Identification of Reticulitermes spp. (Isoptera: Reticulitermatidae) from south central United States by PCR-RFLP

Because of morphological ambiguity, traditional identification of Reticulitermes Holmgren termites has always been difficult and unreliable. A molecular diagnostic method is presented for differentiating Reticulitermes species occurring in the south central United States, which are economically important urban pests. A 379-bp region of the mtDNA COII gene and a 415-bp region of the mtDNA 16S rRNA gene were amplified using polymerase chain reaction (PCR) and sequenced from Reticulitermes flavipes (Kollar), Reticulitermes virginicus (Banks), Reticulitermes hageni Banks, and Reticulitermes tibialis (Banks). Applying DNA sequence data, the PCR-restriction fragment length polymorphism (PCR-RFLP) analysis of two restriction enzymes each for the COII amplicon and the 16S amplicon, were diagnostic for all of the Reticulitermes species analyzed. Based on putative mutation rates, >87% and 97% of the samples should be successfully identified to species with PCR-RFLP of COII and 16S, respectively. To verify the accuracy of our predictions, we examined unclassified Reticultermes populations from Arkansas, Louisiana, Missouri, Oklahoma, Texas, and Virginia using PCR-RFLP. Applying PCR-RFLP, 97 samples were correctly classified to species. This technique allows the use of field-collected specimens preserved in alcohol and can identify termite specimens regardless of caste. PCR-RFLP, resolved with agarose or polyacrylamide gel electrophoresis, provided an efficient method for identification of Reticulitermes species from the south central United States for diagnostic purposes.     

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.     

Molecular relationships among European samples of Reticulitermes (Isoptera, Rhinotermitidae)

Taxonomy and phyletic relationships of the European termites of the holarctic genus Reticulitermes are highly debated and poorly known. Sequencing analyses of the complete cytochrome oxidase subunit II and of a fragment of 16S rDNA mitochondrial genes were performed on 21 Italian and French populations. Distance, parsimony, and maximum-likelihood evaluations on single and combined data sets confirm the presence in central peninsular Italy of R. lucifugus lucifugus, but demonstrate that a coastal Tuscan population and the Sardinian ones pertain to the Corsican subspecies R. lucifugus corsicus, whose distribution appears therefore transtyrrenian. Northeastern Italian samples are highly differentiated from presently analyzed R. lucifugus and constitute a new entity, possibly more related to the Japanese R. speratus. Finally, the French R. santonensis and the North American R. flavipes appear strongly related, so that the supposed synonymy between the two taxa must be accepted.     

Mitochondrial genomic comparisons of the subterranean termites from the Genus Reticulitermes (Insecta: Isoptera: Rhinotermitidae).

Termites of the genus Reticulitermes are some of the most significant pests of structural timber and tree farming in the northern hemisphere, causing losses in the billions of dollars annually because of direct damage and termite control costs. This group has been frequently targeted for population genetic, phylogenetic, and species limit studies, most of which use mitochondrial (mt) genes; however, only a small fraction of the genome has been sequenced. The entire mt genome was sequenced for the eastern North American members of Reticulitermes: R. flavipes, R. santonensis, R. virginicus, and R. hageni. The mt genome has the same gene content and organization as that found in most insect species; however, the nucleotide composition and skew are highly biased (AT% low, strong A- and C-skew). Both the protein-coding and transfer RNA genes show high absolute levels of nucleotide substitution, suggesting that the high rates of mutation within Reticulitermes inferred from analyses of single mt genes are a general characteristic of the entire mt genome. The AT-rich or control region has a remarkable structure not previously observed in insect mt genomes. The majority of the control region is made up of 2 sets of repeat units, typically with 2 full and 1 partial copies of both the A (or small; 186 bp) and B (or large; 552 bp) repeats. The partial repeat units overlap by 36 bp. The size, location, and degree of overlap for the partial repeat units correspond to highly conserved stem/loop structures within the repeat units, suggesting that these structures are involved in the replication-mediated processes that govern repeat-unit evolution within mt genomes. Finally, molecular variation within the mt gene regions was compared with previous regions used in molecular diagnostics or phylogenetics of Reticulitermes. High numbers of single nucleotide polymorphisms were found in each of the mt genes, and some of the highest variability was found in gene regions that have not previously been investigated in this group. The whole mt genome sequence can thus be used to predict useful regions for future investigation.     

