Wing Formation Research Articles

Wing Formation and Reproduction from Insecticide-Treated Cotton Aphids (Homoptera: Aphididae)

Field observations of the cotton aphid, Aphis gossypii Glover, from 1999 to 2001 indicated an increase in percentage of winged aphids in cotton fields after an application of imidacloprid. Cotton aphid wing formation and fecundity of offspring were evaluated in a spray booth following five treatments: imidacloprid near LC50 concentration on cotton, dicrotophos near LC50 concentration on cotton, water spray on cotton, water spray on silk plants, imidacloprid spray near LC50 concentration on silk plants. Silk plants were used to differentiate topical and systemic effects of imidacloprid. Prior to spraying, 40 aphids were transferred onto each plant. Aphids were moved from the silk plants onto unsprayed cotton plants 3 h post-spray. Offspring from imidacloprid-treated aphids on cotton produced twice as many winged offspring (8%) as did aphids from other treatments (3% to 4%) and only one-third as many offspring per founding relative to aphids in other treatments. In addition to increasing emigration by winged aphids, an increase in the proportion of winged aphids among survivors of an imidacloprid treatment may further reduce the number of aphids in a treated field because winged aphids require a longer developmental time, produced fewer offspring, and have an increased risk of mortality.

Genetic basis and fitness consequences of winglessness in the two-spot ladybird beetle, Adalia bipunctata

The genetic basis and fitness consequences of winglessness were investigated in the two-spot ladybird beetle, Adalia bipunctata. By breeding lines from a wingless individual found at The Uithof, Utrecht in The Netherlands, the wingless condition was confirmed to be under the control of a major allele, recessive to the wild type. Wingless individuals, on average, had a longer developmental period, a lower egg production and a shorter lifespan than the wild type with wings, suggesting that the expression of the wingless allele has functionally interrelated gene actions involving a wide range of fitness components. While the wingless allele influences various traits, significant among-family variation in the degree of winglessness suggests that its phenotypic expression is also dependent on the genetic background and modifier loci. Furthermore, there was a consistent pattern of correlation between the degree of winglessness and life history traits; the most extreme wingless individuals showed the lowest fitness while those with more fully developed wings tended to have the highest fitness. This correlation suggests that the modifier genes influence both wing formation and fitness components. The significance of such epistatic effects to the evolution of flightlessness in insects is discussed.

Protein phosphatase 2A as a new target for morphogenetic studies in the chick limb

The family of ser/thr protein phosphatases 2A (PP2A) is a major regulator of cell proliferation and cell death and is critically involved in the maintenance of homeostasis. In order to analyse the importance of PP2A proteins in apoptotic and developmental processes, this review focuses on previous studies concerning the role of PP2A in morphogenesis. We first analyse wing formation in Drosophila, a model for invertebrates, then chick limb bud, a model for vertebrates. We also present a pioneer experiment to illustrate the potential relevance of PP2A studies in BMP signalling during chicken development and we finally discuss the BMP downstream signalling pathways.

Case of unilateral wing formation in the female of the glowworm Lampyris noctiluca.

On July 27, 1999, the first author found a unilaterally winged adult glowworm in a park in the city of Mainz. Except for the wings on the left side, the specimen exhibited female characteristics that extended to external sexual appendages, the lantern and the gonads. The internal organization showed some remarkable differences between right (wingless) and left (winged) side. The right ovary contained three times more mature eggs than the left side and the volume of the corpus allatum of this side was about one-third larger than that of the left side. This suggests that aptery and egg maturation are affected by corpus allatum activity, i.e., juvenile hormone production. The findings do not support the hypothesis of Naisse ([1966] Arch Biol Liège 77:139-201) that wing formation, as a secondary male characteristic, is controlled by an androgenic hormone from the testes in the glowworm. Thus, the observations on this exceptional specimen have implications for the current hypotheses concerning the control of sexual wing dimorphism in Lampyris noctiluca.

