The ＂fly factor＂ was first discovered 〉60 years ago and describes the phe- nomenon that food currently or previously fed on by flies attracts more foraging flies than the same type and amount of food kept inaccessi...The ＂fly factor＂ was first discovered 〉60 years ago and describes the phe- nomenon that food currently or previously fed on by flies attracts more foraging flies than the same type and amount of food kept inaccessible to flies. Since then, there has been little progress made to understanding this phenomenon. Our objectives were （i） to demonstrate the existence of the fly factor in house flies, Musca domestica and （ii） to study underlying mechanisms that may cause or contribute to the fly factor. In 2-choice laboratory bioassays, we obtained unambiguous evidence for a fly factor phenomenon in house flies, in that we demonstrated that feeding flies are more attractive to foraging flies than are nonfeeding flies, and that fed-on food is more attractive to foraging flies than is ＂clean＂ food. Of the potential mechanisms （fly excreta, metabolic output parameters [elevated temperature, relative humidity, carbon dioxide]）, causing the fly factor, fly feces, and regurgitate do at- tract foraging flies but none of the metabolic output parameters of feeding flies does. Even though feeding flies produce significantly more CO2 than nonfeeding flies, elevated levels of CO2 have no behavior-modifying effect on flies. Preferential attraction of house flies to fly feces and regurgitate indicates that the flies sense airborne semiochemicals emana- ting from these sources. Hypothesizing that these semiochemicals are microbe-produced, future studies will aim at isolating and mass producing these microbes to accumulate semiochemicals for identification.展开更多
The house fly, Musca domestica, has been implicated as a vector of Campy- lobacter spp., a major cause of human disease. Little is known whether house flies serve as biological amplifying hosts or mechanical vectors f...The house fly, Musca domestica, has been implicated as a vector of Campy- lobacter spp., a major cause of human disease. Little is known whether house flies serve as biological amplifying hosts or mechanical vectors for Campylobacterjejuni. We in- vestigated the period after C. jejuni had been ingested by house flies in which viable C. jejuni colonies could be isolated from whole bodies, the vomitus and the excreta of adult M. domestica and evaluated the activation of innate immune responses of house flies to ingested C. jejuni over time. C. jejuni could be cultured from infected houseflies soon after ingestion but no countable C. jejuni colonies were observed 〉 24 h postingestion. We detected viable C. jejuni in house fly vomitus and excreta up to 4 h after ingestion, but no viable bacteria were detected 〉 8 h. Suppression subtractive hybridization identi- fied pathogen-induced gene expression in the intestinal tracts of adult house flies 4-24 h after ingesting C. jejuni. We measured the expression of immune regulatory （thor, JNK, and spheroide） and effector （cecropin, diptericin, attacin, defensing, and lysozyme） genes in C. jejuni-infected and -uninfected house flies using quantitative real time PCR. Some house fly factor, or combination of factors, eliminates C. jejuni within 24 h postingestion. Because C. jejuni is not amplified within the body of the housefly, this insect likely serves as a mechanical vector rather than as a true biological, amplifying vector for C. jejuni, and adds to our understanding of insect pathogen interactions.展开更多
文摘The ＂fly factor＂ was first discovered 〉60 years ago and describes the phe- nomenon that food currently or previously fed on by flies attracts more foraging flies than the same type and amount of food kept inaccessible to flies. Since then, there has been little progress made to understanding this phenomenon. Our objectives were （i） to demonstrate the existence of the fly factor in house flies, Musca domestica and （ii） to study underlying mechanisms that may cause or contribute to the fly factor. In 2-choice laboratory bioassays, we obtained unambiguous evidence for a fly factor phenomenon in house flies, in that we demonstrated that feeding flies are more attractive to foraging flies than are nonfeeding flies, and that fed-on food is more attractive to foraging flies than is ＂clean＂ food. Of the potential mechanisms （fly excreta, metabolic output parameters [elevated temperature, relative humidity, carbon dioxide]）, causing the fly factor, fly feces, and regurgitate do at- tract foraging flies but none of the metabolic output parameters of feeding flies does. Even though feeding flies produce significantly more CO2 than nonfeeding flies, elevated levels of CO2 have no behavior-modifying effect on flies. Preferential attraction of house flies to fly feces and regurgitate indicates that the flies sense airborne semiochemicals emana- ting from these sources. Hypothesizing that these semiochemicals are microbe-produced, future studies will aim at isolating and mass producing these microbes to accumulate semiochemicals for identification.
文摘The house fly, Musca domestica, has been implicated as a vector of Campy- lobacter spp., a major cause of human disease. Little is known whether house flies serve as biological amplifying hosts or mechanical vectors for Campylobacterjejuni. We in- vestigated the period after C. jejuni had been ingested by house flies in which viable C. jejuni colonies could be isolated from whole bodies, the vomitus and the excreta of adult M. domestica and evaluated the activation of innate immune responses of house flies to ingested C. jejuni over time. C. jejuni could be cultured from infected houseflies soon after ingestion but no countable C. jejuni colonies were observed 〉 24 h postingestion. We detected viable C. jejuni in house fly vomitus and excreta up to 4 h after ingestion, but no viable bacteria were detected 〉 8 h. Suppression subtractive hybridization identi- fied pathogen-induced gene expression in the intestinal tracts of adult house flies 4-24 h after ingesting C. jejuni. We measured the expression of immune regulatory （thor, JNK, and spheroide） and effector （cecropin, diptericin, attacin, defensing, and lysozyme） genes in C. jejuni-infected and -uninfected house flies using quantitative real time PCR. Some house fly factor, or combination of factors, eliminates C. jejuni within 24 h postingestion. Because C. jejuni is not amplified within the body of the housefly, this insect likely serves as a mechanical vector rather than as a true biological, amplifying vector for C. jejuni, and adds to our understanding of insect pathogen interactions.
