Termite Biomass Research Articles

Comparative respiration and methane production rates in Nearctic termites

Rates of oxygen consumption and the production of carbon dioxide and methane were measured in thirteen Nearctic termite species periodically, for 48h, at 25 °C. Decreased respiration rates were observed in several species with decreasing oxygen and increasing carbon dioxide levels. Those species with apparently higher moisture requirements (i.e. subterranean termites) generally had lower respiration rates compared with the dampwood (highest rates) and dry wood (intermediate rates) termites. Termite biomass significantly influenced respiration rates, with the largest species having the highest rates. Methane production occurred in seven of the thirteen species assayed. Of these apparently methanogenic species, only one of the eleven colonies of Incisitermes minor and one of the two colonies of Prorhinotermes simplex produced methane. The generally reduced respiration rates found at lower oxygen and higher carbon dioxide levels are considered more representative of the conditions encountered in termite galleries. Bioassays conducted under more natural atmospheric conditions may be more representative of termite responses in the field.

Colony Populations and Biomass in Nests of the Amazonian Forest Termite Anoplotermes banksi Emerson (Isoptera: Termitidae)

The arboreal nests of the termite Anoplotermes banksi are abundant in Central Amazonian primary rain forests. Colony size of 7 nests (weight 92–6891 g) varied between 2,593 and 39,256 individuals/nest (1.5 – 22.1 g termites/nest). Average body fresh weight was 0.9 mg for workers and 2.1 mg for alates. Queens weighed 10–30 mg. No relationship between nest weight and maturity was detected, as the ratio of workers to larvae was 1:1, independent of nest size, and alates were found in nests weighing less than 200 g. Nests of A. banksi (12–18 ha -1) accounted for 12–15% of the nest density of all Isopteran species, but the calculated fresh weight of the termites of this species (15–23 mg/m 2) represented only 0.2–0.4% of the total termite biomass in the study area.

The diversity, abundance and biomass of termites under differing levels of disturbance in the Mbalmayo Forest Reserve, southern Cameroon

This paper presents data on the abundance, biomass and species richness of termites in the Mbalmayo Forest Reserve, southern Cameroon. Five plots of differing disturbance level (near primary forest, old secondary forest, young plantation, weededChromolaenafallow, and completely cleared forest) were sampled for termites in two successive years (July 1992 and July 1993, giving a total of ten sampling areas, plus one in the completely cleared plot in November 1992). A stratified sampling regime of soil pits, wood samples, mound samples and soil scrape samples was used. Estimated abundance and biomass were extremely high in the near primary and old secondary plot (maximum estimated abundance, old secondary sampling area 1, 10488 m-2, maximum biomass density, near primary sampling area 1,123.2 g m-2). In all cases termite abundance was highly clumped. Disturbance had apparently little effect on termite abundances and biomass in forested plots, but there were clear reductions in abundance and biomass in the cleared plots. In the completely cleared plot, abundance and biomass fell sharply from year 1 to year 2, presumably because colonies left after clearance had dried out and died. There were large differences in the taxonomic-, nesting- and feeding-group composition of the plots, with soil feeding termites being especially strongly affected by disturbance. The sources of error associated with this sampling programme are discussed. It is argued that the near primary forest plot may have higher microhabitat and concomitant termite assemblage heterogeneity than the more disturbed plots. In most cases over 90 % of the overall abundance in a sampling area was due to a few species; extinction, and will make areas. This may be due to the unpredictable dynamics of colony foundation and extinction, and will make estimations of the effect of termites on overall ecosystem processes (from abundance and biomass data alone) problematical. There is no evidence of immigration of savanna termites into the forest reserve, and thus cleared areas have depauperate forest assemblages. It is concluded that this is the most accurate estimation of termite assemblage parameters yet attempted.

