Productivity, individual-level and colony-level flexibility, and organization of work as consequences of colony size.

In social insects, colony-level complexity may emerge from simple individual-level behaviors and interactions. Emergent global properties such as colony size, which can be viewed as a consequence of life history traits, may influence individual-level behaviors themselves. The effects of colony size on productivity, body size, behavioral flexibility, and colony organization are examined here by considering colony size as an independent variable. Large colony size commonly corresponds with complex colony-level performance, small body size, and lower per capita productivity. Analyzing the construction behavior of various wasp societies reveals that complexity of individual behavior is inversely related to colony size. Parallel processing by specialists in large colonies provides flexible and efficient colony-level functioning. On the other hand, individual behavioral flexibility of jack-of-all trades workers ensures success of the small and early societies.

Temporal, spatial, sex-ratio and body-size heterogeneity of prey species taken by the beewolf Philanthus sanbornii (Hymenoptera: Sphecidae).

More than 3000 prey representing 108 species of bees and wasps were identified from exoskeletal remains taken from nests of the beewolf Philanthus sanbornii at a site in eastern Massachusetts over a period of five years. Quantitative reference samples totalling more than 4000 items were collected from flowers at the same site over a period of four years. These data give a uniquely detailed view of the way in which a generalist predator exploits a diverse prey community. Most species show striking year-to-year variation in relative abundance, in both the prey and reference collections, but the overall abundances of species tend to be similar in the two collections, as do their sex ratios. This shows: (i) that P. sanbornii takes virtually every bee and wasp species found at flowers during its flight season (except for the relatively small number of species too large to handle); (ii) that prey are taken at rates roughly proportional to their local abundances (with a few exceptions); and (iii) that the local bee and wasp communities have lively dynamics (at least on spatial scales equivalent to the flight ranges of P. sanbornii females). Prey species are non-randomly distributed among nests of individual females within years, and among cells within nests, in a pattern suggesting that females often return repeatedly to hunting sites at which they have had success; the pattern does not suggest that individual females develop preferences for particular prey taxa. The size-abundance distributions of female bees appear to be trimodal at both the individual and species levels, most strongly so when cleptoparasitic species are removed from the sample. Such patterns are seen weakly or not at all in the size-abundance distributions of male bees, male wasps, and female wasps. Bees and wasps of both sexes visit flowers for nectar, but only non-parasitic female bees harvest pollen; this suggests that the multimodality may be caused by aspects of pollen collection that tend to scale with size. The seven Philanthus species of eastern North America vary greatly in size, but they share a common set of relatively small prey species. As in other parts of North America, larger species of Philanthus tend to have relatively broad diets because they also take larger prey that are not available to their smaller congeners. However, long-tongued bees appear to be under-represented in the diets of most North American Philanthus outside the zebratus species group.

Cooperative foraging, productivity, and the central limit theorem.

The central limit theorem is applied to group foraging to show an automatic and universal benefit to group living. This may explain the paradoxical inverse correlation between group size and per capita brood production in primitively eusocial insects and why only one of the five major lineages of social insects contains species that revert to solitary habit.

Surface lipids of social waspPolistes melricus say and its nest and nest pedicel and their relation to nestmate recognition.

In eight replicate laboratory tests wherePolistes metricus adults were allowed to choose between their own nest, a second nest, and neither nest, they selected their own nest 66% of the observed time. When the surface hydrocarbons had been extracted from the nests, the wasps chose their own nest only 8% of the time, but after the hydrocarbons were reapplied to the surface of the respective nests, they selected their own nest 47% of the time. These changes are significant. The cuticular lipids were analyzed from individualP. metricus adult females collected from 13 colonies. Surface lipids were recovered from the paper and pedicels of their nests. Eighteen hydrocarbons were identified in these lipid fractions. The major components of the wasp cuticular lipids weren-heptacosane,n-nonacosane, methylhentriacontane, and methyltritriacontane. Factor analysis revealed that extracts of pedicels are all similar in composition, while cuticle and paper extracts vary, sometimes similarly according to colony identity.

Pheromonal covariation and kinship in social beeLasioglossum zephyrum (Hymenoptera: Halictidae).

Both males and females of the primitively eusocial beeLasioglossum zephyrum can distinguish among female conspecifics with regard to genealogical relationship. Closely related females covary with respect to Dufour's gland pheromone products which are believed to function in individual or kin recognition. This is the first report of a population-wide parallel between similarity of communicative glandular product and genetic similarity.