The role of heliothine hairpencil compounds in female Heliothis virescens (Lepidoptera: Noctuidae) behavior and mate acceptance

Studies on numerous insect species suggest that male-produced sex pheromones play a role in attracting females; as aphrodisiacs, making females more quiescent; or as a means of inhibiting competing males. Male heliothine moths display abdominal hairpencils during courtship, but the specific effects of the odors released on female behavior have not yet been elucidated. This study investigates the role of male hairpencil compounds in female Heliothis virescens mating behavior. Female H. virescens were exposed to filter paper loaded with hairpencil extracts of male H. virescens, Heliothis subflexa and Helicoverpa zea, and observed for behavioral responses to odors. Single synthetic compounds found in the H. virescens hairpencil blend were also tested. In mating assays between single male and female H. virescens it was found that: (i) antennectomized females mated less frequently than sham-operated females; (ii) females mated less frequently with males whose hairpencils had been surgically removed; (iii) females mated with males with ablated hairpencils if a filter paper loaded with one male equivalent of H. virescens hairpencil extract was presented simultaneously; and (iv) this effect was species-specific, as presentation of H. subflexa or H. zea hairpencil extracts did not restore mate acceptance. This study suggests that odors released by male hairpencils are important in mate acceptance by female H. virescens, and may play a role in mate choice and species isolation.     

Natural ligands of hamster aphrodisin

The chemical nature of vertebrate pheromones remains largely to be deciphered. Hamster aphrodisin is a rare instance of mammal proteinaceous sexual pheromone. This protein, found in vaginal secretions, facilitates the mounting behaviour of males via activation of a specialized sensory structure named the vomeronasal organ, which activates the accessory olfactory bulb. Since it might carry small pheromonal ligands due to its lipocalin structure, we analysed organic extracts from natural aphrodisin. We identified five predominant compounds specifically bound onto natural aphrodisin as 1-hexadecanol (44.7%), 1-octadecanol (19.5%), Z-9-octadecen-1-ol (18.2%), E-9-octadecen-1-ol (15.4%) and hexadecanoic acid (2.2%). Interestingly, these compounds are also described as part of insect pheromone blends, disclosing the continuing story of amazing coincidences of chemical communication shared by mammals and insects.     

High-resolution magnetic resonance spectroscopy of the mouse vomeronasal organ

The chemical composition of the vomeronasal organ (VNO) was investigated by means of in vitro proton magnetic resonance spectroscopy (MRS) in prepubertal and adult mice of both sexes. Results demonstrate that MRS detects several chemical constituents in the VNO, showing their age- and sex-associated changes in concentration. Preliminary experiments also suggest the ability of MRS to show compositional changes in the VNO after pheromonal stimulation. MRS can serve as a useful technique to investigate vomeronasal chemoreception.     

Microsatellite variation and evolutionary history of PCDHX/Y gene pair within the Xq21.3/Yp11.2 hominid-specific homology block

To better understand the evolutionary dynamics of repetitive sequences in human sex chromosomes, we have analyzed seven new X/Y homologous microsatellites located within PCDHX/Y, one of the two recently described gene pairs in the Xq21.3/Yp11.2 hominid-specific homology block, in samples from Portugal and Mozambique. Sharp differences were observed on X/Y allele distributions, concerning both the presence of private alleles and a different modal repeat length for X-linked and Y-linked markers, and this difference was statistically significant. Higher diversity was found in X-linked microsatellites than in their Y chromosome counterparts; when comparing populations, Mozambicans showed more allele diversity for the X chromosome, but the contrary was true for the Y chromosome microsatellites. Evolutionary patterns, relying on intragenic PCDHX/Y SNPs, also revealed distinct scenarios for X and Y chromosomes. Greater microsatellite diversity was displayed by African X chromosomes within the most common haplotypes shared by both populations, whereas higher microsatellite diversity was found in Portugal for the ancestral Y chromosome haplotype. The most frequent PCDHY haplotype in Portuguese was the derived one, and it was not found in Mozambicans. TMRCA estimated by the rho parameter resulted in 13,700 years (7,500-20,000 years), which is consistent with a recent, post-Out-of-Africa origin for this haplotype. In conclusion, the newly described microsatellite loci generally displayed greater X-linked to Y-linked diversity and this pattern was also detected with slower evolving markers, with a remarkable differentiation between populations observed for Y chromosome haplotypes and, thus, greater divergence among Y chromosomes in human populations.     

