Thiago S. Montagna

Division of labor in colonies of the eusocial wasp, Mischocyttarus consimilis.

Abstract The division of labor between castes and the division of labor in workers according to age (temporal polyethism) in social wasps are crucial for maintaining social organization. This study evaluated the division of labor between castes, and the temporal polyethism in workers of Mischocyttarus consimilis Zikán (Hymenoptera: Vespidae). To describe the behavioral repertory of this species, observations were made of 21 colonies, with 100 hours of observations. In order to observe temporal polyethism, each newly emerged wasp was marked with colored dots on the upper area of the thorax. This allowed the observation of behavioral acts performed by each worker from the time of emergence to its death. Through hybrid multidimensional scaling, a clear division between queens and workers could be identified, in which the behaviors of physical dominance and food solicitation characterized the queen caste; while behaviors such as adult—adult trophallaxis, destruction of cells, alarm, foraging for prey, foraging for nectar, and unsuccessful foraging characterized the worker caste. Hybrid multidimensional scaling characterized two groups, with intra—nest activities preferentially accomplished by younger workers, while extra—nest activities such as foraging were executed more frequently by older workers.

Colony cycle of the social wasp Mischocyttarus consimilis Zikán (Hymenoptera, Vespidae)

Colony cycle of the social wasp Mischocyttarus consimilis Zikan (Hymenoptera, Vespidae). This study describes some aspects of the colony cycle of the Neotropical social wasp Mischocyttarus consimilis, from data obtained under field conditions. Our results showed that the colony cycle in M. consimilis is annual and asynchronous in relation to the months of the year. The colonies remained active for approximately eight months. Most of the abandonments were associated with natural causes, and were most frequent in the pre-emergence stage. The nests were constructed preferentially in man-made structures, especially in sites protected from direct sunlight and rain. Colony foundation was either by haplometrosis or pleometrosis, being the first form predominant.

Nest Architecture, Colony Productivity, and Duration of Immature Stages in a Social Wasp, Mischocyttarus consimilis

Abstract This study examined the nest architecture, colony productivity, and duration of the immature stages of the social wasp Mischocyttarus consimilis Zikán (Hymenoptera: Vespidae). The study was carried out under field conditions. Nests of M. consimilis consist of a single uncovered comb, which is attached to the substratum by a single petiole. The data for the nest architecture showed a positive and significant correlation between the size of the comb and the diameter of the petiole, and also between the height and diameter of the cells. The nests were constructed on horizontal, vertical, and sloping substrata with no apparent preference for a specific orientation. The colonies produced 72.9 cells and 40.7 adults on average. The mean frequency of productive cells was 33.3%, and 19.4% of the cells were reused. The mean duration of the immature stages combined was 69.7 days and the egg, larval, and pupal stages had mean durations of 14.9, 36.0, and 18.8 days, respectively. The duration of each immature stage was significantly shorter in the warmhumid season, and the larval and pupal stages were shorter during the colony pre-emergence stage.

Social Parasitism and Dynamics of Cuticular Hydrocarbons in Paper Wasps of the Genus Mischocyttarus

Abstract Facultative social parasitism has been recorded in several taxa of social insects. Most recently, this phenomenon has been recorded in colonies of the neotropical social wasp Mischocyttarus cerberus (parasitized by Mischocyttarus consimilis). This is the first case of interspecific parasitism described for the genus Mischocyttarus. How social parasites are able to remain in the host colony has been one of the central subjects of studies on this theme. Chemical signals are used by social insects to recognize their nestmates, which suggests that female parasites use a chemical strategy to hide their identity and become accepted as a member in host colonies. This study investigated the dynamics of cuticular hydrocarbons (CHs) of workers of M. consimilis and M. cerberus in both control and host colonies. Fourier Transform Infrared-Photoacoustic Spectroscopy (FTIR-PAS) was used to read the CHs; this technique is somewhat unusual but is quite reliable for this type of study. A stepwise canonical discrimination analysis detected significant differences between the mid-infrared spectra of the two species. This analysis provided a dispersion diagram of the results in order to differentiate the species, in which the first axis explained 61% of the results. These results demonstrated a clear difference in the CHs profile between non-conspecific workers from the control colonies. However, non-conspecific workers from the host colonies underwent a significant modification of CHs in comparison to the workers from the control colonies, and this modification was similar in all the host colonies non-conspecific workers. These data suggest that females of parasitic-specie modify the chemical profile of the host-specie females, and also alter their own profiles in order to be recognized as “nestmates” and to achieve success in parasitism.

First report of interspecific facultative social parasitism in the paper wasp genus Mischocyttarus Saussure (Hymenoptera, Vespidae)

Primeiro registro de parasitismo social facultativo interespecifico em vespas do genero Mischocyttarus Saussure (Hymenoptera, Vespidae). Parasitismo de colonias da vespa social Mischocyttarus cerberus Ducke, 1918 por femeas de Mischocyttarus consimilis Zikan, 1949 foram registrados em uma area rural no municipio de Dourados estado de Mato Grosso do Sul no Brasil. Em todos os casos monitorados a invasao ocorreu na fase colonial de pre-emergencia, e em geral foi executado por uma unica femea de M. consimilis. O periodo de estabelecimento da femea estrangeira na colonia hospedeira foi marcado por comportamentos antagonicos entre as femeas interespecificas. Em geral, a arquitetura do ninho parasitado foi modificada em relacao a arquitetura tipica do ninho da especie hospedeira.

Aspectos bionômicos da vespa social Neotropical Polistes canadensis canadensis (Linnaeus) (Hymenoptera, Vespidae

Bionomics aspects of the Neotropical social wasp Polistes canadensis canadensis (Linnaeus) (Hymenoptera, Vespidae). Certain aspects of the bionomics of the Neotropical social wasp Polistes canadensis canadensis (Linnaeus, 1758) were studied. Twenty-six colonies were observed from April 2004 through July 2006, in the municipal district of Mundo Novo, state of Mato Grosso do Sul, central-Brazil. The results suggest that the colony phenological pattern of this species is asynchronous, and colonies may be founded or abandoned at any time of the year. The mean duration of the immature stages differed between the cold-dry and warm-rainy seasons. Colonies were founded on several different kinds of substrates, but were more successful in environments that provided more-homogeneous physical conditions during the day. Colonies in this species are founded by haplometrosis or pleometrosis, and pleometrotic colonies were more successful.