Reticulitermes Santonensis Research Articles

Distribution of a juvenogen and its metabolites in a laboratory system during juvenogen‐induced caste differentiation in a termite, Reticulitermes santonensis (Isoptera: Rhinotermitidae)

Juvenoids and juvenogens have been for many years considered promising candidates for control of pest insect species including termites. Their use as termite pest management agents requires the generation of knowledge concerning their degradation and distribution in time and space. Groups of 40 Reticulitermes santonensis de Feytaud workers were provided with wood impregnated with a juvenogen, ethyl cis-N-{2-[4-(2-butyryloxycyclohexylmethyl)phenoxy]ethyl}carbamate, labelled with tritium in the benzene ring (305 GBq mmol(-1)). After 14 days the radioactivity was determined in all elements of the experimental system. The majority of the input activity was detected in the wood, only about 1% in the bodies of surviving termites and 1% in the substrate. A considerable part of the input activity was probably lost as gaseous termite metabolites. The activity in workers was significantly higher than in presoldiers, which had differentiated under the influence of the labelled juvenogen. A stable value of radioactivity was detected on the body surfaces. The results suggest good stability of the compound in the wooden carrier and low contamination of the environment with non-gaseous residuals, together with the desired biological impact on termite caste differentiation.

Phylogenetic diversity of ‘Endomicrobia’ and their specific affiliation with termite gut flagellates

'Endomicrobia', a distinct and diverse group of uncultivated bacteria in the candidate phylum Termite Group I (TG-1), have been found exclusively in the gut of lower termites and wood-feeding cockroaches. In a previous study, we had demonstrated that the 'Endomicrobia' clones retrieved from Reticulitermes santonensis represent intracellular symbionts of the two major gut flagellates of this termite. Here, we document that 'Endomicrobia' are present also in many other gut flagellates of lower termites. Phylogeny and host specificity of 'Endomicrobia' were investigated by cloning and sequencing of the small subunit rRNA genes of the flagellate and the symbionts, which originated from suspensions of individual flagellates isolated by micropipette. Each flagellate harboured a distinct phylogenetic lineage of 'Endomicrobia'. The results of fluorescent in situ hybridization with 'Endomicrobia'-specific oligonucleotide probes corroborated that 'Endomicrobia' are intracellular symbionts specifically affiliated with their flagellate hosts. Interestingly, the 'Endomicrobia' sequences obtained from flagellates belonging to the genus Trichonympha formed a monophyletic group, suggesting co-speciation between symbiont and host.

Insect Pest Management Agents: Hormonogen Esters (Juvenogens)

The chemical part of this investigation focused on designing structures and synthesizing a series of six new esters (juvenogens), derived from biologically active insect juvenile hormone bioanalogues (juvenoids, JHAs) and unsaturated short-chain linear and branched fatty acids for possible application as biochemically targeted insect hormonogen agents. The structures of the new compounds were assigned on the basis of a detailed NMR analysis of their (1)H and (13)C NMR spectra. The biological part of this investigation focused on introductory biological screening tests with these compounds against the red firebug (Pyrrhocoris apterus), termites (Reticulitermes santonensis and Prorhinotermes simplex), and the blowfly (Neobellieria bullata). The biological activity of the juvenogens was studied in relation to the fatty acid functionality in the structures. Notable biological activity in topical tests and medium activity in peroral tests was found for the juvenogens 3 and 7 with P. apterus. The compounds 6 and 8 showed the lowest activity in both topical and oral assays with P. apterus. Considerable effect of all tested juvenogens was observed in P. simplex; however, the juvenogens 5 and 6 (derivatives of the only branched short-chain fatty acid) showed no activity against R. santonensis. The effect of the compounds 3-8 on larval hatching of N. bullata was only moderate (larval hatching 80-90%); however, the proliferation effect caused by 5, 6, and 8 is more pronounced than the effect caused by 3, 4, and 7.

Hydrogen is the central free intermediate during lignocellulose degradation by termite gut symbionts