Further developmental roles of the Vestigial/Scalloped transcription complex during wing development in Drosophila melanogaster

The Drosophila homologue of the human TEF-1 gene, scalloped ( sd), is required for wing development. The SD protein forms part of a transcriptional activation complex with the protein encoded by vestigial ( vg) that, in turn, activates target genes important for wing formation. One sd function involves a regulatory feedback loop with vg and wingless ( wg) that is essential in this process. The dorsal–ventral (D/V) margin-specific expression of wg is lost in sd mutant wing discs while the hinge-specific expression appears normal. In the context of wing development, a vg:: sdTEA domain fusion produces a protein that mimics the wild-type SD/VG complex and restores the D/V boundary-specific expression of wg in a sd mutant background. Further, targeted expression of wg at the D/V boundary in the wing disc was able to partially rescue the sd mutant phenotype. This infers that sd could function in either the maintenance or induction of wg at the D/V border. Another functional role for sd is the establishment of sensory organ precursors (SOP) of the peripheral nervous system at the wing margin. Thus, the relationship between sd and senseless ( sens) in the development of these cells is also examined, and it appears that sd must be functional for proper sens expression, and ultimately, for sensory organ precursor development.

Drosophila Eiger Triggers Cell Death

Igaki et al. report the identification of the first Drosophila tumor necrosis factor (TNF) ligand, which they call Eiger and which is most similar to the human ectodyplasin-A protein. Eiger was identified in a genetic screen for genes that when overexpressed cause reduced size of the eye as a consequence of cell death. Overexpression of Eiger in the wing discs completely prevented wing formation. Expression in sensory precursor cells resulted in abnormal bristles, and expression in the abdomen severely impaired development there. These phenotypes are different than those caused by overexpression of Reaper, a protein that stimulates caspase activation in the intrinsic apoptosis pathway. The Eiger-induced reduced eye phenotype was suppressed in the presence of Drosophila inhibitor of apoptosis protein 1 (DIAP1) But it was unaffected in the presence of the caspase inhibitory protein P35 from baculovirus or in the presence of a dominant-negative form of the caspase DRONC. These genetic interactions are unlike those of Reaper. Eiger stimulated cell death and did activate caspases when expressed in the eye, although the extent and location of the caspase activation again differed from that produced by Reaper. In flies with mutations or decreased expression of components of the Jun NH 2 -terminal kinase (JNK) pathway, the reduced-eye phenotype induced by Eiger was suppressed. Additionally, overexpression of Eiger stimulated the phosphorylation of Drosophila JNK (known as Basket) and stimulated the expression of a target gene of the JNK pathway that encodes Puckered (a phosphatase). The authors propose that Eiger stimulates cell death through caspase-dependent and caspase-independent mechanisms and that the latter rely on activation of the JNK pathway. T. Igaki, H. Kanda, Y. Yamamoto-Goto, H. Kanuka, E. Kuranaga, T. Aigaki, M. Miura, Eiger, a TNF superfamily ligand that triggers the Drosophila JNK pathway. EMBO J. 21 , 3009-3018 (2002). [Abstract] [Full Text]

Identification of the Xenopus laevis cDNA for EXT1: a phylogenetic perspective.

The EXT family of genes is involved in the developmentally important biosynthesis of heparan sulfate molecules. Members of the EXT family have a demonstrated role in gastrulation, wing formation in flies, and proper bone development in vertebrates. EXT family members have been isolated from several phylogenetically diverse species. We report here, the isolation of the first Xenopus laevis EXT1 family member and discuss the evolutionary origins of this gene family.

Seasonal Wing Polymorphism in Southern Chinch Bugs (Hemiptera: Lygaeidae)

