RESUMEN
The food chain length represents how much energy reaches different trophic levels in food webs. Environmental changes derived from human activities have the potential to affect chain length. We explore how habitat area and edges affect chain length through: (1) a bottom-up effect of abundance ('pyramid hypothesis'); (2) the truncation of the highest trophic level ('trophic-rank hypothesis'); and (3) changes in species connectivity patterns ('connectivity hypothesis'). We built plant-leaf miner-parasitoid food webs in 19 remnants of a fragmented Chaco forest from central Argentina. On each remnant, we constructed food webs from different locations at the forest interior and edges. For each food web, we registered the abundance of species, the species richness of each trophic level, estimated the connectivity of their networks, and the average food chain length. We used structural equation models to evaluate the direct and indirect effects of habitat area and edge/interior location on food chain length mediated by species richness, abundance and connectivity. We found no direct effects of habitat area on chain length but chains were longer at forest edges than at their interior. The three mechanisms were supported by our results, although they showed different strengths. First, we found that the interior favours a bottom-up abundance effect from herbivores to parasitoids that positively affected chain length; second, we found that the forest area positively affects plant richness, which has a strong effect on the number of resources used by consumers, with a positive effect on chain length. Third, the remnant area and interior position favoured plant richness with a negative effect on the abundance of parasitoids, which had a positive effect on chain length. In general, the strongest effects on chain length were detected through changes in abundance rather than species richness although abundance was less affected by habitat fragmentation. We evaluated for the first time the effects of human-driven habitat fragmentation on the length of trophic chains in highly diverse plant-herbivore-parasitoid networks. Despite the loss of species, small habitat fragments and edges embedded in the agricultural matrix can support interaction networks, making them conservation targets in managed landscapes.
El largo de cadenas tróficas representa cuanta energía alcanza diferentes niveles tróficos en redes tróficas. Los cambios ambientales producto de las actividades humanas tienen el potencial de afectar el largo de las cadenas tróficas. Exploramos como el área de hábitat y los bordes afectan el largo de cadenas tróficas a través de: (1) un efecto ascendente de la abundancia ('hipótesis pirámide'); (2) el truncamiento del nivel trófico superior ('hipótesis de ranking trófico'); y (3) cambios en los patrones de conectividad ('hipótesis de conectividad'). Construimos redes tróficas entre plantas-minadores de hoja-parasitoides en 19 remanentes de bosque Chaqueño serrano altamente fragmentado en el centro de Argentina. Para cada remanente construimos redes tróficas en distintas ubicaciones en el borde e interior del bosque. Para cada red trófica registramos la abundancia media de las especies, la riqueza de cada nivel trófico, estimamos la conectividad de las redes y el largo de cadenas tróficas promedio. Utilizamos modelos de ecuaciones estructurales para evaluar los efectos directos e indirectos del área y la ubicación borde/interior sobre el largo de cadenas tróficas mediado por la riqueza de especies, la abundancia y la conectividad. No encontramos efectos directos del área de hábitat sobre el largo de cadenas, pero las cadenas fueron más largas en los bordes que en el interior. Los tres mecanismos propuestos fueron apoyados por los resultados, pero mostraron distinta fuerza. Primero, encontramos que el interior de los bosques favorece los efectos ascendentes de la abundancia desde los herbívoros a los parasitoides lo que afectó positivamente al largo de las cadenas; segundo, encontramos que el área de bosque afectó positivamente a la riqueza de especies, lo que tuvo un efecto positivo en el largo de cadenas. Tercero, el área de bosque remanente y la ubicación en el interior favorecieron la riqueza de plantas, influyendo negativamente en la abundancia de parasitoides lo que tuvo un efecto positivo en el largo de cadenas. En general, los efectos más fuertes sobre el largo de cadenas se detectaron a través de cambios en la abundancia más que en la riqueza, aunque la abundancia fue menos afectada por la fragmentación del hábitat que la riqueza de especies. En este estudio evaluamos por primera vez los efectos de la fragmentación del hábitat por causas humanas sobre el largo de cadenas tróficas en redes tróficas altamente diversas de plantas, herbívoros y parasitoides. A pesar de la pérdida de especies, los fragmentos pequeños y los bordes de bosque inmersos en una matriz agrícola pueden sostener redes de interacciones, convirtiéndolos en objetivos de conservación en paisajes manejados.
