MOLECULAR DELINEATION OF SPECIES AND SYNGENS IN VOLVOCACEAN GREEN ALGAE (CHLOROPHYTA)1

Two species of the colonial green flagellate family Volvocaceae are worldwide in distribution yet exhibit contrasting species structure. Geographically disparate isolates of Gonium pectorale Mueller can interbreed while isolates of Pandorina morum Bory behave quite differently. More than 20 sexually isolated subpopulations occur within this species; these have been termed “syngens” (sensu Sonneborn). Because prezygotic barriers to mating cause intersyngen pairings to fail, breeding analyses cannot be used to estimate genetic relatedness among the syngens of P. morum. DNA comparisons provide an alternative method of assessing genetic relatedness. We compared the nucleotide sequence of the internal transcribed spacer (ITS) region of the nuclear ribosomal repeat among clones of P. morum and of G. pectorale. Members of syngens of P. morum with distribution restricted to one small geographical area show great similarity. Likewise, members of any syngen of worldwide distribution show near uniformity, even those from different continents. However, the ITS sequence of each syngen differs from that of other syngens. In contrast, G. pectorale, which has an ITS region that is remarkably uniform throughout the world, appears to consist of a single syngen within North America and Europe by mating tests. The molecular data are in complete conformity with previous syngen assignment. Because the latter is based on mating affinity, with two complementary mating types per syngen, the evolution of new mating type pairs appears to be the basis of microevolution in these algae. We infer that either P. morum is a more ancient species than G. pectorale or that P. morum has a less stable genome. In either case, the biogeographic distribution of certain syngens may reflect climatological changes of the past.     

LONG-TERM MAINTENANCE OF FERTILE ALGAL CLONES: EXPERIENCE WITH PANDORINA (CHLOROPHYCEAE)1,2

There is a need for simple, inexpensive methods to maintain algal clones of constant genotype over long periods of time. Pandorina zygospores survive many environmental rigors which destroy the vegetative cells. The zygospores are the preferable from for storage of the alga and remain viable for at least 15 yr. storage procedures and germination techniques are described for zygospores of 2 species. These are compared with reports in the literature concerning other algal genera. General procedures for storage and maintenance of both vegetative cells and spores are proposed.     

EVIDENCE FOR TUBULAR MATING STRUCTURES INDUCED IN EACH MATING TYPE OF HETEROTHALLIC GONIUM PECTORALE (VOLVOCALES,CHLOROPHYTA)1

Gametes were induced separately in cultures of each mating type of the heterothallic, isogamous colonial volvocalean Gonium pectorale O. F. Müll. to examine the tubular mating structure (TMS) of both mating types plus and minus (plus and minus), referred to as “bilateral mating papillae.” Addition of dibutyryl cyclic adenosine monophosphate (DcAMP or db‐cAMP) and 3‐isobutyl‐1‐methylxanthine (IBMX) to approximately 3‐week‐old cultures of each mating type induced immediate release of naked gametes from the cell walls. Both plus and minus gametes formed a TMS in the anterior region of the protoplasts. Accumulation of actin was visualized by antibody staining in the TMS of both mating types as occurs in the TMS (fertilization tubule) of the plus gametes of the unicellular volvocalean Chlamydomonas reinhardtii P. A. Dang. Induction of naked gametes with a TMS in each mating type will be useful for future cell biological and evolutionary studies of the isogametes of colonial volvocalean algae.     

A SEX DETERMINING MECHANISM IN THE CLOSTERIUM EHRENBERGII (CHLOROPHYTA) SPECIES COMPLEX1

Homozygous mt^?/mt^? diploid clones of the Closterium ehrenbergii Menegh. ex Ralfs species complex were obtained by hypertonic treatment from minus vegetative cells, and mating type segregation ratios in the F₁ progeny of “triploid” zygospores between wild type mt⁺ haploid and mt^?/mt^? homozygous diploui were analyzed. The ratio of plus to minus individuals was 1:4.8, and the ratio of the pairs of opposite mating types to those of minus mating type was 1:2.1. The results clearly show that mt^? is dominant to mt⁺ and that the mating type inheritance in these zygospores follows the triploid-like pattern. The validity of our assumption that the two mating types are determined by one genetic factor (mt^? allele dominant) was confirmed in B₁ progeny analyses as well. The results suggest that this sex determining mechanism is working effectively in the C. ehrenbergii species complex, in which several biological species have evolved through polyploidization.     

