Establishment and Vertical Passage of Enterobacter (Pantoea) Agglomerans and Klebsiella pneumoniae through All Life Stages of the Mediterranean Fruit Fly (Diptera: Tephritidae)

Abstract

We investigated the fate of ingested Enterobacter (Pantoea) agglomerans and Klebsiella pneumoniae within adult Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), in a mass rearing facility. This examination revealed the establishment of both bacterial strains as biofilms within the adult intestines, on the apical end of developing and developed eggs, and throughout all subsequent life stages. The bacteria were detected in adults through two generations. Irradiation treatment for the sterile insect technique did not disrupt the vertical transmission of E. (P.) agglomerans or K. pneumoniae. This is the first demonstration of maternal spread of Enterobacter/ Pantoea spp. and Klebsiella spp. through populations of C. capitata. A mixed pattern of vertical and horizontal transmission of symbionts associated with tephritids may be one explanation for the difficulty in defining the symbiotic associations of tephritids.

Phylogenetic, Metabolic, and Taxonomic Diversities Shape Mediterranean Fruit Fly Microbiotas during Ontogeny

“…Sources of variation may be internal, originating from different compositions of the birth presents, or external, originating from the acquisition of different environmental bacteria. Bacteria provided in the adult diet easily establish in the fly's gut (13,16), and specific vertically acquired subpopulations expand during ontogeny (Fig. 2).…”

“…Therefore, some mechanisms should exist to overcome homogenization while sieving out unwanted colonizers. Such mechanisms may be at play in the medfly: as stated above, bacteria introduced by feeding established in the fly gut (13,16) and could be transmitted to the eggs and through two generations (16). These experiments used bacterial strains isolated from fruit flies.…”

“…Probes distinguishing between Klebsiella and Enterobacter, two taxa commonly detected in medflies (3,13,16), were designed based on 140 partial 16S rRNA gene bacterial sequences, including sequences derived from medfly (GenBank accession numbers AY847157 to AY847186, DQ533879 to DQ533882, DQ533884 to DQ533889, DQ533891 to DQ533895, DQ533897, DQ533898, EF117864, EF117865, EF645648 to EF645662, EU026215, DQ533883, and DQ533896), using the 2009 SILVA bacterial 16S rRNA database (22), which is available online (http://www.arb-silva.de/); the ARB software package (23); and the ARB probe design tool. The probes were optimized to centralize mismatches between the probes and nontarget organisms (24), and accessibility was examined as described previously by Behrens et al (25).…”

“…These components of the bacterial community remain stable throughout the fly's life cycle and between geographical regions, and some are inherited vertically (3,12,(14)(15)(16). However, significant genotypic variation underlies this apparent taxonomic stability, as a large microdiversity of the 16S rRNA gene marker is observed at the strain level, and alterations in strain distribution are observed during ontogeny and between individuals (3,14).…”

Insect “Symbiology” Is Coming of Age, Bridging Between Bench and Field

“…In both flies, egg smearing during passage in the ovipositor seems to be the mechanism by which the symbionts are transmitted to the next generation (Estes et al 2009;Lauzon et al 2009;Behar et al 2008a;unpublished results). How can vertical transmission be guaranteed when nutritional needs and therefore the contribution of symbionts may change during the life cycle of the host?…”