Foundress association in the paper wasp Polistes simillimus (Hymenoptera: Vespidae)

Fábio Prezoto, Mariana Monteiro de Castro, André Rodrigues de Souza, Nivar Gobbi

Abstract


In many animal species, females are faced with at least 2 reproductive options: independent or cooperative breeding. Some individuals in cooperative groups choose to help in rearing the broods of conspecific females. Through observations of how females of Polistes simillimus Zikán, 1951 (Hymenoptera: Vespidae) started new nests in the field, we investigated whether ecological constraints and the geographic varia­tions explain group formation in this species. The founding of nests was studied between 1996 and 2000 in various localities of 2 states of southeastern Brazil. Weekly observations were carried out on 109 pre-worker nests. We kept track of 40 colonies in Minas Gerais State and 69 in São Paulo State, each started either by a single female or by an association of females. There was a chance that worker production would become numerically similar in both solitary and associative colonies in both states. An increased number of foundresses did not improve the chance of colony success in Minas Gerais State, but it improved this chance in São Paulo State, so that colonies each with 3 or more found­ressess were always successful. In colonies in both states, nest cell productivity was higher with a greater number of associated females per nest. Females were able to start building nests alone, being the only reproductive, or 2 or more females could cooperate to found a nest, thus increasing worker production. However, the type of environment chosen to establish the nest (anthropogenic or natural) seemed to influence strongly the choice of the founding strategy.

 

Resumen

En muchos animales, las hembras se enfrentan con por lo menos 2 opciones de reproducción: la reproducción independiente o coo­perativa, asi como, el cuidado de los progenies. A pesar de ser potencialmente capaz de reproducción directa, algunos individuos en grupos cooperativos optan por ayudar en criar los progenie de hembras conspecificas. ¿Por qué se asuma el papel de ayudar? Esta pregunta es de interés general, como se observa cría cooperativa en muchas especies de aves, mamíferos e insectos. Basado en las observaciones de campo de la forma en que las hembras de la avispa papel Polistes simillimus Zikán, 1951 (Hymenoptera: Vespidae) fundaron nuevos nidos durante 4 años consecutivos, se discuten algunas hipótesis que pueden explicar la cría cooperativa en esta especie. Una hembra de P. simillimus puede empezar un nido por sí misma y ser la única reproductiva. Por otra parte, varias hembras pueden cooperar para fundar un nido, y de ese modo mejorar la probabilidad de que la cría llegue a la etapa de la producción de los trabajadores. A pesar de informes anteriores que mostraron asimetrías inmediatos o un sesgo reproductivo entre las hembras que cooperan, los ayudantes pueden mejorar su aptitud indirectamente al criar los que no son descendientes de ellas, o incluso mejor su aptitud directamente por esperar de una oportunidad para aparearse.

 

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Keywords


ecological constraints; foundress number; group augmentation; helping; Polistinae

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