Estimating Oral Toxicity of Slow-Acting Toxicants Against Subterranean Termites (Isoptera: Rhinotermitidae)

A method is described for estimating oral toxicities (μg/g) of slow-acting toxicants against subterranean termites, Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar). Groups of termites were fed with a known amount of medium containing a dye marker and a toxicant. Marked termites were evaluated for daily mortality after total consumption of the medium. Toxicant doses ingested by termites were derived from the total amount of toxicant in the feeding medium and the biomass of termites engaged in that feeding. Using oral LD 50 estimates in μg/g, the total amount of toxicant required to control a field colony can be projected

Methane emission from wood-feeding termites in Amazonia

The contribution of termites to the global methane budget has been controversely discussed in the last decade. We measured methane emissions from nests of wood-feeding termite species ( Nasutitermes spp.) of primary and secondary forests of Amazonia. The methane emission rates from single termite nests varied in a broad range between 0.01 and 9.4 mg CH 4 hour −1 nest −1 (average = 2.0 ± 2.4 mg CH 4 hour −1 nest −1), as termite colonies vary considerably in size (biomass). Consequently, data given as methane emission per nest are unsuitable for interspecific comparison. In seek for an appropriate unit the methane flux was related to the biomass of the termites dwelling in the nest. On this basis, the variation between the methane emissions of the nests was far lower (0.4 – 4.9 μg hour −1 g termites −1). Biomass-related methane emission rates averaged 3.0 ± 1.3 μg hour −1 g termites −1, which means that Amazonian termites release significantly (at p = 0.01%) more methane than species from other regions. By extrapolating these emission rates to the estimated global biomass of termites we calculated a total emission of 26 Tg CH 4 year −1, which represents about 5 % of the annual methane flux from all sources to the world atmosphere. Termites are unlikely to contribute essentially to the global budget of the “greenhouse gas” methane.

Genesis of Acetate and Methane by Gut Bacteria of Nutritionally Diverse Termites

The evolution of different feeding guilds in termites is paralleled by differences in the activity of their gut microbiota. In wood-feeding termites, carbon dioxide-reducing acetogenic bacteria were found to generally outprocess carbon dioxide-reducing methanogenic bacteria for reductant (presumably hydrogen) generated during microbial fermentation in the hindgut. By contrast, acetogenesis from hydrogen and carbon dioxide was of little significance in fungus-growing and soil-feeding termites, which evolved more methane than their wood- and grass-feeding counterparts. Given the large biomass of termites on the earth and especially in the tropics, these findings should help refine global estimates of carbon dioxide reduction in anoxic habitats and the contribution of termite emissions to atmospheric methane concentrations.

Species abundance and habitat differences in biomass of subterranean termites (Isoptera) in the wheatbelt of Western Australia

AbstractThe distribution and abundance, and habitat differences in biomass of subterranean termites, were assessed through soil trenching for woodland, mallee and heath habitats in the central wheatbelt of Western Australia. Over an 11 month sampling period, there were no significant habitat differences in biomass. Mean dry biomass in the surficial layer of soil (per 5000 cm3) averaged 46 mg in woodland, 28 mg in mallee, and 23 mg in heath. Termite biomass peaked in September, with 141 mg for woodland, 83 mg for mallee and 47 mg for heath (per 5000 cm3). Soil moisture and termite activity near the surface were positively correlated. A total of 36 species of termites, comprising 11 genera, were identified, and species abundance within and across habitats differed significantly.

生物的自然におけるバランスについて 熱帯におけるシロアリの生活と関連させて

The biomass, feeding strategies and ecological role of termites in the tropical rain forest and savanna ecosystems are discussed in relation to the human impacts on these ecosystems. A speculation is given on the balance of biological community from a coevolutionary viewpoint with reference to the process through which some species of termites become pests of cultivated plants.

