Publisher Summary Salivary function is especially interesting in Hemiptera because of the effects the saliva has on the living and surviving organisms, on which many of these insects feed. The saliva of Hemiptera is by no means a simple secretion—in addition to the usual salivary functions of moistening food and mixing it with hydrolytic enzymes before ingestion, the saliva of phytophagous species plays an important physiochemical role during the mechanical penetration of plant tissues by the piercing and sucking mouthparts; in accomplishing this task, the saliva may vary in its chemical composition and physical consistency from one moment to the next. Moreover, deposits of solidifying components of the saliva of many species persist in the food plants, modifying the long term effects of feeding by the insects. This chapter compiles the various types of investigation on salivary functions in the Homoptera and Heteroptera, and suggests profitable lines of future investigation based on analogous functions in different taxonomic groups.

The Saliva of Hemiptera

The factors responsible for determining the host-plants and feeding sites of aphids, and the various probing activities (the role of the labium, stylet insertion, surface saliva deposition, the behaviour of the aphid, virus transmission) are examined. There is a brief review of stylet structure and movement and the possible sensory nature of these organs, followed by a detailed review of the characteristics of aphid stylet paths in plant tissues. The penetration of epidermis and vascular tissues is treated separately while that within the intermediate tissues is covered in relation to leaves and stems, roots, trees, galls and excised tissue as well as in separate sections on Aphis fabaeScopoli and Myzus persicae (Sulzer). Stylet destinations and behaviour in the sieve tubes are discussed together with general features such as rate and depth of penetration, guidance to the feeding site, effects of tissue hardness and stylet withdrawal. The ingestion rate of plant sap is reviewed and its constitution and importance examined together with the significance of artificial diets. The salivary secretions including sheaths and tracks, their functions and their role in the transference of material between aphid and host are dealt with. The nature of the physical and internal damage resulting from aphid feeding is briefly covered, and also some plant-insect interrelations. The aphid species whose stylets have been examined in plant tissue are listed.

Plant penetration by feeding aphids (Hemiptera, Aphidoidea): a review

Identification of cathepsin B, D and H in the larval midgut of Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae).

Possible Causes of Disease Symptoms Resulting from the Feeding of Phytophagous Heteroptera

Studies on enzymes in the salivary glands of Lygus rugulipennis (Hemiptera, miridae)

As in most Heteroptera, the salivary system of Oncopeltus fasciatus (Dallas) consists of a pair of trilobed principal glands and a pair of tubular accessory glands with associated ducts; the anatomy and histology are reported in detail. Tests for digestive enzymes demonstrated the presence of amylase, protease, invertase, and lipase. The various lobes of the salivary glands contain different digestive enzymes, a finding that is at variance with some published reports on allied Heteroptera.

Anatomy, histology, and secretions of salivary glands of the large milkweed bug, oncopeltus fasciatus (dallas) (hemiptera: lygaeidae)

Biosystematics of the genus euxoa (lepidoptera: noctuidae): ix. morphological and electrophoretic characteristics of the eggs of the “ declarata group”

E. H. Salkeld

Papers

Anatomy, histology, and secretions of salivary glands of the large milkweed bug, oncopeltus fasciatus (dallas) (hemiptera: lygaeidae)

Biosystematics of the genus euxoa (lepidoptera: noctuidae): ix. morphological and electrophoretic characteristics of the eggs of the “ declarata group”

The micropylar area of some hymenopterous eggs