CiteULike: Tag hymenoptera

Life history of learning: performance curves of honeybees in settings that minimize the role of learning

Reuven Dukas — 2008-01-30T11:59:59-00:00

Animal Behaviour, Vol. In Press, Corrected Proof

Life history research has mostly neglected learning even though it is probably a major contributor to lifetime performance in a variety of animals. As part of an ongoing project evaluating the relative contribution of learning, physiology and effort to performance throughout the life span, I quantified lifetime performance of honeybees, Apis mellifera, foraging at a feeder. Unlike natural foraging, where bees may learn a variety of features that contribute to increased performance, food collection from a feeder requires little learning. Foragers showed no long-term change in the rate of food delivery, a pattern that was different from published data indicating a long-term gradual increase in foraging performance in honeybees under natural settings. The discrepancy between bees' lifetime performance in the artificial versus natural settings suggests that learning is the key component contributing to the increase in performance throughout a forager's life as observed in the field.

Bee diversity along a disturbance gradient in tropical lowland forests of south-east Asia

Lee Liow — 2007-05-26T21:52:12-00:00

Journal of Applied Ecology, Vol. 38, No. 1. (2001), pp. 180-192.

Summary 1. Bees are believed to be dominant pollen vectors in tropical forests, yet studies specific to bees in south-east Asia are rare. Regeneration and restoration of the rapidly disappearing lowland forests of this region are reliant on bees, thus there is an urgent need for forest bee data at the community level. 2. Bee communities of eight forested sites in Johor (Malaysia) and Singapore were surveyed three times each from February to August 1999 at the below-canopy level. These sites ranged from relatively undisturbed primary lowland dipterocarp forests to late secondary forests and exotic forests, including an oil palm plantation. We attempted to elucidate the environmental factors that correlated with the distribution of bees. 3. Bee abundance, in particular that of Apidae, was significantly higher in larger primary forests than other types of forests. However, bee species richness was higher in disturbed forests. 4. The distribution of bees was apparently influenced by variables closely related to forest disturbance and resource abundance, such as the density of big trees (diameter at breast height 30-40 cm), temperature and flowering intensity of trees and shrubs. 5. More stingless bees (Trigona spp.) were found where trees were larger and ambient conditions more constant but flowering intensities lower. 6. The differences between the bee communities in forests of urban Singapore and primary forests in Johor may indicate that ecological processes in the forests of Singapore, in particular pollination, may be changing. However, pollination may not be totally intact in the primary forests surveyed, as their bee communities seemed to be depauperate. 7. The role of important pollinators, especially bees, for the long-term survival of tropical lowland forests is poorly understood. Our study indicates that we urgently need more thorough understanding of pollination and pollinators, as some bee species appear to be disappearing from disturbed tropical lowland forests.

Exploring arboreal ant community composition and co-occurrence patterns in plantations of oil palm Elaeis guineensis in Borneo and Peninsular Malaysia

Martin Pfeiffer — 2008-02-21T13:24:26-00:00

Ecography, Vol. 31, No. 1. (February 2008), pp. 21-32.

The oil palm, Elaeis guineensis, is a native of West Africa and is now extensively grown in south-east Asia. In 2005, the crop covered four million ha of Malaysia. We examined the arboreal ant fauna in two oil palm plantations that had been farmed with integrated pest management practices for at least 10 yr. Having cut and examined palm fronds from 595 and 503 palms in Borneo and Peninsular Malaysia respectively, we studied diversity in ant assemblages, analysed composition of ant mosaics by stepwise use of null-models, and explored the influence of exotic vs native species on community structure. Altogether we sampled 52 species of canopy ants, of which 23 species were shared between Borneo and Peninsular Malaysia. Seventeen species in Borneo and 24 species in Peninsular Malaysia accounted for 95% of all species occurrences (SOCs). Fortysix percent of all SOCs belonged to 12 tramp ant species with pan-tropical distributions. Forty percent of all SOCs were exotic ants. Six dominant species were found in Borneo, five in the Peninsula. The three most abundant species, Anoplolepis gracilipes, Oecophylla smaragdina and Technomyrmex albipes were dominant in both sites. Three dominants were invasive species that were found on more palms than the native group. Dominant tramp species coexisted with non-dominants more often and tolerated more species of non-dominant ants than native dominants. Null model analyses indicated that species were arranged in mosaics at both the Peninsular Malaysia and Borneo sites. Dominant species showed much less co-occurrence than expected by chance, pointing towards species segregation (even in presence of introduced, invasive species). Similar results were obtained for all species. Non-dominant ants were either positively associated with their dominants, or co-occurred randomly in the presence of dominant species. In contrast, ant assemblages on palms without dominants showed species segregation.

Complementary sex determination substantially increases extinction proneness of haplodiploid populations.

A Zayed — 2005-08-17T09:26:10-00:00

Proc Natl Acad Sci U S A, Vol. 102, No. 30. (26 July 2005), pp. 10742-10746.