St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntze lawns are used throughout the southern United States for their climatic adaptation and their ability to tolerate full sun to moderate shade. The southern chinch bug, Blissus insularis Barber is the plant's most damaging pest (Crocker 1993). The adaptability of this insect is shown by its developing resistance to insecticides (Reinert & Portier 1983) and overcoming host plant resistance (Busey & Center 1987; Cherry & Nagata 1997). Southern chinch bugs (SCB) can occur as either macropterous or brachypterous adults. However, other than anecdotal reports, there are little field data on the occurrence of these wing forms in SCB. Also, reasons for the occurrence of brachypterous versus macropterous adults in SCB are poorly understood. Wilson (1929) reported that both macropterous and brachypterous SCB adults occur in Florida and these vary in relative numbers during the year, but no data were given. Komblas (1962) reported that population density was a factor in SCB wing form, noting that a larger percentage of nymphs raised under crowded conditions developed into macropterous adults than did uncrowded nymphs. Leonard (1966) discussed migration as an important factor in SCB wing formation. Lastly, Reinert and Kerr (1973) noted that although macropterous and brachypterous adults may be found in SCB, the latter predominates. However, reasons for the occurrence of the two wing forms were not discussed. The objectives of this study were to determine the seasonal occurrence of wing polymorphism in SCB in southern Florida and to determine if wing polymorphism is correlated with field population density. Chinch bugs were collected from infested St. Augustinegrass lawns in Palm Beach County, Florida from December 1999, to December 2000. Five new SCB infestations were located each month by looking for damaged yellow grass and then visually confirming the presence of SCB. Insects were collected by suctioning for 5 minutes a 1 x 1 m area at each infestation. Nymphs and adults were collected by suction into a gasoline powered modified WeedEater? Barracuda blower/vacuum (Poulan/WeedEater, Shreveport, LA). The use of a suction technique for sampling SCB was described by Crocker (1993). After collection, samples were frozen for later counting in a laboratory. Samples were passed through as U.S.A. Standard Testing Sieve #10 (2 mm opening) to remove large debris. Microscopic examination was used to determine the sex and wing form of each adult and count nymphs. In order to determine possible seasonal differences in wing polymorphism, samples from 3 month periods were pooled. For the purposes of this paper, winter is defined as December, January, and February, spring is March, April, and May, summer is June, July, and August, and fall is September, October, and November. These definitions correspond to seasonal definitions for the North Temperate Zone (Guralnik 1982). Mean differences in population density (nymphs + adults per sample) between seasons were determined using Tukey's test. Mean differences in percentage macropterous adults (macropterous adults/total adults per sample) between seasons were also determined using Tukey's test (SAS 1996). Pearson's correlation (SAS 1996) of percentage macropterous adults versus SCB density (adults, nymphs, or total = adults + nymphs) in all samples (N = 60) was conducted to examine possible relationships between wing form and field population density. Pearson's correlation for percentage macropterous males (macropterous males/ total adults) versus percentage macropterous females in all samples (N = 60) was also conducted to determine if both sexes were responding similarly to the factor or factors causing macroptery in the field. There was no significant difference in population density between the four seasons (Table 1). However, means during the winter-spring were lower than the summer-fall. Hence, data from winter and spring were pooled and compared against pooled data from summer and fall. The summer-fall population density (mean = 1746, SD = 3447) was significantly greater (alpha = 0.05) than winter-spring population density (mean = 431, SD = 682) by t-test analysis (t = 2.1, 58 DF). These data are in general agreement with Komblas (1962) and Reinert and Kerr (1973). Komblas (1962) reported that SCB populations decreased during winter in Louisiana. Reinert and Kerr (1973) also reported that field populations of SCB decrease drastically in cooler weather. There was no significant difference in percentage of macropterous adults between the four seasons (Table 1). However, as with population density, means during the winter-spring were again lower than the summer-fall. Hence, data from the winter and spring were again pooled and compared against pooled data from the summerfall. The summer-fall macroptery (mean = 22.3, SD = 18.1) was significantly greater (alpha = 0.05)

Radical fringe negatively modulates Notch signaling in postmitotic neurons of the rat brain

Fringe was originally identified as a novel secreted signaling protein with a key role in wing formation of Drosophila. Three vertebrate fringe homologues, Radical, Lunatic and Manic fringe, were also identified, and have been shown to play major roles in neurogenesis during development. However, the expression and roles of vertebrate fringe homologues in the adult brain remain to be elucidated. We isolated the cDNA encoding rat Radical fringe (334 amino acids) from rat embryos, and found its mRNA to be most abundantly expressed in the adult rat brain by Northern blotting analysis. The localization of Radical fringe mRNA in the adult rat brain was also examined by in situ hybridization. The mRNA was abundantly expressed in most neurons, but not glial cells, throughout the brain. Notch signaling was shown to negatively modulate the stability of neurites and connections in postmitotic primary neurons. Furthermore, genetic evidence indicated that fringe modulated the Notch signaling pathway. Therefore, we examined the effects of Radical fringe on the Notch signaling pathway in primary rat neurons of the cerebral cortex using recombinant rat Radical fringe protein. Radical fringe protein significantly inhibited expression of the Notch effector Hes1 mRNA in primary neurons. These results indicated that Radical fringe functions by inhibiting Notch signaling in postmitotic neurons of the brain.

