Zootermopsis Nevadensis Research Articles

Iron reduction in the metal‐rich guts of wood‐feeding termites

ABSTRACTTermites play important roles in lignocellulose and humus turnover in diverse terrestrial ecosystems, and are significant sources of global atmospheric methane and carbon dioxide. All known termite species engage in obligate, complex nutritional symbioses with their gut microbes to carry out such processes. Several hundred microbial species, representing a broad phylogenetic and physiological diversity, are found within the well‐bounded, microliter‐in‐scale gut ecosystem of a given termite. However, most of these species have never been obtained in laboratory culture, and little can be said about their functional roles in the gut community or symbiosis. Herein, an unappreciated facet of the gut chemistry and microbiology of wood‐feeding termites is revealed: the redox metabolism of iron. Gut fluids from field‐collected termites contained millimolar amounts of ferrous iron and other heavy metals. When iron(III) hydroxides were amended to a filter paper diet of Zootermopsis nevadensis, a dampwood termite collected in the San Gabriel Mountains of Southern California, the specimens accumulated high levels of iron(II) in their guts. Additionally, iron was reduced at rapid initial rates in anoxic gut homogenates prepared from field‐collected Z. nevadensis specimens. A Clostridium sp. and a Desulfovibrio sp. were isolated from dilution‐to‐extinction enrichments of Z. nevadensis gut contents and were found to reduce iron(III), as did the termite gut spirochete Treponema primitia. The iron in the guts of wood‐feeding termites may influence the pathways of carbon‐ and electron‐flow, as well as microbial community composition in these tiny ecosystems of global importance.

Microsatellite markers for two species of dampwood termites in the genus Zootermopsis (Isoptera: Termopsidae)

AbstractDampwood termites in the genus Zootermopsis inhabit forested areas in western North America. To better understand the colony composition and breeding structure of Zootermopsis, we identified polymorphic microsatellite loci to use in population analysis. Microsatellite loci were isolated from Zootermopsis nevadensis nevadensis (Hagen); however, all primers amplified homologous loci in Zootermopsis angusticollis (Hagen) and Zootermopsis nevadensis nuttingi (Hagen). Twelve loci were polymorphic in one or more of the above subspecies and species. The number of alleles per locus ranged from one to six, with some allelic differences among subspecies and species. We are currently utilizing the microsatellite markers to investigate the population genetics of Zootermopsis.

Fungistatic activity of the sternal gland secretion of the dampwood termite Zootermopsis angusticollis

In vivo and in vitro studies indicate that cuticular chemicals from the ventral region of the abdomen where the sternal gland of the dampwood termite Zootermopsis angusticollis is located have fungistatic properties. Germination rates of conidia of the entomopathogenic fungus Metarhizium anisopliae were significantly reduced from 91% (controls) to 38.5% after nymphs walked over conidia-seeded agar medium, but did not differ from controls when the sternal gland and surrounding cuticle were sealed with nail polish. In vitro studies show that germination of fungal conidia was also significantly reduced following incubation with cuticular extracts of either sternal or tergal segments suggesting that cuticular exudates in general may have antifungal properties. Extracts of sternites had greater fungistatic activity than extracts of tergites, but the difference was not statistically significant. Extracts of the sternal gland significantly reduced germination rates by up to 9%. Germination rates were significantly reduced when conidia were incubated with n-hexanoic acid, or its vapor. n-Hexanoic acid has been recovered from whole body extracts of Zootermopsis nevadensis and may indeed be a component of the sternal gland of Z. angusticollis. Here we suggest that sternal gland secretions in termites may have had the original function of controlling microbes within the nest and their prominent role in communication may have evolved secondarily.