Impacts of soil moisture level on consumption and movement of three sympatric subterranean termites (Isoptera: Rhinotermitidae) in a laboratory assay

Three subterranean termite species, Reticuliternes flavipes (Kollar), Reticulitermes tibialis Banks, and Reticulitermes virginicus (Banks), were collected from locations in northern Indiana and tested under laboratory conditions to determine whether preferential differences exist among species. Foraging behaviors and location of all three species were studied using a linear, three-dimensional assay with a soil moisture gradient (5, 15, 25, 35, 45, and 55% moisture by weight) and quantified by (1) consumption weights and (2) location counts. In a 7-d period, R. flavipes and R. tibialis consumed almost twice as much filter paper as R. virginicus. No significant difference in feeding was attributed to moisture level for R. tibialis, but there were differences for R. flavipes and R. virginicus. In terms of location of harborage, there were clear patterns associated with moisture level, as predicted using a Poisson distribution. Results from consumption and location data show unique patterns among species, and illustrate species-specific variation in feeding location and nesting preference in response to moisture. There are significant differences in movement patterns, consumption, and mortality among Indiana Reticulitermes according to the laboratory assay. These findings contribute to the overall understanding of midwestern Reticulitermes termites.     

Phylogenetic analyses of mtDNA sequences corroborate taxonomic designations based on cuticular hydrocarbons in subterranean termites

Cuticular hydrocarbons (CHCs) are valuable characters for the analysis of cryptic insect species with few discernible morphological characters. Yet, their use in insect systematics, specifically in subterranean termites in the genus Reticulitermes (Isoptera: Rhinotermitidae), remains controversial. In this paper, we show that taxonomic designations in Reticulitermes from California (USA) suggested in light of differences among CHC phenotypes are corroborated by phylogenetic analyses using mtDNA sequences. Analyses based on CHC phenotypes and supported, in part, by behavioral and ecological differences have suggested the presence of more species than the two currently recognized: R. hesperus Banks and R. tibialis Banks. We analyze a 680 base pair fragment of the mitochondrial DNA cytochrome oxidase (COII) gene from 45 new (21 collection localities) and two previously recorded samples of Reticulitermes from California using parsimony and maximum likelihood methods. Both methods result in trees with highly similar topologies. Bootstrapping indicates support for six clades of Reticulitermes, and corroborates groupings based on cuticular hydrocarbons. One of the clades, R. hesperus, is already recognized in California, while four clades appear to be previously undescribed taxa. Although identification of the final clade is inconclusive, it includes a sample putatively identified as R. tibialis. Therefore, using phylogenetic analyses we corroborate chemical characters used to identify taxa, associate a chemical phenotype with a previously described species, and provide additional support for undescribed taxa of Reticulitermes.     

Phylogenetic analyses of two mitochondrial genes and one nuclear intron region illuminate European subterranean termite (Isoptera: Rhinotermitidae) gene flow, taxonomy, and introduction dynamics

Phylogenetic analyses of multiple DNA sequences were conducted to elucidate gene flow, evolutionary patterns, taxonomy, and the dynamics of two accidental introductions: Reticulitermes lucifugus grassei into Devon, United Kingdom and R. flavipes into Europe. Two mitochondrial DNA genes totaling 1495 bp and a 380-bp ribosomal intergenic transcribed spacer were sequenced. Neighbor-joining and parsimony analyses revealed that multiple female lineages of R. lucifugus grassei were introduced into Devon possibly from southwestern France, where the species was indigenous. The taxonomic status of the European R. santonensis as a species separate from the North American R. flavipes has been questioned since it was described in 1924. Phylogenetic analyses revealed a close genetic relationship between R. flavipes from the United States and R. santonensis from France. These analyses, coupled with morphological and chemotaxonomic data, provide strong support for R. santonensis and R. flavipes being the same species. They also suggested that R. santonensis infestations likely resulted from R. flavipes being introduced into Europe.     

