Distinct research opportunities in arthropod communication and immune ecology

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We will study 3 modal systems that offer particularly intriguing research opportunities in arthropod communication and immune ecology, as follows: (1) Do sex pheromones of spiders mediate both intra- and inter-sexual communication? Sex pheromones are a primary modality of communication in web-building spiders but only nine pheromones have been identified thus far, and all function in the context of sexual communication. Yet, pheromones are thought to play major roles in many contexts, including honest or dishonest signaling, courtship behavior, mate choice, and habitat selection. Working with the false black widow spider, Steatoda grossa, we will study the source of its pheromones and their roles in both intra- and inter-sexual communication. Specifically, we will test the hypotheses that: (1) contact sex pheromone components of females originate from their silk glands; (2) females, in accordance with their reproductive status, manipulate their webs' pH to facilitate (or not) the hydrolysis of web-borne contact pheromone components and thereby the release (or not) of attractant pheromone components; (3) both starvation status and age of females affect the amount of pheromone they (can) produce; and (4) females facing mate competition adjust their web architecture and its pheromone release in relation to the number-density of webs they experience in a micro-location. We will identify and quantify pheromone components using sophisticated HPLC-MS-MS and NMR spectroscopy. We will track the females' web pH manipulations with a pH meter adjusted for micro measurements. (2) Do ants context-specifically adjust their signaling system? Pheromone blends of insects are typically "rigid" with minimal variation between conspecifics. In social insects such as ants, however, they may need to be "adjustable". Foraging and nest-guarding ants, e.g., encounter different types of distress that require "calls" for many or few nest mates to help. Working with the Western carpenter ant, Camponotus modoc, we will test the hypothesis that distressed worker ants - context-specifically - modulate the composition of their recruitment pheromone and concurrently produce vibratory signals during severe incidences of distress. We will analyze the chemical composition of recruitment "calls" by GC-EAD and GC-MS, and record vibratory signals with a laser Doppler vibrometer. (3) What are the antimicrobial agents in bed bug immune pathways? Bed bugs harbor disease-causing pathogens in their saliva, alimentary tract and hemolymph but unlike other hematophagous arthropods do not vector these pathogens. We will test the hypothesis that bed bugs produce peptides which - in combination - express antimicrobial activity against a wide variety of pathogens. After electrophoresis of cold-extracted proteins/peptides, we will subject gels to agar overlay assays to determine the protein/peptide bands that express antimicrobial activity. These bands will be sequenced for identification.