Comparative studies on alate wing formation in two related species of rotten-wood termites: Hodotermopsis sjostedti and Zootermopsis nevadensis (Isoptera, Termopsidae)

Termite colonies are comprised of several types of castes that differentiate throughout postembryonic development. In termopsid termites (family Termopsidae), alates are normally differentiated from apterous instars by two nymphal instar stages and three moulting events. Here, we report that of the rotten-wood termite Hodotermopsis sjostedti. There is only a single nymphal instar between the pseudergate and alate stages. During the annual alate production season in June/July, we observed some nymphs with small wing buds which were dorsally swollen. Those nymphal individuals subsequently moulted into alates through only a single moult. We examined their histology and internal morphology and observed that the folding pattern of the newly formed wings was very different from that seen in second stage nymphs of the closely related species Zootermopsis nevadensis. The newly formed wings of H. sjostedti are formed inside the relatively smaller wing buds and therefore must be folded in a complicated manner. Our observations revealed that the tips of the folded wings were elongated and bent, such that they overlapped in the median plane. We suggest that heterochronic evolutionary change accounts for the compression of nymphal development into a single instar. We also suggest that this probably occurred at either the individual or colony level in this species.

Characterization of termite lipophorin and its involvement in hydrocarbon transport

The transport of lipids constitutes a vital function in insects and requires the plasma lipoprotein lipophorin. In all insects examined to date, cuticular hydrocarbons are also transported through the hemolymph by lipophorin, and in social insects they play important roles not only in water proofing the cuticle but also in nestmate recognition. High-density lipophorin (HDLp), isolated from Reticulitermes flavipes plasma by KBr gradient ultracentrifugation, contains 66.2% protein and 33.8% lipids; hydrocarbons constitute its major neutral lipid (20.4% of total lipids). Anti-lipophorin serum was generated in rabbit and its specific association with lipophorin, and not with any other plasma proteins, was verified with Western blotting. Immunoprecipitation also confirmed that this antibody specifically recognizes lipophorin, because all hemolymph hydrocarbons of the termites R. flavipes and R. lucifugus and the cockroach Supella longipalpa, which associate only with lipophorin, were recovered in the immunoprecipitated protein. Cross-reactivity of the antiserum with lipophorin from related species was investigated by double immunodiffusion with 10 termite species in the genera Reticulitermes, Coptotermes, Zootermopsis, and Kalotermes, and with five cockroach species. Involvement of lipophorin in hydrocarbon transport was shown by injecting HDLp antiserum into Zootermopsis nevadensis and then monitoring the de novo biosynthesis of hydrocarbons and their transport to the cuticular surface; the antiserum significantly disrupted hydrocarbon transport. ELISA revealed a gradual increase in the lipophorin titer in successively larger R. flavipes workers, and differences among castes in lipophorin titers were highest between nymphs and first instar larvae.

2002 Oklahoma Termite Survey (Isoptera)

More than 200 soil-surface and in-ground termite-monitoring devices were established across Oklahoma to collect termites. Termites were also collected from tree stumps and wooden buildings. Four species of Reticulitermes (Isoptera: Rhinotermitidae), R. flavipes, R. virginicus, R. tibialis, and R. hageni were recovered. From previous records, Gnathamitermes tubiformans (Buckley) is also indigenous to Oklahoma. Based on previous records, non-subterranean species including the dampwood termites Zootermopsis angusticollis (Hagen) and Zootermopsis nevadensis (Hagen), and the drywood termites Cryptotermes brevis (Walker) and Incisitermes minor (Hagen), are occasionally reported in lumber and furniture shipped to Oklahoma from California and Oregon, or from Gulf coast states. Known distributions of R. virginicus and G. tubiformans are extended. Reproductive flights of subterranean termites in Oklahoma peak from mid-March to mid-May. Observations of relative foraging densities across the state are also reported.

Longevity of kings and queens and first time of production of fertile progeny in dampwood termite (Isoptera; Termopsidae; Zootermopsis) colonies with different reproductive structures

