Flower Mimics Roll Out Multicolored Carpets to Lure and Kill the House Fly

SIMPLE SUMMARY: Besides being a nuisance, house flies are known mechanical vectors of bacteria, helminthes, protozoans, and viruses, potentially including Coronaviruses. To prevent the occurrence of these public health issues, efforts have mainly targeted reducing house fly populations with chemical insecticides. However, the development of resistance has impeded success using this strategy. Toxic bait formulations and traps have been crucial components of these control efforts. Although bait-based strategies have sometimes been successful against fly populations, overall, management programs based on this strategy have severely suffered from the development of resistance and lack of attractiveness to the insects. Trapping strategies require the bait to be attuned to the tastes of the target animal. As flies are regular visitors and pollinators that use flowers for numerous other rewards, strategies using blooms as lures may prove effective in managing their populations. Floral mimics have been successfully used to establish preference patterns of insect pollinators. Using dual-choice bioassays with blue-, yellow-, red-, purple-, and pink-colored flowers, we found that colorful designs made of such artificial flowers incorporating a toxicant attracted and killed foraging houseflies. Such attraction of the colorful floral designs suggests the potential for development of sound attract-and-kill devices or strategies integrating artificial flower combinations. ABSTRACT: Flowers and their spatial clustering are important parameters that mediate the foraging behavior and visitation rate of pollinating insects. Visual stimuli are crucial for triggering behavioral changes in the house fly, Musca domestica, which regularly visits plants for feeding and reproduction. The success of bait technology, which is the principal means of combatting flies, is adversely affected by reduced attractiveness and ineffective application techniques. Despite evidence that house flies have color vision capacity, respond to flowers, and exhibit color and pattern preference, the potential of artificial flowers as attractive factors has not been explored. The present study was performed to investigate whether artificial floral designs can lure and kill house flies. Starved wild house flies were presented with equal opportunities to acquire sugar meals, to which boric acid had been added as a toxin, from one flower arrangement (blue-dominated design, BDD; yellow-dominated design, YDD; or pink-dominated design, PDD), and a non-toxic white design (WDD). We also allowed house flies to forage within an enclosure containing two non-toxic floral designs (WDDs). The differences in mortality between the two environments with and without toxicant were examined. The survival rate of Musca domestica was extremely high when WDDs containing non-toxic sugar sources were the only feeding sites available. When given an option to forage in an environment containing a BDD and a WDD, house flies showed a high mortality rate (76%) compared to their counterparts maintained in the WDD environment (2%). When kept in an enclosure containing one YDD and a WDD, flies showed a mortality rate of 88%; however, no mortality occurred among flies confined to a compound with a WDD pair. When provided an even chance of foraging in an enclosure containing a mixed pair of floral arrangements (PDD and WDD) and another with two WDDs, flies showed a higher mortality rate (78%) in the first environment. However, the maximum survival rate (100%) was seen in the WDD environment. Exposure to YDD tended to result in a greater mortality rate than with the two other floral designs. Mortality gradually increased with time among flies exposed to tested artificial floral designs. The results presented here clearly indicated that artificial flower arrangements with a toxic sugar reward were strikingly attractive for house flies when their preferred color (white) was present. These observations offer novel possibilities for future development of flower mimic-based house fly control.