The key role of free hydrogen in the digestion of lignocellulose by wood-feeding lower termites and their symbiotic gut microbiota has been conceptually outlined in the past decades but remains to be quantitatively analyzed in situ. Using Reticulitermes santonensis, Zootermopsis nevadensis and Cryptotermes secundus, we determined metabolite fluxes involved in hydrogen turnover and the resulting distribution of H(2) in the microliter-sized gut. High-resolution hydrogen microsensor profiles revealed pronounced differences in hydrogen accumulation among the species (from <1 kPa to the saturation level). However, flux measurements indicated that the hydrogen pool was rapidly turned over in all termites, irrespective of the degree of accumulation. Microinjection of radiotracers into intact guts confirmed that reductive acetogenesis from CO(2) dominated hydrogen consumption, whereas methanogenesis played only a minor role. Only negligible amounts of H(2) were lost by emission, documenting an overall equilibrium between hydrogen production and consumption within the gut. Mathematical modeling revealed that production dominates in the gut lumen and consumption in the gut periphery for R. santonensis and Z. nevadensis, explaining the large accumulation of H(2) in these termites, whereas the moderate hydrogen accumulation in C. secundus indicated a more balanced radial distribution of the two processes. Daily hydrogen turnover rates were 9-33 m(3) H(2) per m(3) hindgut volume, corresponding to 22-26% of the respiratory activity of the termites. This makes H(2) the central free intermediate during lignocellulose degradation and the termite gut-with its high rates of reductive acetogenesis-the smallest and most efficient natural bioreactor currently known.

Cuticular Hydrocarbon Composition Reflects Genetic Relationship Among Colonies of the Introduced Termite Reticulitermes santonensis Feytaud

Nestmate recognition plays a key role in kin selection to maintain colony integrity in social insects. Previous studies have demonstrated that nestmate recognition is dependent on detection of cuticular hydrocarbons. However, the absence of intraspecific aggression between some colonies of Isoptera and social Hymenoptera questions whether kin recognition must occur in social insects. The purpose of this study was to determine if cuticular hydrocarbon similarity and high genetic relatedness could explain the lack of intraspecific aggression among and within colonies of the introduced subterranean termite Reticulitermes santonensis. We performed both GC analysis of cuticular hydrocarbons and genotyping by using 10 DNA microsatellite loci on the same 10 workers from each of 14 parisian colonies. Multivariate analyses demonstrated correspondence between cuticular hydrocarbon patterns and genetic variation. By using a redundancy analysis combining chemical and genetic data, we found that a few hydrocarbons (mainly short vs. long chains; saturated vs. unsaturated alkanes) were associated with most genetic variation. We also found a strong positive correlation between chemical and genetic distances between colonies, thus providing evidence of a genetic basis for cuticular hydrocarbon variation. However, genetic distance did not account for all chemical variation, thus suggesting that some hydrocarbon variation was environmentally derived. Investigation at the intracolony level indicated that cuticular hydrocarbons did not depend on colony social structure. Based on our findings, we speculate that the absence of intraspecific aggression in R. santonensis may result from a loss of diversity in genetically derived recognition compounds in this species that presumably descended from R. flavipes populations imported from North America.

Differential expression of cytochrome c oxidase subunit III gene in castes of the termite Reticulitermes santonensis

Social insects such as termites live in colonies in which cooperation is assumed by all individuals developing into castes to which specific tasks are allocated. Little has been reported about molecular aspects underlying termite caste-specific gene expression. Genetic regulation has recently been hypothesized to govern caste-specific traits and physiology in social insects. Cytochrome c oxidase (COX) has been shown to be an interesting candidate for expression study in insects. We used the cytochrome c oxidase subunit III gene (COXIII) that was cloned from mRNA in a lower termite, Reticulitermes santonensis De Feytaud (Isoptera; Rhinotermitidae). The full-length cDNA encodes a protein of 262 amino acids that shows high degree of homology with other insects COXIIIs. Reverse transcriptase-PCR and real-time PCR were performed to compare gene expression between larvae, workers, nymphs and soldiers. Analyses performed on head cDNAs revealed that COXIII is differentially expressed between castes. The level of COXIII is caste-regulated with an increase in workers (∼1.9-fold) and nymphs (∼2.8-fold) and a decrease in soldiers (0.8-fold) compared to the expression level in larvae (1.0-fold). These results may emphasize the physiological importance of COX in the termite brain at different developmental stages.

Expression profiles of fhs (FTHFS) genes support the hypothesis that spirochaetes dominate reductive acetogenesis in the hindgut of lower termites

Reductive acetogenesis is an important metabolic process in the hindgut of wood-feeding termites. We analysed diversity and expression profiles of the bacterial fhs gene, a marker gene encoding a key enzyme of reductive acetogenesis, formyl tetrahydrofolate synthetase (FTHFS), to identify the active homoacetogenic populations in representatives of three different termite families. Clone libraries of polymerase chain reaction-amplified fhs genes from hindgut contents of Reticulitermes santonensis (Rhinotermitidae) and Cryptotermes secundus (Kalotermitidae) were compared with previously published fhs gene sequences obtained from Zootermopsis nevadensis (Termopsidae). Most of the clones clustered among the 'Termite Treponemes', which comprise also the fhs genes of the two strains of the homoacetogenic spirochaete Treponema primitia. The high abundance of treponemal fhs genes in all clone libraries was in agreement with the results of DNA-based terminal-restriction fragment length polymorphism (T-RFLP) analysis. Moreover, in mRNA-based T-RFLP profiles of the three termites, only expression of fhs genes of 'Termite Treponemes' was detected, albeit at different levels. In C. secundus, only one of the dominating phylotypes was transcribed, while in R. santonensis, the apparently less abundant fhs genes were the most actively expressed. Our results strongly support the hypothesis that spirochaetes are responsible for reductive acetogenesis in the hindgut of lower, wood-feeding termites.