Summary We report age‐specific survivorship of founding kings and queens and colony age of first production of fertile progeny (alates) of two cohorts, containing 52 and 42 complete colonies, respectively, in the primitive dampwood termite Zootermopsis nevadensis ssp. nevadensis. Longevity of kings and queens was determined and compared in various experimental manipulations of reproductive structure of incipient colonies (removal of king or queen or both vs. unmanipulated pairs as controls) performed one year after pairing. Life span of reproductives was also evaluated in circumstances of interactions between young colonies, a treatment inspired by field observations of natural nest spacing and intraspecific competition between young dampwood termite colonies. In our first experimental series, founding pairs survived 2–7 years (x̄ = 4·5 ± 0·3 SE) after pairing. Kings lived significantly longer (x̄ = 4·7 ± 0·3 years after pairing; range 2·2–7·3 years) in treatments initiated as pairs than when left as the remaining founder in the queen removal treatment (x̄ = 3·2 ± 0·6 years after pairing; range 1·5–5·3 years), even though one or more female replacement reproductives differentiated within several months after queen loss. Queen life span in the absence of kings averaged 4·9 ± 0·4 years (range 3·6–6·3 years) after pairing, not significantly different from the life span of queens living with kings. There was no significant difference between king and queen life spans in non‐interaction treatments in our first experiment. Results from the second experimental series (35 colonies) are presented to date. Survival of pairs until death of one mate was significantly shorter in interaction treatments compared with control colonies, suggesting that intraspecific competition between young colonies may create opportunities for replacement reproductives. The first alates were produced between 1·8 and 6·5 years after pairing in our first experimental series, and between 2·4 and 5 years, to date, in the second experiment. Ecological and evolutionary correlates of long life span in social insect reproductives and other animals are discussed.

Odorant-binding proteins from a primitive termite.

Hitherto, odorant-binding proteins (OBPs) have been identified from insects belonging to more highly evolved insect orders (Lepidoptera, Coleoptera, Diptera, Hymenoptera, and Hemiptera), whereas only chemosensory proteins have been identified from more primitive species, such as orthopteran and phasmid species. Here, we report for the first time the isolation and cloning of odorant-binding proteins from a primitive termite species, the dampwood termite. Zootermopsis nevadensis nevadensis (Isoptera: Termopsidae). A major antennae-specific protein was detected by native PAGE along with four other minor proteins, which were also absent in the extract from control tissues (hindlegs). Multiple cDNA cloning led to the full characterization of the major antennae-specific protein (ZnevOBP1) and to the identification of two other antennae-specific cDNAs, encoding putative odorant-binding proteins (ZnevOBP2 and ZnevOBP3). N-terminal amino acid sequencing of the minor antennal bands and cDNA cloning showed that olfaction in Z. n. nevadensis may involve multiple odorant-binding proteins. Database searches suggest that the OBPs from this primitive termite are homologues of the pheromone-binding proteins from scarab beetles and antennal-binding proteins from moths.

Genetic relatedness and partner preference in a monogamous, wood-dwelling termite

A mate preference study on adult dampwood termites, Zootermopsis nevadensis subspeciesnuttingi , supports the hypothesis that mate-seeking adults avoid forming partnerships with nestmates. The observed proportion of nestmate pairs formed from all potential pairs was significantly less than expected. In addition, fewer pairs formed when there was a higher availability of nestmates versus non-nestmates. Genetic relatedness estimates, obtained from multilocus fingerprints of overwintering pairs, showed that relatedness between partners was not significantly different from background relatednesses of members chosen randomly from the population. Thus, nest-founding reproductive adults typically do not breed incestuously in this wood-dwelling termite. Furthermore, relatedness estimates between adult breeding males and between adult breeding females coinhabiting each log showed that there was a low probability of genetic relatedness among adults of neighbouring pairs, indicating that adults are typically dispersing in ways that minimize contact with relatives. Relatedness between laboratory-reared full siblings produced by field-collected pairs showed that relatedness was not significantly higher thanr =0.50, which is expected if sustained incestuous breeding does not occur, or if cycles of inbreeding occur with negligible frequency among breeding adults. These findings do not support arguments that selection favours inbreeding because it confers disease resistance in termites. They also indicate that the level of genetic relatedness between nest-founding adults and among siblings cannot, by itself, explain the high levels of altruism within colonies of this single-site, wood-dwelling termite. Ecological pressures and the benefits of group living, together with ordinary genetic relatedness characteristics of outbred families appear sufficient to explain the advantages of kin-based altruism in wood-dwelling termites like Zootermopsis.