Asunto(s)
Biodiversidad , Ecosistema , Humanos , Animales , Bosques , Cadena Alimentaria , Herbivoria , PlantasRESUMEN
Urbanization is an important driver of the diversity and abundance of tree-associated insect herbivores, but its consequences for insect herbivory are poorly understood. A likely source of variability among studies is the insufficient consideration of intra-urban variability in forest cover. With the help of citizen scientists, we investigated the independent and interactive effects of local canopy cover and percentage of impervious surface on insect herbivory in the pedunculate oak (Quercus robur L.) throughout most of its geographic range in Europe. We found that the damage caused by chewing insect herbivores as well as the incidence of leaf-mining and gall-inducing herbivores consistently decreased with increasing impervious surface around focal oaks. Herbivory by chewing herbivores increased with increasing forest cover, regardless of impervious surface. In contrast, an increase in local canopy cover buffered the negative effect of impervious surface on leaf miners and strengthened its effect on gall inducers. These results show that-just like in non-urban areas-plant-herbivore interactions in cities are structured by a complex set of interacting factors. This highlights that local habitat characteristics within cities have the potential to attenuate or modify the effect of impervious surfaces on biotic interactions.
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This is the first report of the family Tischeriidae in Colombia. We describe two new species recently discovered in the department of Valle del Cauca in southwestern Colombia: Astrotischeria ochrimaculosa Diskus, Stonis Vargas, sp. nov., and A. colombiana Stonis Vargas, sp. nov. The latter is a leaf miner of Asteraceae, while A. ochrimaculosa is trophically associated with Malvaceae. Astrotischeria colombiana is known only from Colombia, but A. ochrimaculosa is more widely distributed from Colombia to Peru. The new species are illustrated with photographs of their habitats, adults, male and female genitalia, and leaf mines. We comment on the rarity of tischeriids in collections and their current known distribution in the Neotropics.
Asunto(s)
Asteraceae , Lepidópteros , Mariposas Nocturnas , Distribución Animal , Animales , Colombia , Ecosistema , Femenino , Masculino , PerúRESUMEN
Gracillariidae leaf miners include 1987 species of poorly studied micromoths for which the majority of the diversity has been described from temperate regions. The Neotropics harbors one of the richest faunas of Gracillariidae, but the rate of taxon descriptions has been slow because of limited sampling and taxonomic activity. In this illustrated catalogue, we provide, for the first time, 476 high resolution illustrations for the 201 species of named gracillariids occurring in the region and revise their classification, newly considering the family-group names Oecophyllembiini stat. nov., Marmarini stat. nov., and Parornichini stat. nov. as tribes of Phyllocnistinae, in the first two cases and Gracillariinae in the last case respectively. Two species, Sauterina hexameris (Meyrick, 1921) comb. nov. and S. phiaropis (Meyrick, 1921) comb. nov., are transferred to Sauterina from Gracillaria. By making taxonomic, distributional, molecular and biological data available in a concise form, we aim to facilitate taxonomic work on Neotropical gracillariids, and in turn to enhance studies in general on poorly studied organisms such as parasitoids from this biogeographical region.
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Lepidópteros , AnimalesRESUMEN
Sabulopteryxbotanica Hoare & Patrick, sp. nov. (Lepidoptera, Gracillariidae, Gracillariinae) is described as a new species from New Zealand. It is regarded as endemic, and represents the first record of its genus from the southern hemisphere. Though diverging in some morphological features from previously described species, it is placed in genus Sabulopteryx Triberti, based on wing venation, abdominal characters, male and female genitalia and hostplant choice; this placement is supported by phylogenetic analysis based on the COI mitochondrial gene. The life history is described: the larva is an underside leaf-miner on the endemic divaricating shrub Teucriumparvifolium (Lamiaceae), and exits the mine to pupate in a cocoon in a folded leaf of the host plant. The remarkable history of the discovery and rediscovery of this moth is discussed: for many years it was only known from a single sap-feeding larva found in a leaf-mine in a pressed herbarium specimen of the host. The adult was discovered by BHP in Christchurch Botanic Gardens in 2013. Most distribution records of the moth come from a recent search for mines and cocoons on herbarium specimens of T.parvifolium. Sabulopteryxbotanica has high conservation status, and is regarded as 'Nationally Vulnerable' according to the New Zealand Department of Conservation threat classification system, based on the rarity and declining status of its host plant. However, the presence of apparently thriving populations of S.botanica on cultivated plants of T.parvifolium, especially at the type locality, Christchurch Botanic Gardens, suggests that encouraging cultivation of the plant could greatly improve the conservation status of the moth. A revised checklist of New Zealand Gracillariidae is presented, assigning all species to the currently recognised subfamilies. The Australian Macarostolaida (Meyrick, 1880) is newly recorded from New Zealand (Auckland), where it is established on Eucalyptus.