ZYGOTE APPENDAGES (CIRRI), A NEW STRUCTURAL FEATURE IN THE SPHAEROPLEACEAE(CHLOROPHYCEAE)1

Cirri are curled appendages borne on the surface of mature zygotes in some members of the green algal family Sphaeropleaceae. Structures equivalent to cirri have not been reported previously in any green algae. We found cirri in four taxa: Sphaeroplea fragilis Buchheim et Hoffman, Atractomorpha porcata Hoffman, and two new undescribed species of Atractomorpha from Africa. Zygotes of seven other sphaeropleacean taxa were examined, but they did not produce cirri. Cirri may be either simple or compound. Simple cirri are less than 0.5 μm in diameter and show no evidence of longitudinal striations or subunits. Compound cirri are more massive (commonly 2.0–3.5 μm, and up to 4 μm diameter in S. fragilis) and possess longitudinal striations suggesting that each is formed of longitudinally arranged subunits ca. 0.5 μm in diameter. Simple and compound cirri are formed by zygotes of all four taxa that produce cirri. Both types may occur on the same zygote. Nonetheless, the patterns of variation in length, shape, and distribution of the two types of cirri are sufficiently distinct to characterize each taxon. Energy dispersive X-ray microanalysis (EDX) shows that cirri lack appreciable mineralization and are thus primarily organic in nature. The potential value of cirri as a taxonomic character in the Sphaeropleaceae is discussed.     

TIME-LAPSE ANALYSES OF SEXUAL ISOLATION BETWEEN TWO CLOSELY RELATED MATING GROUPS OF THE CLOSTERIUM EHRENBERG SPECIES COMPLEX (CHLOROPHYTA)1

Sexual isolation between Groups A and B of Closterium ehrenbergii, two closely related species, was studied by a multiple-choice mating method, as well as the nochoice mating method which has been used in previous work on microalgae. Time lapse photomicrographs and the difference in cell shape and size between the two mating groups allowed identification of a given cell in the mixture as either Group A or B, even when certain morphological changes occurred during the several day culture required for sexual induction. When plus and minus mating types of Group A were mixed with those of Group B (multiplechoice mating), no intergroup hybrid zygospores were formed. However, many intragroup zygospores of either Group A or B were formed. When one plus strain of Group A was mixed with one minus strain of Group B or when one plus strain of Group B was mixed with one minus strain of Group A (no-choice mating), intergroup sexual interactions took place resulting in a small number of hybrid zygospores; however, the process took much longer than intragroup sexual interactions. It was also shown that cell size difference itself hardly affects sexual interactions between haploid and autodiploid strains of Group A. It is suggested that sexual isolation between Groups A and B would be complete in nature, although they may interact sexually in the laboratory.     

MATURATION OF ALGAL ZYGOTES: ALTERNATIVE EXPERIMENTAL APPROACHES FOR CHLAMYDOMONAS REINHARDTII (CHLOROPHYCEAE)1

Young zygotes from crosses of Chlamydomonas reinhardtii Dang. mutant and wild-type strains were incubated, in the presence or absence of light and/or nitrogen to determine whether continuation of conditions inducing gamete formation permits zygospore formation without loss of viability. Different culture media, continuous illumination vs. dark incubation and various durations of the maturation period were tested, for effect on zygospore germination efficiency, zygospore “burst size” and zoospore viability. Following either the routine maturation procedure of dark incubation on standard minimal medium, or following a new procedure of incubation under continuous illumination on N-free medium, zygospore formation can be ensured and high germination efficiencies obtained within 3 days after mating. Tetrad analysis indicates meiosis occurs normally whether zygotes have been matured in the presence or absence of light or nitrogen. Preliminary data suggest an effect of increased maturation time on the transmission of cytoplasmic genes, if a N-free continuous illumination maturation protocol is followed. Two experimental approaches for the maturation of C. reinhardtii zygotes are suggested and advantages of each are discussed.     

