Molecular and Chemical Basis of Social Olfaction in Polistes Paper Wasps

Abstract

During my graduate studies, I focused on the northern paper wasp Polistes fuscatus, a classic model system in the study of animal recognition behavior. P. fuscatus wasps use cuticular chemicals as a source of information to guide multiple behaviors, such as mate choice and nestmate recognition. I investigated phenotypic variation in P. fuscatus cuticular hydrocarbons (CHCs) using solid-phase microextraction and GC-FID. Chapter 1 presents the CHCs found on P. fuscatus, informed by GC-MS results generously shared by Dr. Kevin Loope, and identifies nest-specific chemical signatures that could mediate nestmate recognition. Chapter 2 presents comparative genomics analyses of the Polistes odorant receptor (OR) gene family. I argue that the OR gene family and 9-exon subfamily expanded in gene copy number during the evolution of sociality in wasps, independent of ants. Patterns of molecular evolution of the 9-exon OR subfamily are investigated, and the relevance of these evolutionary patterns to the perception of complex chemical signatures is discussed. Chapter 3 reports sex-biased antennal gene expression patterns in P. fuscatus, identifying candidate sex pheromone receptors and documenting expression of 9-exon ORs in males, deviating from patterns observed in ants. In Chapter 4, I analyze short-term changes in body posture of P. fuscatus foundresses in response to experimentally introduced conspecific intruders in the field and discuss how persistent vigilance may relate to plasticity in nestmate recognition behavior.