Isolation and identification of a diuretic hormone from Zootermopsis nevadensis☆

A diuretic hormone (DH) was isolated from extracts of heads of Zootermopsis nevadensis, a dampwood termite. The peptide has 46 residues, M r = 5,328.2 Da, with the sequence TGAVPSLSIVNPLDVLRQRLLLEIARRRMRQSQDQIQANREMLQTI-NH 2, showing it to be a CRF-related DH. This peptide increases cyclic AMP production in Malpighian tubules of Manduca sexta. We detected another factor in the head extracts which behaved as a more basic peptide on ion exchange chromatography. The latter factor also stimulated cyclic AMP production in the bioassay, but two large scale attempts to isolate this peptide were unsuccessful. We believe the second peptide is acid labile.

Cyclic carbon dioxide release in the dampwood termite, Zootermopsis nevadensis (Hagen)

Real-time traces of CO 2 release of pseudergates of the dampwood termite, Zootermopsis nevadensis (Hagen) were obtained using flow-through respirometry. Traces were made at each of six temperatures, between 10 and 35°C. Termites released CO 2 in a cyclic pattern at each of the six temperatures. CO 2 release rate (as V ̇ CO 2 in ml h −1) increased significantly with temperature and body mass. Rate of change in V ̇ CO 2 with temperature (or Q 10) was 2.11. Degree of cycling in CO 2 traces was estimable using the coefficient of variability. Coefficient of variability for both acyclic and cyclic traces declined exponentially with increasing temperature.

Rate, Amount, and Distribution Pattern of Alimentary Fluid Transfer via Trophallaxis in Three Species of Termites (Isoptera: Rhinotermitidae, Termopsidae)

Abstract Trophallaxis, defined as the direct transfer of alimentary liquids, including suspended particulates and derivatives, from one nestmate to another via regurgitation or anal feeding, is important in the nutritional dynamics and communication of many social insects. Trophallaxis is a mechanism for the transfer of nutrients, symbionts, pheromones, and information within social insect colonies. We used the radioactive tracer cobalt-60, combined with the vital dye Nile Blue A, in a standard diet to investigate the rate, amount, and distribution pattern of alimentary liquids in the termites Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), R. virginicus (Banks), and Zootermopsis nevadensis subsp. nevadensis (Haverty & Thorne) (Termopsidae). The technique did not affect termite survivorship and enabled determination of the rate and quantity of material transferred from identifiable, marked “donor” individuals to “recipients.” This method of tracing trophallactic transfer of alimentary fluid ...

Cuticular hydrocarbons of the dampwood termite, Zootermopsis nevadensis : Caste differences and role of lipophorin in transport of hydrocarbons and hydrocarbon metabolites

The epicuticular and internal hydrocarbons (HC) from different castes of the dampwood termite Zootermopsis nevadensis were analyzed by gas chromatography–mass spectrometry. The epicuticular HC profiles of workers and alates contained large proportions of n-heneicosane (n-C21), 5-methylheneicosane (5-MeC21), and 5,17- and 5,15-dimethylheneicosane (5,17-, 5,15-diMeC21). Sixty-three HC peaks were identified as normal-, monomethyl-, dimethyl-, and trimethylalkanes up to 41 carbons long. The HC content of the internal tissues was significantly greater than on the epicuticle in all castes examined (2.8-fold in female alates, 5.7-fold in male alates, and 13.7-fold in workers). The hemolymph of all castes, including workers, soldiers, nymphs, and female and male alates, contained large amounts of HC and all hemolymph samples had nearly identical HC profiles. However, the hemolymph profile was remarkably different from the cuticular profile. KBr equilibrium gradient ultracentrifugation of worker hemolymph showed that all HC were associated with a high-density lipophorin (density of 1.12 ± 0.005 g/ml) consisting of two subunits, apolipophorin-I (220 kDa) and apolipophorin-II (82 kDa). After topical application of radiolabeled 3,11-dimethylnonacosane, a HC that is closely related to a native HC, all the internalized HC and radiolabeled lipid metabolites that were recovered from the hemolymph were associated with lipophorin. These findings are consistent with the hypothesis that lipophorin transports HC and some HC metabolites through the hemolymph from the sites of synthesis to the integument and from the integument to metabolic and excretory tissues. In many social insects, different castes have different relative proportions of the same HC and lipophorin appears to play an important role in regulation of the externalization and internalization of HC and, therefore, in the attainment of caste-specific chemical profiles.