THE FLAGELLAR PHOTORESPONSE IN VOLVOX SPECIES (VOLVOCACEAE,CHLOROPHYCEAE)1

Steering their swimming direction toward the light is crucial for the viability of Volvox colonies, the larger members of the volvocine algae. While it is known that this phototactic steering is achieved by a difference in behavior of the flagella on the illuminated and shaded sides, conflicting reports suggest that this asymmetry arises either from a change in beating direction or a change in beating frequency. Here, we report direct observations of the flagellar behavior of various Volvox species with different phyletic origin in response to light intensity changes and thereby resolve this controversy: Volvox barberi W. Shaw from the section Volvox sensu Nozaki (2003) changes the direction of the flagellar beating plane, while species encompassed in the group Eudorina (Volvox carteri F. Stein, Volvox aureus Ehrenb., and Volvox tertius Art. Mey.) decrease the flagellar beating frequency, sometimes down to flagellar arrest.     

THE ZYGOSPORE WALL OF CHLAMYDOMONAS MONOICA (CHLOROPHYCEAE): MORPHOGENESIS AND EVIDENCE FOR THE PRESENCE OF SPOROPOLLENIN1

Chlamydomonas monoica Strehlow is being developed as a model for genetic analysis of zygospore morphogenesis, and many relevant mutant strains are available. To provide the basis for interpreting the ultrastructural phenotypes of zygospore mutants, an analysis of wall morphogenesis in wildtype zygospores of C. monoica was undertaken. Following synthesis of a thick, fibrous, primary zygote wall, granular material accumulated between the plasma membrane and the primary zygote wall and aggregated into a repetitive array of electron-opaque fibrous stripes. A new wall layer, the outer layer of the secondary zygospore wall, first appeared as segments with a fibrous outer surface overlying a well-defined band of electron-translucent material. These segments gave rise to an intact sheath adjacent to the plasma membrane. Beneath this sheath, electron-opaque material (forming the inner layer of the secondary zygospore wall) accumulated unevenly and forced the surface sheath to undulate, creating a pattern of peaks and valleys that was exposed to the external environment 4 rupture and release of the primary zygote wall. The zygospore wall included material resistant to degradation by potassium hydroxide, 2-aminoethanol, and acetolysis, but it was destroyed by exposure to chromic acid. These characteristics, in combination with the autofluorescence of untreated zygospore walls and their failure to stain with phloroglucinol, suggest that sporopollenin may be responsible for many of the resistant properties associated with the mature zygospore of Chlamydomonas.     

MITOCHONDRIAL DNA IN THE OOGAMOCHLAMYS CLADE (CHLOROPHYCEAE): HIGH GC CONTENT AND UNIQUE GENOME ARCHITECTURE FOR GREEN ALGAE1

Most mitochondrial genomes in the green algal phylum Chlorophyta are AT‐rich, circular‐mapping DNA molecules. However, mitochondrial genomes from the Reinhardtii clade of the Chlorophyceae lineage are linear and sometimes fragmented into subgenomic forms. Moreover, Polytomella capuana, from the Reinhardtii clade, has an elevated GC content (57.2%). In the present study, we examined mitochondrial genome conformation and GC bias in the Oogamochlamys clade of the Chlorophyceae, which phylogenetic data suggest is closely related to the Reinhardtii clade. Total DNA from selected Oogamochlamys taxa, including four Lobochlamys culleus (H. Ettl) Pröschold, B. Marin, U. G. Schlöss. et Melkonian strains, Lobochlamys segnis (H. Ettl) Pröschold, B. Marin, U. G. Schlöss. et Melkonian, and Oogamochlamys gigantea (O. Dill) Pröschold, B. Marin, U. G. Schlöss. et Melkonian, was subjected to Southern blot analyses with cob and cox1 probes, and the results suggest that the mitochondrial genome of these taxa is represented by multiple‐sized linear DNA fragments with overlapping homologies. On the basis of these data, we propose that linear mitochondrial DNA with a propensity to become fragmented arose in an ancestor common to the Reinhardtii and Oogamochlamys clades or even earlier in the evolutionary history of the Chlorophyceae. Analyses of partial cob and cox1 sequences from these Oogamochlamys taxa revealed an unusually high GC content (49.9%–65.1%) and provided evidence for the accumulation of cob and cox1 pseudogenes and truncated sequences in the mitochondrial genome of all L. culleus strains examined.     

