Intra- and Inter-colonial Agonistic Behavior in the Termite, Microcerotermes fuscotibialis Sjostedt (Isoptera: Termitidae: Termitinae)

Pairing termite workers from cultures obtained from same colony of Microcerotermes fuscotibialis Sjostedt did not result in agonistic behavior or mortality of the paired individuals. Termite pairings from different colonies located at different distances resulted in serious encounters and aggressive behavior leading to significant mortality of the individuals. Subtle agonistic behavior was observed when colony mates were reunited after months of separation, but this did not result in any significant mortality. These results confirmed observations of non-overlap of foraging trails of these termites in the field which averts possible encounters and conflict. Therefore these termites are able to recognize their colony mates irrespective of period of separation, a factor for colony affiliation, kinship and recognition.     

Field evaluation of a fipronil bait against subterranean termite Odontotermes formosanus (Isoptera: Termitidae)

The subterranean termite Odontotermes formosanus Shiraki is an important pest of agronomic crops, plantations, and forestry, and it endangers earthen dikes and dams in China. A fipronil bait consisting of straw pulp and white sugar was evaluated against field colonies of O. formosanus. Triple mark-capture with Nile blue dye was used to delineate foraging territories and to estimate foraging populations of four O. formosanus colonies locating in the campus of Huazhong Agricultural University, Wuhan, China. Termite activity was monitored by number of termite workers and straw board consumption in underground monitoring stations. Consumption of bait matrix and fipronil was estimated for each testing site. The results showed that approximately 3-5 mg of fipronil could suppress foraging populations of O. formosanus containing 0.4-0.7 million foragers per colony. Baits containing fipronil seem to be a feasible alternative for controlling O. formosanus.     

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.     

Reproductive mechanisms and dynamics of habitat colonization in Microcerotermes biroi (Isoptera: Termitidae)

Abstract. 1. Previous studies on the arboreal termite community in coconut plantations of northern New Guinea showed that Microcerotermes biroi is the most abundant species, despite the fighting superiority of two competitor species Nasutitermes princeps and N.novarumhebridarum. In this study we tested the hypothesis that the success of M.biroi is due to its efficiency at colonizing new habitats following nuptial flights.
2. We demonstrated experimentally the ability of M.biroi colonies to replace their reproductives when removed, or to produce reproductives in satellite nests when isolated from the remainder of the colony. Replacement reproductives were always neotenics, derived from nymphs or workers.
3. Despite the ability of neotenics to differentiate within their home colonies, 84% of field colonies were headed by dealated imagos. This value constitutes a minimum estimate of the proportion of field colonies founded independently by imagos after the nuptial flight.
4. The monitoring of a young plantation during the first 31/2 years of its colonization by arboreal nesting termites revealed its invasion by M.biroi , which colonized 63% of the trees while neither Nasutitermes species appeared.
5. Our results demonstrate that M.biroi is actually a pioneer species, able to invade a new habitat by means of nuptial flights. They outline the importance of each species' reproductive strategy in shaping the arboreal-nesting termite community.     

Divergence times in the termite genus Macrotermes (Isoptera: Termitidae)

The evolution of fungus-growing termites is supposed to have started in the African rain forests with multiple invasions of semi-arid habitats as well as multiple invasions of the Oriental region. We used sequences of the mitochondrial COII gene and Bayesian dating to investigate the time frame of the evolution of Macrotermes, an important genus of fungus-growing termites. We found that the genus Macrotermes consists of at least 6 distantly related clades. Furthermore, the COII sequences suggested some cryptic diversity within the analysed African Macrotermes species. The dates calculated with the COII data using a fossilized termite mound to calibrate the clock were in good agreement with dates calculated with COI sequences using the split between Locusta and Chortippus as calibration point which supports the consistency of the calibration points. The clades from the Oriental region dated back to the early Tertiary. These estimates of divergence times suggested that Macrotermes invaded Asia during periods with humid climates. For Africa, many speciation events predated the Pleistocene and fall in range of 6-23 million years ago. These estimates suggest that savannah-adapted African clades radiated with the spread of the semi-arid ecosystems during the Miocene. Apparently, events during the Pleistocene were of little importance for speciation within the genus Macrotermes. However, further investigations are necessary to increase the number of taxa for phylogenetic analysis.     

Microsatellite markers for the polygamous termite Nasutitermes corniger (Isoptera: Termitidae)

We developed eight highly variable microsatellite markers for the termite Nasutitermes corniger. Allele number per locus ranged from nine to 34, and expected heterozygosity from 0.45 to 0.94, in samples from seven sites in the former canal zone of Panama. The utility of these markers was assessed for five congeners varying in phylogenetic distance to N. corniger. The markers will be useful for fine‐scale examination of population and colony genetic structure in N. corniger and other closely related species.     

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.     

Queen-specific volatile in a higher termite Nasutitermes takasagoensis (Isoptera: Termitidae)

In social insect colonies, queen-produced pheromones have important functions in social regulation. These substances influence the behavior and physiology of colony members. A queen-produced volatile that inhibits differentiation of new neotenic reproductives was recently identified in the lower termite Reticulitermes speratus. However, there are no known queen-specific volatiles of this type in any other termite species. Here, we report volatile compounds emitted by live queens of the higher termite Nasutitermes takasagoensis. We used headspace gas chromatography mass spectroscopy (HS GC-MS) to analyze volatiles emitted by live primary queens, workers, soldiers, alates, and eggs collected in a Japanese subtropical forest. Among 14 detected compounds, 7 were soldier-specific, 1 was alate-specific, 1 was egg-specific, and 1 was queen-specific. The queen-specific volatile was phenylethanol, which is different than the compound identified in R. speratus. The identification of this queen-specific volatile is the first step in determining its functions in higher termite social regulation. Comparisons of queen pheromone substances regulating caste differentiation among various termite taxa will contribute to a better understanding of the evolution of social systems in termites.     

