Seasonal changes in activity of subterranean termite species (Isoptera) in Western Australian wheatbelt habitats

Subterranean termite assemblages in woodland, mallee and heath habitats of the Western Australian wheatbelt were sampled for seasonal changes in species richness and species abundance. The study was carried out in Durokoppin and Kodj Kodjin Nature Reserves between January and November 1988, and a trench method was used to sample termites. Species richness changed over time, with monthy means of: woodland 10 species (range: 5–15), mallee 8 species (range: 4–15), heath 8 species (range: 5–15). Species richness was highest in autumn and spring when termite activity in the soil was also highest due to favourable soil moisture. Amitermes neogermanus and Tumulitermes petilus were the most abundant species in woodland and mallee in all seasons. During summer, the pooled observations of these two species accounted for 50% (woodland) and 82% (mallee) of all observations. Their predominance may be due to greater tolerance of low soil moisture and a more diverse diet than obligate wood-feeders (e.g. Rhinotermitidae). The latter were generally absent near the soil surface in summer, possibly because food sources deeper within the soil were utilized. Four species were abundant in heath: Tumulitermes dalbiensis (monthly mean 20% of all species observations), T. comatus (13%), Amitermes. sp.‘R’ (18%)and Drepanotermes rubriceps (12%). These four species showed no seasonal change in their relative abundance, possibly because their diet restricted them to surface-foraging.     

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

The 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.     

Influence of vegetation and soil types on the wheatbelt termite,Drepanotermes tamminensis (Hill), in the Western Australian wheatbelt

A survey of the distribution and density of mounds of the harvester termite,Drepanotermes tamminensis (Hill), was carried out in the Durokoppin Nature Reserve, Western Australia in 1990. Vegetation and, to a lesser extent, soil type, appear to be important factors in determining density and distribution of termite mounds within the Reserve. A more detailed study of mounds in Wandoo (Eucalyptus capillosa) woodland and Casuarina (Allocasuarina campestris) shrubland indicated that the total number and size of mounds were significantly higher in the woodland than in the shrubland. The total wet weight biomass ofD. tamminensis was calculated as 3.74 gm⁻² (37.4 kg ha⁻¹) in the woodland and 1.69 gm⁻² (16.9 kg ha⁻¹) in the shrubland. Thus, of the two favored habitats, Wandoo woodland appears to be more optimal for this termite species than the Casuarina shrubland.     

Resistance of insecticide-treated foam board insulation against the eastern subterranean termite and the Formosan subterranean termite (Isoptera: Rhinotermitidae)

Three foam board types, one untreated control, one containing 2,000 ppm disodium octaborate tetrahydrate (DOT), and one containing 1,000 ppm deltamethrin, were exposed to field populations of the eastern subterranean termite, Reticulitermes flavipes (Kollar), and the Formosan subterranean termite, Coptotermes formosanus Shiraki. There was no significant difference in termite damage between foam boards treated with 2,000 ppm DOT and the untreated control. Form boards containing 1,000 ppm deltamethrin were not damaged by R. flavipes, whereas only minor damage occurred after exposure to C. formosanus.     

Distribution of Formosan subterranean termite (Isoptera: Rhinotermitidae) in Mississippi

An extensive monitoring and survey program in Mississippi was conducted from 2000 to 2004 to investigate the distribution of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). Seventy-two towns from 22 counties in southern Mississippi were monitored with a total of 3914 traps that catch alates during the swarming season. In addition, 259 licensed pest management professionals in Mississippi were surveyed to determine the locations of termite infestations treated. The alates of C. formosanus were recovered in 12 counties with light traps, and termite infestations were documented in an additional 13 from data collected in the termite survey. Infestations of C. formosanus have been documented in urban, urban cluster, rural, and forested areas of Mississippi. However, the distribution in mean total capture of alates for 4 yr differed significantly among the four ecological areas with the highest percentage in forested areas (31%) and the lowest percentage in urban cluster areas (17%). Most of the infestations of C. formosanus were geographically distributed along the coastal areas of southern Mississippi from Gulfport to Pascagoula. The greatest total number of alates captured in light traps was documented in Pearl River County. Mass swarming of C. formosanus occurred primarily in May or June, depending on weather conditions. The number of documented counties with the evidence of large and widely dispersed swarms of C. formosanus in different ecological areas, and the increase in total annual alate captures from 2000 to 2003, suggest that this invasive termite species is now firmly established in Mississippi.     