ASEXUAL AND SEXUAL REPRODUCTION IN GONIUM QUADRATUM (CHLOROPHYTA) WITH A DISCUSSION OF PHYLOGENETIC RELATIONSHIP WITHIN THE GONIACEAE1

Morphological details of asexual and sexual reproduction in Gonium Quadratum Pringsheim ex Nozaki (Goniaceae, Chlorophyta) were observed by light microscopy, based on clonal cultured materials originating from Nepal. In asexual reproduction, the alga exhibited two different patterns of cell cleavage during formation of 8-and 16-celled daughter colonies. Sexual reproduction was heterothallic and isogamous. The gametes bore a tubular mating structure (bilateral mating papilla) at the base of the flagella, and the papillae of the two gametes. The germinating zygote gave rise to four biflagellate gone cells joined in a colony (germ colony). Possible phylogenetic relationships within the Goniaceae at the species level are outlined, mainly on the basis of reproduction characteristics.     

A POLYPLOID SPECIES COMPLEX IN SPIROGYRA MAXIMA (CHLOROPHYTA,ZYGNEMATACEAE), A SPECIES WITH LARGE CHROMOSOMES1

A species complex in Spirogyra consists of the series of filament morphotypes of various ploidal levels arising from an original morphotype within a clonal culture or in nature. A clonal culture of filaments identified as Spirogyra maxima (Hassall) Kützing produced several morphotypes, i.e. filament types of distinctly different widths and ploidal levels. Banding patterns and satellites were visible on chromosomes stained at mitotic prophase and metaphase. The original culture of S. maxima contained filaments averaging 127 μ wide. Vegetative cells of the original culture contained six large chromosomes (>4 μ long), identifiable as three distinct pairs based on banding patterns and presence of satellites: (1) one pair of short chromosomes (ca. 5.0 μ); (2) one pair of long chromosomes (ca. 8.0 μm); and (3) a second pair of long chromosomes (ca. 9.0 μm) including a nucleolar organizing region and satellite. A larger morphotype averaging 175 μm in width contained 12 chromosomes, with two pairs of short chromosomes and four pairs of long chromosomes (satellites were usually indistinct). Aneuploid chromosome numbers ranging from 5 to 13 were observed in a few cells. Binucleate and trinucleate cells were also observed. A twobanded chromosome fragment was observed in a few cells with 6 chromosomes and a few cells with 12 chromosomes. The variety of morphotypes derived in this study could be identified as four different species of Spirogyra by conventional taxonomic criteria. The banding patterns and satellites on chromosomes suggest that three pairs of homologous chromosomes are present in filaments of the original clonal culture and that these filaments are themselves autopolyploid (diploid) descendants of ancestral form with a base chromosome number of x = 3.     

DIVERGENCE IN MORPHOLOGY AND MATING SIGNALS,AND ASSORTATIVE MATING AMONG POPULATIONS OF CHORTHIPPUS PARALLELUS (ORTHOPTERA: ACRIDIDAE)

Three geographically widely separated populations of the grasshopper Chorthippus parallelus (Orthoptera: Acrididae) have been examined for morphological divergence, divergence in characteristics of the acoustic sexual signals of males, and assortative mating. Significant assortative mating existed between two of the three pairwise combinations of populations in multiple-choice tests. This may be caused by divergence in three of the four acoustic signal parameters measured. The populations also differed in morphology, including characters associated with signal production. The results are discussed in relation to theories for the origin of premating isolation, and it is argued that the observed divergence has developed rapidly, possibly indicating the action of selection. However, this selection could not have been caused by interactions with closely related taxa.     

MATING SYSTEM,SEXUAL REPRODUCTION,AND AUXOSPORULATION IN THE ANOMALOUS RAPHID DIATOM EUNOTIA (BACILLARIOPHYTA)1

The diatom genus Eunotia is unusual among raphid diatoms in having a raphe system consisting of two short slits that are not integrated into the primary pattern center. This and other characteristics, particularly the presence of rimoportulae, are consistent with the hypothesis that Eunotia is a basal lineage within the raphid group. We studied auxosporulation in E. bilunaris (Ehrenberg) Mills and E. tropica Hustedt for comparison with other raphid pennate diatoms and with araphid pennates; E. bilunaris was studied in parental and F1 generations. Like araphid pennates, E. bilunaris and E. tropica are heterothallic. Clones of the same mating type did not interact sexually, and intraclonal sexual reproduction was absent or very rare. Clones retained the same sex throughout the life cycle, as shown by experiments using abrupt size reduction to produce clones of similar age but different size and using subclones derived from a single initial cell within six mitotic generations. Unlike in araphid pennate diatoms, in the Eunotia species the gametes are not visibly or behaviorally differentiated. Gametogenesis is merogenous, because the gametangium formed a supernumerary cell as well as a single gametic cell, both undergoing meiosis II to form a surviving functional nucleus and a nucleus that quickly degenerated. Plasmogamy is via papillae that grew out toward each other from the ends of the gametangia to create a copulation canal. After plasmogamy, the gametes moves bodily into the copulation canal, producing an elongate zygote, which expands to form a curved sausage‐like auxospore.     

