Biologie dePimpla instigator F. 1793 [Ichneumonidae,Pimplinae]

Résumé Le mode de reconnaissance de l’h?te (chrysalides de Lépidoptères) parPimpla instigator (Hyménoptère, Ichneumonide) a été analysé. Les chrysalides sont déposées dans un étui de papier. On a montré quePimpla découvrait son h?te dans les conditions suivantes: absence de contact avec la chrysalide, h?te soustrait de sa vue, impossibilité de reconnaissance par marquage de l’étui lors de la première ponte, impossibilité de s’orienter par rapport à l’enceinte ou par rapport à une anisotropie du milieu. Dans ces conditions, seul un mode de reconnaissance de l’h?te par olfaction a permis àPimpla de découvrir la chrysalide.

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Summary Host finding byPimpla investigator (Hymenoptera, Ichneumonidae) has been investigated. The pupae were put into tubes made of rolled up paper. It has been shown thatPimpla was able to recognize its host, even under the following conditions: no contact with the pupae, the host being removed from sight, impossibility to discover the pupae in the tube because of certain materials deposited on the paper during the first egg-laying, impossibility to take bearings in relation with to the experimental cage, or any anisotropic difference. Therefore, we are allowed to assume that the discovery of the pupae byPimpla is due to olfaction.

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Travail réalisé avec la collaboration technique de MmeF. Frey.     

Action d'agents mutagènes sur la lignée germinale femelle dePimpla instigator [Hym.: Ichneumonidae]

Résumé Les rayons X et l'éthyl-méthyl-sulfonate provoquent une létalité des cellules de la lignée germinale des femelles dePimpla instigator F. Il n'y a pas de rétention d'œufs importante dans les conditions utilisées. Les œufs m?rs sont plus sensibles aux traitements que les cellules moins différenciées. Au cours de ces expériences, nous avons isolé quelques mutants, ce qui montre que les conditions expérimentales utilisées permettent l'obtention de mutants chezP. instigator. Il existe des variations de létalité qui dépendent du nombre d'œufs m?rs qu'une femelle possède. Pour obtenir une létalité reproductible, il faut tenir compte de l'age et des conditions de ponte des femelles.

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Summary Both X rays and E.M.S. can induce a cell lethality in the female germ line ofPimpla instigator F. There is not any important egg retention following the treatments. Mature eggs are the most sensitive stage. A few mutants were isolated, therefore our experimental conditions permit the isolation of mutants inP. instigator. The apparent lethality depends upon the number of mature eggs that the females retain, according to their age and egg-laying history. The various difficulties which have been mastered here could be generalized in other species of entomophagous wasps.

     

Study of the sound produced byPimpla instigator [Hymenoptera,Ichneumonidae] during host selection

When females ofPimpla instigator inspect objects as possible oviposition sites, they use their antennae to make the objects resonate. The antennae are not used as drum sticks, but serve merely to transmit shock waves generated within the female's body. Transmission of the shock waves to the substrate is mediated through vesicles situated at the extreme tip of the distal segment of each antenna. The present results support the hypothesis that acoustical inspection of the environment is a part of the exploratory behaviour of this insect.      

Host recognition byPimpla instigator F. (Hymenoptera: Ichneumonidae): Preferences and learned responses

This study identifies some previously unreported tactile and visual cues used by the pupal parasitoid Pimpla instigatorF. (Ichneumonidae) to recognize potential hosts. Paper cylinders were presented to the wasps as simple models of lepidopteran pupae. Acceptance of these models was evaluated by determining the frequency with which the wasps punctured the cylinders with their ovipositors. The length of the cylinders did not influence acceptance of the models; however, both surface texture and structural modifications to the ends of the cylinder did affect the frequency of punctures. Smooth cylinders were punctured more often than roughened cylinders, and cylinders with closed ends were frequently punctured, whereas open-ended cylinders were consistently rejected. The wasps also discriminated between blue and yellow cylinders and could be trained to associate blue or yellow with the presence of hosts. Preferences were established during a single 90- min training period and persisted for at least 4 days following training.     