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Both species and genetic diversity of plant communities can affect insect herbivores, but a few studies have compared the effects of both diversity levels within the same experimental context. We compared the effects of tree species and genetic diversity on abundance, species richness, and ß-diversity of leaf-miner communities associated with silver birch using two long-term forest diversity experiments in Finland where birch trees were planted in monocultures and mixtures of birch genotypes or other trees species. Although both abundance and species richness of leaf miners differed among birch genotypes at the tree level, birch genetic diversity had no significant effect on miner abundance and species richness at the plot level. Instead, birch genetic diversity affected leaf-miner ß-diversity with species turnover being higher among trees within genotypic mixtures than among trees within monoclonal plots. In contrast, tree species diversity had a significant negative effect on both leaf-miner abundance and species richness at plot level, but no effect on miner ß-diversity. Significant tree species diversity effects on leaf-miner abundance and species richness were found only in plots with high tree density. We have demonstrated that plant species and genetic diversity play important but contrasting roles in structuring associated herbivore communities. Tree species diversity largely affects miner abundance and species richness, whereas tree genetic diversity affects miner ß-diversity. These results have important implications for conservation and management of woodlands.
Asunto(s)
Betula , Árboles , Animales , Biodiversidad , Ecosistema , Finlandia , Variación GenéticaRESUMEN
We review eleven Astrotischeria Puplesis Diskus (Lepidoptera: Tischeriidae) species which possess a novel character for the Tischeriidae family: a highly modified valva of the male genitalia with one ventral and two dorsal lobes (or processes). The species are distributed in the Americas, including the USA, Caribbean (St. Thomas), Central America (Belize, Guatemala and Honduras), and South America (Ecuador, Bolivia, and Brazil). Species for which the biology has been studied are associated with host plants from Asteroidea of the Asteraceae family. The following seven species are described as new: Astrotischeria trilobata Diskus Stonis, sp. nov., A. amazonica Diskus Stonis, sp. nov., A. maya Diskus Stonis, sp. nov., A. selvica Diskus, Carvalho-Filho Stonis, sp. nov., A. casila Diskus Stonis, sp. nov., A. onae Diskus Stonis, sp. nov., and A. furcata Stonis Diskus, sp. nov. A new informal species unit, the A. trilobata group, is designated for diagnostic purposes despite some doubts about monophyly of the group. Astrotischeria longeciliata (Frey Boll) is synonymized here with the North American A. helianthi (Frey Boll), a species not belonging to the A. trilobata group, syn. nov. For the first time, a method of rearing of adults from mining larvae, specifically adopted for Tischeriidae, is detailed. All species treated in the paper are illustrated with photographs or drawings of the adults, male genitalia, and, if available, the female genitalia, leaf mines and habitats. A distribution map for the species of the A. trilobata group and a scheme of the trophic relationships of the global Tischeriidae fauna are also provided.
Asunto(s)
Asteraceae , Lepidópteros , Distribución Animal , Animales , Región del Caribe , América Central , Femenino , Genitales Masculinos , Masculino , Mariposas Nocturnas , Estados UnidosRESUMEN
Chelonus (Areselonus) spinigaster sp. n., (Hymenoptera: Braconidae: Cheloninae) is described from India. The new species was reared from the moth species Acrocercops lysibathra (Meyr.) on Cordia latifolia Roxb.
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We provide the first report of Tischeriidae on Ulmaceae, a novel host-plant family, and describe Tischeria ulmella Xu Dai, sp. nov., a new species discovered in the Yellow River Scenic Area of Zhengzhou (Henan Province, China), feeding on Ulmus pumila L. We also provide a redescription of the Quercus-feeding Tischeria naraensis Sato discovered in China for the first time. Both species are illustrated with photographs of the adults, male and female genitalia, and the leaf mines.