THE ECOLOGY OF EPIPELIC ALGAE OF FIVE WELSH LAKES,WITH SPECIAL REFERENCE TO VOLVOCALEAN GREEN FLAGELLATES (CHLOROPHYCEAE)1

The ecology of epipelic algae on the marginal sediments of five Welsh lakes was studied over an annual cycle. The lakes, Llydaw, Cwellyn, Padarn, Maelog and Coron ranged from very oligotrophic to nutrient-rich. Attention was focussed on chlamydomonad flagellates, diatoms, blue-green algae and euglenoids and the different proportions of these in algae in the epipelon of lakes of contrasting water quality. A total of 75 algal taxa was found in the five lakes, 25 were species of volvocalean flagellates. Mean annual population density of these flagellates differed by an order of magnitude between the lakes. The greatest population density was recorded for Chlamydomonas anticontata Schiller in nutrient-rich Llyn Maelog. Twenty species of pennate diatoms were recorded frequently in the epipelon. In the nutrient-rich lakes, Maelog and Coron, pennate diatoms were dominant on the sediments, where they exhibited population maxima in spring and autumn. Increase in numbers of epipelic diatoms was recorded when silica concentrations were minimum in the overlying lake waters. Navicula hungarica Grun. achieved the maximum population density, 260 000 cells · cm^?2. Euglenoids formed large epipelic populations during late-summer and autumn in these nutrient-rich lakes. Blue-green algae were more important, proportionally, in the nutrient-poor mountain lakes, which had sediments of higher organic content. Chlamydomonads were the major algal component of the epipelon in the mountain lakes, Llydaw and Cwellyn, where the sediments were characterized by larger particle size, and higher organic content. In the nutrient-rich lakes, where the sediments had higher calcium content, chlamydomonads formed significant populations only during spring and summer, when nutrient levels were minimal in the overlying lakewaters.     

A METHOD FOR THE CRYOCONSERVATION OF DUNALIELLA SALINA (CHLOROPHYCEAE): EFFECT OF GLYCEROL AND COLD ADAPTATION1

The unicellular green alga Dunaliella salina Teod. was frozen according to the following procedure: 3 days cold adaptation at 4°C, addition of 3.5 M glycerol as a cryoprotectant, slow cooling to –40°C, immersion in liquid nitrogen, and rapid thawing. The survival rate was higher when cells were grown, before freezing, in the presence of 2 M NaCl instead of 1 M NaCl (78 and 48% survival, respectively). This difference is probably due to the intracellular amount of glycerol, which increases with external NaCl concentration and, therefore, may enhance cell protection. Although cells grown in 4 M NaCl accumulated a large amount of glycerol in response to osmotic stress, they did not withstand freezing. The use of cryoprotectant was absolutely necessary for the cells to recover from storage at –196°C. Glycerol was used because it is naturally produced by Dunaliella salina and therefore is not toxic. Provided it was added slowly to avoid osmotic shock, 3.5 M glycerol gave better results than 1M glycerol (48 and 18% survival, respectively). Cold adaptation in the dark increased postthaw viability. Cells grown in 1 M or 2 M NaCl had a survival rate of 48 and 78%, respectively, when cold-adapted, against 10 and 42% when not cold-adapted. This adaptation could be due to the synthesis, at low temperature, of specific proteins because two bands (28–29 kDa) appeared when electrophoretically separated proteins from cold-adapted cells and control cells were compared. Also, it could be due to the degradation of starch that occurs in the dark and leads to glycerol accumulation. Our procedure has never been used to cryopreserve microalgae and could enhance reported survival rates.     

