Impact of antibiotic treatment on mating behavior, microbial diversity, and gene expression in Lucilia cuprina

The blowfly (Lucilia cuprina) is used as a model organism to develop genetic tools for controlling the screwworm (Cochliomyia hominivorax), a devastating agricultural pest. One such tool is the Tetracycline Transactivator system (tTA). In this system, target genes are repressed in the presence of a tetracycline-class compound. Therefore, by incorporating tetracycline (or a related compound) into the flies' diet, genes important for development are turned off. This is a powerful and flexible system that can be leveraged for pest population control. However, antibiotics, including tetracyclines, have been repeatedly shown in the literature to have negative effects on arthropod physiology and behavior, including reproduction. Furthermore, recent studies have demonstrated that these negative effects can be inherited by the untreated offspring of antibiotic-treated parents. In an effort to better understand how dietary tetracyclines affect blowflies, I investigated flies' mating behavior, gene expression, and microbial diversity under three dietary regimens: doxycycline (a potent antibiotic and tetracycline-class compound), anhydrotetracycline (a tetracycline-class compound lacking antibiotic activity), and supplemental water (control). Flies treated with doxycycline were less reproductively successful, had less-diverse microbiota, and displayed a distinct transcriptional profile compared to flies treated with either anhydrotetracycline or water. Similar patterns were observed in the untreated offspring of doxycycline-treated flies, lending support to previous findings that the effects of antibiotics can be inherited. This work expands our understanding of how antibiotics affect arthropods, and highlights a potential role for non-antibiotic compounds like anhydrotetracycline in the tTA system.