Showing papers by "Edward O. Wilson published in 1985"

The Sociogenesis of Insect Colonies

Abstract: Studies on the social insects (ants, bees, wasps, and termites) have focused increasingly on sociogenesis, the process by which colony members undergo changes in caste, behavior, and physical location incident to colonial development. Caste is determined in individuals largely by environmental cues that trigger a sequence of progressive physiological restrictions. Individual determination, which is socially mediated, yields an age-size frequency distribution of the worker population that enhances survival and reproduction of the colony as a whole, typically at the expense of individuals. This "adaptive demography" varies in a predictable manner according to the species and size of the colony. The demography is richly augmented by behavioral pacemaking on the part of certain castes and programmed changes in the physical position of colony members according to age and size. Much of what has been observed in these three colony-level traits (adaptive demography, pacemaking, and positional effects) can be interpreted as the product of ritualization of dominance and other forms of selfish behavior that is still found in the more primitive insect societies. Some of the processes can also be usefully compared with morphogenesis at the levels of cells and tissues.

Invasion and extinction in the west Indian ant fauna: evidence from the dominican amber.

Abstract: Of 37 genera and well-defined subgenera identified in the amber of the Dominican Republic (late Oligocene or early Miocene), 34 have survived somewhere in the New World tropics to the present, although the species studied thus far are extinct. Of the surviving genera and subgenera, 22 persist on Hispaniola. Fifteen genera and subgenera have colonized the island since amber times, restoring the number of genera and well-defined subgenera now present on Hispaniola to 37. A higher extinction rate has occurred in genera and subgenera that are either highly specialized or possess less colonizing ability, as evidenced by their restriction to the New World.

Correlates of variation in the major/minor ratio of the ant, Pheidole dentata (Hymenoptera: Formicidae).

Abstract: Major workers of the ant, Pheidole dentata , show a stronger alarm/defense response to members of the genus Solenopsis , including the fire ant, S. invicta , than to other kinds of ants. Nevertheless colonies stressed for 19 weeks (more than 3-fold the developmental time from egg to pupa) with S. invicta invaders failed to alter the rate of production of major workers. Production of queens and males begins when the colonies reach an adult worker population of 3,000 or more, and it is associated with a sharp reduction in major worker production. Colonies of P. dentata vary markedly among themselves in the adult major/minor ratio. The differences are restored after the ratio has been perturbed experimentally, and they are also restored after the colonies pass through episodes of queen and male production.

Between-caste aversion as a basis for division of labor in the ant Pheidole pubiventris (Hymenoptera: Formicidae)

Abstract: When deprived of minor workers under expermental conditions, major workers of the ant Pheidble pubiventris dramatically increase their repertory and rate of activity, and the change is due in good part to the greater attention they pay the brood. When minor workers are reinstated in appropriate numbers, the majors reduce their attention to the immature stages to the ordinary, low levels. Their response consists of the active avoidance of minors while in the vicinity of the immature stages. However, majors do not turn from other majors near the brood as much as they do from the minors, and they do not avoid minors at all while in other parts of the nest. In addition, minors do not avoid either minors or majors anywhere in the nest. The result is a striking division of labor with reference to brood care.

Ants From the Cretaceous and Eocene Amber of North America

Abstract: The discovery of Sphecomyrmafreyi in amber from New Jersey disclosed the existence of an extinct subfamily of ants (Sphecomyrminae) intermediate in some traits between modern ants and nonsocial wasps and dating as far back as the lower part of the Upper Cretaceous (Wilson et al., 1967a, b): Subsequently Dlussky (1975, 1983) described a series of new genera from the Upper Cretaceous of the Taymyr Peninsula (extreme north-central Siberia), southern Kazakh S.S.R., and the Magadan region of extreme eastern Siberia. Among the various specimens assigned to these taxa (the genera are Archaeopone, Armania, Armaniella, Cretomyrma, Cretopone, Dolichomyrma, Paleomyrmex, Petropone, Poneropterus, and Pseudarmania), the ones well enough preserved to disclose subfamily-level diagnostic characters appear to fall within the Sphecomyrminae. Indeed it is difficult to find sound reasons for separating most of them from Sphecomyrma, providing we limit ourselves to the same criteria applied to contemporary genera and tribes. There seems to be little justification for placing them in a separate family, the Armaniidae, as suggested by Dlussky. If this interpretation of the Russian material is correct, we have established that the most primitive known group of ants, the Sphecomyrminae, lived over much of the northern hemisphere during middle and late Cretaceous times. Other discoveries have revealed that by Eocene times, some 50 million years later, higher forms of ants had come into existence, but the evidence remains very scanty and ambiguous. Eomyrmex guchengziensis, described from amber in the Eocene coal beds of Fushun, Manchuria, appears from the description and illustrations to be a relatively primitive ponerine with traits reminiscent of the Sphecomyrminae (Hong et al., 1974). Because of its possibly intermediate status, a further study of the single worker would be a valuable exercise. The giant Eoponera

Time to revive systematics.

Abstract: Science serves its readers as a forum for the Systemat discussion of important issues related to the advancement of the mere c science, including the presentation of minority or conflicting points of view, rather than by publishing onl material on which a among the I consensus has been reached. Accordingly, a articles published in Science-including editorials, news and comment, and book the nearest reviews-re signed and reflect the individual views of the authors and not official points of view adopted by the AAAS or Approxima the institutions with which the authors are affiliated. about 250( PubUdber: WILLIAM D. CAaEY meticulous

Caste-specific techniques of defense in the polymorphic ant Pheidole embolopyx (Hymenoptera: Formicidae)

Abstract: 1. The queen of the Brazilian speciesPheidole embolopyx is unique among ants in possessing a posteriorly truncated abdomen; in addition, the rear surface is clothed in unusual, hook-shaped hairs (fig. 1–3). Contrary to expectation, however, our studies have shown that the queen does not use the abdomen to block nest entrances or otherwise to oppose opponents directly. 2. The queen is also unique in possessing gelatinous sheaths on the scapes, anterior clypeal border, and frontal carinae. The sheaths vary in size and shape among queens and on the same queen with time (fig. 4), and they are often absent altogether. These unusual structures seem to be neither especially attractive nor repellent to theP. embolopyx workers. 3. We offer a different explanation of the queen's modified anatomy. The truncation of the abdomen and gelatinous sheaths are associated with flange-like protrusions of the pronotum and first gastric segment in an overall “chelonian” (turle-like) body form. The most vulnerable parts of the body are thus better protected from biting attacks, especially when the queen hides in tight spaces. But the meaning of this peculiar syndrome remains unknown. We believe it unlikely, for example, that the queen is a temporary social parasite. 4. Minor and major woerkers display different responses during recruitment and alarmdefense of the nest and food sources. These caste-specific behaviors are nevertheless coordinated to create efficient group-level reactions. Only the minor workers lay odor trails, which originate from the poison gland. Both castes cooperate in defending food finds, in the form of encircling clusters that persist for hours or even days. The minor workers seize the legs of intruding ants, while the majors attack their bodies directly. Both castes communicate alarm by means of abdominal pheromones, which in the case of the major worker has been pinpointed to the pygidial gland.