Comparison of Laboratory Methods for Estimating Wood Consumption Rates by Coptotermes formosanus (Isoptera: Rhinotermitidae)

Three methods of calculating wood consumption rates (milligrams of wood per gram of termite per day) by laboratory groups of the termite, Coptotermes formosanus Shiraki, were compared. Rates calculated from 6- and 8-week data confirmed that a model which assumed no termite mortality during the feeding trial significantly underestimated wood consumption. A second model which assumed a linear increase in mortality during the trial gave consumption rates for 42-day tests which did not differ significantly from those derived from a third model based upon actual mortality records. This suggests that consumption rates can be predicted accurately in 42-day experiments with a model that assumes mortality increases linearly. Wood consumption rates calculated at 8 weeks were lower than those at 6 weeks, indicating that feeding rates were declining. This occurred even though little or no mortality was observed beyond day 28. It is proposed that feeding trials be carried out only while wood consumption (milligrams of wood per gram of termite) remains constant. In 6-week trials, C. formosanus consumed 55.04 mg/g per day when termite biomass was based on a linear-mortality model. This was more than 16% greater than consumption at 8 weeks based on termite weight calculated with a no-mortality model (46.56 mg/g per day).

Termites of a South African savanna : IV. Subterranean populations, mass determinations and biomass estimations.

Shallow soil cores taken every four weeks for a year in broad-leaved savanna and in Acacia savanna at Nylsvley Reserve, northern Transvaal, supported evidence on termite distribution and abundance reported in earlier papers. Surface activity was markedly affected by soil moisture, and the extent to which the core results can be used to assess subterranean populations is discussed. Live and dry masses for 14 species of termite are reported, and these results plus epigeal nest populations published elsewhere are used to calculate termite density and biomass in the two vegetation types. Tentative figures are 3,00 workers m-1 (=8 g m-1 fresh mass; 2.5 g m-1 dry mass) in broad-leaved savanna, and 725 workers m-1 (=1 g m-1 fresh mass; 0.3 g m-1 dry mass) in Acacia savanna. Excluding the mass of soil in the guts of soil-feeding species, these masses are reduced to 3 g m-1 (fresh) and 1 g m-1 (dry) in broad-leaved savanna, and 0.5 g m-1 (fresh) and 0.15 g m-1 (dry) in Acacia.

Nitrogen fixation by intact colonies of the termite Nasutitermes corniger

Whole colonies of the arboreal termite Nasutitermes corniger (lsoptera, Termitidae, Nasutitermitinae) from a Costa Rican rainforest were assayed for nitrogen fixation by the acetylene reduction method, using a 21-1 test chamber. Nitrogenase activity was positively correlated with termite biomass for the nexts examined, providing the experiment was performed within 2 h of removal of the colony from the field. Total colony fixation rates of 0.25-1.0 mg N per colony per hour indicate a nitrogen doubling time of 200-600 days, thereby making possible complete replacement of the nest population 1-2 times per year.

Nutrient cycling by the subterranean termite Gnathamitermes tubiformans in a Chihuahuan desert ecosystem.

We estimated the density of subterranean termites Gnathamitermes tubiformans at 800,000 · ha-1 for a standing crop biomass of 2 kg · ha-1 Predation losses were estimated to be 5,73 kg · ha-1 · yr-1 representing the major release of nutrients from termites to surficial soil layers. Nutrient fluxes from termites to predators amounted to 410g N·ha-1·yr-1, 33 g S · ha-1 · yr-1 and 19 g P · ha-1 · yr-1. These fluxes account for 8% of the litter N, 1.5% of the litter P and 2.9% of the litter S. The termites fixed an estimated 66 g · ha-1 · yr-1 atmospheric N and returned an estimated 100 g · ha-1 · yr-1 in the surface gallery carton. Since losses of elements from subterannean termites were greater than standing crops, we estimated an annual turnover of N at 3.5 times per year, P of 2.5 times per year, and S of 2.5 per times per year.Since surface foraging, predation and alate flights are pulse regulated by rainfall, nutrient flows through subterranean termites are episodic and releases of nutrients accumulated in termite biomass preceeds or is coincident with productivity "pulses" of some shallow rooted plants. We propose that subterranean termites are important as regulators in desert nutrient cycles.

The distribution of soil macrofauna on the west ridge of Gunung (Mount) Mulu, Sarawak.

