Co-occurrence of three types of egg policing in the Norwegian wasp Dolichovespula norwegica

In insect societies, workers often try to challenge the reproductive monopoly of the queen by laying their own eggs. Successful worker reproduction, however, is frequently prevented by queen policing or worker policing, whereby either the mother queen or non-reproductive workers selectively kill worker-laid eggs. Recently, a third mechanism-""selfish"" worker policing-has also been described in which the workers selectively police worker-laid eggs but also lay eggs themselves. Here, we present results from the monogynous wasp Dolichovespula norwegica, which show that all three kinds of policing-queen policing, worker policing and ""selfish"" worker policing-co-occur. The net effect of these three kinds of policing collectively favoured the queen`s reproduction, as within 1 day 44% of the worker-laid eggs versus only 8% of the queen-laid eggs were eaten. Of the worker-laid eggs that were killed by workers, approximately two thirds were eaten by the reproductive workers even though these made up only a small proportion, 8%, of the work force. This means that policing workers obtained both direct fitness benefits as well as indirect (inclusive) fitness. In addition, we show that worker policing was carried out by a limited, specialised set of workers that was estimated to constitute approximately one quarter of the whole colony and of which 66% were non-reproductive.

Discrete dimorphism among castes of the bald-faced hornet Dolichovespula maculata (Hymenoptera: Vespidae) in different phases of the colony cycle

Morphological and physiological caste differences were compared from colonies of Dolichovespula maculata in middle and late phases of the colony cycle. The females showed three patterns of ovarian development and only females classified as queens were inseminated. In both phases, queens were larger than workers for most measures. Discriminant analyses showed high distinction of caste in both phases. We also found highly pronounced qualitative differences: workers had hairs covering the entire body whereas queens had no hair and also some colour differences in the gaster. These results indicate that D. maculata presents pre-imaginal differentiation as seen in other Vespinae, and that size variation occurs from colony to colony such that queens of one colony may be comparable to workers of a different colony although the castes are always distinguishable within colonies.

Worker policing in the german wasp Vespula germanica

In some ants, bees, and wasps, workers kill or "police" male eggs laid by other workers in order to maintain the reproductive primacy of the queen. Kin selection theory predicts that multiple mating by the queen is one factor that can selectively favor worker policing. This is because when the queen is mated to multiple males, workers are more closely related to the queen's sons than to the sons of other workers. Earlier work has suggested that reproductive patterns in the German wasp Vespula germanica may contradict this theory, because in some colonies a large fraction of the adult males were inferred to be the workers' sons, despite the effective queen mating frequency being greater than 2 (2.4). In the present study, we reexamine the V. germanica case and show that it does support the theory. First, genetic analysis confirms that the effective queen mating frequency is high, 2.9, resulting in workers being more related to the queen's sons than to other workers' sons. Second, behavioral assays show that worker-laid eggs are effectively killed by other workers, despite worker-laid eggs having the same intrinsic viability as queen-laid ones. Finally, we estimate that approximately 58.4% of the male eggs but only 0.44% of the adult males are worker derived in queenright colonies, consistent with worker reproduction being effectively policed.

Worker policing in the german wasp Vespula germanica

In some ants, bees, and wasps, workers kill or "police" male eggs laid by other workers in order to maintain the reproductive primacy of the queen. Kin selection theory predicts that multiple mating by the queen is one factor that can selectively favor worker policing. This is because when the queen is mated to multiple males, workers are more closely related to the queen's sons than to the sons of other workers. Earlier work has suggested that reproductive patterns in the German wasp Vespula germanica may contradict this theory, because in some colonies a large fraction of the adult males were inferred to be the workers' sons, despite the effective queen mating frequency being greater than 2 (2.4). In the present study, we reexamine the V. germanica case and show that it does support the theory. First, genetic analysis confirms that the effective queen mating frequency is high, 2.9, resulting in workers being more related to the queen's sons than to other workers' sons. Second, behavioral assays show that worker-laid eggs are effectively killed by other workers, despite worker-laid eggs having the same intrinsic viability as queen-laid ones. Finally, we estimate that approximately 58.4% of the male eggs but only 0.44% of the adult males are worker derived in queenright colonies, consistent with worker reproduction being effectively policed.

Key to the paper and social wasps of Central Europe (Hymenoptera: Vespidae)

A determination key to the Central European paper wasps (Polistinae – Polistes Latreille, 1802 – eight species) and social wasps (Vespinae – 11 species: Vespa Linnaeus, 1758 – one species, Vespula Thomson, 1869 – four species, Dolichovespula Rohwer, 1916 – six species) is given. Distribution and biotope requirements of all species in the Czech Republic and Slovakia are briefly mentioned. All social wasps occur more or less regularly in both countries. Four paper wasps are relatively common but four other species (Polistes atrimandibularis Zimmermann, 1930, P. sulcifer Zimmermann, 1930, P. associus Kohl, 1898, and P. gallicus (Linnaeus, 1767)) are very rare with the Czech Republic and/or Slovakia at the northern edge of their range.

Discrete dimorphism among castes of the bald-faced hornet Dolichovespula maculata (Hymenoptera: Vespidae) in different phases of the colony cycle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Expanded food choice as a possible factor in the evolution of sociality of Vespidae (Hymenoptera)

A recent theory suggests that economic considerations are more important than genetic ones in the emergence and maintenance of social behavior. Evolution of social behavior in wasps, thus, could be based on the development of worker castes, which increase the efficiency of brood care and energy use of the colony. If so, social wasps should collect a larger range of prey, favoring polyethism, as social behavior should increase the adaptive value of social species among wasps by increasing the range of prey accessible. We explored the literature and showed that the Eumeninae, which are mostly solitary, draw prey from significantly fewer orders of arthropods than wasps in the subfamily Vespinae and Polistinae, which are mainly social, supporting the hypothesis that social behavior may have emerged as a more efficient way to feed and care for the young by opening a wider range of food sources, increasing the amount of food and quality of care provided to the young. Two alternative explanations of this data are also discussed.

Biologia comportamental de Synoeca surinama: enxameio e interações socias (Vespidae, Polistinae: Epiponini)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The Usefulness of the Sting Apparatus in Phylogenetic Reconstructions in Vespids, with Emphasis on the Epiponini: More Support for the Single Origin of Eusociality in the Vespidae

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)