Prevalence and virulence factors of Candida spp. associated with blow flies

Objective:To investigate the prevalence of Candida spp.and the virulence factors of Candida albicans(C.albicans) isolated from external surfaces of blow flies collected from Mae Sot,Tak Province,Thailand.Methods:The blow flies were collected by sterile sweep nets from three areas in Mae Sot.Yeast isolation was first performed on Sabouraud dextrose agar(SDA) supplemented with chloramphenicol and cycloheximide.The yeast isolates were then identified by using chromogenic agar,a yeast identification test kit,a germ tube formation test and a carbohydrate utilization test.The β-hemolysis was determined on 7% sheep blood agar,while phospholipase activity was measured on SDA agar supplemented with 10% egg yolk suspension.Antifungal susceptibility testing was determined by broth micro-dilution testing against ketoconazole and amphotericin B.Results:The prevalence rate of Candida spp.on the external surfaces of the blow flies was 78.1%.All C.albicans isolated from the blow fly demonstrated b-hemolysin and potent phospholipase activities and 47.1% of C.albicans were resistant to ketoconazole with MIC values 128 mg/m L.Conclusions:The results indicate that blow flies could play an essential role in the transmission of potentially pathogenic and antifungal resistant C.albicans into the environment.Further investigation on other virulence factors and genetic relatedness among isolates from the blow flies,the environment and clinical specimens is required to confirm this role.

Is aggregated oviposition by the blow flies Lucilia sericata and Phormia regina （Diptera： Calliphoridae） really pheromone-mediated？

When female blow flies Lucilia sericata and Phormia regina （Diptera： Cal- liphoridae） oviposit in aggregations on carrion, even-aged larval offspring reportedly de- velop faster, and fewer are parasitized or preyed upon. The benefits of aggregated ovipo- sition equally affect con- and heterospecific larvae sharing a resource. The benefits imply that female blow flies engage in coordinated, pheromone-mediated oviposition behavior. Yet, repeated attempts to identify oviposition pheromones have failed invoking doubt that they exist. Simply by regurgitating and feeding on carrion, flies may produce attractive semiochemicals. If flies were to aggregate in response to feeding flies rather than oviposit- ing flies, then the semiochemical cue（s） may be associated with the salivary gland. Working with L. sericata and P.. regina and using liver as a surrogate oviposition medium, we test the hypotheses, and present data in their support, that （i） gravid or nongravid females ovipositing and/or feeding on liver enhance its attractiveness to gravid and nongravid fe- males; （ii） females respond to semiochemicals from feeding heterospecific females; （iii） females respond equally well to semiochemicals from feeding con- and heterospecific females; （iv） macerated head tissues of females applied to liver enhance its attractiveness; and （v） females in direct contact with and feeding on liver, but not when next to yet physically separated from liver, enhance attraction of flies. We conclude that oviposition site-seeking females do not respond to an oviposition pheromone. Instead, they appear to coopt semiochemicals associated with feeding flies as resource indicators, taking chances that resources are suitable for oviposition, and that ovipositing flies are present.