David C. Post

Morphology and function of sternal glands in polistine wasps (Hymenoptera: Vespidae)

SummaryThe morphology of sternal glands and associated cuticular specializations are described for female polistine social wasps. Their distribution among 25 of the 28 genera of the subfamily is examined in light of what is known of the functions of these glands. Species in which queens found colonies independently of workers (four genera plus part of Ropalidia) have clusters of ducted gland cells on the sixth (terminal) gastral sternite. In all species examined the gland cells open into a tuft of long setae which probably functions as a reservoir/applicator brush. There is at least circumstantial evidence for all five genera that this gland produces an ant repellent substance that is smeared onto the nest petiole, where it serves as a defensive barrier against ants. The remaining genera (20 plus part of Ropalidia) consist of species in which queens are accompanied by a swarm of workers in the initiation of a new colony. In 12 of these genera females have a gland of ducted cells on sternite 5 (penultimate), associated with cuticular sculpturing of various types. Experimental or circumstantial evidence for several of these genera indicates that the product of this gland is used to lay an odor trail that guides the swarm from the parent nest to a new nest site. One genus has a similar gland on the sixth sternite, another has glands on both the fifth and the sixth, and the remaining six genera lack any evidence of sternal glands. The independent-founding species of Ropalidia have a sixth sternal gland associated with a tuft of setae, while the swarm-founding species have the tuft but lack the gland. Our interpretation of this is that the gland produces an ant repellent substance in the independent-founding species, but in the swarm-founding Ropalidia such a substance is of little value and so the gland has been lost.

Recognition of former nestmates during colony founding by the social wasp Polistes fuscatus (Hymenoptera: Vespidae)

SummaryIn the laboratory overwintered females of Polistes fuscatus preferentially associated with former nestmates during the founding of a colony. They did not associate with non-nestmates or only with nestmates with whom they had overwintered, but affiliated with all former nestmates, regardless of where the former nestmates overwintered.

Alarm response to venom by social waspsPolistes exclamans andP. fuscatus (Hymenoptera: Vespidae).

The venoms ofPolistes exclamans andP. fuscatus elicit alarm behavior and attract attacking wasps. The response is not species specific, for both hetero- and conspecific venoms elicit similar responses in both species. A test in a wind tunnel provided no support for the hypothesis that alarmed wasps release an alarm pheromone on the nest.

Venom as an interspecific sex pheromone, and species recognition by a cuticular pheromone in Paper Wasps (Polistes, Hymenoptera: Vespidae)

ABSTRACT. The venoms of Polistes fuscatus (subspecies fuscatus) (F.) and P. exclamans Viereck from sympatric populations in North Carolina, U.S.A., contain a pheromone which attracts males and stimulates sexual behaviour in both conspecific and heterospecific males. Males of P. fuscatus (subspecies variatus Cresson), a subspecies from Wisconsin, respond to venom of P. fuscatus fuscatus, P. exclamans, and Vespula maculifrons (Buysson) from North Carolina, although the levels of response to P. exclamans and V. maculifrons venom are less than that to P. fuscatus variatus venom.

Venom Source of a sex pheromone in the social waspPolistes fuscatus (Hymenoptera: Vespidae).

Females ofPolistes fuscatus possess a sex pheromone in the venom gland and sac. The pheromone attracts males from short distances and releases male copulatory behavior.

Honeybee (Apis mellifera L.) queen feces: Source of a pheromone that repels worker bees.

When placed in a small observation arena with workers, most young virgin honeybee queens released fecal (hindgut) material during agonistic interactions with workers and with each other. On release of this material, workers moved to the sides of the arena and groomed themselves. Bioassays of virgin queen fecal material demonstrated that it contains pheromone that repels workers and stimulates grooming behavior. Pheromone was present only in the feces of virgin queens that were more than 24 hr old and less than 2 weeks old. Feces of 2- to 4-day-old workers and virgin queens more than 2 weeks old did not elicit an avoidance response by workers. Moreover, the feces of young virgin queens had a strong fragrance, while that of older queens had a rancid odor and that of young workers had no detectable odor.

Morphology of the Sternal Glands of Polistes Fuscatus and P. Canadensis (Hymenoptera: Vespidae)

Although 13 exocrine glands have been located in wasps of the genus Polistes, and 12 in Mischocyttarus (Landolt and Akre, 1979), their morphology and functions have been little studied. Recently, however, the sternal gland on the sixth gastral (terminal) segment of females of these wasps has attracted attention because its secretion is repugnant to some species of ants. Female wasps rub the secretion onto the nest petiole, thus forming a chemical barrier against predatory ants (Jeanne, 1970; Hermann and Dirks, 1974; Turillazzi and Ugolini, 1978, 1979; Post, 1980).

