The species present, and the frequencies and intensities of termite attack on 600 paper baits exposed at the soil surface were compared over three seasonal exposures and between two savanna sites of contrasting vegetation structure in northern Australia. Eleven species were recorded, with Microcerotermes nervosus and Schedorhinotermes actuosus comprising 43% and 27% of collections respectively. The most commonly sampled species nest underground or build epigeal mounds and are known to feed on sound and decaying wood. Changes in species dominance occurred between seasons and the two forest types. In both vegetation types, the number of species active and the frequency of attack increased with the duration of bait exposure and decreased in the order: transitional > wet > dry. Bait consumption was greater in the site with higher canopy cover, and did not differ significantly between seasons. No direct relationships were noted between rainfall recorded at the sites and species richness, frequency and intensity of attack on baits. We recommend exposure of paper baits for at least 2 mo during the transitional period as the optimal protocol for sampling at the time of greatest activity and diversity of those species within the guild of wood-feeding species regularly attracted to paper baits.

Abstract.  1. Cellulose baits are commonly used for semi‐quantitative sampling of subterranean wood‐feeding termites, with a single food choice sampling programme implemented most often. In most situations, however, the composition and feeding preferences of the subterranean termite assemblage remain unknown. 2. The diversity, frequency, foraging activity, and intensity of attack of termites were assessed regularly at 144 baits representing 12 different bait choices over 8.5 months, in two northern Australian tropical savanna sites that differed in vegetation structure (closed vs open). Baits differed in type (paper rolls, cardboard, wooden stakes), position (surface, buried), and moisture status at installation (wet, dry). 3. Sixteen species were recorded, including 11 wood‐feeders. Average species diversity, foraging activity, and bait consumption were greater at buried baits than at surface baits. Wooden baits were most attractive early in the experiment, and paper baits more attractive later. Mean species diversity was greatest at wooden stakes in the closed site. Species frequency of occurrence varied across bait choices. 4. A composite bait sampling protocol of stakes and paper rolls installed above and below ground gave an accurate assessment of the activity, diversity, and structure of the termite guild sampled across all baits over 8.5 months. 5. The choice of bait, its presentation, and time of examination are critical to the success of a termite baiting programme. If the aim is to characterise the structure and foraging activity of the subterranean termite assemblages that are attracted to baits, composite baiting protocols should be implemented.

Termite species richness, frequency of occurrence and functional diversity at Holmes Jungle Nature Reserve, a monsoon rainforest patch in northern Australia, was investigated at the end of the wet season in 2003. A sampling protocol that employed direct search, soil pits and baiting techniques was used to sample litter, wood, mound, soil and arboreal nest microhabitats for termites. Five species from five genera and three families (Mastotermitidae, Rhinotermitidae and Termitidae) were recorded. This included the first record of Ephelotermes taylori (Hill) from monsoon forest in Australia. The family Termitidae was dominant and represented 70% of termite occurrences. Termites were most frequently encountered in carton runways on tree trunks, followed by lying dead wood and baits. Four nesting habits were represented: arboreal, epigeal, hypogeal and within wood. The arboreal nestbuilder Nasutitermes graveolus (Hill) accounted for 61% of termite encounters. Epigeal moundbuilding species were rare. Wood-feeders were the only trophic group represented. Relatively high activity of Mastotermes darwiniensis Froggatt was recorded at baits within 2.5 months. The low species richness recorded at Holmes Jungle is consistent with the low diversity reported for Australian rainforests generally, but remains relatively depauperate compared with other monsoon forest and savanna habitats of the Northern Territory.

A comprehensive karyological characterization of 20 Australian and three European species of Isoptera, together with a mitochondrial gene analysis is presented. Higher termites appear karyotypically very uniform, while lower termites are highly variable. The differences in chromosome number are explained through Robertsonian changes or multiple translocation events. An ancestral acrocentric karyotype can be suggested as the most primitive one. In Kalotermitidae chromosomal repatterning has repeatedly arisen with the X0-male type possibly representing a XY-derived condition. This argues against a simple origin of termites from cockroaches. The fixed chromosome number of Rhinotermitidae and Termitidae (2n=42, XY/XX) may be explained with the non-random nature of chromosomal evolution. A sex-linked multivalent, either with a ring or a chain structure, is found in the majority of species. Phylogenetic analyses on COII sequences recognize Mastotermitidae as the basal lineage and define the Rhinotermitidae+Termitidae cluster with a good bootstrap support. Kalotermitidae fail to be joined in a single cluster in agreement with the detected chromosomal variability. On the other hand, the karyotypic conservation of the Termitidae family contrasts with the polytomy evidenced at the subfamily level.

