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| | 1. |
2007 Mar 20 |
DNA barcodes affirm that 16 species of apparently generalist tropical parasitoid flies (Diptera, Tachinidae) are not all generalists
Smith, Wood, Janzen, Hallwachs, Hebert
Proc Natl Acad Sci U S A 2007 Mar 20;104(12):4967-4972.
Abstract
Many species of tachinid flies are viewed as generalist parasitoids because what is apparently a single species of fly has been reared from many species of caterpillars. However, an ongoing inventory of the tachinid flies parasitizing thousands of species of caterpillars in Area de Conservación Guanacaste, northwestern Costa Rica, has encountered >400 species of specialist tachinids with only a few generalists. We DNA-barcoded 2,134 flies belonging to what appeared to be the 16 most generalist of the reared tachinid morphospecies and encountered 73 mitochondrial lineages separated by an average of 4% sequence divergence. These lineages are supported by collateral ecological information and, where tested, by independent nuclear markers (28S and ITS1), and we therefore view these lineages as provisional species. Each of the 16 apparently generalist species dissolved into one of four patterns: (i) a single generalist species, (ii) a pair of morphologically cryptic generalist species, (iii) a complex of specialist species plus a generalist, or (iv) a complex of specialists with no remaining generalist. In sum, there remained 9 generalist species among the 73 mitochondrial lineages we analyzed, demonstrating that a generalist lifestyle is possible for a tropical caterpillar parasitoid fly. These results reinforce the emerging suspicion that estimates of global species richness are likely underestimates for parasitoids (which may constitute as much as 20% of all animal life) and that the strategy of being a tropical generalist parasitic fly may be yet more unusual than has been envisioned for tachinids.
[Pubmed: 17360352]
| | 2. |
2008 Oct 28 |
Hindwings are unnecessary for flight but essential for execution of normal evasive flight in Lepidoptera
Jantzen, Eisner
Proc Natl Acad Sci U S A 2008 Oct 28;105(43):16636-16640.
Abstract
In Lepidoptera, forewings and hindwings are mechanically coupled and flap in synchrony. Flight is anteromotoric, being driven primarily by action of the forewings. Here we report that lepidopterans can still fly when their hindwings are cut off, a procedure reducing their total wing surface, on average, by nearly one half. However, as we demonstrate by analysis of three-dimensional flight trajectories of a moth and a butterfly (Lymantria dispar and Pieris rapae), hindwing removal causes lepidopterans to incur a loss in both linear and turning acceleration, so that they are unable to exercise their normal flight maneuverability. Without hindwings they still are able to zigzag aerially (the ablation has no effect on their turning radius in flight) but at lesser speed and therefore less evasively. Consequently, hindwings in the expanded state in which they occur in lepidopterans seem to contribute in an essential way to lepidopteran survival. Moths in today's world, we argue, may rely on their evasive flight primarily to avoid capture by bats, whereas butterflies, which we propose advertise their evasiveness collectively through shared aposematism, may depend upon it primarily for defense against birds. Aerial agility thus may be the chief adaptive asset derived by lepidopterans from possession of oversize hindwings.
[Pubmed: 18936482]
| | 3. |
1916 Oct 06 |
Weekly Reports for OCTOBER 6, 1916
Public Health Rep 1916 Oct 06;31(40):2753-2813.
[Pubmed: 19314532]
| | 4. |
1916 Feb 25 |
Weekly Reports for FEBRUARY 25, 1916
Public Health Rep 1916 Feb 25;31(8):421-511.
[Pubmed: 19314500]
| | 5. |
1916 Apr 14 |
Weekly Reports for APRIL 14, 1916
Public Health Rep 1916 Apr 14;31(15):933-988.
[Pubmed: 19314507]
| | 6. |
1915 Oct 22 |
Weekly Reports for OCTOBER 22, 1915
Public Health Rep 1915 Oct 22;30(43):3117-3199.
[Pubmed: 19314482]
| | 7. |
2007 Oct 06 |
Wing coloration and pigment gradients in scales of pierid butterflies.