Toxicity, repellency, and effects of acetamiprid on western subterranean termite (Isoptera: Rhinotermitidae)

The insecticidial and biological activity of the cyano-substituted neonicotinoid acetamiprid was determined against the western subterranean termite, Reticulitermes hesperus Banks (Isoptera: Rhinotermitidae). Acetamiprid was very active against termites in topical applications, with an LD50 = 0.02 ng per termite. Even though acetamiprid was extremely toxic in topical applications, deposits > or =50 ppm on sand were required to consistently provide >90% kill of termites within 7 d after a 1-h exposure. Termites were quickly affected by brief exposures to sand treated with 1 ppm acetamiprid and within 1 h, their locomotion was dramatically impaired. Acetamiprid was transferred from donors to recipients only when donors were held on deposits > or =50 ppm for 1 h. Deposits even as low as 1 ppm were repellent and termites failed to tunnel into treated sand, and there was no significant mortality. Exposure to acetamiprid impaired locomotion of termites as did other slow-acting neonicotinoids, such as imidacloprid. Acetamiprid was repellent at all concentrations tested, acting like type I pyrethroid treatments in soil. A new subcategory of type III soil termiticides is proposed that incorporates the sublethal and delayed effects observed in neonicotinoid insecticides, and repellency at certain concentrations.     

Effect of fipronil on subterranean termite colonies (Isoptera: Rhinotermitidae) in the field

To assess possible colony-level effects of fipronil, a commonly used nonrepellent termiticide, we conducted a field study of eight houses in the Raleigh, NC, area with infestations of the eastern subterranean termite Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae). We installed an extensive grid of in-ground monitoring stations on each property (mean = 68.6 monitors per property) and collected samples from these stations as well as from mud tubes in the structure and wood debris in the yard for approximately 6 mo. We genotyped all samples by using microsatellite markers to identify the number and locations of colonies present on each property. Houses were treated with either a full treatment (n = 5) or exterior/localized interior treatment (n = 3). After treatment, the monitors were checked monthly for 3 mo and then quarterly for 3 yr to track the fate of colonies. Wood debris in natural areas was checked semiannually for 3 yr. All 11 of the treated colonies (those attacking structures) disappeared within 90 d of treatment and were not found again. These colonies were presumed to be eliminated. In contrast, 60% of untreated colonies (those located > 6 m from the foundation wall at the time of treatment) continued to persist throughout the study, as did 25% of the likely treated colonies (those occupying monitors 0.5 m from the foundation wall where the treatment was applied). Our results provide strong evidence for potent colony wide effects of fipronil on subterranean termites leading to colony suppression and likely colony elimination under field conditions.     

Effect of orange oil extract on the formosan subterranean termite (Isoptera: Rhinotermitidae)

The Formosan subterranean termite, Coptotermesformosanus Shiraki (Isoptera: Rhinotermitidae), accidentally brought into the United States, has become a major urban pest, causing damage to structures and live trees. Because of increasing restrictions on the use of conventional termiticides, attention is focused on finding safer alternative methods for termite management. Oil from citrus peel, referred to here as orange oil extract (OOE), contains -92% d-limonene, and it is generally known to be toxic to insects. In laboratory experiments, 96 and 68% termites were killed in 5 d when OOE at 5 ppm (vol:vol) was dispensed from the top or bottom, respectively, with termites held at the opposite end of a tight-fitting plastic container. Apart from high mortality, workers exposed to vapor consumed significantly less filter paper than controls. However, when termites were exposed to OOE vapor, even at 10 ppm, in the void of a model wall, there was very little mortality. Termites did not tunnel through glass tubes filled with sand treated with 0.2 or 0.4% OOE. Sand treated with OOE was extracted each week for 8 wk to determine the remaining amount of d-limonene. Results indicated that there was a sharp decline in the quantity of d-limonene during the first 3 wk to a residual level that gradually decreased over the remaining period. With a suitable method of application and in combination with other control practices, OOE can be effectively used for the control of subterranean termites.     

