Experimental hybridization between chromosomal races in Kalotermes approximatus,a termite with extensive sex-linked translocation heterozygosity

In order to elucidate the evolutionary pathway of sex-chromosome translocations in the termite Kalotermes approximatus, reciprocal matings were made between the winged reproductives from two different colonies, one in which there was a multivalent chain of 13 in male meiosis, and one in which there was a chain of 17 (or 19, in some cells). From the cross in which the male parent came from the chain-of-13 colony, the male offspring had a chain of 13 (or 15, in some cells) in meiosis; from the reciprocal cross, the male offspring had a chain of 15. Careful analysis of the multivalent chains in the hybrid males, combined with previous observations on chromosome variation in this species (Syren and Luykx, 1981), permit the following conclusions: (i) The two parent colonies differ by five distinct translocations, involving both X and Y chromosomes. (ii) In the evolution of the sex-multivalent, all of these kinds of translocations have occurred: X-X, Y-Y, X-autosome, and Y-autosome. (iii) Out of a total of 8 sex-chromosome translocations that can now be unambiguously characterized, 6 have involved X-chromosomes, and 2 have involved Y-chromosomes. (iv) In this species, different chromosomal races in adjacent geographic locales may differ in both their males and their females (where translocations have involved X-chromosomes), or they may differ only in their males (where translocations have involved Y-chromosomes).     

Untersuchungen am Ei-Chorion der termite Kalotermes flavicollis fabr. unter normalen bedingungen und nach behandlung des weibchens mit colcemid (Insecta,Isoptera)

Zusammenfassung Das Chorion mit der präsumptiven Rißstelle und den Mikropylen von normalen Eiern und solchen, die von Weibchen gelegt werden, denen Colcemid in das Abdomen injiziert worden war, wurde untersucht. Die Richtungsdivergenzen der Mikropylenkanäle beiderseits der durch die präsumptive Rißstelle markierten Chorionmediane, die in den meisten Fällen der Halbierungslinie des Eies entspricht, weisen die bilaterale Symmetrie des Eichorions aus. Dementsprechend müssen die zellen des Follikelepithels qualitativ verschieden sein. Am normalen Ei finden sich 5–61 Mikropylen. Nach Injektion von Colcemid kann die Zahl der Mikropylen erniedrigt oder erhöht sein, und es können dort Mikropylen induziert werden, wo sic normalerweise nicht auftreten. Außerdem kann die Chorionmediane verlagert werden. Es gibt am Ei einen Bereich größter Mikropylenhäufigkeit, jedoch nicht spezifische Mikropylenbildungszellen, und auch eine Hemmwirkung zwischen benachbarten Mikropylen besteht nicht. Es treten Schäden an einzelnen Chorionfeldern and am gesamten Chorion auf, d. h. während der Endphase der Oogenese muß das Follikelepithel in seiner Gesamtheit eine labile Phase durchlaufen.

---

Investigations of the egg-Chorion of the termite Kalotermes flavicollis Fabr. under normal conditions and after treatment of the female with Colcemid (Insecta, Isoptera)

Chorion-structures of normal eggs, the preformed field for hatching of the embryo and especially the micropyles have been investigated and compared with changes after the influence of colcemid upon oögenesis.

     

Complex sex-linked translocation heterozygosity: Its genetics and biological significance

Chromosomal translocations (interchanges and fusions) can alter linkage and random assortment when present in the heterozygous condition. In certain circumstances, this heterozygosity can be maintained through an indefinite number of generations. Sex-linked translocation heterozygosity, in which males are perpetually heterozygous for translocations while females are perpetually homozygous, is disproportionately frequent in social and eusocial arthropod species. This article surveys the reported instances of sex-linked translocation heterozygosity, and reviews recent explanations for the observed correlation with social behaviour.     

A sex-linked ring quadrivalent in Termitidae (Isoptera)

A sex-linked ring of four multiple has been identified at male meiosis in 21 African species of Termitidae. Since this ring occurs only in the males it is clear that it represents a multiple sex chromosome system of the X₁X₂Y₁Y₂X₁X₁X₂X₂ type.     

