Response of adult Cochliomyia macellaria, Musca domestica, and Sarcophaga bullata (Diptera: Calliphoridae, Muscidae, Sarcophagidae) to odors produced by commercial fly baits in a two-choice olfactometer bioassay

Abstract

We developed a two-choice spatial olfactometer to evaluate the response of adult secondary screwworm (Cochliomyia macellaria), house fly (Musca domestica), and flesh fly (Sarcophaga bullata) to two commercially available fly-trap attractants, Captivator and FliesBeGone in three-dimensional space. Liquid fly baits were prepared according to the manufacturer's recommendations and aged to discern the relative attraction of fresh and older baits. Each 0.07 m3 (2.5 ft3) arena was fitted with two fresh air intake ports, collection chambers containing the attractant or a blank control, and air exhaust ports. We released adult flies into an arena with sufficient space to allow free flight and response to the test attractants. Each comparison was replicated eight times with fresh flies. Flies were more responsive to commercial bait than the water control. Air flowrates, as measured through the intake ports, was determined to be a limiting factor for C. macellaria and S. bullata with significant responses rates observed to flowrates ≤0.14 m3/min (5 ft3/min) and ≤0.25 m3/min (9 ft3/min), respectively. In contrast, M. domestica appeared to respond similarly to all flowrates tested (≤0.31 m3 (11 ft3/min). In direct comparisons with a water control, M. domestica was attracted to baits regardless of bait age. In similar experiments, C. macellaria was significantly responsive to FliesBeGone aged 2 and 3 d but not Captivator regardless of age. Lastly, S. bullata was most responsive to FliesBeGone aged 3 and 4 d, and Captivator aged 4 d. Female flies responded to fly baits more frequently than males.

Keywords: Ecology & behavior; chemical ecology; veterinary entomology.

Fig. 1.

Diagram of olfactometer apparatus used in laboratory bioassays of commercial fly baits. Airflow within the arena was generated by means of a vacuum pump controlled by a variable autotransformer that pulled outside air in through the inlet ports, across the vials containing test materials, into the arena containing the test subjects and subsequently exhausted out of the arena through vacuum port attachments in the base. Air flowrate was measured using an anemometer inserted into the exhaust piping downstream from each arena.

Fig. 2.

Diagram of olfactometer apparatus “collection chamber” and assembly parts used in laboratory bioassays of commercial fly baits: A) ventilated collection jar; B) funnel that acted as a trapping device; C) single test tube holder; D) ventilated cylinder for directing airflow and fixed tube holder; and E) assembled “collection chamber”.

Fig. 3.

A) Mean response (+SEM) of Cochliomyia macellaria, B) Musca domestica, and C) Sarcophaga bullata flies in laboratory olfactometer airflow standardization bioassays testing either 4 d Captivator or 3 d FliesBeGone with a distilled water control and varying airflow rates recorded in m³/min (CMM). The observed number of responding flies (no. of flies responding) represents the combined count of 8 distinct biological replicates for each experimental flowrate. Statistical analyses were performed using χ² analysis and Poisson regression (*P < 0.05).

Fig. 4.

A) Mean response (+ SEM) of Cochliomyia macellaria, B) Musca domestica, and C) Sarcophaga bullata flies in laboratory olfactometer bioassays testing distilled water controls. Flowrates used were 0.08 m³/min for C. macellaria and S. bullata trials and 0.19 m³/min for M. domestica experiments. The observed number of responding flies (no. of flies responding) represents the combined count of 8 distinct biological replicated for each distilled water treatment. Statistical analyses were performed using χ² analysis (*P < 0.05).

Fig. 5.

A) Mean response (+SEM) of Cochliomyia macellaria, B) Musca domestica, and C) Sarcophaga bullata flies in laboratory olfactometer bioassays testing 6 distinct ages of the commercial fly bait Captivator, prepared according to the manufacturer’s protocol, with a distilled water control. Flowrates used were 0.08 m³/min for C. macellaria and S. bullata trials and 0.19 m³/min for M. domestica experiments. The release rate of Captivator was 2 ± 0.2 mg/min for all ages tested. The observed number of responding flies (no. of flies responding) represents the combined count of 8 distinct biological replicated for each distilled water treatment. Statistical analyses were performed using χ² analysis (*P < 0.05).

Fig. 6.

A) Mean response (+SEM) of Cochliomyia macellaria, B) Musca domestica, and C) Sarcophaga bullata flies in laboratory olfactometer bioassays testing 6 distinct ages of the commercial fly bait FliesBeGone, prepared according to the manufacturer’s protocol, with a distilled water control. Flowrates used were 0.08 m³/min for C. macellaria and S. bullata trials and 0.19 m³/min for M. domestica experiments. The release rate of FliesBeGone was 1.5 ± 0.3 mg/min for all ages tested. The observed number of responding flies (no. of flies responding) represents the combined count of eight distinct biological replicated for each distilled water treatment. Statistical analyses were performed using an adjusted χ² analysis (*P < 0.05).