Identification of Chilean &lt;I&gt;Reticulitermes&lt;/I&gt; (Isoptera: Rhinotermitidae) Inferred from Three Mitochondrial Gene DNA Sequences and Soldier Morphology

Abstract Results of Bayesian, maximum parsimony (MP), and neighbor joining (NJ) analysis of mitochondrial COII, 16S, and 12S gene DNA sequences and soldier morphology identified Chilean samples of a Reticulitermes species as the eastern subterranean termite, Reticulitermes flavipes (Kollar). All Chilean R. flavipes samples had identical gene sequences for all loci examined, suggesting a single geographic introduction. The combined DNA sequences for Reticulitermes santonensis Feytaud collected from France were almost identical to those of R. flavipes samples from Florida, which agreed with previous studies suggesting that R. santonensis is a junior synonym of R. flavipes. One unexpected finding was a R. flavipes sample collected from California that closely resembled the Chilean R. flavipes in their combined mitochondrial DNA sequences. We hypothesize that the Chilean R. flavipes may have been introduced from California or vice versa or that both Chilean and Californian R. flavipes may have the same origin...

Genetic Evidence for the Synonymy of Two &lt;I&gt;Reticulitermes&lt;/I&gt; Species: &lt;I&gt;Reticulitermes flavipes&lt;/I&gt; and &lt;I&gt;Reticulitermes santonensis&lt;/I&gt;

By applying the 16S rRNA mitochondrial marker to 434 populations of Reticulitermes termites from North, Central, and South America; France; and Germany with other locations around the world that we have analyzed, identical DNA sequence data were obtained from Reticulitermes flavipes (Kollar) in North America and Germany and for Reticulitermes santonensis Feytaud from undisturbed (nonurban) forested locations in western France. We also discovered identical DNA sequence data from previously unidentified Reticulitermes specimens from South America and Easter Island. Haplotypes F, M, and GG were observed in France; haplotype F in Germany; and haplotype GG was found on Easter Island, Santiago, Chile, and Montevideo, Uruguay. All of these haplotypes are found in numerous states within the continental United States. In light of their well documented morphological, chemical, and phylogenetic relationships, coupled with this new data that directly link these disjunct groups, R. flavipes and R. santonensis should be synonymized. Compared with other studies that largely suggest phyletic similarities, this is the first study that specifically matches haplotypes from North America (where populations of R. flavipes are endemic) with populations in Europe (where R. flavipes, described as R. santonensis, is presumed exotic).

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.

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.

Juvenogens as potential agents in termite control: laboratory screening.

Preliminary screening tests of eight juvenogens, fatty acid esters of two parent juvenoid alcohols, showed high juvenilizing effect in the termite Prorhinotermes simplex (Hagen). This effect is manifested by differentiation of termite workers into pre-soldiers, soldiers and/or soldier-intercastes ('soldiers'). Juvenogen 9 was tested with five other termite species: Zootermopsis angusticollis Hagen, Kalotermes flavicollis F, Cryptotermes declivis Tsai & Chen, Reticulitermes santonensis de Feytaud, and R flaviceps Oshima, and showed promising efficacy in force-feeding (FF) as well as in choice bioassays. In the economically important subterranean termites R santonensis and R flaviceps, after application of 0.5 mg ml(-1) in FF experiments ca 57 and 73%, respectively, of workers changed into soldiers. In Zootermopsis angusticollis application of 0.05 mg ml(-1) caused differentiation in 62% soldiers, and 57% soldiers differentiated after topical application of 1 microg of the tested compound per termite. Differentiation of excessive soldiers induced by a juvenile hormone-mimicking compound may cause disruption of the social structure and ultimately the death of the colony.