Mitochondrial and nuclear markers highlight the biodiversity of Kalotermes flavicollis (Fabricius, 1793) (Insecta, Isoptera, Kalotermitidae) in the Mediterranean area

The biodiversity of the European termite Kalotermes flavicollis is here studied through the analysis of mitochondrial (303 bp of control region and 912 bp of COI/tRNA(Leu)/COII) and nuclear (five microsatellite and 20 Inter-SINE loci) markers on 18 colonies collected in Southern France, Corsica, Sardinia, peninsular Italy, the Balkans and Greece. Different statistical analyses (Bayesian phylogenetic analysis,parsimony network, F-statistics, PCA) were performed. Mitochondrial sequences produced an unresolved polytomy including samples from peninsular Italy, Balkans and Greece, and three main clades: southern France, Corsica-Sardinia and Portoscuso(SW Sardinia). Nuclear markers confirm these data, further highlighting a more significant divergence at the regional scale. The results obtained for the peri-Tyrrhenian area agree with major paleogeographic and paleoclimatic events that shaped the biodiversity of the local fauna. K. flavicollis biodiversity and its phylogeographic pattern are also evaluated in the light of the data available for the other native European termite taxon (genus Reticulitermes), in order to produce a more complete scenario of the Mediterranean. In the area comprised between southern France and Italy, the degree of diversity is similar; however, in the eastern area, while K. flavicollis is differentiated only at the population level, the genus Reticulitermes comprises at least six entities of specific and/or subspecific level. This discrepancy may be explained by taking into account the different evolutionary histories of the two taxa.     

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.     

Patterns of activity of nucleolar organizer regions during spermatogenesis and oogenesis in Kalotermes flavicollis Fabr. (Insecta: Isoptera) analyzed by silver staining

The distribution and the behaviour of the nucleolus organizer regions (NORs) were analysed during the spermatogenesis and oogenesis of K. flavicollis with the silver staining method. The Ag-stainability of the NORs increases in growing spermatocytes up to pachytene and is absent during the remainder of the meiotic prophase. During female meiosis the nucleolar material undergoes a more complex transformation. It is active until pachytene; in early diplotene the mass of silver stainable material progressively increases as an effect of rDNA amplification. By the end of meiotic prophase the nucleolar strands disappear and a large nucleolus is rebuilt in the mature oocyte.     

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.     

On the respiratory quotient (RQ) of termites (Insecta: Isoptera)

The respiratory quotient (RQ) at 28 degrees C was determined by Warburg manometry in 23 species of termites from the Mbalmayo Forest Reserve (Cameroon) and three sub-tropical species cultured under laboratory conditions in the U.K. or freshly collected in Australia. The data are tabulated with other recently reported RQs (determined by manometry or GC) and with measured CH(4) emission rates to provide a survey of 29 species covering both lower and higher termites in all major trophic (functional) categories. In all species, except the wood-feeding Coptotermes acinaciformis and the soil-feeding Cubitermes fungifaber, the observed mean values (with manometry corrected for known fluxes of H(2) and CH(4)) were at or well above 1.00. Soil-feeding forms (except C. fungifaber) generally showed a high apparent RQ (not corrected for H(2)), with nine species (out of 13) above 1.20 and six species above 1.30. Well-replicated laboratory experiments with Reticulitermes lucifugus showed that there was a tendency for RQ to fall with time over a 4-h incubation, although remaining greater than 1.00.The observed RQs are consistent with carbohydrate being the principal substrate supporting respiration in all trophic and taxonomic categories, with little or no contribution from the degradation of lignin or other polyaromatic materials. However, in many species (especially soil-feeders), the observed RQ is greater than that expected from known fluxes of O(2), CO(2) and CH(4) on the assumption that carbohydrate is the respiratory substrate. This presupposes that there is a large hydrogen sink (additional to CH(4) production), possibly the emission of H(2) gas, and/or the existence of unresolved digestive mechanisms or electron routings. Uncertainties in the use of manometry with termites are discussed.     

Soldier-like intercastes in the rotten-wood termite Hodotermopsis sjostedti (Isoptera: Termopsidae)

All termite species possess a distinct sterile-soldier caste in their colonies, although reproductive soldiers, with soldier characteristics and reproductive ability, have been reported from several species of the family Termopsidae. Such intercastes have been considered the primitive-soldier caste, and based on this many researchers have discussed the evolutionary origin of termite soldiers. We investigated whether such soldier-reproductive intercastes also exist in the Japanese rotten-wood termite Hodotermopsis sjostedti. Abnormal individuals with soldier-like characteristics were found and designated as soldier-like intercastes, which appeared to have both soldier and reproductive characteristics. Based on our morphometric analyses and histological examinations, we suggest that the developmental origin of this intercaste is a pseudergate, nymph or sixth-instar larva. In addition, the intercaste was found to have relatively well-developed gonads, although mature oocytes and spermatozoa were not found in female ovaries and male seminal vesicles, respectively. We conclude that the soldier-like intercaste of H. sjostedti does not have reproductive ability, which is different from all other known soldier-like intercastes in Termopsidae.     

