North American Fireflies Host Low Bacterial Diversity

Abstract

Although there are numerous studies of firefly mating flashes, lantern bioluminescence, and anti-predation lucibufagin metabolites, almost nothing is known about their microbiome. We therefore used 16S rRNA community amplicon sequencing to characterize the gut and body microbiomes of four North American firefly taxa: Ellychnia corrusca, the Photuris versicolor species complex, Pyractomena borealis, and Pyropyga decipiens. These firefly microbiomes all have very low species diversity, often dominated by a single species, and each firefly type has a Pyractomena borealis and Pyropyga decipiens [2]. These 4 types of fireflies occur sympatrically, ranging from the eastern coast of Canada, south to Florida, and west to the Great Plains [2, 3]. All four of these fireflies are carnivorous or omnivorous as larvae, attacking snails as their prey, and/or eating nectar and plant sap [4]. Ellychnia corrusca, Pyractomena borealis and Pyropyga decipiens are all closely related to each other, and both E. corrusca and Pyropyga decipiens are diurnal with no lantern [2]. Ellychnia corrusca, Pyractomena borealis, and many other North American fireflies use lucibufagins as a chemical defense. Lucibufagins are cardioactive C-24 steroidal pyrenes and a subclass of the bufadienolides [5-8] that create a disagreeable taste to predators and thereby provide fireflies with protection from bats, birds, and spiders [5].However, the biosynthetic origin of lucibufagins is not known. At least five genera of fireflies, including the groups in this study, ingest the nectar of the common milkweed plant (Asclepias syriaca L.). Although eating is not required for adult firefly survival, cardenolides (a type of toxic steroid) found on milkweed plants are ingested by adult fireflies and may be used to produce lucibufagins [9].In this study, we focused especially on two fireflies with unique lifestyles: E. corrusca and the Photuris versicolor species complex. Ellychnia corrusca is nicknamed the winter firefly because it has a winter-spring activity cycle, in contrast to the late spring-summer activity cycles of most other fireflies [2,10]. Ellychnia corrusca larvae in New England (North America) extend their larval stage across two years instead of one to ensure that they ingest ample calories, emerging in the late fall of their second year as adults and sexually maturing during the winter to start mating, which lasts until late spring [11]. Normally, adult fireflies do not need to feed because they only survive as adults for 2 to 4 weeks [2,4]. However, E. corrusca firefly adults live for ~9 months, and in Massachusetts USA they ingest interstitial fluid and sap from maple .

Trachymyrmex septentrionalis Ant Microbiome Assembly Is Unique to Individual Colonies and Castes

“…Some pupae were ethanol-washed and others were not to determine if the Tenericutes symbionts were located on their exoskeleton or internally. DNA was extracted from these surface-cleaned ants using the bead-beating and chloroform-isopropanol protocol described previously ( 52 , 55 ). Our preliminary data showed minimal differences between microbiomes generated using whole, surface-cleaned ants and ant guts, so we used whole, surface-cleaned ants throughout this study for simplicity ( Fig.…”

Trachymyrmex septentrionalis ant microbiome assembly is unique to individual colonies and castes

“…Some pupae were ethanol-washed and others were not to determine if the Tenericute symbionts were located on their exoskeleton or internally. DNA was extracted from these surface-sterilized ants using the bead-beating and chloroform-isopropanol protocol described previously [34,37]. Our preliminary data showed minimal differences between microbiomes generated using whole surface-sterilized ants and ant guts, and so we used whole, surface-sterilized ants throughout this study for simplicity (Suppl.…”