The macrofauna of the soils on the west ridge of Gunung Mulu in 4th Division, Sarawak, were sampled during February and March 1978. The eleven sampling sites ranged from near the base of the mountain at 130 m a.s.1. to the summit at 2.376 m.Altitudinal changes from lowland rain forest (mixed dipterocarp forest) to lower montane and upper montane rain forests are concomitant with changes in soil from red yellow podzolics and regosols to peaty gley podzolics and organic peats.The abundance of the total macrofauna declined from 2,579 individuals m-2 at 130 m to 145 m-2 at 2,376 m. Declining population densities of ants and termites correlated significantly with increasing altitude but the effect on other groups was variable. Changes in total biomass were erratic and varied from 4.1-6.2 g m-2 (alc. w.w.) in the dipterocarp forest soils to 5.8 g m-2 in the lower montane, 9.3-20.2 g m-2 in the upper montane (tall facies) and 1.9-9.5 g m-2 in the upper montane (short and summit facies). Only the decline in the biomass of termites and ants correlated significantly with altitude. Other groups remained fairly constant, varied erratically or increased in the middle altitudes.The dipterocarp forest soil macrofaunal biomass was dominated by termites, beetles and earthworms (Megascolecidae and Moniligastridae), with ants the dominant predators. The lower montane forest was a transitional and ill-defined zone on the mountain and the soil macrofauna was also transitional to some extent. Termite biomass fell substantially and earthworms replaced them as the dominant detritivores, with beetles in a secondary role. Formicidae remained as the major predators. With the inception of peats in the upper montane forest (tall facies), the macrofauna was dominated by Coleoptera with earthworms, Diptera larvae and Blattodea in lesser roles. With increasing exposure in the upper montane forests (short and summit facies), several major groups disappeared altogether. The soils were dominated by Blattodea with Coleoptera and Megascolecidae of lesser importance. Chilopoda and Arachnida replaced Formicidae as the dominant predators.

Predation by Megaponera foetens (Fabr.) (Hymenoptera: Formicidae) on termites in the Nigerian southern Guinea Savanna.

At Mokwa, in the Nigerian southern Guinea Savanna, Macrotermitinae are the only recorded prey of the obligate termite predator, Megaponera foetens. The main prey species is Macrotermes bellicosus (141 termites m-2 a-1) followed by Odontotermes spp. (42 termites m-2 a-1). Predation on other species, Ancistrotermes cavithorax, Macrotermes subhyalinus and Microtermes spp., amounts to only 10 termites m-2 a-1. Macrotermes bellicosus is not the most abundant termite in the primary savanna. It is concluded that factors including termite abundance, termite foraging regimes and seasonality, termite biomass and the reactions of the ants to the termites and their products are involved in successful predation of termites by Megaponera.

Population Density and Biomass of the Desert Termite Gnathamitermes Tubiformans (Isoptera: Termitidae) in a Shortgrass Prairie: Relationship to Temperature and Moisture

Fluctuations in the population density and biomass of Gnathamitermes tubiformans (Buckley) in the upper 30.2 cm of soil were determined over a 2—yr period in a shortgrass community in Garza County, Texas. Linear stepwise multiple regression was used to determine the relationships of termite population densities with environmental factors in this soil increment. Termites were not present in the upper 30.2 cm when the soil temperature at 15 cm was < 9 degrees C. Termite population densities in the upper 30.2 cm of soil varied significantly between years as a function of air and soil temperatures, precipitation and soil moisture. Consideration of data from relatively short time periods alleviated many difficulties in identifying biologically important causal factors. In a year of above—normal precipitation, temperature was the most important factor affecting desert termite population densities, whereas during a year of below—normal precipitation, soil moisture was the most important factor. Biomass of desert termites in the upper 30.2 cm of soil averaged 5.83 g/m2 (live—weight) over the 2—yr period and reached a peak of 23.03 g/m2 during September 1972. The abundance of tunnels and chambers of G. tubiformans decreased with depth in the soil profile. Termites migrated below 124 cm in subterranean galleries to avoid soil temperatures < 10 degrees C.