Formosan subterranean termite swarming behavior and alate sex-ratio (Isoptera: Rhinotermitidae)

Summary The Formosan subterranean termite (Coptotermes formosanus Shiraki) was first sighted in the cities of New Orleans and Lake Charles, Louisiana, in 1966. Its distribution in the historic French Quarter of New Orleans 23 years later (1989) and in 1991 and 1992 is reported here using counts of alates from light-traps. Light-trappings revealed a Quarter-wide distribution of the termite.C. formosanus shows an extended pause in flight behavior in the middle of the two-month flight season that is predictable and independent of weather. A colony-level mechanism, namely, developmental inhibition of nymphs by alates, may regulate this intermission in flight. The sex-ratio of light-trapped alates varies over time, but is generally female-biased, especially at the height of the flight season.     

DNA-based identification of the eastern subterranean termite, Reticulitermes flavipes (Isoptera: Rhinotermitidae)

A DNA-based system for the identification of Reticulitermes flavipes (Koller) was established based on the following criteria: adequate molecular variation, comprehensive specimen sampling, explicit morphological species identification, and cladistic analysis. Termite soldiers were identified by labral shape, and these specimens and associated pseudergates were used in subsequent molecular analyses. Mitochondrial DNA from the AT-rich region was sequenced for 173 R. flavipes, Reticulitermes hageni Banks and Reticulitermes virginicus (Banks) soldiers and pseudergates collected from several widely dispersed Texan localities. Cladistic analysis was performed after exploration of an optimal sequence alignment inclusive of DNA sequences from Texas and published sequences from Georgia and Canada. Among the Texan individuals, 29, 5, and 1 mitochondrial DNA haplotypes were identified respectively with R. flavipes, R. hageni, and R. virginicus. One haplotype from El Paso likely represented a different Reticulitermes species. Species were monophyletic; however, individual relationships were unresolved in a strict consensus of 700 most parsimonious trees. Texas haplotypes were isolated by distance, and a correlation between genetic and geographic distance was observed among the Texas, Georgia, and Canada haplotypes. These results suggest that the methods outlined in this study will allow for the identification of R. flavipes from localities between Texas and Canada.     

Parthenogenetic reproduction in neotenics of the subterranean termite Reticulitermes speratus (Isoptera: Rhinotermitidae)

Experiments with artificial colonies consisting of only female workers and those of female nymphs and workers of a subterranean termite, Reticulitermes speratus, showed that neotenics (ergatoids and nymphoids) can reproduce parthenogenetically. The larvae hatched from the eggs produced partheno‐genetically by the neotenics were all female and did not have any aberrant external morphology. They had 42 chromosomes and were diploid. The analysis of genotypes at microsatellite loci revealed that the eggs produced parthenogenetically had only one of the two alleles that the mother neotenics possessed, indicating that the eggs were produced by automixis.     

Identification of two subterranean termite species (Isoptera: Rhinotermitidae) using cellulase genes

To identify subterranean termite species, we designed a pair of common primers that amplified 381-bp fragments from cDNAs encoding the endo-beta-1,4-glucanases (EGases) of Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe). cDNAs from C. formosanus and R. speratus, and genomic DNA from R. speratus, were amplified by polymerase chain reaction (PCR) by using this primer pair and then cloned and sequenced. Sequences amplified from C.formosanus cDNA displayed 97-99% identity to cDNA encoding the EGase of C. formosanus (CfEG), and 92-94% identity to cDNA encoding the EGase of R. speratus (RsEG). By contrast, cDNA from R. speratus displayed 99-100% identity to RsEG cDNA and 93-94% identity to CfEG cDNA. CfEG and RsEG cDNAs can therefore be used as markers for the identification of these termite species. This is the first report of the successful identification of termite species by using cDNA and genomic DNA sequences of termite origin.     

The termite (Isoptera) fauna of a monsoonal rainforest near Darwin, northern Australia

Abstract  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 nest-builder Nasutitermes graveolus (Hill) accounted for 61% of termite encounters. Epigeal mound-building 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.     

