Shôichi F. Sakagami

Life tables for worker honeybees

Life tables for worker honeybees covering all life span, and those for adults, were prepared for three seasonal cohorts,June bees, July bees andwintering bees. Survivorship curves forJune andJuly bees show a convex type being exceptional for insects, with relatively high mortality at egg and feeding larval stages and at later adult stage after most bees became potential foragers. Adult longevity greatly lengthens inWinteriing bees and survivorship curve drops approximately with the same rate. A remarkable similarity of survivorship curves for men and honeybees was demonstrated, apparently due to highly developed social care in both. Some comments were given on mortality factors. The importance of life tables for population researches was shown by applying our result to the population growth curve made byBodenheimer, based upon the data byNolan. At the asymptote of the uncorrected curve, the ratio of total population estimated by uncorrected curve to that by corrected curve reaches about 3∶2.

Some presumably presocial habits of JapaneseCeratina bees, with notes on various social types in Hymenoptera

SummarySome Japanese species ofCeratina bees exhibit habits which seem to be precursors to social life, namely: 1) Removal of larval feces by the mother, accompanied by destruction and reconstruction of cell partitions. 2) Transport of immatures within nest. 3) Guarding by the mother at the nest entrance, which is effective in protecting the immatures from parasites. 4) Association of the mother and juvenile adults in autumn, with pollen intake by juveniles from the mother, and 5) Prolonged life span of some females, followed by brood rearing in the second year.Three nests ofC. japonica and four ofC. iwatai, each containing two or more females in brood rearing condition are recorded. The relations among co-habiting females are variable: semisocial, delayedly eusocial,eosocial (nom. nov.) and quasisocial. The significance of these findings are discussed in connection with social evolution and various social types found or assumed in Hymenoptera.ZusammenfassungEinige japanischen Bienarten der GattungCeratina zeigen folgende Lebensgewohnheiten die als evolutionäre Vorstufen zur Staatsbildung aufgefasst werden können. 1) Das Weibchen entfernt den Kot seiner Brut, wobei es die Scheidewände zwischen den Brutzellen durchbricht und wieder aufbaut. 2) Larven werden innerhalb des Nestes transportiert. 3) Das Weibchen bewacht den Nesteingang und schützt dabei die Brut vor Parasiten. 4) Mutter und Jungbienen bewohnen im Herbst gemeinsam das Nest wobei die Jungbienen von ihrer Mutter Pollen übernehmen. 5) Die Lebensdauer einiger Weibchen ist soweit verlängert, dass eine weitere Brutaufzucht im zweiten Jahr möglich ist.Ueber drei Nester vonC. japonica und vier vonC. iwatai wird berichtet, die während einer Brutperiode je zwei oder mehr Weibchen enthielten. Die Form der Wechselbeziehungen zwischen den zusammenlebenden Weibchen variiert von semisozial, aufgeschoben eusozial, biseosozial (nom. nov.) und quasisozial. Die Bedeutung dieser Befunde in Bezug auf die Evolution der Insektensozietäten wird erörtert unter Bezug auf die verschiedenen aktuellen und hypothetischen Sozialtypen der Hymenopteren.

The False-Queen: Fourth Adjustive Response in Dequeened Honeybee Colonies1)

Dequeened honeybee colonies may produce a false-queen, which shows certain queen-like traits and is attended by other workers as if it were a true queen, though externally it is merely a normal worker, except for its slightly extended and polished abdomen. Certain observations on the behaviour of these false-queens are described. In one Apis cerana cerana queenless nucleus, the worker oviposition was almost ceased during the occurrence of a false-queen. The false-queen seems to be a response of dequeened workers, which try to reproduce the lost harmony of queen-worker differentiation essential to the life of colony.

Worker brood survival in honeybees

The brood survival in honeybee workers was measured in order to obtain the data basic to the preparation of life tables. Under normal condition, that is, at the center of brood area, the survival is high. The survival/stage function runs 100.0 eggs, 94.2 unsealed brood (=feeding larvae), 86.4 sealed brood (=post-feeding larvae and pupae) and 85.1 adults. The total duration of immature stages is 20 days in 87.1%, 21 days in 8.3% and 19 days or more than 22 days in the residual fraction of successfully emerging workers. The survival remarkably decreases at peripheral areas within the hive. Various factors affecting the brood survival are discussed and the importance of a dense worker cover on the brood area is stressed in relation to the maintenance of thermal conditions optimal to the brood. The occurrence of one factor, which is not expected in solitary animals, the self-control of population by egg eating, is pointed out.

Age-Survival Curves for Workers of Two Eusocial Bees (Apis Mellifera and Plebeia Droryana) in a Subtropical Climate, with Notes on Worker Polyethism in P. Droryana

SummaryUnder the subtropical climate of Ribeirao Preto, Brazil, the relationships between age and survival in worker bees were studied with Apis mellifera and a stingless bee (Plebeia droryana), using 3 colonies of each. In contrast to colonies in the temperate region, winter workers of A. mellifera did not show a prolongation of life span. A marked prolongation was observed in workers of two broodless colonies of P. droryana, one queenless and the other not, compared with a normal brood-rearing colony. In the normal colony, workers changed activities in relation to age as they do in A. mellifera, but their mean life span was much longer.