Soil macroinvertebrates play an important role in sustaining production and biodiversity in Australia s tropical savannas. For example, termites, through their foraging and nesting activities, recycle nutrients and carbon and produce soil pores that facilitate water infiltration. The challenge ahead is to quantitatively understand the relationships and processes that drive this. What roles do different species and functional groups of macroinvertebrates play in various landscape processes? What are the effects of different land management practices (e.g., domestic cattle grazing, fire) on these relationships, and the consequences for landscape health? This paper presents preliminary results from studies in northern Australia, that examine the effects of land condition and domestic cattle grazing on soil macroinvertebrates, and the potential for termites to be used as a tool to restore soil function in degraded areas. In northern Australia, increased degradation seems to be associated with declines in the diversity and activity of macroinvertebrates. Termites appear to be one of the most resilient groups, with some species capable of maintaining activity in degraded landscapes.

Early dry season fires are a common land management regime employed across the tropical savannas of northern Australia. The rationale is that this reduces fuel loads and so reduces fire risk in the latter part of the dry season. Despite the acceptance of fire as a major management tool the ecological effects of fire remain uncertain. Vegetation patches and their associated macroinvertebrates play a critical role in the capture and recycling of water and nutrients. The aim of this study was to examine the responses of soil macroinvertebrates, within different types of vegetation patches, to early dry season fires in tropical savanna woodland in northern Australia. The abundance of major macroinvertebrate taxa and functional groups, and taxon richness were quantified in three vegetation patch types 2 weeks before and 2 weeks after burning. Termites dominated the soil macroinvertebrate assemblage sampled. Fire led to significant decreases in ant and spider abundances and overall taxon richness. Functional group analyses showed significant overall declines in the abundances of macropredators and litter transformers. There were also interactions between fire and patch type; in tree patches, fire significantly reduced total macroinvertebrate abundance, as well as the abundance of termites and ecosystem engineers. These changes in soil macroinvertebrates will potentially influence patch functionality, with important implications for soil processes and landscape health.

This study contributes to the paucity of knowledge on the structure of Australian tropical savanna termite assemblages, compared with that available for tropical savannas elsewhere in the world. Termite species diversity, frequency of occurrence and functional diversity in Charles Darwin National Park, a savanna woodland reserve in tropical northern Australia, were assessed. In four 50 ¥ 50 m sites, a direct search and bait sampling protocol was used to sample mounds, standing and lying dead wood, litter, soil and arboreal nest microhabitats for termites between April and June 2003. Results were compared with a priori predictions of termite community structure based on the work by Braithwaite et al. (1988). Sixteen species from nine genera and three families (Mastotermitidae, Rhinotermitidae and Termitidae) were recorded, including the first record of Ephelotermes taylori (Hill) from open savanna woodland habitat and the first official record of Macrognathotermes errator Miller from north Australian savanna. The family Termitidae represented 69% of termite occurrences. From this family, the wood/soil interface feeder Nasutitermes eucalypti (Mjöberg) represented 30% of encounters. High levels of termite activity were recorded at baits within 6 weeks. Four nesting habits were represented: epigeal (mounds above ground), hypogeal (subterranean nests), nests within wood and arboreal nests. Termites were most frequently encountered in epigeal mounds and lying dead wood. Wood and wood/soil interface feeders were the most common. The findings partially supported the a priori predictions proposed. The termite assemblage structure was represented by species commonly found in other Northern Territory savanna woodland habitats. However, species diversity was lower; soil feeders and live wood feeders were less common and grass-harvesting species were absent. Soil nitrogen and phosphorus and species richness and patchiness of ground vegetation may contribute to these differences. The lower species diversity recorded contrasts with the richer termite faunas of tropical savannas recorded elsewhere.

Despite continued interest in the relative roles of top‐down (predation) and bottom‐up (productivity) factors in structuring ecological communities, there have been few studies of diverse terrestrial arthropod systems. Top‐down theory predicts that decreased predator populations will result in increased herbivore populations and reduced plant populations. Bottom‐up theory predicts that a positive producer level response to nutrients will support greater herbivore and predator populations. Few studies simultaneously examine both theories. In the present study, the roles of predators and nutrients in structuring an Australian chenopod shrubland community were investigated, by using a complete 2 × 2 factorial design with three replicated plots with and without nutrients (fertilizer) and predators (two wolf spiders and two ants). Producer and major arthropod taxa responses, predator densities and soil nutrient levels were monitored from April 1996 to February 1998. In agreement with bottom‐up theory, the abundances of some plants and herbivores increased with the addition of nutrients, but most effects varied temporally and did not increase the abundances of any predator taxa. The effects of predator removal propagated down the food web to influence some herbivore and producer taxa but, in contrast to top‐down theory, effects were temporally dependent and varied in the direction of response within each trophic level. Predators and nutrients only interacted significantly to determine the abundance of one taxon. The findings suggest that true trophic cascades are not a primary determinant of chenopod community structure, with ‘conditional trophic trickles’ a better descriptor for the effects of predators and nutrients on this community. It is suggested that the expression of top‐down and bottom‐up effects is conditional on appropriate timing and extent of rainfall. The results provide further support for the theory that food webs are more complex in terrestrial than in aquatic systems, with abiotic and biotic heterogeneity, intraguild interactions and non‐consumptive interactions between adjacent trophic levels all confounding the classic consumptive interactions that are required for the expression of top‐down and bottom‐up forces.