Giraldo MA, Stavenga DG
Arthropod Struct Dev. 2008 Mar;37(2):118-28. Epub 2007 Oct 06.
Abstract
Depending on the species, the individual scales of butterfly wings have a longitudinal gradient in structure and reflectance properties, as shown by scanning electron microscopy and microspectrophotometry. White scales of the male Small White, Pieris rapae crucivora, show a strong gradient in both the density in pigment granules and the reflectance. After pigment extraction by aqueous ammonia, scales of male P. r. crucivora closely resemble the unpigmented scales of female P. r. crucivora. Only a minor gradient exists in the white and orange scales of the male Orange Tip, Anthocharis cardamines. Pigment extraction of orange scales of A. cardamines causes bleaching. Partial bleaching transforms the scales so that they resemble certain scales of Phoebis philea that have a natural extreme gradient. Reflectance measurements on an artificial stack of two overlapping scales as well as on the scale stacks existing on intact and partially denuded wings of the Large White, Pieris brassicae, quantitatively demonstrate the reflectance enhancement by scale stacking.
[Pubmed: 18089132]
| | 8. |
2007 Jan 22 |
Quantitative analysis of changes in movement behaviour within and outside habitat in a specialist butterfly
Schtickzelle, Joiris, Van Dyck, Baguette
BMC Evol Biol 2007 Jan 22;7:4. published online before print
Abstract
Dispersal between habitat patches is a key process in the functioning of (meta)populations. As distance between suitable habitats increases, the ongoing process of habitat fragmentation is expected to generate strong selection pressures on movement behaviour. This leads to an increase or decrease of dispersal according to its cost relative to landscape structure. To limit the cost of dispersal in an increasingly hostile matrix, we predict that organisms would adopt special dispersal behaviour between habitats, which are different from movements associated with resource searching in suitable habitats.
[Pubmed: 17241457]
| | 9. |
2007 Jan 07 |
Sexual dichroism and pigment localization in the wing scales of Pieris rapae butterflies
Giraldo, Stavenga
Proc Biol Sci 2007 Jan 07;274(1606):97-102.
Abstract
The beads in the wing scales of pierid butterflies play a crucially important role in wing coloration as shown by spectrophotometry and scanning electron microscopy (SEM). The beads contain pterin pigments, which in Pieris rapae absorb predominantly in the ultraviolet (UV). SEM demonstrates that in the European subspecies Pieris rapae rapae, both males and females have dorsal wing scales with a high concentration of beads. In the Japanese subspecies Pieris rapae crucivora, however, only the males have dorsal wing scales studded with beads, and the dorsal scales of females lack beads. Microspectrophotometry of single scales without beads yields reflectance spectra that increase slightly and monotonically with wavelength. With beads, the reflectance is strongly reduced in the UV and enhanced at the longer wavelengths. By stacking several layers of beaded scales, pierid butterflies achieve strong colour contrasts, which are not realized in the dorsal wings of female P. r. crucivora. Consequently, P. r. crucivora exhibits a strong sexual dichroism that is absent in P. r. rapae.
[Pubmed: 17018427]
| | 10. |
2005 Apr 22 |
Tracking butterfly flight paths across the landscape with harmonic radar
Cant, Smith, Reynolds, Osborne
Proc Biol Sci 2005 Apr 22;272(1565):785-790.
Abstract
For the first time, the flight paths of five butterfly species were successfully tracked using harmonic radar within an agricultural landscape. Until now, butterfly mobility has been predominantly studied using visual observations and mark–recapture experiments. Attachment of a light-weight radar transponder to the butterfly's thorax did not significantly affect behaviour or mobility. Tracks were analysed for straightness, duration, displacement, ground speed, foraging and the influence of linear landscape features on flight direction. Two main styles of track were identified: (A) fast linear flight and (B) slower nonlinear flights involving a period of foraging and/or looped sections of flight. These loops potentially perform an orientation function, and were often associated with areas of forage. In the absence of forage, linear features did not provide a guiding effect on flight direction, and only dense treelines were perceived as barriers. The results provide tentative support for non-random dispersal and a perceptual range of 100–200 m for these species. This study has demonstrated a methodology of significant value for future investigation of butterfly mobility and dispersal.