Seasonal changes of glycogen/trehalose contents, supercooling points and survival rate in mature larvae of the overwintering soybean pod borer Leguminivora glycinivorella

Abstract The mature larvae of the soybean pod borer Leguminivora glycinivorella, spend over 9 months (October-next August) in the inactive state until pupation down to 3 cm below the surface in soil. Trehalose content of inactive larvae increases in early winter, attaining a maximum (ca 30 mg/g), and decreases in spring, with a concomitant decrease and increase of glycogen. The median supercooling points seasonally change from −19.8°C (October) to −25.0°C (February), and to −17.0°C (June). The lower supercooling points in winter are in part due to the absence of unusually high values (> −18°C). The increase in trehalose does not seem to be effective in depressing the supercooling points. The larvae are freeze-intolerant, but ambient temperatures in outdoor conditions are always above the supercooling points. The survival rates are very high throughout the inactive period.

Nest architecture and brood development in a neotropical bumblebee,Bombus atratus

Recently the biology of bumblebees has been greatly clarified by the successive appearance of many excellent contributions. But our knowledge on this interesting group depends nearly entirely on the observations made in temperate species. Information upon the species inhabiting other climates, especially those in the tropics is still very scanty.: In the revision of the Brazilian bumblebees, one of us (S.F.S.) summarized and reviewed biological accounts so far obtained in South American lowlands (MOUnE and SAKAGAMI, 1962. In this work the observations made by M~YERS (1935), on B. transversalis (Olivier), cited as B. incarum, is omitted from citation). But until the appearance of two papers by DIAS (1958, 1960) only fragmentary and careless observations have been carried out, and among them only the old paper by v. IHERING (1903) has been repeatedly cited by Northern Hemisphere specialists, as suggesting probable difference of life cycle and social organization from the well known haplometrotic and annual colony life in temper:ate areas. In 1963-1965 we succeeded in rearing one colony of B. (Fervido-

Vespa dybowskii André as a facultative temporary social parasite

SummaryVespa dybowskii André can establish the nest either by the independent foundation like as other hornets, or by the usurpation of the nests ofV. crabro L. orV. xanthoptera Cameron already established. Namely, this hornet belongs to the facultative temporary social parasite like asVespula squamosa (Drury) and certain bumblebees. The marked aggressiveness of this hornet and other biological observations were described together with some considerations on the labour parasitism among the social insects.ZusammenfassungVespa dybowskii André kann ihre Nest falls durch die unabhängige Gründung wie andere Hornisse, falls aber durch die Oberung der schon gegründeten Nester vonV. crabro L. oderV. xanthoptera Cameron, gründen. Nämlich gehört diese Hornis zum fakultativen temporären Sozialparasit wieVespula squamosa (Drury) und gewisse Hummelarten. Die bemerkbare Kampflustigkeit dieser Hornisse und andere biologische Beobachtungen wurden zasammen mit einige Betrachtungen über die Arbeitsparasitismus in den sozialen Insekten beschrieben.RésuméVespa dybowskii André nidifie soit en construisant elle-même son nid comme les autres guêpes, soit en usurpant des nids deVespa crabro L. ouV. xanthoptera Cameron déjà construits. Cette guêpe appartient donc aux

Discovery of Successful Absconding in the Stingless Bee Trigona (Tetragonula) Laeviceps

SummaryThe first authentic record of the occurrence of absconding in stingless bees is described for Trigona (Tetragonula) laeviceps in Sumatra. In the reproductive swarm of stingless bees, a virgin queen goes to a new nest. An ovipositing queen has so far been considered to be unable to fly. However, the characteristics of the queen and workers in a swarm indicated that it was an absconding swarm. On the basis of her worn wings and dark pigmentation, this queen was estimated to be more than 6 months old. Her metasoma, with developed ovaries, was intermediate in size between that of actively laying and of pre-laying queens. The number of workers in the swarm was 82, and only 4% of them were younger than 20 days. Compared with the reproductive swarm of the same species, the number of workers was much smaller and their ages much greater.

An extraordinary concentration of stingless bee colonies in the Philippines, with notes on nest structure (Hymenoptera: Apidae:Trigona spp.)

SummaryA bamboo farmhouse on Negros island, Philippines harbored at least 84 colonies ofTrigona (Tetragonula) fuscobalteata andT. (Tetragonula) sapiens in a ratio of about 3∶1.Nests were in bamboo stem cavities of 0.7–3.0 1 volume. In neither species does The nest show specialized features relative to the subfamily. The entrance tube is simple and of medium length. The tube aperture is longer and narrower inT. sapiens thanT. fuscobalteata, although the former species has a greater head-width. Brood-cells are arranged in clusters, not in organized combs, and are not surrounded by an involucrum. p There is some indication that within the Philippines stingless bees are more abundant in drier areas.ZusammenfassungAuf der Insel Negros, Philippinen, wurde ein aus Bambus gebautes Bauernhaus entdeckt, das mindestens 84 Kolonien von stachellosen Bienen beherbergte, und zwar der beiden ArtenTrigona (Tetragonula) fuscobalteata undT. (Tetragonula) sapiens in einem Verhältnis von ungefähr 3∶1.Die Nester waren in Bambussegmenten, je mit einem Rauminhalt von 0,7–3,0 1. Die Neststruktur entspricht generell dem Typus der Unterfamilie. Die Flugröhre ist einfach und nicht besonders lang. Die Röhrenöffnung ist beiT. sapiens länger und enger als beiT. fuscobalteata, obwohlT. sapiens einen breiteren Kopf besitzt. Die Brutzellen sind nicht in Waben angeordnet, sondern bilden traubenförmige Haufen. Sie sind auch nicht von einem Involucrum umgegeben.Es gibt Hinweise, daß stachellosen Bienen in trockenen Gebieten der Philippinen häufiger vorkommen.