IDENTIFICATION OF CRYPTIC SPECIES IN THE LESSONIA NIGRESCENS COMPLEX (PHAEOPHYCEAE,LAMINARIALES)1

The kelp Lessonia nigrescens Bory is the most ecologically and economically important seaweed in rocky intertidal and shallow subtidal habitats along the temperate Pacific South American coasts. Recent molecular studies suggest the existence of two lineages, one (northern lineage) from 17° S to 30° S and a second (central lineage) from 29° S to 41° S. To identify and name these lineages we performed morphological, nomenclatural and field studies. Four external and three internal anatomical traits permitted a morphological separation of the two lineages. The internal structure of both lineages was different from the isolectotype of Lessonia nigrescens. It is therefore concluded that the name Lessonia nigrescens should not be used for the Chilean material. Chordaria spicata Suhr appears as the oldest available name for the central lineage, while Lessonia berteroana Montagne is the oldest name for the northern lineage. In both cases, the type material consisted of small‐sized, apical branches of larger plants. The new combination Lessonia spicata (Suhr) Santelices is proposed for the central lineage and we reinstate Lessonia berteroana for the northern lineage. Laminaria scissa Suhr is reduced to synonym of L. spicata. Representative specimens of Lessonia nigrescens were not found during new visits to its type locality in Cape Horn and along Chile. Future studies should verify the status of this species.     

EVOLUTION,PHYLOGENY, SEXUAL DIMORPHISM AND MATING SYSTEM IN THE GRACKLES (QUISCALUS SPP.: ICTERINAE)

According to theory, two consequences of sexual selection are sexual dimorphism in size and secondary sexual characteristics, due to either intra- or intersexual selection. In this paper I suggest three criteria for the test of an evolutionary hypothesis involving quantitative morphological characters. First, the postulated change must be shown to have occurred in evolutionary time. Second, this change must be positively correlated with a change in the proposed selective agent. Third, given two taxa with different degrees of sexual size dimorphism and different mating system, the possible influence of drift must be rejected. If the hypothesis is not rejected by these three criteria, then we still have no proof of causality, but we can at least be more confident about its plausibility. This is applied to the particular hypothesis that sexual dimorphism in the Boat-tailed and Great-tailed grackles (Quiscalus spp; Icterinae; Aves) is caused by the highly polygynous mating system in these species. In relation to an outgroup, both species have increased disproportionately in male tarsus and tail size, creating an increased sexual dimorphism. This has cooccurred with the evolution of their particular mating system. However, the variance among species in male tarsus size can be accounted for by drift, and need not be a result of selection for increased size. In contrast, the variance among species in male tail size was much larger than expected under a null model of drift, indicating directional selection for long tails. The variance in female tail size was not larger than expected by drift, whereas the variance in female tarsus size was in fact lower than expected by drift, indicating stabilizing selection. The data are consistent with the hypothesis with regard to tail size, but not with regard to body size.     

THE UPTAKE OF MANNITOL AND SORBITOL BY A SPECIES OF CHLORELLA (CHLOROPHYCEAE)1

Chlorella saccharophila (Krüger) Nadson takes up mannitol and sorbitol in the light and the dark. The rate of uptake is concentration dependent. is not affected by pH in the range pH 6.0 to 8.0 and ii not stimulated by light. Uptake is inhibited by the respiration inhibitor sodium azide (10^-2 M) but not by 3-(3,4-dichlorophenyl)-1,1-di-methyl urea (10^-6 M), an inhibitor of photosynthesis. Sorbitol. but not mannitol, stimulates the rate of dark respiration but both support the heterotrophic growth of the alga. Both compounds permeate the cells of C. miniata. and two strains of C. pyrenoidosa but do not support the heterotrophic growth of these algae. The cells of C. vulgaris are impermeable to both compounds.     

性信息素2，6-二氯酚在长角血蜱交配行为中的作用

长角血蜱Haemaphysalis longicornis的交配行为包括7个时期,行为的完成依赖于性信息素的调节。生物测定表明：雄蜱的行为反应受雌蜱分泌的性信息素影响。堵塞雌蜱盾窝其行为受到抑制,点滴2,6-DCP或雌蜱盾窝腺提取物则被恢复。用气相色谱法测定了雌蜱盾窝腺中2,6-DCP的含量;吸血后1～２天含量最高(11.12 ng/只);吸血后3～５天即交配前下降交维持在一较恒定的水平;吸血后6～７天即交配后明显降低;饱血后检测不到2,6-DCP。2,6-DCP是长角血蜱性信息素的一种成分。