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.     

Combination of antibiotics and chitin synthesis inhibitors for the control of Microcerotermes diversus (Isoptera: Termitidae)

The symbiotic microorganisms in the gut of termites play a key role in the digestion of cellulose and nitrogen metabolism. Therefore, disruption of these symbioses activity can open a door toward termite management. Thus, the current study aimed to exploit termite gut bacterial capacity in order to utilize it for efficient termite control. So, in the current study, gut bacteria of Microcerotermes diversus have been extracted, cultivated on both liquid and solid media, and screened with a range of antibiotics to find the most effective antibiotics. Results showed that chloramphenicol and nalidixic acid were the most effective antibiotics in preventing the colony unit formation of the gut bacteria amongst 16 antibiotics tested. Also, from two chitin synthesis inhibitors tested hexaflumuron with an LC₅₀ of 613.9 µg ml⁻¹ was more toxic than lufenuron with an LC₅₀ of 1414.5 µg ml⁻¹. Thus, two antibiotics (chloramphenicol and nalidixic acid) were used simultaneously with a sub-lethal concentration of hexaflumuron against the termite and a variety of factors such as wood consumption rate, running speed, body water content, and tunneling activity were evaluated under laboratory conditions. Results showed that the combination of these two antibiotics (chloramphenicol and nalidixic acid) with hexaflumuron caused a significant decrease in termite consumption rate, running speed, and tunneling behavior, but didn’t affect the body water contents of termites. These results suggest that using a combination of antibiotic/s and hexaflumuron is a promising management practice to get a suitable control measure for the studied termite.     

Habitat-specific life-history variation in the Caribbean termite Nasutitermes acajutlae (Isoptera: Termitidae)

Abstract.  1. Population and individual colony characteristics of Nasutitermes acajutlae on St John, U.S. Virgin Islands were studied over a 5-year period.
2. Four habitat types (dry forests, moist forests, sparse vegetation, and woodlands) were sampled for N. acajutlae , using quadrat-based methods. Lying dead wood was also quantified in the same sites.
3. Habitats differed significantly in the volume of lying dead wood, and total termite nest volume within quadrats was positively related to wood volume. It was hypothesised that the volume of dead wood affected growth, reproduction, and yearly survival of individual colonies.
4. In a sample of > 100 colonies assessed in 1998, 2000, 2001, and 2002, no significant differences in the growth rate of colonies (= increase in nest volume) could be found between habitat types; however, colonies in sparse vegetation were smaller, less likely to survive, and reproduced at a smaller size compared with those in the other three habitats.
5. Overall nest volume in sparse vegetation was high, compared with dry and moist forest, but colonies showed, on average, poorer survival (interpreted as lower fitness), and produced alates at an early stage of development. Optimum habitat characteristics for N. acajutlae may include not only favourable microclimate but also the reliable acquisition of new dead wood after storms.     

Caste differentiation pathways in the Neotropical termite Silvestritermes euamignathus (Isoptera: Termitidae)

Termites are hemimetabolous insects that commonly exhibit a bifurcation in post‐embryonic development, with the presence of two lines: (i) the nymphal–imaginal line; and (ii) the apterous line. The former comprises the reproductive imagoes of the colonies and their preceding immature stages, whereas the latter is composed of workers, soldiers and their precursors. In this study, we analyzed the developmental pathways of caste differentiation in the Neotropical termite Silvestritermes euamignathus and compared it to the known sibling species, Silvestritermes holmgreni. Our results show that the apterous line is composed of male and female workers without sexual dimorphism and that soldiers are exclusively females. The imaginal line comprises five instars of nymphs, which may develop into either nymphoid neotenics or alates. Similarities found in our study between caste patterns of S. euamignathus and of S. holmgreni suggest a shared evolutionary history in these termite species. Some biological differences between the species are also discussed.     

Tunnel specificity and forager movement in subterranean termites (Isoptera: Rhinotermitidae and Termitidae)

The movement of foragers of two species of Australian, subterranean, mound-building termites, Coptotermes lacteus (Froggatt) (Rhinotermitidae) and Nasutitermes exitiosus (Hill) (Termitidae), was investigated in their natural habitat using artificial feeding sites along trenches dug to mimic natural forager tunnels that radiate out from the central mound-nests. Termites were dyed by self-feeding on cardboard soaked with histological fat-stains on one or two trenches and then termites were collected from other feeding sites at two and four weeks after the fat-stains were placed. At two and four weeks after marking commenced, 60-75% of marked termites were found in trenches containing the marked paper, and 2-16% were found in trenches on the opposite side of the nest. The proportion of marked termites in a sample was three to eight times greater in the trenches containing the marked paper relative to other trenches. Although difficulties with fat-stains used as markers might explain some of the observed patterns, it is evident that C. lacteus and N. exitiosus foragers do not move randomly between feeding sites in their natural habitat.     

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.     

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.