Polymorphic microsatellite loci in the European subterranean termite, Reticulitermes santonensis Feytaud

AbstractWe report on the identification and characterization of two dinucleotide, two trinucleotide and eight tetranucleotide microsatellite DNA loci isolated from the European subterranean termite Reticulitermes santonensis. We tested the loci on 51–92 individuals from 46 colonies from different regions of France. Eleven loci were polymorphic with 2–8 alleles per locus and low observed heterozygosities (0.10–0.48). We also tested the loci on 17–20 individuals from 10 colonies in the closely related North American species R. flavipes and found significantly more alleles (2–9 alleles per locus) and higher observed heterozygosities (0.15–0.80) than in R. santonensis. The lower observed heterozygosities in R. santonensis are consistent with higher levels of inbreeding in these colonies due to the presence of numerous inbred replacement reproductives.

Phylogenetic relationships of nearctic Reticulitermes species (Isoptera: Rhinotermitidae) with particular reference to Reticulitermes arenincola Goellner

DNA sequence comparisons of the mitochondrial COII, 16S, and 12S rRNA genes were used to infer phylogenetic relationships among the six known US Reticulitermes species ( Reticulitermes flavipes, Reticulitermes arenincola, Reticulitermes tibialis, Reticulitermes hageni, Reticulitermes virginicus, and Reticulitermes hesperus) and the closely related European species Reticulitermes santonensis. The interspecific pairwise sequence divergence, based on uncorrected “ p” distance, varied up to 10% across the COII, 4.9% across the 16S, and 3% across the 12S fragments. Phylogenetic trees were constructed using maximum parsimony, likelihood, and distance methods. The combined results suggest several phylogenetic relationships including: (i) R. flavipes, R. arenincola, and European R. santonensis are possibly conspecific; (ii) R. virginicus and R. hageni are closely related species; and (iii) R. tibialis and R. hesperus are closely related species. Interestingly, while there is apparent synonymity between R. flavipes and R. arenincola by DNA sequence, there are clear morphological differences in the soldier caste. This finding suggests a combination of molecular and morphological approaches are necessary for accurate species identification. These data lend resolution to the complex problem of Reticulitermes systematics, and will assist future efforts directed toward characterizing species distribution and ecology.

Repellent Effects of Isoborneol on Subterranean Termites (Isoptera: Rhinotermitidae) in Soils of Different Composition

The repellence of the plant-derived bicyclic monoterpenoid isoborneol on subterranean termites was assessed in short-term laboratory bioassays. Depending on concentration, application of isoborneol to different soil types was efficient in creating repellent soil barriers, which were not penetrated by workers of Reticulitermes santonensis De Feytaud or R. flavipes Kollar within 2 wk after adding the substance to the substrate. Isoborneol-treated barriers did not affect termite survival. The bioavailability of the active ingredient decreased with increasing clay content of the soil. Evaporation of isoborneol from treated soil increased with increasing particle size of the substrate and could be reduced by covering the soil surface.

Repellent and toxic effects of plant extracts on subterranean termites (Isoptera: Rhinotermitidae).

The effects of four plant extract formulations on the orientation and survival of subterranean termites were tested. In choice experiments, extract-treated filter paper had a significantly repellent effect on groups of Reticulitermes santonensis De Feytaud, R. virginicus (Banks), Coptotermes formosanus Shiraki, and Schedorhinotermes intermedius Breinli. There was no species-specific difference in avoidance behavior toward the tested concentrations. No-choice experiments revealed toxic properties of all investigated extracts by contact or airborne compounds against R. santonensis. However, high termite mortality was only achieved by forced direct or forced indirect exposure to the plant material, Feeding deterrence or digestive toxicity could not be judged in these experiments. One of the extracts was efficiently used for soil treatments to protect a food substrate against R. santonenis infestation. Extract-treated barriers in the experiments did not affect mortality compared with control trials but prevented termites from penetrating treated soil.

A juvenile hormone analogue with potential for termite control: laboratory tests with Reticulitermes santonensis, Reticulitermes flaviceps and Coptotermes formosanus (Isopt., Rhinotermitidae)

Laboratory experiments with three species of termites were conducted to study the efficacy of a carbamate derivative of 2‐(4‐hydroxybenzyl)‐1‐cyclohexanone (W‐328). The compound has been found to be highly active causing differentiation of termite workers into presoldiers, soldiers and/or soldier‐intercastes. Differentiation of excessive soldiers induced by juvenile hormone analogues (JHAs) may disrupt the social homeostasis and consequently cause death of the whole termite colony. W‐328 induced differentiation into soldiers in 41–100% of individuals when applied in range of 50–500 ppm to a feeding substrate of wood in force‐feeding and choice bioassays with groups of Reticulitermes santonensis Feytaud and R. flaviceps (Oshima). Efficacy of W‐328 was also confirmed in choice bioassays with isolated groups of workers and soldiers and with incipient colonies of Coptotermes formosanus Shiraki. A high proportion of JHA‐induced differentiation into soldier caste was accompanied by increased mortality. Termites accept a matrix treated with W‐328 quite well. Significant feeding deterrence of the compound was observed only at higher concentrations: 500 ppm in some tests with Reticulitermes spp. and 5000 ppm in colonies of C. formosanus. Adequate persistence of W‐328 in corrugated cardboard (a potential feeding substrate for baits) was confirmed by bioassay with R. santonensis and by chemical analysis. The residue levels of the compound, applied at 500 ppm concentration, after 27 days of conditioning remain high enough to result in significant soldier differentiation.