Apolipophorin-III-like protein expressed in the antenna of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae)

Antennal proteins of the male fire ant (Solenopsis invicta) were analyzed by two-dimensional gel electrophoresis, with the objective of identifying pheromone-binding proteins, which have not previously been found in ant antennae. The major low-molecular weight protein found in the male fire ant antenna was subjected to Edman degradation to determine the N-terminal amino acid sequence. Degenerate PCR primers based on this sequence were used to obtain a cDNA sequence corresponding to the full-length protein sequence. In-gel trypsin digestion followed by MALDI-TOF mass spectrometry and HPLC-ESI/MS/MS demonstrated that the protein gel spot contained only the protein corresponding to the cDNA sequence obtained by PCR. The sequence is similar to apolipophorin-III, an exchangeable lipid-binding protein. Fire ant apolipophorin-III is expressed in the antenna as well as the head, thorax and abdomen.     

Fatty acid and sex pheromone changes and the role of glandular lipids in the Z-strain of the European corn borer, Ostrinia nubilalis (Hübner)

Lipids in the sex pheromone gland of females of the Z-strain of Ostrinia nubilalis were analyzed for fatty acyl pheromone analogs (FAPAs) and other potential biosynthetic intermediates. More than 80% of the FAPAs were found in the triacylglycerols (TGs), with smaller amounts found in the phosphatidyl cholines, ethanolamines, and serines. Analysis of the TGs by lipase revealed that the two FAPAs were distributed fairly evenly among all three stereospecific positions. Comparison of changes in titers of key glandular fatty acids with those of pheromone components, with respect to photoperiodic time and age of females, showed that both FAPA and pheromone titers exhibited a cyclical pattern with peaks in the scotophase and valleys in the photophase. However, whereas pheromone titer tended to peak in the first half of the scotophase, FAPA titer peaked at the end of the scotophase. Significantly, the titer of the FAPA of the minor component, (E)-11-tetradecenyl acetate (3% of pheromone), was always much greater than the titer of the FAPA of the major component, (Z)-11-tetradecenyl acetate (97%), of the pheromone. Titer of myristate, an intermediate in pheromone biosynthesis, was also higher during the scotophase than the photophase. However, myristate titer showed a pronounced dip in the middle of the scotophase. These data suggest two roles for glandular lipids in sex pheromone biosynthesis in O. nubilalis. Firstly, they remove excess FAPA of the minor component so the fatty acid reductase system is not presented with a high ratio of this isomer (which would otherwise result from the reductase's own selectivity), which could cause changes in the final pheromone ratio. Secondly, hydrolysis of the large amounts of stored saturated fatty acids from the TGs may provide substrate for pheromone biosynthesis.     

Pleistocene glaciation is implicated in the phylogeographical structure of Potamopyrgus antipodarum, a New Zealand snail

Pleistocene glaciation has been identified as an important factor shaping present-day patterns of phylogeographical structure in a diverse array of taxa. The purpose of this study was to use mitochondrial sequence data to address whether Pleistocene glaciation is also a major determinant of phylogeographical patterns in Potamopyrgus antipodarum, a freshwater snail native to New Zealand. We found that haplotypes were separated by no more than 3.7% sequence divergence, and major genetic divisions tended to occur on a north-south axis. These data fit the predictions of the hypothesis that isolation of P. antipodarum in glacial refugia at the northern and southern tip of the South Island of New Zealand during the Pleistocene glaciation underlies the present-day phylogeographical structure. Because sexual P. antipodarum occasionally produce asexual offspring, we also used these data to show that the appearance of asexuality is not phylogeographically constrained. This means that the maintenance of sex in P. antipodarum cannot be wholly due to limited contact between sexual and asexual lineages and must instead be linked to a selective advantage of sexual reproduction.     