The role of genetic factors in extinction is firmly established for diploid organisms, but haplodiploids have been considered immune to genetic load impacts because deleterious alleles are readily purged in haploid males. However, we show that single-locus complementary sex determination ancestral to the haplodiploid Hymenoptera (ants, bees, and wasps) imposes a substantial genetic load through homozygosity at the sex locus that results in the production of inviable or sterile diploid males. Using stochastic modeling, we have discovered that diploid male production (DMP) can initiate a rapid and previously uncharacterized extinction vortex. The extinction rate in haplodiploid populations with DMP is an order of magnitude greater than in its absence under realistic but conservative demographic parameter values. Furthermore, DMP alone can elevate the base extinction risk in haplodiploids by over an order of magnitude higher than that caused by inbreeding depression in threatened diploids. Thus, contrary to previous expectations, haplodiploids are more, rather than less, prone to extinction for genetic reasons. Our findings necessitate a fundamental shift in approaches to the conservation and population biology of these ecologically and economically crucial insects.

The "Language" and Orientation of the Bees

Karl von Frisch — 2005-04-27T04:04:00-00:00

Proceedings of the American Philosophical Society, Vol. 100, No. 5. (1956), pp. 515-519.

Phylogenetic relationships among the Braconidae (Hymenoptera: Ichneumonoidea) inferred from partial 16S rDNA, 28S rDNA D2, 18S rDNA gene sequences and morphological characters

M Shi — 2006-02-14T05:21:31-00:00

Molecular Phylogenetics and Evolution, Vol. 37, No. 1. (October 2005), pp. 104-116.

Phylogenetic relationships among the Braconidae were examined using homologous 16S rDNA, 28S rDNA D2 region, and 18S rDNA gene sequences and morphological data using both PAUP* 4.0 and MRBAYES 3.0B4 from 88 in-group taxa representing 35 subfamilies. The monophyletic nature of almost all subfamilies, of which multiple representatives are present in this study, is well-supported except for two subfamilies, Cenocoelinae and Neoneurinae that should probably be treated as tribal rank taxa in the subfamily Euphorinae. The topology of the trees generated in the present study supported the existence of three large generally accepted lineage or groupings of subfamilies: two main entirely endoparasitic lineages of this family, referred to as the "helconoid complex" and the "microgastroid complex," and the third "the cyclostome." The Aphidiinae was recovered as a member of the non-cyclostomes, probably a sister group of Euphorinae or Euphorinae-complex. The basal position of the microgastroid complex among the non-cyclostomes has been found in all our analyses. The cyclostomes were resolved as a monophyletic group in all analyses if two putatively misplaced groups (Mesostoa and Aspilodemon) were excluded from them. Certain well-supported relationships evident in this family from the previous analyses were recovered, such as a sister-group relationships of Alysiinae + Opiinae, of Braconinae + Doryctinae, and a close relationship between Macrocentrinae, Xiphozelinae, Homolobinae, and Charmontinae. The relationships of "Ichneutinae + ((Adeliinae + Cheloninae) + (Miracinae + (Cardiochilinae + Microgastrinae)))" was confirmed within the microgastroid complex. The position of Acampsohelconinae, Blacinae, and Trachypetinae is problematic.

Dracula ant phylogeny as inferred by nuclear 28S rDNA sequences and implications for ant systematics (Hymenoptera: Formicidae: Amblyoponinae).

C Saux — 2006-09-20T16:43:56-00:00

Mol Phylogenet Evol, Vol. 33, No. 2. (November 2004), pp. 457-468.

Ants are one of the most ecologically and numerically dominant families of organisms in almost every terrestrial habitat throughout the world, though they include only about 1% of all described insect species. The development of eusociality is thought to have been a driving force in the striking diversification and dominance of this group, yet we know little about the evolution of the major lineages of ants and have been unable to clearly determine their primitive characteristics. Ants within the subfamily Amblyoponinae are specialized arthropod predators, possess many anatomically and behaviorally primitive characters and have been proposed as a possible basal lineage within the ants. We investigate the phylogenetic relationships among the members of the subfamily, using nuclear 28S rDNA sequence data. Outgroups for the analysis include members of the poneromorph and leptanillomorph (Apomyrma, Leptanilla) ant subfamilies, as well as three wasp families. Parsimony, maximum likelihood, and Bayesian analyses provide strong support for the monophyly of a clade containing the two genera Apomyrma+Mystrium (100% bpp; 97% ML bs; and 97% MP bs), and moderate support for the monophyly of the Amblyoponinae as long as Apomyrma (Apomyrminae) is included (87% bpp; 57% ML bs; and 76% MP bs). Analyses did not recover evidence of monophyly of the Amblyopone genus, while the monophyly of the other genera in the subfamily is supported. Based on these results we provide a morphological diagnosis of the Amblyoponinae that includes Apomyrma. Among the outgroup taxa, Typhlomyrmex grouped consistently with Ectatomma, supporting the recent placement of Typhlomyrmex in the Ectatomminae. The results of this present study place the included ant subfamilies into roughly two clades with the basal placement of Leptanilla unclear. One clade contains all the Amblyoponinae (including Apomyrma), Ponerinae, and Proceratiinae (Poneroid clade). The other clade contains members from subfamilies Cerapachyinae, Dolichoderinae, Ectatomminae, Formicinae, Myrmeciinae, and Myrmicinae (Formicoid clade).