Reptin52 Inhibits β-Catenin Signaling

Bauer et al. have identified and characterized a protein, termed Reptin52 that associates with Pontin52, which positively regulates β-catenin-mediated transcription in the Wnt pathway. Reptin52 and Pontin52 exhibited homo- and heterotypic association, as assayed by immunoprecipitation. Furthermore, Reptin52 associated with β-catenin and the TATA-box binding protein (TBP). Precipitation assays performed using truncated β-catenin mutants demonstrated that Pontin52 and Reptin52 bind the same site on β-catenin. Overexpression of Reptin52 strongly inhibited transcription of a reporter gene by the β-catenin-TCF4 (T-cell factor 4) complex, even in the presence of Pontin52, which may suggest that Reptin52 has greater affinity than Pontin52 for β-catenin. Genetic experiments in Drosophila mutants revealed that drep or dpon null mutants were lethal; however, conditional mutation crosses demonstrated that for wing formation dPon functions as a positive regulator of Wg (Wnt) signaling, whereas dRep represses Wg signaling. Thus, another level of complexity has been uncovered in Wnt signal control, and the authors suggest that the ability of Pontin52 and Reptin52 to homo- and hetero-oligomerize might allow for incremental changes in β-catenin-TCF4-mediated transcription. Bauer, A., Chauvet, S., Huber, O., Usseglio, F., Rothbächer, U., Aragnol, D., Kemler, R., and Pradel, J. (2000) Pontin52 and Reptin52 function as antagonistic regulators of β-catenin signaling activity. EMBO J . 19 : 6121-6130. [Abstract] [Full Text]

Raman-Scattering Wings of Hα in Symbiotic Stars

Nussbaumer and colleagues proposed that broad Hα wings can be formed through Raman scattering of Lyβ photons, and in this Letter we argue that the Hα wings prevalently seen in symbiotic stars may indeed be formed in this way. Assuming a flat incident UV radiation around Lyβ, we generate template wing profiles around Hα that are formed through Raman scattering in a plane-parallel H I region. We perform profile-fitting analyses to show that the template wing profiles are in excellent agreement with the observed ones recently provided by van Winckel et al. and Ivison et al. The wing flux is determined by the scattering H I column density and the incident Lyβ flux strength and profile. From our profile analysis it is proposed that the Raman-scattering component may be identified with the neutral envelope with a column density ranging 1018-1020 cm-2 that surrounds the binary system. We briefly discuss alternative candidates for the wing formation mechanism and observational implications of Raman scattering in symbiotic stars and in other astronomical objects including planetary nebulae, post-asymptotic giant branch stars, and active galactic nuclei.

The influence of parasitoids on wing formation in aphids, possible interactions with the endocrine system.

The influence of parasitoids on wing formation in aphids, possible interactions with the endocrine system.

DER signaling restricts the boundaries of the wing field during Drosophila development.

Arthropod and vertebrate limbs develop from secondary embryonic fields. In insects, the wing imaginal disk is subdivided early in development into the wing and notum subfields. The activity of the Wingless protein is fundamental for this subdivision and seems to be the first element of the hierarchy of regulatory genes promoting wing formation. Drosophila epidermal growth factor receptor (DER) signaling has many functions in fly development. Here we show that antagonizing DER signaling during the second larval instar leads to notum to wing transformations and wing mirror-image duplications. DER signaling is necessary for confining the wing subregion in the developing wing disk and for the specification of posterior identity. To do so, DER signaling acts by restricting the expression of Wingless to the dorsal-posterior quadrant of wing discs, suppressing wing-organizing activities, and by cooperating in the maintenance of Engrailed expression in posterior compartment cells.