Morphology of sternal glands in male polistine wasps (Hymenoptera: Vespidae)

SummaryThe sternal glands of 28 species of male wasps belonging to 12 polistine genera are described. Glands and associated cuticular modifications of these males and of males described in past studies are compared to those of conspecific females. Males in species of four swarm-founding genera have glandular areas similar in morphology and location to those of females. The glands are comprised of ducted cells associated with either a bed of erect cuticular scales along the anterior edge of the fifth sternite (Metapolybia, Chartergus, andPolybia) or a band of hairs along the anterior margin of both the fifth and sixth sternites(Apoica). Ropalidia montana males have ducted gland cells on sternites five and six, rather than just on six as in congeneric females;Brachygastra augusti males have them on sternites five through seven, rather than just on five as in their conspecific females. Also unlike those of conspecific females, these glands are not associated with any cuticular modification. Species in the remaining three swarm-founding genera lack male sternal glands. Males of independent-founding genera (Mischocyttarus, Polistes, Belonogaster, andParapolybia) have glandular cells covering the posterior 2/3 or 1/2 of the sternite, rather than the anterior portion as in their congeneric females.ZusammenfassungMännliche Sternaldrüsen sind beschrieben für 28 Wespenarten von 12 polistinen Gattungen. Drüsen und zugehörene kutikulare Änderungen dieser und früherer beschreibten Männchen wurden mit Drüsen der konspezifischen Weibchen verglichen. Es stellte sich heraus, dass Männchen in 4 schwärmenden Gattungen Drüsen haben, die morphologisch und örtlich denen der Weibchen ähnlich sind. Diese Drüsen haben Kanäle, welche entweder mit aufrechten Schuppen am vorderen Rand des fünften Sterniten (Metapolybia, Chartergus, undPolybia) oder mit einem Band von Haaren an dem vorderen Rand des vierten und füften Sterniten (Apoica) versehen sind. Männchen vonRopalidia montana haben Kanal-Zellen auf dem fünften und sechsten Sterniten, während Weibchen solche nur auf dem sechsten Sterniten haben. Bei Männchen vorBrachygastra augusti sind Kanal-Zellen auf dem fünften, sechsten und siebten Sterniten zu finden, während die Weibchen solche nur auf dem fünften haben. Im gegensatz zu Weibchen, haben diese Drüsen keine abgeänderte Kutikula. Arten, die zu den anderen drei Schärmenden Gattungen gehören, zeigen bei Männchen keine Sternaldrüsen vor. Männchen von Gattungen, die Kolonien unabhängig gründen (Mischocyttarus, Polistes, Belonogaster, Parapolybia), haben Drüsenzellen die den hinteren 2/3 oder halben Teil des Sterniten bedecken, während bei Weibchen, diese Drüsenzellen am vorderen Teil des Sternits vorkommen.

Sex Pheromone inPolistes fuscatus (Hymenoptera: Vespidae): Effect of age, caste and mating

SummaryFemales of all ages, castes, and prior mating experiences elicited sexual behavior in males of the social waspPolistes fuscatus (F.). The venoms of workers, queens, uninseminated gynes more than 24 hours old, and inseminated gynes more than 14 days old were effective in stimulating male sexual behavior, and thus contained sex pheromone. The venom of gynes less than 15 hours old did not stimulate a significantly greater frequency of male sexual behavior than did the control.ZusammenfassungWeibchen jeden Alters, Kasten als wohl als solche mit früherer Kopulationserfahrung verursachten geschlechtliches Verhalten bei Männchen der sozialen WespePolistes fuscatus (F.). Gifte der Arbeiter, Königinnen, unbefruchteten Weibchen > 24 Stunden alt und befruchtete Weibchen > 14 Tage alt waren wirksam und riefen männliches sexual Verhalten hervor. Aus diesem Grunde enthalten diese Gifte Geschlechtspheromone. Gift von Weibchen < 15 h alt riefen kein heufigeres Geschlechtsverhalten hervor als Kontrol-Weibchen.

Richards' gland and associated cuticular modifications in social wasps of the genusPolybia Lepeletier (Hymenoptera, Vespidae, Polistinae, Polybiini)

SummaryO.W. Richards recently discovered an exocrine gland that opens on the fifth (penultimate) sternite of females of many species of polybiine wasps. Recent experimental evidence indicates that this gland produces the trail pheromone used to guide the swarm during emigration to a new nest site. In the present paper we describe the morphology of the gland in four species ofPolybia as seen using light microscopy. The gland cells open via individual ducts onto the surface near the anterior margin of the sternite, where their secretion is evidently stored in a reservoir formed by the intersegmental membrane. The modifications of the sternal cuticle associated with the gland opening, which we examined in 12Polybia species using scanning electron microscopy, are of two types: in five species the gland opens into a transverse groove, while in the other seven the cuticle is raised into erect scales. There is some evidence that the groove type is correlated with larger gland size; there is only a poor correlation with larger body size.ZusammenfassungO.W. Richards hat in letzter Zeit eine exocrine Drüse entdeckt, deren Offnung sich am fünften (Penultimal) Sterniten von Weibchen befindet. Diese Insekten gehören zu einer ganzen Zahl von Polybiine Wespen Arten. Wir beschreiben hier die Morphologie einer Drüse, bestimmt durch Licht-Microscopie, in vier Arten vonPolybia. Die Drüsenzellen haben individuelle Offnungen an der Oberfläche des Sterniten, wo ihre Absonderung in einem von der intersegmentalen Membrane Behälter aufgehoben wird.Die Anderungen in der sternalen Cuticula, wo sich die Drüsenöffnung befindet, wurden in 12Polybia Arten mit dem Elektronen-mikroskop untersucht. Wir fanden 2 Typen von Anderungen: bei 5 Arten öffnet sich die Drüse in eine transverse Rinne, und bei 7 Arten bildet die Cuticula aufrechte Schuppen. Es hat den Anschein daß Drüsen dort grösser sind wo Rinnen vorkommen, obwohl das Insekt an sich nicht grösser ist.