‘Candidatus Streptomyces philanthi’, an endosymbiotic streptomycete in the antennae of Philanthus digger wasps

Abstract

Symbiotic interactions with bacteria are essential for the survival and reproduction of many insects. The European beewolf (Philanthus triangulum, Hymenoptera, Crabronidae) engages in a highly specific association with bacteria of the genus Streptomyces that appears to protect beewolf offspring against infection by pathogens. Using transmission and scanning electron microscopy, the bacteria were located in the antennal glands of female wasps, where they form dense cell clusters. Using genetic methods, closely related streptomycetes were found in the antennae of 27 Philanthus species (including two subspecies of P. triangulum from distant localities). In contrast, no endosymbionts could be detected in the antennae of other genera within the subfamily Philanthinae (Aphilanthops, Clypeadon and Cerceris). On the basis of morphological, genetic and ecological data, ‘Candidatus Streptomyces philanthi’ is proposed. 16S rRNA gene sequence data are provided for 28 ecotypes of ‘Candidatus Streptomyces philanthi’ that reside in different host species and subspecies of the genus Philanthus. Primers for the selective amplification of ‘Candidatus Streptomyces philanthi’ and an oligonucleotide probe for specific detection by fluorescence in situ hybridization (FISH) are described.

Refining the Roots of the Beewolf-Streptomyces Symbiosis: Antennal Symbionts in the Rare Genus Philanthinus (Hymenoptera, Crabronidae)

“…Streptomyces philanthi"-specific forward primer Strep_phil_fwd3 in combination with the general actinomycete reverse primer Act-A19) ( Table 1) to check for the presence of "Ca. Streptomyces philanthi" (14). Subsequently, the primers fD1 and Spa-2R were used for amplification of about 2060 bp of the 16S rRNA gene, including parts of the 16S-23S intergenic spacer region (12,30).…”

“…Subsequently, the primers fD1 and Spa-2R were used for amplification of about 2060 bp of the 16S rRNA gene, including parts of the 16S-23S intergenic spacer region (12,30). The amplicon was purified, and 1,490 bp were sequenced bidirectionally with primers fD1 and rP2 (14,17,30). PCRs were performed on a VWR thermocycler in total reaction volumes of 12.5 l containing 1 l of template, 1ϫ PCR buffer (10 mM Tris-HCl, 50 mM KCl, 0.1% Triton X-100), 2.5 mM MgCl 2 , 240 M deoxynucleoside triphosphates, 20 pmol of each primer, and 1 U of Taq DNA polymerase (VWR).…”

“…Solitary digger wasps of the genera Philanthus and Trachypus (Hymenoptera, Crabronidae), the so-called beewolves, have been shown to engage in a highly specialized symbiotic association with actinobacteria of the genus Streptomyces ("Candidatus Streptomyces philanthi") (14,15,17). The symbionts are cultivated in unique antennal gland reservoirs that constitute invaginations of the outer antennal cuticle (9).…”

“…The antennal Streptomyces symbionts have been described for the genera Philanthus (14,15) and Trachypus (17), while other genera of the subfamily Philanthinae (Cerceris, Aphilanthops, and Clypeadon) apparently lack the symbionts (14). The rare genera Philanthinus and Pseudoscolia, however, have not yet been investigated.…”

Mycobiota in the brood cells of the European beewolf, Philanthus triangulum (Hymenoptera: Crabronidae)

“…The entire "cocktail" has a broad range of inhibi-tory activity that is achieved by combining complementary strain specifi c inhibition of single components (Kroiss et al, 2010). This combination therapy is effective against a wide range of opportunistic and entomopathogenic fungi and bacteria, including A. fl avus and F. oxysporum (Kaltenpoth et al, 2005(Kaltenpoth et al, , 2006Kroiss et al, 2010).…”