Sagehen Creek Field Station

07 Jun, 01 PM - 09 Jun, 06 PM

Eusocial insects are categorized by their multi-generational, cooperative societies that are divided into a reproductive and worker caste. Chemical recognition systems in Hymenoptera (ants, bees and wasps) maintain these tight knit colonies as a way for individuals to discriminate between nestmates and non-nestmates so that altruism is directed appropriately at colony members. Strict recognition systems guard against cheaters who would otherwise exploit the wealth of resources that a social society provides, including protection from predators, brood care and food. Despite these efforts, social parasites have evolved a suite of strategies for hacking the chemical cues of their hosts so that they may infiltrate colony boarders and steal resources. Slave-making social parasitism has been an infamous example for parasitic relationships in ants. In this form of parasitism, newly mated parasite queens enter the nest of a host colony, kill the resident queen and live unscathed in the foreign nest with a workforce of enslaved hosts. These host workers aid in rearing the queen parasites offspring. To replenish this host worker caste, parasite workers conduct impressive raids on neighboring, free-living host colonies, capturing their pupa and continuing the cycle of enslavement. Here, I investigate slave-making social parasitism in ants described in the Formica genus where species of the Sanguinea group are facultative parasites. Species in this group depend on a host nest for colony founding and raid and enslave host workers until they have the parasite worker capacity to live independently as a pure colony. Formica aserva is one of the Nearctic facultative slave-makers found across North America with concentrated populations in Northern California. As a group, researchers know very little about the evolution of this form of parasitism and the mechanisms that parasites employ during the founding, raid, capture and integration of a host species. For this upcoming field research, I propose answering the question, What chemical strategies do facultative parasites use during the acquisition of a host species Objectives: Nestmate recognition cues are crucial for discriminating against non-members that might otherwise exploit a colonys resources7. Social parasites with an exploitative nature must therefore find a way to manipulate such cues for their own benefit. Here, I will investigate the proximate cause of (1) host integration by parasite workers and (2) host usurpation by newly mated parasite queens. Field site: The proposed research will be conducted at the Sagehen Creek Field Station located NW of Truckee, CA, in the Sierra Nevada mountain range. The habitat consists of a watershed with mixed conifer and red fir forests along with scattered mountain meadows at an elevation of ~6,500 feet. I will require a spot GPS/satellite phone, marking flags, trowels, buckets, forceps/aspirators (for collecting workers) and collection vials. Additionally, I will need to update my NOLS Wilderness First Aid training so that I am certified to lead a team of researchers in the backcountry. Hypothesis 1: Parasite workers label enslaved hosts with their own recognition cues Recent progress has been made by Wlodarczyk & Szczepaniak on the strategies used by the facultative slave-maker, Formica sanguinea; a close parasitic relative to Formica aserva. Their study revealed that parasite workers do not modify their CHC profile to mimic the recognition code of the host but, instead, label the enslaved host workers with their own species- and colony-specific odors6. It is likely that F. aserva workers use a similar labeling strategy for manipulating the nestmate recognition cues of enslaved workers. Hypothesis 2: Founding parasite queens chemically evade host attacks during usurpation Relative to the research that exists on parasite worker manipulation of host recognition cues, very little work has been done to investigate what types of strategies the parasite queens use to establish their nest within an existing host colony6. The strategy used by the newly mated queens may be evidence for more sophisticated chemical mimicry since this dependent-founding behavior is risky for a queen who might otherwise face potentially fatal interactions upon entering a foreign nest without such camouflage. The force of selection is most likely stronger in this scenario and thus may have resulted in adaptations to queen pheromones and/or denovo biosynthesis of host-specific odors. Significance and progress: Facultative socially parasitic ants are woefully understudied in the literature. Significant gaps include crucial aspects of their natural history (i.e. queen founding, division of labor among parasite and host workers, raiding) and chemical ecology. This research will provide further evidence for the mechanisms with which facultative parasite workers manipulate the recognition cues of their host. Additionally, novel research on the natural history of facultative parasite colony founding and the corresponding chemical strategies of this behavior will be a significant step towards understanding the evolution of the Formica slave-making clade. To date, I have mapped 13 parasite and 20 free-living host colonies in a montane habitat located NW of Truckee, CA. These colonies were discovered over a two-month period at the Sagehen Creek Field Station in the summer of 2017. I conducted ecological surveys using pitfall traps to assess the ant species diversity existing within a parasites range while also performing full colony extractions in the backcountry with the help of my research team.

Visit #57371 @Sagehen Creek Field Station

Approved

Under Project # 40871 | Research

CHAPTER TWO: A Wolf in Sheeps Clothing? Chemical deception strategies of the slave-making ant, Formica aserva

graduate_student - University of California, Berkeley

Reservation Members(s)

Ali Setayesh Jun 8 - 9, 2018 (2 days)
Charlotte Knopp Jun 8 - 9, 2018 (2 days)
Elizabeth Cash Jun 8 - 9, 2018 (2 days)
Kelsey Scheckel Jun 7 - 9, 2018 (3 days)

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Cabin 1 Jun 7 - 10, 2018
Cabin 3 Jun 8 - 10, 2018