Population density, species abundance, and breeding structure of subterranean termite colonies in and around infested houses in central North Carolina

Pressure from subterranean termites is known to vary geographically across the United States, but there are few quantitative studies concerning the threat of structural infestation for any geographic region. We assessed the number and locations of termite colonies present on 20 infested residential properties in central North Carolina, where subterranean termite pressure is considered to be heavy. This was achieved by using microsatellite markers to determine colony identity of termites collected over 6-14 mo from mud tubes in structures, below-ground monitors, and wood debris in the yard. In total, we identified 188 distinct colonies and determined their breeding structures. Reticulitermes flavipes (Kollar) was by far the most common species, accounting for nearly 90% of all colonies; the remaining colonies belonged to Reticulitermes hageni Banks and Reticulitermes virginicus (Banks). In four cases, there were two colonies infesting a structure simultaneously; in all other cases only a single colony was detected in the structure. Colony densities were high, averaging 62 colonies per ha (25 per acre) with a maximum of 185 colonies per ha (75 colonies per acre). Foraging ranges of R. flavipes and R. hageni colonies were generally small (<30 linear m), and most colonies were headed by a single pair of monogamous reproductives with nearly all the remaining colonies headed by relatively few inbreeding descendants of the original monogamous pair. These results provide the most detailed picture to date of the number, distribution, and colony characteristics of subterranean termite colonies located in and around residential structures.     

Isolation and characterization of norharmane from Reticulitermes termites (Isoptera: Rhinotermitidae)

The fluorescent alkaloid norharmane has been isolated from Reticulitermes termites and characterized by 1H NMR, UV/Vis, mass spectrometry, and gas chromatography/mass spectrometry. Microcoil 1H NMR spectroscopy allowed spectra to be obtained from mass-limited material, facilitating the identification of norharmane, which is the major component in termite fluorescence under UV light. Norharmane was uniformly present at approximately 1 ng/mg in Reticulitermes tibialis Banks workers, soldiers, and alates; Reticulitermes flavipes (Kollar) workers; and Reticulitermes virginicus (Banks) workers. Some termites were observed to fluoresce with less intensity, but no differences in norharmane levels were detected. Mechanisms that may account for fluorescent differences are discussed as are the possible ecological implications of norharmane in termites.     

Culture and Phylogenetic Characterization of Trichomitus trypanoides Duboscq & Grassè 1924, n. comb.: a Trichomonad Flagellate Isolated from the Hindgut of the Termite Reticulitermes santonensis Feytaud

ABSTRACT. A trichomonad flagellate strain R1 was isolated from the hindgut contents of the termite Reticulitermes santonensis Feytaud. The flagellate was cultivated at 28° C in anaerobic medium containing yeast extract, minerals and vitamins. The isolate fed on living bacteria. It showed the typical morphological and ultrastructural features of the trichomonads. closely resembling Trichomitus trypanoides. In order to determine its phylogenetic position the small subunit ribosomal DNA (SSU rDNA) of the flagellate was amplified in vitro using the polymerase chain reaction (PCR), cloned in a plasmid vector and sequenced. Comparison of the obtained sequence with so far available SSU rRNA/rDNA sequences showed strongest similarity (89%) to the sequence of Tritrichomonas foetus. The phylogenetic analysis with parsimony and distance matrix methods placed Trichomitus trypanoides strain R1 near by the root of the phylogenetically so far analyzed eukaryotic organisms. This confirms that termites harbour hindgut symbionts, which originate from very early evolved eukaryotes.     

Niche heterogeneity determines bacterial community structure in the termite gut (Reticulitermes santonensis)