Revision of the termite family Rhinotermitidae (Isoptera) in New Guinea

Recently, we completed a revision of the Termitidae from New Guinea and neighboring islands, recording a total of 45 species. Here, we revise a second family, the Rhinotermitidae, to progress towards a full picture of the termite diversity in New Guinea. Altogether, 6 genera and 15 species are recorded, among which two species, Coptotermes gambrinus and Parrhinotermes barbatus, are new to science. The genus Heterotermes is reported from New Guinea for the first time, with two species restricted to the southern part of the island. We also provide the first New Guinea records for six species of the genera Coptotermes and Schedorhinotermes. We briefly describe soldiers and imagoes of each species and provide a key based on soldier characters. Finally, we discuss the taxonomic and biogeographical implication of our results. A replacement name, Schedolimulus minutides Bourguignon, is proposed for the termitophilous staphylinid Schedolimulus minutus Bourguignon, to solve a question of secondary homonymy.     

Geographic variation in Pemphigus populitransversus (Insecta: Aphididae)*†

The geographic variation of 33 morphological characters of two morphs of the gall-forming aphid Pemphigus populitransversus is studied in 214 locality samples. Among-locality variation ranges from 1 to 69% in the elongate morph and from 0 to 44% in the globular morph. The design of the study permits separation of interlocality correlations from intralocality correlations. The former are partly a function of the latter, confirming early observations on another Pemphigus species and on ticks. Factor analyses of both correlation matrices for both morphs yield four factors. Within localities these factors agree for the two morphs; among localities only one factor corresponds. Multiple discriminant analyses among localities of the two data sets do not correspond. There is little correlation between characters of stem mother and alate morphotypes within localities but such correlations are strong among localities. Maps are furnished for characters representing the independent dimensions of variation for each morph. Patterns of variation are shown to be significant by spatial autocorrelation analysis for both morphs but are much more marked in the elongate morph. Significant positive autocorrelation occurs up to 1000 km in the elongate morph – mostly only up to 200 km in the globular morph. There are two to three geographic variation patterns in the elongate morph, whereas in the globular morph the classes of patterns are less well defined and involve few characters. The environmental factors to which the globular and elongate morphs are adapting would appear to have different autocorrelation patterns. In each morph the patterns are clearly different and cannot be explained by a single microevolutionary process. The findings are compared with an earlier study in the related and largely sympatric P. populicaulis.     

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.     

An early Cretaceous termite from southern England (Isoptera: Hodotermitidae)

Valditermes brenanae gen. et sp.n. is described from the Weald Clay (Neocomian: (?) Hauterivian; c. -120 million years) of Surrey; it is the earliest described termite and social insect. Valditemes is referred to the extinct subfamily Cretatermitinae of the family Hodotermitidae, previously known only from a single specimen (Cretatermes carpenteri Emerson, 1967) from the Ceno- manian (c. -95 m.y.) of Labrador. Valditermes represent a more generalized condition than Cretatermes and may be the ancestor of Cretatemes. The geo- logical occurrence of Valditermes, other records o f Cretaceous termites, and finds of fossil termites in Britain are summarized.     

Geographic variation in Pemphigus populicaulis (Insecta: Aphididae) in Eastern North America*,†

The geographic variation of 33 morphological characters of the gall-forming aphid Pemphigus populicaulis is studied for 118 localities east of 100^oW longitude. Variation can be partitioned into within-gall, among-gall and among-locality components. Among localities variation ranges from 26 to 54%, being significant for all characters. Variation among galls within localities ranges from 24 to. 56%, that within-galls from 8 to 4796. The design of the study permits computation of character correlation matrices within and among localities. Gall size is correlated with tnorphometric characters only on an interlocality but not on an intralocality basis. Interlocalily correlations are a function of intralocality correlations, confirming earlier predictions. There is little correlation between characters of stem mother and alate morphotypes within localities, whereas among localities such correlation is appreciable. This phenomenon may be caused by aspects ol the environment that vary among localities but remain reasonably constant through the earlv life cycle of the aphid. When subjected to factor analysis both correlation matrices yield four factors. Multiple discriminant analysis of the data set results in five interpretable significant axes. Maps are furnished for characters representing the independent dimensions of variation and for discriminant function scores. The patterns of variation can be shown to be significantly nonrandom by Mantel's test and by spatial autocorrelation analysis. All variables are significantly positively autocorrelated at 200 km, many at 400 km and a few at 600 km; few general statements can be made about significant autocorrelations at higher distances. The positive autocorrelation at relatively short distances may be related to the pool of clones from which the genotypes of any one locality sample are taken. There are three correlogram patterns that can be associated with four clusters of variation patterns of characters. The separate patterns presumably cannot be explained by a single microevolutionary process.     

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.     

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

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

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.