Hamish G. Robertson

Comparison of leaf litter ant communities in woodlands, lowland forests and montane forests of north-eastern Tanzania

Ants were extracted in Winkler bags from sifted leaf litter sampled in arange of forest and woodland types in and around Mkomazi Game Reserve innorth-eastern Tanzania, including the Eastern Arc Mountains of South Pare andWest Usambara. A total of 87 ant species were recorded, of which 32.2% were onlyrecorded from montane forests (1400–1850 m altitude), 6.9%only from lowland forest (540–810 m), 19.5% only fromwoodland (300–1080 m), and 16.1% in all three forest types.Of the 28 species recorded only from montane forests, 12 species were only foundin the Mkomazi forests, four only in the Pares and seven species only in theUsambaras. Sites of similar altitude grouped together in a cluster analysis, andspecies richness decreased with an increase in altitude. The lowland forest andclosed woodland sites did not form distinct communities. To ensure preservationof ant species, forests from a full range of altitudes need to be conserved.This study confirms the status of the West Usambara forests as having a highlyendemic biota, and the critical need to adequately conserve the remainingvestiges of montane forest within Mkomazi Game Reserve.

Conservation value of road verges in the semi-arid Karoo, South Africa: ants (Hymenoptera: Formicidae) as bio-indicators

Ground-foraging ants (Hymenoptera: Formicidae) were used to assess the conservation value of road verges in a semi-arid region around Prince Albert, Western Cape Province, South Africa. Ant communities were sampled using pitfall traps on 50 sites along two roads. Four transects were sampled at each site, two in the road verge and two in adjacent rangeland. A total of 43,298 individual ants of 34 species were caught, with 31 and 32 species in the road verge and adjacent rangeland respectively, but on average road verges were the more species-rich. Road verges also contained relatively more rare species (i.e. those species that occurred in <10% of the traps. Ant species richness appeared to be influenced by food availability. Although ants appeared to be negatively impacted by higher grazing intensities in the rangeland, there was no difference in species richness between fenced and unfenced road verges. Species in the road verge may benefit directly from road kills, and indirectly from lower grazing pressure on plants, increased surface run-off and differences in soil surface temperatures. No alien ant species were observed or captured at any of the sites.

Osmoregulation and temperature effects on water loss and oxygen consumption in two species of african scorpion

1. 1. Aspects of the physiology of two southern African scorpions have been examined. The scorpions are the large desert species Parabuthus villosus (Peters) (Buthidae) and the more mesic, burrowing species Opisthophthalmus capensis (Herbst) (Scorpionidae). 2. 2. Evaporative water losses were higher in Opisthophthalmus at all temperatures. 3. 3. Analysis of haemolymph during prolonged desiccation showed good osmotic and ionic regulation in Parabuthus but no regulation in Opisthophthalmus. 4. 4. Oxygen consumption of Parabuthus was measured after acclimation to 10 and 30°C. Metabolic rates were extremely low but there was no metabolic compensation to increased temperatures.

Mating behaviour in three species of myrmicine ants (Hymenoptera: Formicidae)

The mating behaviours of Carebara vidua, Meranoplus peringueyi and Crematogaster sp. are described. C. vidua fits the female calling-syndrome whereas the other two species fit the male-aggregation syndrome. Differences in mating postures are illustrated. The occurrence of the two syndromes in the Myrmicinae, and factors that might select the nature of mating behaviour, are discussed.

Ant assemblages at three potential breeding sites for the Brenton blue butterfly, Orachrysops niobe (Trimen)

Conservation of South Africas butterflies is critically dependent on knowledge of their ecology. Many endangered species are in the family Lycaenidae and have a more-or-less obligate relationship with a particular species of ant. An ecosystem capable of hosting such butterfly species must also be able to sustain substantial populations of the host ant. The Brenton blue, Orachrysops niobe, is one of the most endangered South African butterflies, and is known only from one site in the Western Cape. Ant assemblages were investigated at this site and two other ecologically similar sites where the host plant of O. niobe, Indigofera erecta, also occurs, but O. niobe was absent. The ant assemblages differed significantly, with the host ant of O. niobe, Camponotus baynei, only occurring at the Brenton site where the butterfly was breeding. Vegetation composition, structure and microclimate differed at the three sites and these appear to be key factors in determining the ant assemblages that a site will support. The two sites where C. baynei was absent had a history of recent fire, which contributed to the vegetation changes and deprived the ant of dead wood for nesting. The invasive Argentine ant, Linepithema humile, was not detected at any of the study sites, and the reasons for this are discussed.