棉铃虫性外激素成分的化学分析和田间试验

利用毛细柱的气相色谱和质谱对棉铃虫（鳞翅目：夜蛾科）雌蛾腺体提取物的分析,鉴定出了他和十六碳醛、顺－9－十六碳烯醛、顺－11－十六碳烯醛、饱和十六碳醇和顺－11－十六碳烯醇,其相对比例为6．1：4．5：100：3．5：8．8。在山东、山西省的田间试验中,2mg的顺－11－十六碳烯醛和顺－9－十六碳烯醛（97：3）置橡胶塞上能有效地引诱棉铃虫雄蛾。增加4％－7％他和十六碳醛到二元混合物中诱蛾量超过二元混合物。增加1％顺－11－十六碳烯醇到二元或三元混合物中减少诱蛾量,当增加5％顺－11－十六碳醇时诱蛾量大量减少。     

Female egg dumping and the effect of sex ratio on male egg carrying in a coreid bug

Phyllomorpha laciniata Vill (Heteroptera, Coreidae) is uniqueamong terrestrial insects in that females glue eggs on the backsof other conspecifics. Egg carrying byP. laciniatamales haspreviously been considered as paternal care. We explored femaleoviposition with respect to previous mating experience of femalesand tested whether sex ratio affects male egg-carrying. Thehypothesis that male egg-carrying is a form of paternal carepredicts that a male should always accept eggs after matingwith a female. However, if male egg-carrying is a form of postcopulatorymate guarding rather than paternal care, egg carrying shouldincrease in the presence of other males. When two couples wereplaced together, females laid eggs on the backs of all individualsenclosed, including the backs of other females. However, whena female was accompanied by 2 males, 22 out of 26 females ovipositedon their mating partner. Thus, sexual competition rather thanpaternity alone, affects a male's eagerness to carry eggs. However,even if males sometimes carry their own eggs, females lay eggson the backs of all conspecifics they can easily acquire. Thus,egg carrying in P. laciniata is partially voluntary and partiallythe result of female egg dumping     

Why make daughters larger? Maternal sex-allocation and sex-dependent selection for body size in a mass-provisioning wasp, Trypoxylon politum

Mass-provisioning wasps package maternal investment into broodcells, sealed structures that contain all the provisions necessaryfor an offspring's growth and development. Optimal sex-allocationtheory predicts that if maternal provisions determine the sizeof each offspring, and the amount of provisions available toeach offspring varies, females should allocate well-stockedbrood cells to the sex that benefits most from being large.I tested this hypothesis using observations of organ-pipe wasps,Trypoxylon politum, and dissections of their nests. A Mississippipopulation of T. politum was intensively studied from 1993 to1995. This population fit the assumptions of optimal sex-allocationmodels by Green and Brockmann and Grafen. Female weight at emergencewas 1.29 times that of males, and wing length was 1.15 timesthat of males. This discrepancy in size occurred because thevolume of parental provisions strongly influenced adult bodysize, and better-stocked brood cells were preferentially allocatedto daughters. Brood-cell volume correlated with both wing lengthand weight at emergence in both sexes, and the chance that agiven brood cell contained a female offspring increased withincreasing brood-cell volume. Fitness was positively relatedto body size for females, but I found no evidence of an advantageto large males. Although there was evidence of stabilizing selectionfor male wing length in one year, there was no evidence of anincreasing relationship between body size and fitness (directionalselection) for males in either 1993 or 1994. Female fecunditywas positively related to body size in both years, indicatingthat larger females have increased reproductive success. Therate at which females provisioned brood cells was also correlatedwith body size. Observed patterns of investment in brood cellsare quantitatively consistent with the predictions of optimalsex-allocation theory, but certain aspects of female provisioningbehavior suggest females are not following a single "optimal"strategy. Patterns of provisioning were variable among differentfemales at the study site during the same year. Large femalestended to produce larger offspring. Although Brockmann and Grafen'smodel predicts a single, population wide "switchpoint" fromthe production of male to female offspring, there was no evidencefor such a switchpoint