Publisher Summary The scent glands are epidermal glands and, as invaginations formed from epidermis, are lined with a cuticle continuous with that of body wall. There is wide variation in the details of scent gland structure and function among Heteroptera. This chapter reviews the nature of these details and their significance for physiological and ecological studies on Heteroptera. The scent glands consist of integument similar in basic structure to that forming the body wall. There are three basic layers; a relatively thin, extracellular, basal layer called basement membrane; a middle layer consisting of epithelial cells arranged as in a monolayer; a relatively thick, extracellular, apical layer—the gland lining cuticle or gland cuticular intima. Postulated functions include defense against predators; defense against microorganisms; and release of specific patterns of behavior. A protective role for the scent glands against small vertebrate and invertebrate predators has been established for coreid and pentatomid bugs. Corixid larvae similarly may be protected against the small predator Plea. Mechanisms of self-protection against the scent substances and comparisons between scent glands and other epidermal glands have been discussed.

The Scent Glands of Heteroptera

Cardiac glycosides in North American Asclepiadaceae, a basis for unpalatability in brightly coloured Hemiptera and Coleoptera

1. The higher formicine ants base their chemical alarm-defense systems primarily on a limited array of acyclic terpenes discharged from the mandibular glands, and alkanes and ketones discharged from Dufour's gland. All of these substances appear to be utilized in defense, and most, especially those at the lower end of the range of molecular weight (C9-C13), also function as alarm pheromones. The active space of the pheromones reaches over a distance of centimeters and is relatively short-lived. The alarm response of the various species can be classified roughly as either "panic" or "aggressive" in nature. 2. Two major adaptive alterations in the basic alarm-defense system have occurred within the higher Formicinae. In the genus Acanthomyops, the mandibular gland has been enlarged and made the site of storage of unusually large quantities of citronellal and two isomers of citral. We suggest that the changes are causally linked to the development of a strongly aggressive form of alarm communication. The res...

https://www.jstor.org/stable/info/2459556

The Evolution of the Alarm-Defense System in the Formicine Ants

Six rhizobacteria isolated from common bean and able to protect bean plants from the common bacterial blight causal agent, were in vitro evaluated for their potential antifungal effects toward different plant pathogenic fungi, mostly soil-borne. By dual culture assays, the above bacteria resulted producing diffusible and volatile metabolites which inhibited the growth of the majority of the pathogens under study. In particular, the latter substances highly affected the mycelium growth of Sclerotinia sclerotiorum strains, one of which was selected for further studies either on mycelium or sclerotia. Gas chromatographic analysis of the bacterial volatiles led to the identification of an array of volatile organic compounds (VOCs). Time course studies showed the modification of the VOCs profile along a period of 5 days. In order to evaluate the single detected VOC effects on fungal growth, some of the pure compounds were tested on S. sclerotiorum mycelium and their minimal inhibitory quantities were determined. Similarly, the minimal inhibitory quantities on sclerotia germination were also defined. Moreover, observations by light and transmission electron microscopes highlighted hyphae cytoplasm granulation and ultrastructural alterations at cell organelles, mostly membranes, mitochondria and endoplasmic reticulum. The membranes appeared one of the primary targets of bacterial volatiles, as confirmed by haemolytic activity observed for the majority of pure VOCs. However, of interest is the alteration observed on mitochondria as well.

/pdf/biocide-effects-of-volatile-organic-compounds-produced-by-1um9no2yk6.pdf

A. Baggini

Papers

On the components of secretion of mandibular glands of the ant .

Ricerche sulle secrezioni difensive di Insetti Emitteri Eterotteri (Hem. Heteroptera)