Differences in microenvironment and interactions of microorganisms within and across habitat boundaries should influence structure and diversity of the microbial communities within an ecosystem. We tested this hypothesis using the well characterized gut tract of the European subterranean termite Reticulitermes santonensis as a model. By cloning and sequencing analysis and molecular fingerprinting (terminal restriction fragment length polymorphism), we characterized the bacterial microbiota in the major intestinal habitats - the midgut, the wall of the hindgut paunch, the hindgut fluid and the intestinal protozoa. The bacterial community was very diverse (> 200 ribotypes) and comprised representatives of several phyla, including Firmicutes (mainly clostridia, streptococci and Mycoplasmatales-related clones), Bacteroidetes, Spirochaetes and a number of Proteobacteria, all of which were unevenly distributed among the four habitats. The largest group of clones fell into the so-called Termite group 1 (TG-1) phylum, which has no cultivated representatives. The majority of the TG-1 clones were associated with the protozoa and formed two phylogenetically distinct clusters, which consisted exclusively of clones previously retrieved from the gut of this and other Reticulitermes species. Also the other clones represented lineages of microorganisms that were exclusively recovered from the intestinal tract of termites. The termite specificity of these lineages was underscored by the finding that the closest relatives of the bacterial clones obtained from R. santonensis were usually derived also from the most closely related termites. Overall, differences in diversity between the different gut habitats and the uneven distribution of individual phylotypes support conclusively that niche heterogeneity is a strong determinant of the structure and spatial organization of the microbial community in the termite gut.     

Septate Gregarines From Reticulitermes Flavipes and Reticulitermes Virginicus (Isoptera: Rhinotermitidae)

ABSTRACT. The gregarine parasites of Reticulitermes virginicus and Reticulitermes flavipes begin their development as trophozoites attached to the midgut epithelium by a small button-shaped epimerite. the epimerite is lost when the parasite becomes free-living in the gut lumen as a solitary gamont. Syzygy is late and was not observed. When full-grown, gamonts enter the hemocoel and fuse in pairs to form large gametocysts that are attached to the midgut of the termite by a duct. Thousands of sporocysts are formed within the original gametocyst. the mature sporocysts are released into the lumen of the midgut through the connecting duct. They are then passed out with the feces. These gregarines are believed to be identical to Gregarina termitis Leidy which was described from a single gamont and later erroneously placed in the genus Hirmocystis by Henry.     

Genetic analysis of the breeding system of an invasive subterranean termite, Reticulitermes santonensis, in urban and natural habitats

Reticulitermes santonensis is a subterranean termite that invades urban areas in France and elsewhere where it causes damage to human-built structures. We investigated the breeding system, colony and population genetic structure, and mode of dispersal of two French populations of R. santonensis. Termite workers were sampled from 43 and 31 collection points, respectively, from a natural population in west-central France (in and around the island of Oleron) and an urban population (Paris). Ten to 20 workers per collection point were genotyped at nine variable microsatellite loci to determine colony identity and to infer colony breeding structure. There was a total of 26 colonies, some of which were spatially expansive, extending up to 320 linear metres. Altogether, the analysis of genotype distribution, F-statistics and relatedness coefficients suggested that all colonies were extended families headed by numerous neotenics (nonwinged precocious reproductives) probably descended from pairs of primary (winged) reproductives. Isolation by distance among collection points within two large colonies from both populations suggested spatially separated reproductive centres with restricted movement of workers and neotenics. There was a moderate level of genetic differentiation (F(ST) = 0.10) between the Oleron and Paris populations, and the number of alleles was significantly higher in Oleron than in Paris, as expected if the Paris population went through bottlenecks when it was introduced from western France. We hypothesize that the diverse and flexible breeding systems found in subterranean termites pre-adapt them to invade new or marginal habitats. Considering that R. santonensis may be an introduced population of the North American species R. flavipes, a breeding system consisting primarily of extended family colonies containing many neotenic reproductives may facilitate human-mediated spread and establishment of R. santonensis in urban areas with harsh climates.     

Attraction of subterranean termites (Isoptera) to carbon dioxide

Subterranean termites, Reticulitermes spp., were attracted to carbon dioxide (CO2) in laboratory and field tests. In behavioral bioassays, Reticulitermes flavipes (Kollar), Reticulitermes tibialis Banks, and Reticulitermes virginicus Banks were attracted to CO2 concentrations between 5 and 50 mmol/mol. In further bioassays, R. tibialis and R. virginicus were attracted to the headspace from polyisocyanurate construction foam that contained 10-12 mmol/mol CO2. In soil bioassays in the laboratory, more termites foraged in chambers containing CO2-generating formulations than in unbaited control chambers. In field tests, stations containing CO2-generating baits attracted R. tibialis away from wooden fence posts at rangeland sites in Colorado. For all of the CO2 formulations tested, termites foraged in significantly more bait stations at treatment fenceposts than in bait stations at the control fenceposts. By the end of the 8-wk study, the number of bait stations located by termites at treatment fenceposts ranged from 40 to 90%. At control fenceposts, termites foraged in only a single station and the one positive station was not located by termites until week 5 of the study. At treatment fenceposts, termites foraged equally in active stations (containing a CO2-generating bait) and passive stations (with no CO2-generating bait), indicating that bait stations may benefit passively from a proximal CO2 source in the soil. CO2 used as an attractant in current baiting systems could improve their effectiveness by allowing earlier exposure of termites to an insecticide.     

