Assessment of blow fly, Lucilia sericata Meigen, resting behavior on plants using regurgitation and defecation spots

 

Filth flies have been implicated in the mechanical transmission of food borne pathogens such as Escherichia coli O157:H7 and Salmonella enterica.  When at rest, filth flies regurgitate and defecate on solid surfaces.  To quantify resting activity, two levels of blow fly, Lucilia sericata Meigen, infestations were compared by counting fly regurgitation and defecation spots on romaine lettuce exposed to the flies for 18-24 hours.  Spots from groups of 25 and 100 adults were counted and converted to spots per leaf area (cm²).    A one-way ANOVA was utilized to compare the total number of spots on the lettuce plants as well as spots per cm² between 25 flies and 100 flies.   One hundred flies produced significantly more spots (716 spots per plant) and spots per cm² than the 25 flies (218 spots per plant) (df=1, 39, F=71.16 and p<0.0001). These data are currently being used to develop a model for assessing fly resting behavior or plant preference in laboratory experiments.