Cycle biologique et répartition de <i>Megastigmus wachtli</i> (Seitn.) (Hymenoptera, Torymidae), chalcidien ravageur des graines de cyprès dans le Bassin Méditerranéen

Roques, Alain; Raimbault, Jean-Paul

doi:10.1111/j.1439-0418.1986.tb00871.x

Cited by 9 publications

(8 citation statements)

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“…Entomol. 1994.39:179-212 noptera, and Lepidoptera can extend their normal winter diapause for one to seven additional years (4, 21,26,33,54,64,70,79,90,95,101,124,126,128,139,143,154,160,163,178,180,183,190,204,222,223; A Roques & JJ Turgeon, unpublished data). PD occurs either in late instars, pupae, or pharate adults.…”

Section: Behavioral Adaptationsmentioning

confidence: 99%

Insect Fauna of Coniferous Seed Cones: Diversity, Host Plant Interactions, and Management

Turgeon¹,

Roques²,

Groot³

1994

Annu. Rev. Entomol.

139

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PERSPECTIVE AND OVERVIEW Tree reproductive structures-pollen and seed cones, or micro-and mega sporangia-represent an extremely rich source of food for many animals (166). Although some species exploit pollen cones (189), in this review we deal exclusively with those exploiting seed cones prior to seed dispersal. Insects are considered the most important seed predators during the predispersal phase of seed development (59). Previous reviews have exam ined insect predation on angiosperm seeds and fruits, insect-seed interactions, as well as insect ecology, evolution, and interactions with other animals (86, 166). No general overview of the insects exploiting seed cones of 179

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Section: Behavioral Adaptationsmentioning

confidence: 99%

Insect Fauna of Coniferous Seed Cones: Diversity, Host Plant Interactions, and Management

Turgeon¹,

Roques²,

Groot³

1994

Annu. Rev. Entomol.

139

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“…Although the seed chalcid M. wachtli colonises cones when they are young and soft, and therefore cannot attack serotinous cones, the latter serve as a refuge for chalcids under extended diapause [22]. Cypress tree families did not differ in attack level when the number of cones bearing at least one emergence hole was analysed, but they did for the number of emergence holes per cone.…”

Section: Discussionmentioning

confidence: 93%

“…To emerge, adult chalcids tunnel the cone scales from the seed up to the cone surface. Emergence occurs prior to seed maturation and cone opening but it may be delayed up to 2 additional years in case of prolonged larval diapause [22]. Thus, cypress trees, which bear both nonserotinous and serotinous cones, could constitute a good model to understand how serotiny may affect the interactions among the host plant, the phytophagous insects, and the tree pathogens.…”

Section: Introductionmentioning

confidence: 99%

Serotinous cones of Cupressus sempervirens provide viable seeds in spite of high seed predation

Battisti

Cantini²,

Rouault³

et al. 2003

Ann. For. Sci.

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-Five half-sib families in an 18-year old family test of Cupressus sempervirens in Italy were compared for cone crop size, cone serotiny, and seed damage. The mean number of serotinous cones per tree was significantly different among families although families did not differ by the total number of cones produced during tree's lifetime. More than 60% of the cones were colonised either by a seed chalcid, Megastigmus wachtli, or by a seed bug, Orsillus maculatus, whereas pathogenic fungi (Seiridium cardinale, Pestalotiopsis funerea) were observed in less than 25% of these cones. The quantity and quality of seeds varied significantly among families and age of cones. Seed loss due to predators and pathogens was very important in serotinous cones, varying from 75.3% up to 90.8%. However, the remaining sound seeds showed a germination rate higher than 70% and cone serotiny seemed to play an important role in cypress reproductive biology.Cupressus sempervirens / cone / serotiny / seed predation / pathogenic fungi Résumé -Les cônes sérotineux de Cupressus sempervirens portent des graines viables même si les dégâts des ravageurs sont très importants. La production de cônes, la sérotinie et les dégâts causés aux graines ont été comparés entre cinq familles de demi-frères au sein d'un test de familles de Cupressus sempervirens de 18 ans d'âge en Italie. Des différences significatives entre familles ont été observées pour le nombre moyen de cônes sérotineux par arbre mais pas pour le nombre total de cônes produits par l'arbre au cours de sa vie. Plus de 60 % des cônes ont été attaqués par un chalcidien des graines, Megastigmus wachtli, ou par une punaise des graines, Orsillus maculatus, mais des champignons pathogènes (Seiridium cardinale, Pestalotiopsis funerea) n'ont été observés que dans moins de 25 % de ces cônes. La qualité et la quantité de graines a varié significativement entre familles et selon l'âge des cônes. La perte de graines due aux prédateurs et pathogènes a été plus importante dans les cônes sérotineux, s'élevant de 75,3 % à 90,8 % du potentiel de départ. Cependant, les graines restées saines étaient susceptibles de germer à plus de 70 %. Il semble que la sérotinie joue un rôle important dans la biologie reproductive du cyprès.Cupressus sempervirens / cône / serotinie / prédation des graines / champignons pathogènes

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“…wachtli is a common species specialized on C . sempervirens occurring from the eastern Mediterranean basin to Southern Europe with records extending back from several centuries [ 32 ]. Adults emerge in the beginning of summer from two-year old cones and then oviposit immediately in the young growing ones.…”

Section: Methodsmentioning

confidence: 99%

Host-Parasite Interactions from the Inside: Plant Reproductive Ontogeny Drives Specialization in Parasitic Insects

et al. 2015

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Host plant interactions are likely key drivers of evolutionary processes involved in the diversification of phytophagous insects. Granivory has received substantial attention for its crucial role in shaping the interaction between plants and their seed parasites, but fine-scale mechanisms explaining the role of host plant reproductive biology on specialization of seed parasites remain poorly described. In a comparative approach using plant histological techniques, we tested the hypotheses that different seed parasite species synchronize their life cycles to specific stages in seed development, and that the stage they target depends on major differences in seed development programs. In a pinaceous system, seed storage products are initiated before ovule fertilization and the wasps target the ovule’s nucellus during megagametogenesis, a stage at which larvae may benefit from the by-products derived from both secreting cells and dying nucellar cells. In a cupressaceous system, oviposition activity peaks later, during embryogenesis, and the wasps target the ovule’s megagametophyte where larvae may benefit from cell disintegration during embryogenesis. Our cytohistological approach shows for the first time how, despite divergent oviposition targets, different parasite species share a common strategy that consists of first competing for nutrients with developing plant structures, and then consuming these developed structures to complete their development. Our results support the prediction that seed developmental program is an axis for specialization in seed parasites, and that it could be an important parameter in models of their ecological and taxonomic divergence. This study provides the basis for further investigating the possibility of the link between plant ontogeny and pre-dispersal seed parasitism.

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Cycle biologique et répartition de Megastigmus wachtli (Seitn.) (Hymenoptera, Torymidae), chalcidien ravageur des graines de cyprès dans le Bassin Méditerranéen

Cited by 9 publications

References 1 publication

Insect Fauna of Coniferous Seed Cones: Diversity, Host Plant Interactions, and Management

Insect Fauna of Coniferous Seed Cones: Diversity, Host Plant Interactions, and Management

Serotinous cones of Cupressus sempervirens provide viable seeds in spite of high seed predation

Host-Parasite Interactions from the Inside: Plant Reproductive Ontogeny Drives Specialization in Parasitic Insects

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