Courting strategies and conflicts in a monogamous, biparental termite

In species where parental investment is extensive for both sexes, both males and females are predicted to exhibit choosiness when seeking their lifetime partners. Evidence is presented that both courting males and females are choosy in the wood–dwelling, biparental termite Zootermopsis nevadensis . There are, however, sex differences both in the method of mate rejection and in the mate–choice criteria. In particular, females are more likely than males to invite an extra suitor into the nest, whereas males are more likely than females to leave their nest and partner and seek a replacement elsewhere. Correlational analyses of adults show that head width is a mate–choice criterion used by females, whereas body mass and fat mass are used by males. Among males and females that sought replacement mates, those that had been rejected previously were more likely to end up paired with an adult that also had been rejected, compared with adults that had not been rejected. Additional findings reveal a rich repertoire of courting behaviours characterized by extensive intra– and intersexual conflict, including mate rejection, intrasexual combat, and even intrapair aggression.

Mechanism of hydrocarbon biosynthesis from aldehyde in selected insect species: Requirement for O 2 and NADPH and carbonyl group released as CO 2

The mechanism of hydrocarbon biosynthesis was examined in the fleshfly Sarcophaga crassipalpis, the blowfly Phormia regina, the German cockroach Blattella germanica, the house cricket Acheta domesticus, the Mormon cricket Anabrus simplex, the dampwood termite Zootermopsis nevadensis and compared to the house fly, Musca domestica. Microsomal preparations from each species readily converted [9,10- 3H 2]octadecanal (18:0 Ald) to heptadecane. NADPH and O 2 were required for enzymic activity in all cases, and very little hydrocarbon was formed under anaerobic conditions. Radio-GLC analyses of the head space gas formed from the metabolism of [1- 14C]18:0 Ald by microsomes from M. domestica, S. crassipalpis, P. regina and B. germanica clearly showed that 14CO 2 and not 14CO was formed. Quantitation of the products from the metabolism of [1- 14C] and [9,10- 3H 2]18:0 Ald in microsomes from M. domestica, P. regina, S. crassipalpis, B. germanica and Z. nevadensis showed that an approximate 1 1 ratio of 14CO 2/[ 3H] heptadecane was formed. The data support a mechanism in which the aldehyde is converted to hydrocarbon and CO 2 in insects.

Mitochondrial Dna Variation within and among Species of Termites in the Genus Zootermopsis (Isoptera: Termopsidae)

Population structure and speciation in the eusocial but fully diploid Isoptera are not well understood. Mitochondrial DNA (mtDNA) restriction site variation was analyzed in the three species of the genus Zootermopsis. One colony of Zootermopsis nevadensis (Hagen) contained individuals with two different mtDNA haplotypes in approximately equal frequencies. This suggests the possibility of reproductive contribution to the colony from females of different parentage. Two recently named subspecies of Z. nevadensis have been suggested to be incipient species based on distinct cuticular hydrocarbon differences, allopatric distribution, and variation in ecology; however, the mtDNA data reported here cannot be used to confirm or reject this hypothesis. Individual colonies of these subspecies were not well resolved in phylogenetic analyses, but a Monte Carlo randomization procedure indicated they are differentiated with respect to haplotype frequencies. Considerable site variation exists among the three currently recognized species, and parsimony and distance analyses demonstrate they are distinct and monophyletic. These results provide further information on the relatively unknown areas of genetic structuie and speciation in termites.