Contribution of the Western Australian wheatbelt termite,Drepanotermes tamminensis (Hill), to the soil nutrient budget

The role of soil modification by the mound-building termite,Drepanotermes tamminensis (Hill), was studied during 1991 in the Durokoppin Nature Reserve, Western Australia. Soil chemical parameters were quantified for ‘soils’ in nests and for surrounding soil in both a Wandoo (Eucalyptus capillosa) woodland and a Casuarina (Allocasuarina campestris) shrubland plot. All ‘soils’ in nests were more acidic than the surrounding soil within each study plot. Generally, nutrient levels in the nested soils were higher than the un-nested soil within each study plot and were also higher in the woodland than in the shrubland plot. Depending on the nuttient concerned, the nested soil contained between 0.3 and 21.9% of the total nutrient load per hectare within each study plot. The quantities of nutrients per hectare in termite mounds were higher in the woodland than in the shrubland plot. It is concluded that mounds of this species of termite form a significant bank of nutrients, although time for release of such nutrients depends on the degree of erosion and on the longevity of mounds.     

Factors affecting mate choice in the subterranean termite Reticulitermes chinensis (Isoptera: Rhinotermitidae)

Termites are a group of eusocial insects. Mate choice is the most important step which affects the subsequent new colony foundation and development in termites. This study investigated the effects of the four factors on mate choice in the subterranean termite Reticulitermes chinensis Snyder, including colony origin, entry time, physical damage of antennae, and fresh body weights of male dealates. The results showed that the pairing number of dealates from the different colonies was significantly higher than that from the same colonies. The male dealates with early entry time achieved a significantly higher pairing number than the male dealates with late entry time. The male dealates with complete antennae achieved a the significantly higher pairing number than the male dealates lacking the six terminal segments of antennae. Moreover, the heavier male dealates achieved a significantly higher pairing number than the lighter male dealates. However, there were no significant differences in the pairing time for all the experimental treatments. These results suggested that the male dealates, which are heterogenous, healthy, heavy, and more familiar with the environment in R. chinensis, have the obvious advantages in the mate choice. This rule of mate choice is helpful for termites to avoid inbreeding and to maintain the genetic diversity of offspring, which is very important for the environmental adaptability and development of termite colonies.     

The influence of soil heterogeneity on exploratory tunnelling by the subterranean termite Coptotermes frenchi (Isoptera: Rhinotermitidae)

The exploration of sand-filled arenas by workers of an entire colony of the Australian, subterranean foraging, tree-nesting termite, Coptotermes frenchi Hill was investigated under laboratory conditions. The first experiment tested whether termite exploration of sand was influenced by the presence of gaps or objects in the sand. Gaps and objects were chosen to represent soil heterogeneity in the urban environment: gaps to represent tunnels dug by other animals, perspex strips to represent cables and pipes, and wood strips to represent roots. Termites always chose to explore gaps thoroughly before they began tunnelling in the sand. Significantly more and longer tunnels were excavated from the end of gaps at the far end of the arenas, and relatively little tunnelling occurred around and along objects. Termite density was significantly greater around and along wood compared with perspex blocks. The second experiment tested whether termite exploratory tunnelling was influenced by soil moisture. The termites tunnelled slowly in dry sand, but after discovering a patch of wet sand, increased tunnelling five-fold until it was completely explored, after which activity declined. Energy and water conservation may be behind these patterns of exploratory tunnelling as well as those seen in large field studies, but caution is urged when interpreting small scale laboratory experiments to explain large scale field data.     

Harvesting rate of the termite,Drepanotermes tamminensis (Hill) within native woodland and shrubland of the Western Australian wheatbelt

The Western Australian termite,Drepanotermes tamminensis (Hill), harvests various plant materials according to biomass availability. The main litter components harvested by this termite in a woodland dominated byEucalyptus capillosa are bark and leaves of the major tree species, while in shrubland dominated byAllocasuarina campestris, shoots of this species are taken. Harvesting mainly occurs during the autumn (April–May) and spring (September–October) seasons. The commencement and duration of harvesting appears to depend partly on weather conditions, with harvesting taking place at temperatures between 15 and 25°C after periods of rain. This species of termite harvests approximately 15.6 g m⁻² year⁻¹ and 3.2 g m² year⁻¹ (dry weight of plant material) in the woodland and shrubland, respectively.