Parasitism of subterranean termites (Isoptera: Rhinotermitidae: Termitidae) by entomopathogenic nematodes (Rhabditida: Steinernematidae; Heterorhabditidae)

In laboratory bioassays, Steinernema riobrave Cabanillas, Poinar and Raulston (355 strain), Steinernema carpocapsae (Weiser) (Mexican 33 strain), Steinernemafeltiae (Filipjev) (UK76 strain), and Heterorhabditis bacteriophora Poinar (HP88 strain) were all capable of infecting and killing three termite species, Heterotermes aureus (Snyder), Gnathamitermes perplexus (Banks), and Reticulitermes flavipes (Kollar) in laboratory sand assays. S. riobrave and S. feltiae caused low levels of Reticulitermes virginicus (Banks) mortality under the same conditions. At 22 degrees C, significant mortality (> or = 80%) of worker H. aureus and G. perplexus was caused by S. riobrave, in sand assays, indicating the need for further study. Because of the short assay time (3 d maximum), reproduction of the nematodes in the target host species was not recorded. All nematode species were observed to develop to fourth-stage juveniles, preadult stages, or adults in all termite species with the exception of R. virginicus. Only S. riobrave developed in R. virginicus. Nematode concentration and incubation time had significant effects on the mortality of worker H. aureus. S. riobrave consistently generated the highest infection levels and mortality of H. aureus in sand assays.     

Phylogenetic diversity of termite gut spirochaetes

A molecular phylogenetic analysis was done of not-yet-cultured spirochaetes inhabiting the gut of the termite, Reticulitermes flavipes (Kollar). Ninety-eight clones of near-full-length spirochaetal 16S rDNA genes were classified by ARDRA pattern and by partial sequencing. All clones grouped within the genus Treponema , and at least 21 new species of Treponema were recognized within R. flavipes alone. Analysis of 190 additional clones from guts of Coptotermes formosanus Shiraki and Zootermopsis angusticollis (Hagen), as well as published data on clones from Cryptotermes domesticus (Haviland), Mastotermes darwiniensis Froggatt, Nasutitermes lujae (Wasmann) and Reticulitermes speratus (Kolbe), revealed a similar level of novel treponemal phylogenetic diversity in these representatives of five of the seven termite families. None of the clones was closely related (i.e. all bore ≤ 91% sequence similarity) to any previously recognized treponeme. The data also revealed the existence of two major phylogenetic groups of treponemes: one containing all of the currently known isolates of Treponema and a large number of phylotypes from the human gingival crevice, but only a minority of the termite gut spirochaete clones; another containing the majority of termite spirochaete clones and two Spirochaeta ( S. caldaria and S. stenostrepta ), which, although free living, group within the genus Treponema on the basis of 16S rRNA sequence. Signature nucleotides that almost perfectly distinguished the latter group, herein referred to as the 'termite cluster', occurred at the following ( E. coli numbering) positions: 289-G · C-311; A at 812; and an inserted nucleotide at 1273. The emerging picture is that the long-recognized and striking morphological diversity of termite gut spirochaetes is paralleled by their phylogenetic diversity and may reflect substantial physiological diversity as well.     