Asunto(s)
Mariposas Nocturnas , Quercus , Distribución Animal , Animales , China , Femenino , Masculino , Hojas de la Planta , UlmaceaeRESUMEN
Several herbivorous insects and plant-associated microorganisms control the phytohormonal balance, thus enabling them to successfully exploit the plant by inhibiting plant defenses and withdrawing plant resources for their own benefit. The leaf-mining moth Phyllonorycter blancardella modifies the cytokinin (CK) profile of mined leaf-tissues, and the insect symbiotic bacteria Wolbachia is involved in the plant manipulation to the benefit of the insect host. To gain a deeper understanding into the possible origin and dynamics of CKs, we conducted an extensive characterization of CKs in larvae and in infected apple leaves. Our results show the enhanced CK levels in mines, both on green and yellow leaves, allowing insects to control their nutritional supply under fluctuating environmental conditions. The spatial distribution of CKs within the mined leaves shows that hormone manipulation is strictly limited to the mine suggesting the absence of CK translocation from distant leaf areas toward the insect feeding site. Mass spectrometry analyses reveal that major CK types accumulating in mines and larvae are similar to what is observed for most gall-inducers, suggesting that strategies underlying the plant manipulation may be shared between herbivorous insects with distinct life histories. Results further show that CKs are detected in the highest levels in larvae, reinforcing our hypothesis that CKs accumulating in the mines originate from the insect itself. Presence of bacteria-specific methylthio-CKs is consistent with previous results suggesting that insect bacterial symbionts contribute to the observed phenotype. Our study provides key findings toward the understanding of molecular mechanisms underlying this intricate plant-insect-microbe interaction.
Asunto(s)
Citocininas/metabolismo , Interacciones Huésped-Parásitos , Malus/metabolismo , Mariposas Nocturnas/fisiología , Animales , Larva/fisiología , Hojas de la Planta/metabolismoRESUMEN
The paper treats fifteen species of leaf-mining pygmy moths (Insecta, Lepidoptera, Nepticulidae) discovered in the Neotropics (British Virgin Islands, Belize, Costa Rica, Venezuela, and Ecuador), and Ando-Patagonian region (Argentina and Chile). Except for two species, all belong to Stigmella Schrank. Twelve species are new, and are named and described in the current paper: Stigmella apicibrunella Diskus & Stonis, sp. nov.; S. decora Diskus & Stonis, sp. nov.; S. unicaudata Remeikis & Stonis, sp. nov.; S. sanmartini Remeikis & Stonis, sp. nov.; S. patula Remeikis & Stonis, sp. nov.; S. torosa Remeikis & Stonis, sp. nov.; S. monstrata Remeikis & Stonis, sp. nov.; S. huahumi Remeikis & Stonis, sp. nov.; S. venezuelica Remeikis & Stonis, sp. nov.; S. virginica Remeikis & Stonis, sp. nov.; Fomoria miranda Diskus & Stonis, sp. nov.; and Hesperolyra robinsoni Stonis, sp. n. Newly discovered variation of male genitalia of the Andean Stigmella rudis Puplesis & Robinson, 2000 is briefly discussed, and the formerly poorly understood Stigmella hylomaga (Meyrick, 1931) is redescribed and documented with photographs for the first time. We also present more photographs and add some addtional information on Stigmella gallicola van Nieukerken & Nishida, a recently described gall-maker from Costa Rica.The paper also provides new host-plant data: some of the described (or redescribed) species are reported for the first time as leaf-miners on plants belonging to Euphorbiaceae (Acalypha padifolia Kunth), Salicaceae (Azara microphylla Hook. f.), Fabaceae (Inga spectabilis (Vahl) Willd. or I. edulis Mart.), Rhamnaceae (Colletia spinosissima J. F. Gmel.), Geraniaceae or Vivianiaceae (Rhynchotheca spinosa Ruiz & Pav.), and Asteraceae (Mutisia decurrens Cav.). All species treated in the paper are illustrated with photographs of the adults and genitalia, a distribution map, and also photographs of the leaf-mines and host plants when available.
