Heliconiusbutterflies host characteristic and phylogenetically structured adult-stage microbiomes

Abstract

1 2 Evolutionary transitions in animal diets often coincide with shifts in the microbiome, but 3 the degree to which diet-microbiome feedbacks vary across host taxa and development is 4 unresolved. We examined these potential feedbacks from the perspective of Lepidoptera 5 (butterflies and moths), a diverse clade in which little is known about adult-stage microbial 6 associations. With the exception of Heliconius butterflies, most lepidopteran adults are short-7 lived and either feed on simple substrates, like nectar, or do not feed at all. Heliconius consume 8 pollen as adults, which provides amino acids and allows the butterflies to have an extended 9 lifespan. Using 16S rRNA gene sequencing of 214 field-collected individuals, we found that 10 adult passion-vine butterfly microbiomes exhibited a strong signal of host phylogeny, with a 11 clear distinction between Heliconius and non-pollen-feeding relatives. This pattern was largely 12 driven by differing relative abundances of bacterial phylotypes shared among host taxa, as 13 opposed to the presence or absence of host-specific phylotypes. Using shotgun metagenomic 14 sequencing, we also discovered trypanosomatids and microsporidia to be prevalent in butterfly 15 guts, suggesting potential interactions with co-localized gut bacteria. Overall, we show that a 16 major transition in adult-stage lepidopteran diet and life history coincides with a shift in 17 microbiomes, and our work provides a foundation for future tests of microbiome function in 18 adult butterflies. 19 20 Lepidoptera (butterflies and moths) are a diverse and ecologically important group in 31 which microbiome roles are likely to be highly specific to certain host taxa and life stages. For 32 lepidopteran larvae (caterpillars), even major shifts in larval diet do not coincide with 33 functionally relevant shifts in the microbiome [9][10][11]. Lepidopteran larvae typically harbor a 34 very low number of gut microbes, and most of these microbes are transient with the exception of 35 pathogen infections [9]. However, the microbiomes of insects that undergo complete 36 metamorphosis, such as Lepidoptera, often exhibit profound shifts in size, composition and 37 function across host life stages [7]. A recent survey of various butterfly species found that adult-38 stage gut bacterial communities were generally abundant (median ~10 8 16S rRNA gene copies 39 per gut) and distinct from diet-associated bacterial communities [12]. It is possible that 40 evolutionary transitions in the diet of adult lepidopterans could cause, or be caused by, 41 concomitant transitions in adult-stage microbiomes. 42Arguably, the single most dramatic and consequential transition in adult diet among the 43 150,000+ described species of Lepidoptera [13] occurred in the ancestors of neotropical 44Heliconius butterflies (Nymphalidae: Heliconiini). While adults of other lepidopterans either do 45 not feed at all, or feed on comparatively nitrogen-poor and/or inconsistently available substrates 46 [14], Heliconius evolved the abili...

First report on the characterization of the gut microbiota in Heliconius erato phyllis caterpillars (Lepidoptera-Nymphalidae) from southern Brazil

“…This study is the first to assess gut bacterial communities in 5th instar caterpillars of H. erato phyllis in Brazil. Our findings align with previous research by Hammer et al (2014Hammer et al ( , 2020 and van Schooten et al (2018) on Heliconius subspecies from Panama.…”

“…Microorganisms in the guts of insects play crucial roles in improving nutrition, synthesizing vitamins, establishing metabolic pathways, participating in xenobiotic degradation, and defending against pathogens. Despite its significance, the gut microbiota of Heliconius butterflies have been explored in only a few studies to date (Hammer et al, 2014(Hammer et al, , 2020van Schooten et al, 2018).…”