Eiiti Kasuya

On “intercolonial” cannibalism in Japanese paper wasps,Polistes chinensis antennalis Pérez andP. Jadwigae dalla torre (hymenoptera: Vespidae)

Foundresses of two species of Japanese paper wasps,Polistes chinensis antennalis andP. jadwigae, attacked other colonies of the same species. A foundress ofP. chinensis antennalis visited two nests of the same species, and ate larvae from them, while two foundresses ofP. jadwigae each visited a nest of the same species, eating larvae and pupae even when the foundress of the attacked nest was on her nest. In addition, a foundress ofP. jadwigae distributed flesh balls thus obtained among their larvae. Discussion was made on the adaptive significance of the inter-colonial cannibalism. It was considered that, at first, it increases the foraging efficiency and secondly it plays a role in regulating population density.

Internidal drifting of workers in the Japanese paper waspPolistes chinensis antennalis (Vespidae; Hymenoptera)

SummarySome workers of the Japanese paper wasp,Polistes chinensis antennalis Pérez drifted from the maternal nests to other nests. Some of these workers performed tasks for nests they had drifted in. One possible cause of drifting should be errors in the memory of terrains around the nests by these workers.ZusammenfassungEinige Arbeiterinnen der japanischen Faltenwespe,Polistes chinensis antennalis Pérez verflogen aus den mütterlichen Nestern auf fremde Nester. Diese verflogene Arbeiterinnen beschaftigen sich an Sozialdienste in den fremden Nestern. Der möglichen Ursachen muss Gedächtnisirtümer in Bezug auf Terrain der Nester von diesen Arbeiterinnen sein

SOCIAL BEHAVIOR OF EARLY EMERGING MALES OF A JAPANESE PAPER WASP, POLISTES CHINENSIS ANTENNALIS (HYMENOPTERA: VESPIDAE)

Five cases of the early emergence of males in a Japanese paper wasp,Polistes chinensis antennalis, in which male emerged together with the first group of workers, were described. In one case of the five where the queen disappeared before the emergence of male, worker(s) produced female offspring. The frequency of the nests where the early emergence of male was observed was 16.7% (5/30 nests). In two colonies, worker(s) and/or queen chased off males. But in an orphan nest where worker(s) produced female offspring, the dominance order among workers which was similar to that of colony without male was observed. The significance of the early emergence of male in the social evolution of wasps was discussed.

Central place water collection in a Japanese paper wasp, Polistes Chinensis antennalis

Abstract The water collection behaviour of colony foundresses of a Japanese paper wasp, Polistes chinensis antennalis , was recorded. A single round-trip of water collection consists of (1) an outward flight, (2) water-sucking, and (3) a homeward flight. The rate of water intake decreased as the length of water-sucking increased. There was a positive correlation between the duration of the outward flight and that of water-sucking. The variance of time for outward flights was larger than that for homeward flights. The data were consistent with the predictions of the central place foraging model of Orians & Pearson (1979) .

Nest foundation by a single worker of the Japanese paper waspPolistes chinensis antennalis (Hymenoptera: Vespidae)

SummaryThe nest foundation by a single worker of the Japanese paper waspPolistes chinensis antennalis was observed in July, 1979. This worker had emerged from another nest in June 1979, and repaired an abandoned nest and reared some larvae there. This is the first discovery of nest foundation by a worker in the subfamily PolistinaeZusammenfassungDie Nestgründung von einer Arbeiterin der japanischen Falten WespePolistes chinensis antennalis wurde im Juni 1979 beobachtet. Diese Arbeiterin ausschlüpft im Juni 1979 aus einem anderen Nest und reparierte ein verlassenes Nest und zog darin einige Larven aus. Diese ist die erste Entdeckung der Nestgrüdung von einer Arbeiterin in der Unterfamilie Polistinae.

