Culture-independent characterization of the microbiota of the ant lion Myrmeleon mobilis (Neuroptera: Myrmeleontidae)

Ant lions are insect larvae that feed on the liquefied internal components of insect prey. Prey capture is assisted by the injection of toxins that are reportedly derived from both the insect and bacterial symbionts. These larvae display interesting gut physiology where the midgut is not connected to the hindgut, preventing elimination of solid waste until adulthood. The presence of a discontinuous gut and the potential involvement of bacteria in prey paralyzation suggest an interesting microbjal role in ant lion biology; however, the ant lion microbiota has not been described in detail. We therefore performed culture-independent 16S rRNA gene sequence analysis of the bacteria associated with tissues of an ant lion, Myrmeleon mobilis. All 222 sequences were identified as Proteobacteria and could be subdivided into two main groups, the alpha-Proteobacteria with similarity to Wolbachia spp. (75 clones) and the T-Proteobacteria with similarity to the family Enterobacteriaceae (144 clones). The Enterobacteriaceae-like 16S rRNA gene sequences were most commonly isolated from gut tissue, and Wolbachia-like sequences were predominant in the head and body tissue. Fluorescence in situ hybridization analyses supported the localization of enterics to gut tissue and Wolbachia to nongut tissue. The diversity of sequences isolated from freshly caught, laboratory-fed, and laboratory-starved ant lions were qualitatively similar, although the libraries from each treatment were significantly different (P = 0.05). These results represent the first culture-independent analysis of the microbiota associated with a discontinuous insect gut and suggest that the ant lion microbial community is relatively simple, which may be a reflection of the diet and gut physiology of these insects.