Asexual queen succession in the subterranean termite Reticulitermes virginicus

Termite colonies are founded by a pair of primary reproductives. In many species, including subterranean termites (family Rhinotermitidae), the primary king and queen can be succeeded by neotenic reproductives that are produced from workers or nymphs within the colony. It is generally believed that these neotenics inbreed within the colony, sometimes for many generations. Here, we show that primary queens of the North American subterranean termite, Reticulitermes virginicus, are replaced by numerous parthenogenetically produced female neotenics. We collected functional female neotenics from five colonies of R. virginicus in North Carolina and Texas, USA. Genetic analysis at eight microsatellite loci showed that 91-100% of the neotenics present within a colony were homozygous at all loci, indicating that they were produced through automictic parthenogenesis with terminal fusion. In contrast, workers, soldiers and alates were almost exclusively sexually produced by mating between the female neotenics and a single king. This is the second termite species shown to undergo asexual queen succession, a system first described in the Japanese species, Reticulitermes speratus. Thus, the conditional use of sexual and asexual reproduction to produce members of different castes may be widespread within Reticulitermes and possibly other subterranean termites.     

Molecular phylogeny of parabasalids based on small subunit rRNA sequences, with emphasis on the Trichomonadinae subfamily

We determined small subunit ribosomal DNA sequences from three parabasalid species, Trichomitus batrachorum strain R105, Tetratrichomonas gallinarum, and Pentatrichomonas hominis belonging to the Trichomonadinae subfamily. Unrooted molecular phylogenetic trees inferred by distance, parsimony, and likelihood methods reveal four discrete clades among the parabasalids. The Trichomonadinae form a robust monophyletic group. Within this subfamily T. gallinarum is closely related to Trichomonas species as supported by morphological data, with P. hominis and Pseudotrypanosoma giganteum occupying basal positions. Our analysis does not place T. batrachorum within the Trichomonadinae. Trichomitus batrachorum (strains R105 and BUB) and Hypotrichomonas acosta form a well-separated cluster, suggesting the genus Trichomitus is polyphyletic. The emergence of T. batrachorum precedes the Trichomonadinae-Tritrichomonadinae dichotomy, emphasizing its pivotal evolutionary position among the Trichomonadidae. A third cluster unites the Devescovinidae and the Calonymphidae. The fourth clade contains the three hypermastigid sequences from the genus Trichonympha, which exhibit the earliest emergence among the parabasalids. The addition of these three new parabasalid species did not however resolve ambiguities regarding the relative branching order of the parabasalid clades. The phylogenetic positions of Tritrichomonas faetus, Monocercomonas sp., Dientamoeba fragilis, and the unidentified Reticulitermes flavipes gut symbiont 1 remain unclear.     

Differential adsorption of allospecific hydrocarbons by the cuticles of two termite species,Reticulitermes santonensis and R. lucifugus grassei,living in a mixed colony. Passive transfer by contact

When members of the two termite species Reticulitermes santonensis and Reticulitermes lucifugus grassei were placed together, each species acquired some of the allospecific cuticular products. When living individuals of each of these two species were placed together, their cuticular hydrocarbon profiles changed very quickly, since it was within the first two hours of cohabitation that they differed most from those of the corresponding control individuals. After the first two hours, the profiles of the R. santonensis individuals continued to change only very little if at all, whereas 24h later, the process of change continued in the R. lucifugus grassei individuals until their profiles resembled those of the mixed R. santonensis individuals more than their own original profiles. The profiles of the R. l. grassei individuals therefore underwent a greater change than those of the R. santonensis individuals during the period of cohabitation. The fact that similar results were obtained when dead members of these two species were placed together suggests that this difference in the adsorption of allospecific hydrocarbon by the cuticles of the members of the two species cannot be attributable to any behavioural differences, but to differences in physico-chemical composition of the cuticles between the two species.     

Factors that Affect Aggression Among the Worker Caste of Reticulitermes spp. Subterranean Termites (Isoptera: Rhinotermitidae)

Aggression was observed among both inter- and intraspecific combinations of four colonies of Reticulitermes flavipes (Kollar) and Reticulitermes hageni Banks in laboratory assays each month for 4 consecutive months. Termites were most frequently aggressive toward colonies of a different species. Number of individuals that displayed aggression decreased over the study period, from April to July. There was a slight trend toward reduced aggressive behavior as termites were maintained in the laboratory for 3 months. Passive and aggressive individuals were identified and reexamined for display of aggressive or passive behavior toward nonnestmates. Eighty-nine percent of previously aggressive termites displayed aggression a second time. Eighty-eight percent of previously passive termites were passive upon reexamination. Differences in head capsule size between passive and aggressive individuals provided no correlation between the presence of aggressiveness and the head capsule size in the worker caste.