Comparison of the spatial distribution and reproductive cycle of Reticulitermes santonensis Feytaud and Reticulitermes lucifugus grassei Clément (Isoptera, Rhinotermitidae) suggests that they represent introduced and native species, respectively

The termites Reticulitermes santonensis (Rs) and R. lucifugus (Rl) were first regarded as different species (Feytaud, 1924) and then as the same species (Buchli, 1958). In later studies, Clement (1978, 1986) and Bagneres et al. (1990) used morphological and chemical (cuticular hydrocarbons) criteria to show that they actually are two distinct species. Feytaud (1924) and Bagneres et al. (1990) suggested that Rs could have originated from a North American population of R. flavipes that was introduced into Europe. The present study examined the distribution and reproductive cycle of Rs and an Rl sup-species, Rl grassei (Rlg), which are partly sympatric in southwest France. In the wild, Rs has an aggregated distribution related to human surroundings (past or present), i.e. populations are either dense or entirely absent. Conversely, Rlg is distributed randomly (from dense to few) throughout its range. For example, Rs is not found in towns within the Landes Forest, an area in southwest France that remained economically depressed and sparsely settled until after 1850 (Sargos, 1997), while Rlg is quite common there. Their respective reproductive strategies show that Rs populations spread through budding (swarms are scarce and many brachypterous nymphs and neotenics are found), whereas Rlg populations reproduce by both swarming and budding. It is likely that Rs is an introduced species and Rlg a native one that has reached its northern limits in France. A closer examination of North American Reticulitermes species, particularly R. flavipes, might reveal a relationship with the European species.

Thin-layer chromatography assessing feeding stimulation by labial gland secretion compared to synthetic chemicals in the subterranean termite Reticulitermes santonensis.

The labial gland of the French subterranean termite Reticulitermes santonensis De Feytaud contains a polar, heat-resistent, and persistent chemical signal that is released onto the food during food exploitation and stimulates feeding in nestmates. Separation of the labial gland secretion by thin-layer chromatography on cellulose plates revealed that the secretion contains components with reducing and amino groups. In feeding bioassays conducted on the cellulose plate after TLC, termites preferred the area between Rf 0.46 and 0.88 (biologically active zone) for feeding, indicating the location of the feeding-stimulating signal. Thirty-five synthetic chemicals with similar chemical properties as the feeding-stimulating signal were analyzed with TLC. None of them covered the biologically active zone. Therefore, all chemical classes tested, such as sugars, amino acids, and salts, are unlikely as possible sources for the signal structure. In feeding choice tests with synthetic chemicals, termites showed clear feeding preference only for sugarlike components with physiologically excessive concentrations of 10 mmol and 100 mmol. Amino acids induced only light feeding preference. The intensity of feeding stimulation by the natural signal from the labial gland as compared to synthetic phagostimulants is discussed.

Food exploitation in termites: indication for a general feeding-stimulating signal in labial gland secretion of isoptera.

The paired labial glands are located in all termite species in the thorax. During food exploitation workers of the French termite Reticulitermes santonensis and the African termite Schedorhinotermes lamanianus release the secretion of their labial glands directly onto the food. The secretion carries a water-soluble, heat-resistant, nonvolatile signal that stimulates gnawing and feeding and leads to aggregations of feeding workers. In a feeding bioassay, extracts of the labial glands of 11 termite species from five families all proved to have this feeding-stimulating effect both on R. santonensis and S. lamanianus. The heat resistance of the feeding-stimulating signal also could be shown for selected species from all termite families tested. A combined thin layer chromatography-feeding bioassay on cellulose TLC plates showed that after chromatography of labial gland secretion, the feeding-stimulating signal is located in all 11 species in the same area from Rf 0.46 to 0.88. An extract of labial glands of cockroaches stimulated feeding in R. santonensis and S. lamanianus as well, but was not active after heat treatment and after TLC. This points towards a general feeding-stimulating signal having evolved only in the labial gland secretion of termites.