Behavioral ecology of Japanese paper wasps,Polistes spp. IV. Comparison of ethograms between queens and workers ofP. chinensis antennalis in the ergonomic stage

Behavioral catalogues, transition matrices between 2 consecutive behavioral acts, and the frequency distribution of time spent in each behavioral act were described for queens and workers of a Japanese paper wasp,Polistes chinensis antennalis in the ergonomic stage (the period from the emergence of the first worker to the emergenece of the first reproductive). The results were; (1) The whole behavior repertoire of queens was completely included in that of workers. Workers oviposited frequently in queen-right colonies. (2) The proportion of off-nest activities to the number of total acts for workers was higher than that for queens. The proportion of time spent off the nest in workers was 5 times as high as that in queens. (3) There was no significant difference in the proportion of number of oviposition to the total number of acts between queens and workers. The oviposition rate was 0.06 eggs/h for workers and 0.37 eggs/h for queens. Queens made more dominance behavior and workers more subordinated behavior. Queens made abdomen wagging more frequently than workers. (4) For behavioral acts common in both queens and workers, the mean duration of a specific act was approximately equal for both. The mean duration of unsuccessful flesh collection for workers was 3.4 times as longs as that for queens. Workers did not search for flesh in 10.1% of duration of flesh collections in the field. (5) The pattern of transitions between 2 consecutive behavioral acts in workers was similar to that in queens. (6) Alien workers approaching a nest with a load were more often accepted by the nest occupants than alien workers with no load. Alien workers with no load were not accepted as often as a legitimate nestmates with no load. The reproductive division of labor between queens and workers inP. chinesis antennalis was incomplete. This suggests worker-queen conflict in different reproductive strategies among colony members. Several behaviors were consistent with the view that they are the behavioral expression of this conflict.

Factors governing the evolution of eusociality through kin selection

The evolution of eusociality through kin selection was analyzed by simple population genetical models. Models were solved analytically with no approximation. The main results are (1) Sex ratio in reproductives in a colony of haplodiploid species does not affect the direction of evolution, contrary to the hypothesis ofTrivers andHare (1976). Female biased sex ratio increases the rate of evolution irrespective of its direction. (2) The only factor that determines the direction of evolution is the balance of benefit and cost of altruism of workers. (3) The value of ratio of benefit to cost of altruism of workers when the change of gene frequency of altruistic allele does not take place is unity in both haplodiploid and diploid species. There is no theoretical reason that the eusociality through kin selection evolves more easily in haplodiploidy than in diploidy, contrary to the hypotheses ofHamilton (1964) andTrivers andHare (1976). (4) The larger the colony size is, the lower the rate of evolution is irrespective of its direction. Sex ratio in reproductives in a colony of haplodiploid species does not affect the direction of evolution, contrary to the hypothesis ofTrivers andHare (1976). Female biased sex ratio increases the rate of evolution irrespective of its direction. The only factor that determines the direction of evolution is the balance of benefit and cost of altruism of workers. The value of ratio of benefit to cost of altruism of workers when the change of gene frequency of altruistic allele does not take place is unity in both haplodiploid and diploid species. There is no theoretical reason that the eusociality through kin selection evolves more easily in haplodiploidy than in diploidy, contrary to the hypotheses ofHamilton (1964) andTrivers andHare (1976). The larger the colony size is, the lower the rate of evolution is irrespective of its direction. It was concluded that discussion on the evolution of altruism which depended on only the values of the degrees of relatedness is misleading. The importance of life history structure, oviposition of workers and number of relating gene(s) in the evolution of eusociality were discussed.

Behavioral ecology of Japanese paper wasps,Polistes spp. III. Decision making byP. chinensis antennalis foundresses at the departure from nests

Analysis of the behavior of foundresses of a Japanese paper wasp,Polistes chinensis antennalis Pérez, was made to clarify the patterns of decision making. It was found that: (1) Foundresses postponed the next activity off the nest after being attacked by a foundress from another colony. (2) After a spiral flight, the frequency of subsequent spiral flights and patrol flights around the nest increased. (3) Following successful flesh collection, the frequency of flesh collection increased. (4) Following successful flesh collection, the time spent for a single trip of flesh collection increased. It was concluded thatP. chinensis antennalis foundresses solve their dilemma between the need of nest defence and resource gathering by decision making based on intraspecific attacks and the intake of the most difficult resource to obtain.