Limited Nutrients in a Dampwood Termite: Nest Preference, Competition and Cooperative Nest Defence

1. Prior laboratory manipulation of nitrogen availability indicated that monogamous pairs of Zootermopsis nevadensis (Isoptera: Termopsidae) exhibit cooperative behaviour patterns that increase nitrogen availability for reproduction and larval growth. I now present field evidence that reproductives preferentially seek and cooperatively defend nests rich in cambium-nitrogen. 2. Higher densities of newly flown adults disperse to logs with greater quantities of total cambium-nitrogen, but not to logs having greater amounts of wood xylem. Nest settlement occurs in an ideal free distribution in relation to cambium-nitrogen. The average nearest inter-nest distance between new pairs varies inversely with a log's average percentage nitrogen in the cambium layer

Vibrational alarm communication in the damp‐wood termite Zootermopsis nevadensis

Abstract. Vibrational alarm communication was studied in the New World, damp‐wood termite Zootermopsis nevadensis (Isoptera: Termopsidae). Workers and soldiers react to disturbance such as sudden bright light or air currents by drumming their heads against the substratum. This drumming has been described as alarm signalling; its functional significance and perception by the nest mates, however, remained unclear. In the present study we analysed spectral and temporal properties and absolute amplitudes of the vibrational signals and used behavioural responses of the termites to determine the thresholds of the sense of vibration and to find out if and how the termites discriminate the conspecific alarm signals from the background noise.The drumming signals are trains of pulses of vibrations of the substratum with a pulse repetition rate of about 20 Hz. The carrier frequency depends on the substratum; in the nests studied it was in the range 1–3 kHz. The highest vibrational amplitudes measured close to the signal emitters are usually about 10m/s2 (acceleration, RMS). The threshold of the behavioural response is about 1m/s2 over a wide range of frequencies (10 Hz to 5 kHz), indicating that the termites can detect these signals as vibrations of the substratum. The animals respond preferentially to temporal patterns similar those of the natural signals; temporal rather than spectral cues seem to be used for signal discrimination.

Juvenile hormone binding proteins of termites detected by photoaffinity labeling: Comparison of Zootermopsis nevadensis with two rhinotermitids

AbstractThe hemolymph of each caste of the primitive dampwood termite Zootermopsis nevadensis (Isoptera, Termopsidae, Termopsinae) contains a high molecular mass lipoprotein which functions as a specific, high affinity carrier for juvenile hormone (JH) III, as detected by JH III‐displaceable covalent modification by the tritium‐labeled photoaffinity analog (10R)‐10, 11‐epoxyfarnesyl diazoacetate ([3H]EFDA). The Formosan termite Coptotermes formosanus (Rhinotermitidae, Coptotermitinae) and Eastern subterranean termite Reticulitermes flavipes (Rhinotermitidae, Rhinotermitinae) possess analogous proteins. Variations among the major proteins and the JH‐binding lipoproteins are described.

Gut tract microorganisms supply the precursors for methyl-branched hydrocarbon biosynthesis in the termite, Zootermopsis nevadensis

In vivo and in vitro experiments were performed to examine the role of succinate and other potential precursors of the methylmalonyl-CoA used for methyl-branched hydrocarbon biosynthesis in the termite Zootermopsis nevadensis. The in vivo incorporation of [1,4- 14C]succinate and [2,3- 14C]succinate into hydrocarbon confirmed that succinate is a direct precursor to the methyl branch unit. The other likely precursors, the branched chain amino acids valine and isoleucine, were not efficiently incorporated into hydrocarbon. Carbon-13 NMR showed that one of the labeled carbons of [1,4- 13C]succinate labeled position 6 of 5-methylalkanes and positions 6 and 18 of 5,17-dimethylalkanes, indicating that succinate, as a methylmalonyl-CoA unit, was incorporated as the third unit to form 5-methylheneicosane and as both the third and ninth units to form 5,17-dimethylheneicosane. Analysis of organic acids after the in vivo metabolism of [2,3- 14C]succinate showed that succinate was converted to propionate and methylmalonate. Labeled succinate injected into the hemolymph was readily taken up by the gut tract. Isolated gut tissue efficiently converted succinate to acetate and propionate, both of which were released into the incubation media. Mitochondria from termite tissue (minus gut tract) converted succinate to methylmalonate and propionate only in the presence of malonic acid, an inhibitor of succinate dehydrogenase. The results of these studies show that while termite mitochondria are able to convert succinate to propionate and methylmalonate, most of the propionate used for methyl-branched hydrocarbon biosynthesis is produced by gut tract microorganisms. The propionate is then presumably transported through the hemolymph to epidermal cells for use in methyl-branched hydrocarbon biosynthesis.