The influence of parasitism on wing development in male and female pea aphids

Wing formation in presumptive alate morphs (virginoparae and males) was observed for the pea aphid, Acyrthosiphon pisum, exposed to attack by the parasitoid, Aphidius ervi, at different stages of host development. Morphological abnormalities in parasitized aphids such as complete apterization (development of a wingless form), formation of rudimentary wing buds, and deformed wings indicate a possible disruption of the endocrine system. Changes in the body shape and the number of olfactory secondary rhinaria on the antennae could indicate an influence of juvenile hormone in parasitized A. pisum but the development of fifth-stadium supernumerary larvae (indicated by an extra moult and which can be induced by exogenous juvenile hormone treatments) was not found in parasitized aphids. In addition, while apterization of virginoparae can also be induced by the pro-allatocidal compound Precocene III, this was not possible in the male. Males which survived parasitoid attack without forming aphid mummies (indicating that oviposition had not occurred) developed as wingless individuals suggesting that the reproductive-tract-fluids from the female parasitoid were important in the wing inhibition process. Teratocytes from the parasitoid appeared to promote developmental arrest in parasitized aphids.

Expression of ecdysteroid-regulated genes is reduced specifically in the wing discs of the wing-deficient mutant (fl) of Bombyx mori.

The wing-deficient mutant, flügellos (fl), of the silkworm, lacks four wings in the pupa and the adult. Previous studies have suggested that the fl wing discs lose responsiveness to ecdysteroid during metamorphosis. To test this hypothesis at the molecular level we compared the expression of 12 genes when the wing discs from the wild-type (WT) and fl larvae were cultured in the presence or absence of 20-hydroxyecdysone (20E). Most of the genes tested here, ecdysteroid-inducible (EcR-A, -B1, and E75) and noninducible genes (actin A3, beta-tubulin, apterous (ap), USP, and BHR38) were normally expressed in the fl wing discs. However, the amounts of mRNAs of two ecdysteroid-inducible genes, BHR3 (early-late gene; Bombyx homologue to DHR3 and MHR3) and Urbain (wing-specific late gene), were reduced to about 50% and 20% of WT in the cultured fl wing discs, respectively. We analyzed developmental profiles of these mRNAs during metamorphosis. They also demonstrated decreased BHR3 and Urbain mRNA 2 days after the onset of wandering. This reduction in transcription of BHR3 in the fl mutant was observed only in the wing disc, not in the testis and fatbody. These results imply that the aberrant expression of the fl gene affects the downstream pathway of ecdysteroid signaling specifically in the wing discs and thus leads to a deficiency in wing formation.

TONDU (TDU), a novel human protein related to the product of vestigial (vg) gene of Drosophila melanogaster interacts with vertebrate TEF factors and substitutes for Vg function in wing formation

The mammalian TEF and the Drosophila scalloped genes belong to a conserved family of transcriptional factors that possesses a TEA/ATTS DNA-binding domain. Transcriptional activation by these proteins likely requires interactions with specific coactivators. In Drosophila, Scalloped (Sd) interacts with Vestigial (Vg) to form a complex, which binds DNA through the Sd TEA/ATTS domain. The Sd-Vg heterodimer is a key regulator of wing development, which directly controls several target genes and is able to induce wing outgrowth when ectopically expressed. Here we show that Vg contains two distinct transcriptional activation domains, suggesting that the function of Vg is to mediate transcriptional activation by Sd. By expressing a chimeric GAL4-Sd protein in Drosophila, we found that the transcriptional activity of the Vg-Sd heterodimer is negatively regulated at the AP and DV boundary of the wing disc. We also identify a novel human protein, TONDU, which contains a short domain homologous to the domain of Vg required for interaction with Sd. We show that TONDU specifically interacts with a domain conserved in all the mammalian TEF factors. Expression of TDU in Drosophila by means of the UAS-GAL4 system shows that this human protein can substitute for Vg in wing formation. We propose that TDU is a specific coactivator for the mammalian TEFs.

Temperature and plant nutrient effects on the development, survival and reproduction of Cinara sp. nov., an invasive pest of cypress trees in Africa

