Observations on the Anatomy, Histology, Release Site, and Function of Brindley's. Glands in the ... the thorax of 5th-stage R. prolizus caused rapid para-.
Observations on the Anatomy, Histology, Release Site, and Function of Brindley's Glands in the Blood-sucking Bug, Rhodnius prolixus 1 ( Heteroptera: Reduviidae) MARGARETE KALIN AND F. MICHAEL BARRETT Department of Zoology, University of Toronto, Toronto, Ontario, Canada ABSTRACT The anatomy, histology, release site, and function of vapor into an olfactometer containing adult insects Brindley's glands were studied in adults of the blood- caused rapid arousal and disruption of an equilibrium sucking bug, Rhodnius prolizus (Stal). The 2 glands, aggregation whereas no such effect was observed on a present in both males and females, are located dorsally comparable equilibrated aggregation of 5th-stage insects. extending into the lateral part of the 2nd abdominal Furthermore, 0.5 µl of pure isobutyric acid applied to segment. the thorax of 5th-stage R. prolizus caused rapid paraBrindley's gland secretion is released by fed or unfed lysis whereas twice this amount applied to either head, males and females in response to various types of thorax, or abdomen of adults had no effect. The imhandling or mechanical stimulation and can apparently plications of these findings in relation to a possible be synthesized over an extended period of time. The defensive function for the Brindley gland secretion are presumed major volatile constituent of the scent is discussed. isobutyric acid. Introduction of pure isobutyric acid The metasternal scent glands of adult Rhodnius prolixus (Stal) are located on the inner side of the furca at the anterior margin of each metacoxal cavity (Brindley 1930) and are morphologically similar to the metathoracic scent glands found in other adult Heteroptera (Carayon 1962, 1971, Henrici 1940). These glands are thought to be the source of a defensive secretion in all members of this order (Remold 1962, Carayon 1971). However, R. proli.rus adults also possess a pair of dorsal glands described by Brindley ( 1930) as " ... the glands of the first abdominal segment" and subsequently referred to as "Jes glandes de Brindley" (Carayon 1962) and Brindley's glands (Pattenden and Staddon 1972). To date, these glands have only been found in the Reduviidae (Carayon 1971) and it seems likely that they produce the scent released by adult. R. prolixus. One major constituent of Brindley's glands, isobutyric acid (Pattenden and Staddon 1972). has also been found in the defensive secretion of both Papilio machaon L. (Eisner and Meinwald 1965) and Papilio aegeus Donovan (Seligman and Doy 1973). Acids are present in the defensive secretion of a number of other Heteroptera (McCullough 1970). Our interest in Brindley's glands in R. prolixus was prompted by the observation that some adults, partially juvenilized as a result of juvenile hormone (JH) treatment during the 5th stadium, appear unable to give off the characteristic adult odor (Barrett 1974). Since insects treated with JH somewhat later in the 5th stage develop into adults which , although still partly j uvenilized, can produce the scent, it would appear that JH exerts some control over any or all of: ( 1) development of Brindley's glands; (2) development of the release site on the metathorax; ( 3) development of the metabolic pathway for scent production. Previously published reports on Brindley's glands in R. prolixus (Brindley 1930; Pattenden and Stad1 Hemiptera (Heteroptera) : Reduviidae. lication July 8, 1974.
don 1972) are not sufficiently detailed to allow further investigation of this phenomenon. The present study was undertaken to pro,·ide a more detailed description of the anatomy, histology and release site of these glands and to offer further evidence concerning their function. MATERIALS AND METHODS
Received for pub-
Insects used in this study were nymphs and adults of the blood-sucking bug, Rhodnius prolixus (Stal), taken from a colony reared at 25°C in a humid atmosphere and fed routinely on rabbit blood once every 40 days. The size of the Brindley gland was measured in situ using a 5-mm rule held adj a cent to the gland, previously exposed by securing a decapitated adult in a waxed dish and removing several abdominal tergites. Histological sections of the gland were obtained using 2 different procedures. In the first, one side of the thorax from a freshly-ecdysed adult was dissected out, fixed in glutaraldehyde, embedded in araldite (Cargille NYSEM) as described by LaiFook (1970) and sectioned 1-3 µ, thick. Sections were dried for 5 min at 60-70°C on a hotplate and then stained for 5 min at the same temperature with 1o/o methylene blue in 1o/o borax. Alternatively, the thoracic tissue (removed as described above) was fixed in Carnoy's solution, dehydrated with alcohol, embedded in paraffin, sectioned 5 µ, thick and then stained for 10 min at room temperature with Delafield's Haematoxylin. Scanning electron microscopy was done on unfed adult males and females previously anaesthetized with carbon dioxide to prevent release of secretion onto the cuticular surface. The metapleuron was dissected out, taking care not to moisten the area to be viewed, and then mounted on a stub using contact cement. Samples were gold-coated 4 h prior to observation on a Cambridge Stereoscan microscope.
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January 1975]
KALIN AND BARRETT: BRINDLEY's GLANDS IN
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