Seasonal abundance, daily trends and parity status of stable flies (Diptera: Muscidae) at Glenlea, Manitoba
Khumalo, William Vezi
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Seasonal abundance of the stable flies, Stomoxys calcitrans (L.) was studied at Glenlea, Manitoba for two years (from June to mid-September, 1988 and 1989). Alsynite (TM) fibre glass sticky traps were used in which Tanglefoot (TM) was used as an adhesive. The efficiency of the Williams sticky trap system used was determined to be 36.2%. Two study sites were established, one at the animal confinement facility and the other at the pasture. Traps were operated for nine hours per day once a week at each site. Trapped flies were removed from traps after a predetermined time interval of one or more hours. Trapped flies were counted, sexed and a subsample of 15-30 females was dissected to determine the parity status. A sweep net sample was also obtained on each sampling occasion and processed like the trap catches. The abundance of the stable flies was 7.5-fold larger at the animal confinement site than at the pasture in 1988 and about 2.1-fold larger at the animal confinement site than pasture in 1989. Peak abundance occurred from 16 June to 30 August at the animal confinement site when >50 flies per trap in nine hours of trapping were collected in 1988. The maximum number of flies collected from the animal confinement site was more than 1200 flies/trap on 28 June, 1988. Pasture stable fly peak abundance occurred from 17 June to 26 August when >15 flies per trap were collected in nine hours. The highest number of flies at the pasture was 160 flies/trap which was collected on 26 July, 1988. Diurnal activity of the stable flies yielded a peak abundance between 0700-1100 hrs when more than 60% of the daily catch was collected at the animal confinement site and 55-70% of the daily total at the pasture. In June and July, 1989 hourly temperatures were recorded during trapping and it was found that stable fly diurnal activity was influenced largely by temperature, rather than time of day. Maximum daily activity, as shown by mean bi-hourly trap catch, occurred at temperatures between 20oC and 31oC and very little flight activity took place outside this range...