Asunto(s)
Lepidópteros , Animales , Argentina , Belice , Chile , Costa Rica , Ecuador , Masculino , Plantas , VenezuelaRESUMEN
ABSTRACT The Neotropical micromoth genus Leurocephala Davis & Mc Kay, 2011 (Lepidoptera, Gracillariidae) was originally described to include only the type species, L. schinusae Davis & Mc Kay, 2011, whose leaf miner larvae are associated with Anacardiaceae in Argentina, Brazil and Paraguay. An integrative analysis including morphology, life history and DNA barcode sequences revealed that specimens collected on Schinus molle L. (Anacardiaceae) in the coastal valleys of the Atacama Desert of northern Chile belong to a second species of this formerly monotypic genus. Adults of Leurocephala chilensis Vargas & Moreira sp. nov. are herein described and illustrated in association with the immature stages and life history, and corresponding phylogenetic relationships are assessed based on DNA barcode sequences. This finding provides the first record of Leurocephala from west of the Andes Range, expanding remarkably its geographic range. It is suggested that the extent of diversity within Leurocephala is much greater and that variation in geographic factors and host plant use may have modeled it, an evolutionary hypothesis that should be assessed in further studies.
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A catalogue of all named Nepticulidae and Opostegidae is presented, including fossil species. The catalogue is simultaneously published online in the scratchpad http://nepticuloidea.info/ and in Catalogue of Life (http://www.catalogueoflife.org/col/details/database/id/172). We provide a historical overview of taxonomic research on Nepticuloidea and a brief 'state of the art'. A DNA barcode dataset with 3205 barcodes is made public at the same time, providing DNA barcodes of ca. 779 species, of which 2563 are identified as belonging to 444 validly published species. We recognise 862 extant and 18 fossil species of Nepticulidae in 22 extant genera and the fossil form genus Stigmellites. We count 192 valid Opostegidae species in 7 genera, without fossils. We also list seven dubious Nepticulidae names that cannot be placed due to absent type material and poor descriptions, 18 unavailable names in Nepticulidae that cannot be placed and we also list the 33 names (including four fossils) that once were placed as Nepticulidae or Opostegidae but are now excluded. All synonyms and previous combinations are listed. The generic classification follows the Molecular phylogeny that is published almost simultaneously. Subfamilies and tribes are not recognised, Trifurculinae Scoble, 1983 is synonymised with Nepticulidae Stainton, 1854 and Opostegoidinae Kozlov, 1987 is synonymised with Opostegidae Meyrick, 1893. The status of Casanovula Hoare, 2013, Etainia Beirne, 1945, Fomoria Beirne, 1945, Glaucolepis Braun, 1917, Menurella Hoare, 2013, Muhabbetana Koçak & Kemal, 2007 and Zimmermannia Hering, 1940 is changed from subgenus to full genus, whereas two genera are considered synonyms again: Manoneura Davis, 1979, a synonym of Enteucha Meyrick, 1915 and Levarchama Beirne, 1945, a synonym of Trifurcula Zeller, 1848. We propose 87 new combinations in Nepticulidae and 10 in Opostegidae, largely due to the new classification, and re-examination of some species. We propose the following 37 new synonymies for species (35 in Nepticulidae, 2 in Opostegidae): Stigmella acerifoliella Dovnar-Zapolski, 1969 (unavailable, = Stigmella acerna Puplesis, 1988), Stigmella nakamurai Kemperman & Wilkinson, 1985 (= Stigmella palionisi Puplesis, 1984), Nepticula amseli Skala, 1941 (unavailable = Stigmella birgittae Gustafsson, 1985), Stigmella cathepostis Kemperman & Wilkinson, 1985 (= Stigmella microtheriella (Stainton, 1854)), Stigmella populnea Kemperman & Wilkinson, 1985 (= Stigmella nivenburgensis (Preissecker, 1942)), Nepticula obscurella Braun, 1912 (revised synonymy, = Stigmella myricafoliella (Busck, 1900)), Nepticula mandingella Gustafsson, 1972 (= Stigmella wollofella (Gustafsson, 1972)), Stigmella rosaefoliella pectocatena Wilkinson & Scoble, 1979 (= Stigmella centifoliella (Zeller, 1848)), Micropteryx pomivorella Packard, 1870 (= Stigmella oxyacanthella (Stainton, 1854)), Stigmella crataegivora Puplesis, 1985 (= Stigmella micromelis Puplesis, 1985), Stigmella scinanella Wilkinson & Scoble, 1979 (= Stigmella purpuratella (Braun, 1917)), Stigmella palmatae Puplesis, 1984 (= Stigmella filipendulae (Wocke, 1871)), Stigmella sesplicata Kemperman & Wilkinson, 1985 (= Stigmella lediella (Schleich, 1867)), Stigmella rhododendrifolia Dovnar-Zapolski & Tomilova, 1978 (unavailable, = Stigmella lediella (Schleich, 1867)), Stigmella oa Kemperman & Wilkinson, 1985 (= Stigmella spiculifera Kemperman & Wilkinson, 1985), Stigmella gracilipae Hirano, 2014 (= Stigmella monticulella Puplesis, 1984), Nepticula chaoniella Herrich-Schäffer, 1863 (= Stigmella samiatella (Zeller, 1839)), Bohemannia piotra Puplesis, 1984 (= Bohemannia pulverosella (Stainton, 1849)), Bohemannia nipponicella Hirano, 2010 (= Bohemannia manschurella Puplesis, 1984), Sinopticula sinica Yang, 1989 (= Glaucolepis oishiella (Matsumura, 1931)), Trifurcula collinella Nel, 2012 (= Glaucolepis magna (A. Lastuvka & Z. Lastuvka, 1997)), Obrussa tigrinella Puplesis, 1985 (= Etainia trifasciata (Matsumura, 1931)), Microcalyptris vittatus Puplesis, 1984 and Microcalyptris arenosus Falkovitsh, 1986 (both = Acalyptris falkovitshi (Puplesis, 1984)), Ectoedemia castaneae Busck, 1913, Ectoedemia heinrichi Busck, 1914 and Ectoedemia helenella Wilkinson, 1981 (all three = Zimmermannia bosquella (Chambers, 1878)), Ectoedemia chloranthis Meyrick, 1928 and Ectoedemia acanthella Wilkinson & Newton, 1981 (both = Zimmermannia grandisella (Chambers, 1880)), Ectoedemia coruscella Wilkinson, 1981 (= Zimmermannia mesoloba (Davis, 1978)), Ectoedemia piperella Wilkinson & Newton, 1981 and Ectoedemia reneella Wilkinson, 1981 (both = Zimmermannia obrutella (Zeller, 1873)), Ectoedemia similigena Puplesis, 1994 (= Ectoedemia turbidella (Zeller, 1848)), Ectoedemia andrella Wilkinson, 1981 (= Ectoedemia ulmella (Braun, 1912)), Nepticula canadensis Braun, 1917 (= Ectoedemia minimella (Zetterstedt, 1839)), Opostega rezniki Kozlov, 1985 (= Opostega cretatella Chrétien, 1915), Pseudopostega cyrneochalcopepla Nel & Varenne, 2012 (= Pseudopostega chalcopepla (Walsingham, 1908)). Stigmella caryaefoliella (Clemens, 1861) and Zimmermannia bosquella (Chambers, 1878) are taken out of synonymy and re-instated as full species. Lectotypes are designated for Trifurcula obrutella Zeller, 1873 and Nepticula grandisella Chambers, 1880.
RESUMEN
Gall-inducing insects are iconic examples in the manipulation and reprogramming of plant development, inducing spectacular morphological and physiological changes of host-plant tissues within which the insect feeds and grows. Despite decades of research, effectors involved in gall induction and basic mechanisms of gall formation remain unknown. Recent research suggests that some aspects of the plant manipulation shown by gall-inducers may be shared with other insect herbivorous life histories. Here, we illustrate similarities and contrasts by reviewing current knowledge of metabolic and morphological effects induced on plants by gall-inducing and leaf-mining insects, and ask whether leaf-miners can also be considered to be plant reprogrammers. We review key plant functions targeted by various plant reprogrammers, including plant-manipulating insects and nematodes, and functionally characterize insect herbivore-derived effectors to provide a broader understanding of possible mechanisms used in host-plant manipulation. Consequences of plant reprogramming in terms of ecology, coevolution and diversification of plant-manipulating insects are also discussed.
