Transcriptional effects of predator cues in the brain of Spodoptera frugiperda (lepidoptera: noctuidae) moths exposed to bat ultrasound

Exposure to predators induces broad behavioral and physiological responses that have traditionally been considered acute and transitory. However, prolonged frequent exposure to predators and the chemical, visual, tactile, and auditory cues they broadcast to the environment are now known to have long-term impacts on prey physiology and life-histories. Knowledge on the molecular mechanisms responsible for inducing both acute and chronic responses to predator exposure is limited. Although several studies have assessed acute and chronic stress responses in a variety of taxa, these efforts have often involved a priori expectations of the molecular pathways involved in the physiological response, such as glucocorticoid and neurohormone production. While relatively little is known about physiological and molecular predator-induced stress responses in insects, many dramatic defensive behaviors in insects have been reported. Within several moth families, such as Noctuidae, tympanic organs for recognizing ultrasonic bat calls have evolved and facilitate the avoidance of predation via eliciting flight cessation or aerial maneuvers when stimulated by ultrasound. In this study, I exposed adult male fall armyworm (Spodoptera frugiperda) moths to recorded ultrasonic bat foraging and attack calls for a prolonged period and constructed a de novo transcriptome using RNA-Seq on mRNA extracted from the brains of predator-exposed and unexposed moths. I then identified differentially-expressed transcripts between the exposed and control groups and used functional gene analysis and Gene Ontology (GO) enrichment analysis to reveal that the majority of differentially expressed transcripts corresponded to a broad range of proteins involved in cellular processes in the brain, including glutamate production and metabolism, ionotropic sensory receptor expression, mitochondrial metabolism, actin cytoskeleton dynamics, chromatin binding and other epigenetic modifications, axonal guidance and remodeling, cilia function and development, Wnt signaling, and TOR signaling. The top five significantly over-represented GO terms included chromatin binding, macromolecular complex binding, glutamate synthase activity, glutamate metabolic process, and glutamate biosynthetic process. Although limited by a de novo approach, this study demonstrates that predator-induced transcriptional responses in S. frugiperda vary broadly in their physiological and molecular functions. As a first assessment of auditory predator cues on transcriptional responses in moth prey, this study also lays the foundation for future research on the complex array of integrated behavioral, physiological, and cellular responses to predators observed in ultrasound-sensitive Lepidoptera.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Entomology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2016

Author dc:creator

• Cinel, Scott Dominic

Contributors dc:contributor

• Taylor, Steven J.
• Berenbaum, May R.
• Bell, Alison M.
• Allan, Brian F.

• predator
• prey
• bat-moth
• auditory
• brain
• transcription
• stress
• lepidoptera
• Spodoptera
• fall armyworm

Statement dc:rights

• © 2016 Scott Dominic Cinel

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/92757

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/92757