[Pubmed: 15888410]
| | 11. |
2000 Sep 12 |
Sexual conflict promotes speciation in insects
Arnqvist, Edvardsson, Friberg, Nilsson
Proc Natl Acad Sci U S A 2000 Sep 12;97(19):10460-10464.
Abstract
Speciation rates among extant lineages of organisms vary extensively, but our understanding of the causes of this variation and, therefore, the processes of speciation is still remarkably incomplete. Both theoretical and empirical studies have indicated that sexual selection is important in speciation, but earlier discussions have focused almost exclusively on the potential role of female mate choice. Recent findings of postmating reproductive conflicts of interest between the sexes suggest a quite different route to speciation. Such conflicts may lead to perpetual antagonistic coevolution between males and females and may thus generate rapid evolutionary divergence of traits involved in reproduction. Here, we assess this hypothesis by contrasting pairs of related groups of insect species differing in the opportunity for postmating sexual conflict. Groups where females mate with many males exhibited speciation rates four times as high as in related groups where females mate only once. Our results not only highlight the general importance of postmating sexual selection in speciation, but also support the recent suggestion that sexual conflict is a key engine of speciation.
[Pubmed: 10984538]
| | 12. |
1974 Oct |
Food additives
Spencer
Postgrad Med J 1974 Oct;50(588):620-624.
Abstract
Food additives are discussed from the food technology point of view. The reasons for their use are summarized:
[Pubmed: 4467857]
| | 13. |
1941 Sep |
THE CYTOLOGY OF BACTERIA
Lewis
Bacteriol Rev 1941 Sep;5(3):181-230.
[Pubmed: 16350071]
| | 14. |
1915 Apr 23 |
Weekly Reports for APRIL 23, 1915
Public Health Rep 1915 Apr 23;30(17):1225-1302.
[Pubmed: 19314456]
| | 15. |
1915 Jan 22 |
Weekly Reports for JANUARY 22, 1915
Public Health Rep 1915 Jan 22;30(4):207-307.
[Pubmed: 19314443]
| | 16. |
1914 Nov 13 |
Weekly Reports for NOVEMBER 13, 1914
Public Health Rep 1914 Nov 13;29(46):3027-3099.
[Pubmed: 19314433]
| | 17. |
1914 Oct 23 |
Weekly Reports for OCTOBER 23, 1914
Public Health Rep 1914 Oct 23;29(43):2821-2881.
[Pubmed: 19314430]
| | 18. |
1914 Oct 02 |
Weekly Reports for OCTOBER 2, 1914
Public Health Rep 1914 Oct 02;29(40):2575-2706.
[Pubmed: 19314427]
| | 19. |
1914 Sep 18 |
Weekly Reports for SEPTEMBER 18, 1914
Public Health Rep 1914 Sep 18;29(38):2417-2473.
[Pubmed: 19314425]
| | 20. |
1913 Apr 25 |
Weekly Reports for APRIL 25, 1913
Public Health Rep 1913 Apr 25;28(17):769-832.
[Pubmed: 19314352]
| | 21. |
1906 May 11 |
Weekly Reports for May 11, 1906
Public Health Rep 1906 May 11;21(19):467-499.
[Pubmed: 19313989]
| | 22. |
1906 Feb 02 |
Weekly Reports for February 2, 1906
Public Health Rep 1906 Feb 02;21(5):83-113.
[Pubmed: 19313975]
| | 23. |
1903 Oct 23 |
Weekly Reports for October 23, 1903
Public Health Rep 1903 Oct 23;18(43):1817-1873.
[Pubmed: 19313852]
| | 24. |
1901 Dec 06 |
Weekly Reports for December 6, 1901
Public Health Rep 1901 Dec 06;16(49):2833-2891.
[Pubmed: 19313751]
| | 25. |
1900 May 11 |
Weekly Reports for May 11, 1900
Public Health Rep 1900 May 11;15(19):1111-1176.
[Pubmed: 19313668]
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