Halliday & Holm 1987, Koehler 1997). The most common macrochelid carried by stable