Asunto(s)
Insectos/fisiología , Plantas/parasitología , Animales , Herbivoria , Interacciones Huésped-Parásitos , Hojas de la Planta/parasitología , Tumores de Planta/parasitologíaRESUMEN
Internally feeding herbivorous insects such as leaf miners have developed the ability to manipulate the physiology of their host plants in a way to best meet their metabolic needs and compensate for variation in food nutritional composition. For instance, some leaf miners can induce green-islands on yellow leaves in autumn, which are characterized by photosynthetically active green patches in otherwise senescing leaves. It has been shown that endosymbionts, and most likely bacteria of the genus Wolbachia, play an important role in green-island induction in the apple leaf-mining moth Phyllonorycter blancardella. However, it is currently not known how widespread is this moth-Wolbachia-plant interaction. Here, we studied the co-occurrence between Wolbachia and the green-island phenotype in 133 moth specimens belonging to 74 species of Lepidoptera including 60 Gracillariidae leaf miners. Using a combination of molecular phylogenies and ecological data (occurrence of green-islands), we show that the acquisitions of the green-island phenotype and Wolbachia infections have been associated through the evolutionary diversification of Gracillariidae. We also found intraspecific variability in both green-island formation and Wolbachia infection, with some species being able to form green-islands without being infected by Wolbachia. In addition, Wolbachia variants belonging to both A and B supergroups were found to be associated with green-island phenotype suggesting several independent origins of green-island induction. This study opens new prospects and raises new questions about the ecology and evolution of the tripartite association between Wolbachia, leaf miners, and their host plants.
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The effects of a forest road on Castanopsis carlesii (Hemsley) Hayata (Fagales: Fagaceae) seedlings and their leaf herbivory were investigated in a subtropical forest at Jiulianshan National Nature Reserve, Jiangxi, China. A total of 1124 seedlings, 33949 leaves, 468 leaf mines, and 205 leaf galls were found. Generally, individual numbers, tree heights, and leaf numbers of C. carlesii seedlings became lower with increasing distances from the road. These results might indicate that old seedlings were fewer and survival rate of seedlings was lower in forest interiors. Leaf miners preferred the seedlings close to the forest road, while leaf gallers preferred the seedlings about 2 m from the road. Species diversity of leaf miners was higher in the forest interior area, while species diversity of leaf gallers was higher near the road. However, both leaf miners and leaf gallers decreased in general from the road to the interior forest. There were interspecific differences in the effects of roads on leaf miner species and leaf galler species. The effects of the road on seedlings and insects could be explained by varying microhabitat conditions and different ecological strategies.
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Ambiente , Fagaceae/crecimiento & desarrollo , Herbivoria , Insectos/fisiología , Animales , China , Cadena Alimentaria , Bosques , Hojas de la Planta/crecimiento & desarrollo , Plantones/crecimiento & desarrolloRESUMEN
At Sand Lake, Leon County, Florida, mines of Stilbosis quadricustatella, a leaf-mining moth, occur on sand live oak trees (Quercus geminata) over a broad range of densities. Some trees have fewer than 2% of their leaves mined (lightly infested), others up to 70% (heavily infested). Similar levels of infestation are maintained on the same trees year after year. There are no significant negative correlations of miner density per tree with any mortality factor that might explain miner preferences for certain trees. Nor is there a positive correlation with host leaf quality as measured by foliar nitrogen or by total or individual amino acid concentrations of host leaves. Egg-transfer experiments showed that larvae from eggs transferred to lightly infested trees were more likely to be killed by leaf abscission than were those that were transferred to and developed on heavily infested trees. This is the first demonstration that variation in rates of leaf abscission could be an important cause of the observed distribution pattern of sessile insects between conspecific host plants.
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We examined patterns of density and species diversity for leaf-mining Lepidopterans and gall-forming Hymenopterans in two oak (Quercus spp.) hybrid zones: Quercus depressipes x Q. rugosa and Q. emoryi x Q. coccolobifolia. In both species complexes, hybrid hosts typically supported significantly lower densities and species diversity of parasites than did parental types. This contradicts the findings of Whitham (1989) that suggested that hybrid hosts may act as parasite sinks both in ecological and evolutionary time. We discuss features of hybrid zones that are likely to influence patterns of herbivory.