Ablation of Caterpillar Labial Salivary Glands: Technique for Determining the Role of Saliva in Insect–Plant Interactions

Abstract

There has been an ardent interest in herbivore saliva due to its roles in inducing plant defenses and its impact on herbivore fitness. Two techniques are described that inhibit the secretion of labial saliva from the caterpillar, Helicoverpa zea, during feeding. The methods rely on cauterizing the caterpillar's spinneret, the principal secretory structure of the labial glands, or surgically removing the labial salivary gland. Both methods successfully inhibit secretion of saliva and the principal salivary enzyme glucose oxidase. Caterpillars with inhibited saliva production feed at similar rates as the untreated caterpillars, pupate, and emerge as adults. Glucose oxidase has been suggested to increase the caterpillar's survival through the suppression of inducible anti-herbivore defenses in plants. Tobacco (Nicotiana tabacum) leaves fed on by caterpillars with ablated salivary glands had significantly higher levels of nicotine, an inducible anti-herbivore defense compound of tobacco, than leaves fed upon by caterpillars with intact labial salivary glands. Tomato (Lycopersicon esculentum) leaves fed upon by caterpillars with suppressed salivary secretions showed greatly reduced evidence of hydrogen peroxide formation compared to leaves fed upon by intact caterpillars. These two methods are useful techniques for determining the role that saliva plays in manipulating plant anti-herbivore defenses.

Robotic mechanical wounding (MecWorm) versus herbivore-induced responses: early signaling and volatile emission in Lima bean (Phaseolus lunatus L.)

“…In contrast, continuous mechanical damage by MecWorm stimulates in Lima bean leaves the emission of the full spectrum of volatiles that are characteristic for feeding insects . Since also OS of herbivores play an important role in triggering specific plant responses (Turlings et al 2000;Musser et al 2006;Shukle et al 2009;Petzold et al 2009) their genuine effect without being superimposed by mechanical effects is an important information that is necessary to reduce the complex scenario of plant defense into discrete signaling pathways. By employing MecWorm, we have been able to investigate and compare the plant defense-inducing capability of continuous mechanical damage and insect-derived chemical signals in detail.…”

Survey of a Salivary Effector in Caterpillars: Glucose Oxidase Variation and Correlation with Host Range

“…In some cases, GOX may contribute to the initial oxidative burst of H 2 O 2 observed in leaves damaged by herbivores (Bi and Felton, 1995;Bi et al, 1997a;Orozco-Cardenas and Ryan, 1999;Musser et al, 2006). GOX belongs to the family of GMC-oxidoreductases (Iida et al, 2007) and catalyzes the following reaction: D À glucoseþO 2 !…”

Volatiles from a Mite-Infested Spruce Clone and Their Effects on Pine Weevil Behavior

“…The reactions of plants attacked by herbivores are complex and include the release of "stress compounds", e.g., linalool, 4,8-dimethylnona-1,3,7-triene (DMNT), (E,E)-α-and (E)-β-farnesene (Pare and Tumlinson 1999). In plants, induced stress reactions can be initiated by specific compounds present in the oral secretions of herbivores (Musser et al 2006). Such reactions have been found to be herbivorespecific (Takabayashi et al 1991;Delphia et al 2007).…”