Insect saliva: An integrative approach
Authors: Musser Richard O. 
Published: January 2005

An organism's saliva has a direct “intimacy” with the environment. Saliva is an oral secretion from salivary glands that can be a watery or an oily matrix of substances that interfaces with the outside world. Insect saliva has numerous functions and properties such as digestion, maintenance of mouth parts, water balance, pathogen transmission, acts as a vehicle for pheromones, provides anti‐predator defenses, has anti‐microbial activity, and can aid in circumventing animal‐host defenses and plant‐host defenses.

This Special Issue of Archives of Insect Biochemistry and Physiology is based on papers presented during a symposium held at the 51st Annual Meeting of the Entomological Society of America, October 2003. The symposium was entitled “Insect Saliva: An Integrative Approach”. The goal of the symposium was to foster discussion among scientists who study insect saliva in relation to animal and plant hosts. The presentations and thus this Special Issue were heavily focused on the function of insect saliva in relation to the interactions of the insect and their host. All articles in this Issue have undergone a rigorous review process.

This special Insect Saliva edition nicely complements the symposium presentations. James Tumlinson's and Cameron Lait's article discusses the biosynthesis of fatty acid amide elicitors of plant defenses. These elictors are synthesized by enzymes embedded in the membranes of the insect's crop and anterior midgut. John Labavitch, Kenneth Shackel, Elaine Backus, and colleagues provide a nice contribution showing that much of plant damage by Lygus is due to polygalacturonase activity found in the saliva. Cesar Rodriguez‐Saona, Livy Williams, and colleagues contribute an article that investigates volatile emissions of plants responding to piercing‐sucking herbivores. A report by John Andersen and colleagues provides a look at the role of the salivary protein family, lipocalin, found in the blood‐sucking bug Rhodnius prolixus. Gary Felton and colleague demonstrate in their study that glucose oxidase levels in Helicoverpa zea are altered due to the host plant that the caterpillar feeds on. Ken Korth, Susana Gomez, and colleagues show that terpene synthases, which form the important terpene plant defenses, are elicited in Medicago truncatula by oral secretions of the caterpillar Spodoptera exigua. Richard O. Musser, Gary Felton, and colleagues provide two contributions demonstrating that glucose oxidase has two functions that increase the survival of the caterpillar Helicoverpa zea. The first report further confirms that glucose oxidase is the primary salivary factor to suppress the induction of the anti‐herbivore defense, nicotine, in tobacco plants. The second report shows that the salivary enzyme has anti‐microbial properties that suppress the infectivity of potential bacterial pathogens.

Insect saliva holds exciting potential to better understand the co‐evolution of insect‐host interactions. Studying the complex properties and functions of insect saliva will require integrative and collaborative effort of scientists specializing in various areas.