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Species of the subgenus Augochlora have been considered solitary, and their behavior was postulated as a reversal from the social condition known for its closest relatives. In this study, conclusive evidence of eusocial behavior in the wood-dwelling subgenus Augochlora is presented. Direct observation of behavior within artificial nests in the laboratory allowed studying the suite of behaviors that characterize social structure in the species Augochlora (Augochlora) phoemonoe. The following behaviors were recorded and analyzed: locomotion, feeding, construction activities within the nest, pollen collecting, guarding, oviposition, sudden retreats, antennation-tarsation, passing, and following. The last three behaviors represented interactions between nestmates. Social behavior in this temperate South American species is characterized by: a solitary nest initiation phase, followed by an eusocial phase with at least two broods; the small size of the colonies, with 1-3 first-brood females during the summer foraging period; the long-lived foundresses, alive until the end of the season; lack of morphological differentiation between dominant and subordinate individuals, evidenced by size only, but strong physiological differentiation, with a high reproductive skew; short egg-to-adult developmental time (approximately 30 days); and delayed male production to the second or subsequent broods. Indexes of division of labor ranged between 0.32 and 0.76 for the studied nests, indicating behavioral specialization between colony members. During the eusocial phase, daughter bees had the highest frequencies of construction, pollen collection and guarding. Colony integration was mediated by high rates of social interactions, initiated by the foundress.

Recent studies have assessed the influence of different types of gradients (e.g. altitudinal, latitudinal and temporal, among others) on the structure and function of community-level plant-pollinator webs. Although the importance of humidity as a major driver of species-richness gradients worldwide has been stressed by recent reviews, no studies have been specifically designed to address the influence of precipitation gradients on pollination webs. In the present paper we describe for the first time the turnover of species of plants and their associated flower visitors between eight communities located along a steep precipitation gradient in north-west Patagonia, Argentina. Our results show that: (i) there is a high spatial turnover of plant communities and their associated pollinators; (ii) this turnover is strongly related to precipitation changes across the region; and (iii) the turnover rate is similar for plants and pollinators. Our results support the view that the precipitation gradient is a significant factor associated with the regional turnover of plants and their pollinators in the temperate forests of southern South America.

Citing articles: 9 View citing articles Boll. Zool. 60: 169-183 (1993) The evolution of the apoid endophallus, its phylogenetic implications, and functional significance of the genital capsule (Hymenoptera, Apoidea)* ARTURO ROIG-ALSINA** Department of Entomology and Snow Entomological Museum, University of Kansas, Lawrence, Kansas 66045 (USA) ABSTRACT An eversible endophallus is present in most groups of bees. Its presence or absence and its morphological variation were studied in 122 species, representing nine families of bees. An eversible endophallus is absent in the sphecoid wasps and other aculeate Hymenoptera, as well as in the bee families Colletidae and Oxaeidae, and part of the subfamily Andreninae of the Andrenidae. It is suggested that the families Colletidae and Oxaeidae may represent early offshoots in bee phylogeny. Extremely complex endophalli occur in some groups of bees: a positive correlation between complex endophalli and polyandrous mating system was found, suggesting that sexual selection may be the evolutionary force shaping endophallic morphology. The function of the endophallus, as well as of other parts of the external genitalia, was studied in specimens in copula of Nomia nevadensis and Perdita albipennis. The study of the mechanics of copulation was extended to other species, showing that the several sclerotized parts of the bee genital capsule function as clasping devices.