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In eusocial Hymenoptera, workers usually cannot mate but can lay male-destined haploid eggs. In contrast, in many species, worker reproduction is regulated by means of worker policing, which consists of two behavioral categories: aggression towards workers that have developed ovaries, and the destruction of worker-laid eggs. We focused on the latter behavior in the ant Diacamma sp. from Japan, in which a mated worker (gamergate) serves as the functional queen in each colony. An experiment in which we introduced both worker-laid eggs and gamergate-laid eggs from foreign colonies showed that workers preferentially destroyed the worker-laid eggs. This indicates that workers can discriminate worker-laid eggs from gamergate-laid eggs. In contrast, gamergates destroyed all introduced eggs that they discovered. Our chemical analysis of egg surface substances revealed that the worker-laid eggs clearly differed from gamergate-laid eggs in their surface hydrocarbons (SHCs), with the former containing more long-chain components. However, a bioassay to test whether specific components of the SHCs trigger the observed discrimination behavior by workers remains to be done. [ABSTRACT FROM AUTHOR]

Sex mosaicism, also called gynandromorphism, refers to an accidental phenomenon in dioecious organisms (mainly animals) in which an individual phenotype includes both female and male characteristics. Despite the rarity of this phenomenon, elucidating the mechanisms of naturally occurring sex mosaicism should deepen our understanding of diverse sex determination and differentiation systems in nature. We report the results of a genetic study of a sex mosaic individual of the ant Diacamma sp. from Japan's Okinawa Island. Parentage analysis using microsatellite markers revealed that the female and male parts of the sex mosaic showed different inheritance patterns: female parts had alleles consistent with their biparental inheritance, whereas most of the male parts had alleles consistent with their paternal inheritance (i.e., androgenesis). We discuss plausible cytogenetic mechanisms that gave rise to the male parts of this individual: polyspermy and the subsequent independent cleavage by a surplus sperm pronucleus, and maternal genome elimination after fertilization of an ovule. Moreover, we hypothesize that the androgenetically produced males found in some Hymenoptera might share the same underlying cytogenetic mechanism with hymenopteran sex mosaicism. [ABSTRACT FROM AUTHOR]

In eusocial Hymenoptera, information on the presence of a queen is considered to play an important role in regulating worker reproduction. We examined the mode of transmission of this putative queen information to workers. Previous studies have reported that, in Diacamma sp. from Japan, unmated helper workers perceive the presence of a gamergate (functional queen) only through direct physical contact with her. In contrary to this conclusion, we showed, by an experiment that exposed workers either to the gamergate or to the eggs laid by the gamergate, that the presence of eggs laid by the gamergate to some extent suppressed the workers' dominance interaction, a behavior that is associated with self-reproduction by unmated workers. We discuss the relative importance of direct and indirect transmission of gamergate-presence information under natural conditions in this ant. [ABSTRACT FROM AUTHOR]

We studied the reproductive behavior of the ponerine ant Hypoponera bondroiti from Okinawa, Japan. This species has dimorphic wingless ergatoid males (major and minor), dimorphic reproductive females (alate queens and wingless reproductive intercastes), and workers. Workers have neither ovarioles nor spermatheca. Major ergatoid males are the largest colony members. Two major males fought one another in the nest until one disappeared, leaving the other to occupy the nest chambers where queens emerge and mate. Minor ergatoid males also fought one another, although they seemed to be less pugnacious, resulting in occasional cohabitation of multiple minor males in the same nest chamber. Major males never attacked minor ones, allowing them to coexist in the same nest chamber. Minor males seemed to mimic females. Both major and minor males mated with both alate queens and intercastes within the nest. After mating, some alate queens shed their wings and remained in the nest, while the others left the nest for dispersal in the laboratory. Intercastes remained in the nest. [ABSTRACT FROM AUTHOR]

Groups of virgin Cerapachys biroi workers produced females (workers) in the laboratories. This is the first report of thelytoky in Cerapachyinae. [ABSTRACT FROM AUTHOR]

Queens do not exist in Diacamma sp. from Japan, and a single worker ('gamergate') mates and monopolizes reproduction in each colony. We isolated small groups of workers without the gamergate, and confirmed that after 7-15 days many workers were able to oviposit (Tab. 1). These egg-laying individuals engage in stereotyped attacks towards each other. In six groups of individually marked workers (Tabs. 3 to 7), the pattern of aggressive interactions always indicated that one worker was dominant. She usually initiated a large number of attacks, but was herself never attacked. This dominant worker ('alpha') also ate the eggs just laid by others. There was no linear dominance hierarchy, although a second highest-ranking worker could be recognized (she was only attacked by alpha). When these workers were dissected 4-6 weeks after being orphaned, only the alpha worker had active ovaries; other individuals that had been observed to oviposit earlier exhibited resorbed ovaries. Dissection of another 12 orphaned groups, kept together for different periods of time (Tab. 2), confirmed that one dominant worker is able to suppress the ovarian activity of all others in her group. We discuss how these aggressive interactions also function to regulate the production of males in other contexts, even when the gamergate is present. This aggression is separate, however, from another competitive interaction, mutilation of the gemmae, that functions as a control of mating activity in this species. [ABSTRACT FROM AUTHOR]

Females of Technomyrmex albipes consist of winged queens, intercastes and workers. In established colonies, reproduction is performed by many intercastes (wingless females which have intermediate phenotypes between queen and worker characters). Dissection and morphological examination revealed that intercastes had a spermatheca, but workers did not. Intercastes can be divided into three classes: major intercastes with three ocelli, medium intercastes with one ocellus, and minor intercases without ocelli. Workers have no ocelli. The thoracic structure of intercastes gradually becomes more complex from minors to majors. The body size of intercastes gradually increases from minors to majors, and so does the number of overioles. The body size distributions of minor intercastes and workers overlap considerably, but the distributions of ovariole numbers overlap less. Winged queens had distinctly larger body sizes, more ovarioles and larger spermathecae than intercastes. Most intercastes were inseminated with developed ovaries and appeared to reproduce. The caste system and reproductive division of labour in T. albipes is compared to those of ant species in which permanently wingless females reproduce. [ABSTRACT FROM AUTHOR]

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