Abstract Cinara sp. nov., previously identified as Cinara cupressi (Buckton) (Homoptera: Aphididae), is an important alien aphid pest of cypresses and junipers, and invaded Africa in the late 1980s. The work reported here was carried out as part of a larger programme aimed at the classical biological control of the aphid in Africa. Basic life history attributes including life table statistics of the aphid were quantified in order to facilitate the development of efficient aphid culturing methods and essential baseline information necessary for the culturing of potential parasitoid biological agents prior to selection for introduction to Africa. Developmental rates and fecundity were studied under four constant temperatures (10 °C, 15 °C, 20 °C, and 25 °C). The effects of several plant nutrients (nitrogen, potassium and phosphorus) supplied at different dose levels on life history attributes of Cinara sp. nov. were also studied.Unlike most other aphids, the apterous morph of Cinara sp. nov. developed through only three instars, and the alate four instars. The aphid is highly aggregative and exploits a wide range of feeding sites from young green branches to woody stems. The developmental period of Cinara sp. nov. ranged from 9.3 days at 25 °C to 22.3 days at 10 °C and the developmental threshold was 0.61 °C. Reproduction was delayed, because of the longer duration of development, and nymph production decreased with decreasing temperature. The intrinsic rate of increase ranged between 0.117 at 25 °C and 0.060 at 10 °C. Aphid size increased significantly as temperature was lowered. Wing formation was not induced when apterae were reared for up to three generations at each constant temperature but continuous crowding in the supply cultures held at 21 °C resulted in a high number of alates being formed. No appreciable effects of the different plant nutrients, supplied either singly or in combination, on the duration of instars or overall survival could be detected.

Scalloped functions in a regulatory loop with vestigial and wingless to pattern the Drosophila wing.

The development of the Drosophila wing involves progressive patterning events. In the second larval instar, cells of the wing disc are allotted wing or notum fates by a wingless-mediated process and dorsal or ventral fates by the action of apterous and wingless. Notch-mediated signalling is required for the expression of the genes vestigial and scalloped in the presumptive wing blade. Later, wingless, Notch and cut are involved in cell fate specification along the wing margin. The function of scalloped in this process is not well understood and is the focus of this study. We show that patterning downstream of Notch and wingless pathways is altered in scalloped mutants. Reduction in scalloped expression results in a loss of expression of wing blade- and margin-specific markers. Misexpression of scalloped in the presumptive wing causes misexpression of scalloped, vestigial and wingless reporter genes. However, high levels of scalloped expression have a negative influence on wingless, vestigial and its own expression. Our results demonstrate that scalloped functions in a level-dependent manner in the presumptive wing blade in a loop that involves vestigial and itself. We suggest that wing development requires the regulated expression of scalloped together with vestigial-the "wing formation" effects of Vestigial in other imaginal discs are probably due to its interaction with the scalloped gene product normally expressed in these discs.

The evolution and development of dipteran wing veins: a systematic approach.

In this review, we use the wing veins of dipteran insects as potential models for understanding the evolution of development. We briefly discuss previous work in this field and examine the genetic complexity of wing formation, discussing the genes involved in wing formation and their roles in Drosophila wing development and vein formation. Furthermore, patterns of wing vein formation, addition, and reduction are discussed as they occur throughout the Diptera. Using the phyletic phenocopy paradigm, we draw attention to many wing vein morphologies that phenocopy various wing mutants in Drosophila melanogaster. The systematic issues of the nature of characters, homology, and the role of modern developmental approaches to evolutionary studies, which has recently become important, can be addressed from the perspective of the wing. We argue that further developmental evolutionary studies, and the interpretation of data therefrom, must be conducted within the context of a well-supported phylogeny of the organisms under study.

Enhancement of short wing formation and ovarian growth in the genetically defined macropterous strain of the brown planthopper, Nilaparvata lugens

When JH II, III or methoprene was applied in the nymphal stages to two different strains of the brown planthopper which were selected to produce long (macropterous) or short (brachypterous) wing forms, no effect was observed on the molting profile or metamorphosis. Brachypterization of a majority of the presumptive macropters was, however, observed by application of these chemicals, although there was no effect on wing form in the presumptive brachypters. The results show that the sensitive periods for the brachypterization of the presumptive macropters falls between early antepenultimate instar and within 1 or 2 days of the penultimate instar, and that the chemicals were effective, in the following order of potency: methoprene>JH III>JH II. Ovarian growth was greatly enhanced in the presumptive macropters when JH III or methoprene was applied twice, within 12 h of the 3rd or 4th nymphal instar and 6 h before adult emergence. JH II on the other hand had no effect on ovarian growth when applied to the presumptive macropters at any of the nymphal stages. None of the chemicals had any effect on ovarian growth in the presumptive brachypters.