Biology ofAgrothereutes tunetanus Haber. [Hym. Ichneumonidae] an ectoparasite ofOrgyia dubia Tausch. [Lep. Lymantriidae]

Résumé Les auteurs décrivent le cycle évolutif et le comportement de ponte de l'Agrothereutes tunetanus Haber. (Ichneumonidae, Cryptinae) dans les conditions de laboratoire (25°C et 50–60% H.R.). Le développement des œufs des larves et des nymphes, le comportement des stades larvaires, les habitudes alimentaires, l'accouplement et le comportement pendant l'oviposition sont décrits. A. tunetanus est un parasite de l'Orgyia dubia Tausch., attaquant le dernier stade larvaire de la femelle après que celle-ci ait tissé son cocon, mais avant la nymphose. Le même degré d'activité de ponte du parasite est provoqué par le dernier stade larvaire et la nymphe des femelles h?tes. Une moindre activité est suscitée par les femelles m?res dans les cocons et le dernier stade larvaire male, tandis que l'activité de ponte provoquée par les nymphes males est presque nulle. Le nombre moyen d'œufs pondus par une femelle durant une seule attaque (entre 3 et 4) ne dépend pas (de manière significative) du nombre de cocons présents. Le nombre d'attaques effectuées parA. tunetanus en 24 heures dépend de la quantité de cocons disponibles, les facteurs limitants sont le nombre d'œufs m?rs dans de la femelle gravide et la quantité d'œfus pondus pendant chaque attaque. Avec 6 cocons en 24 heures, une femelle, au maximum de sa fécondité, arive à une moyenne de 3,27 attaques. La fécondité d'une femelle est en moyenne de 308 œufs.

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Part of the M. Sc. thesis done under the supervision of the first author and submitted to the Department of Zoology of the Tel-Aviv University.     

Molecular phylogeny and systematics of the Polysphincta group of genera (Hymenoptera,Ichneumonidae, Pimplinae)

The phylogenetic relationships between genera of the Polysphincta group of Pimplinae (Ichneumonidae) were surveyed using molecular markers, partial sequences of cytochrome c oxidase I (COI), 28S rRNA and elongation factor 1α, and maximum likelihood and Bayesian approaches to obtain a robust phylogenetic hypothesis to understand the evolution of the group. The Polysphincta group was recovered as monophyletic, although relationships between genera were different from previous hypotheses based on morphological data. Within the Polysphincta group, three major clades were recognized and phylogenetic relationships among them were well resolved as (Schizopyga subgroup + (Acrodactyla subgroup + Polysphincta subgroup)). The Schizopyga subgroup consisted of the genera Piogaster, Schizopyga, Zabrachypus and Brachyzapus. As the genus Schizopyga was found to be polyphyletic, the genus Dreisbachia, which had been synonymized under Schizopyga, was resurrected and Iania gen.n. is proposed for Dreisbachia pictifrons, to maintain monophyletic genera. Species of the Schizopyga subgroup utilize spiders constructing egg‐laying chambers or funnel webs as hosts. The genus Piogaster was not recovered as the sister to all other members of the genus group, unlike previous hypotheses, but was nested in this clade as (Zabrachypus + ((Brachyzapus + Schizopyga) + (Dreisbachia + (Iania + Piogaster)))). Members of the Acrodactyla and Polysphincta subgroups attack spiders that weave aerial webs. The host range of the former is centred on tetragnathid and linyphiid spiders, the host range of the latter seems to centre mainly on orb‐weaving araneids and partly on theridiids weaving three‐dimensional (3D) irregular webs. Based on the obtained phylogeny of the group, the evolution of larval and cocoon morphology, and the mode of parasitism are discussed. Acrodactyla varicarinata Uchida & Momoi and A. inoperta Kusigemati are transferred to the genus Megaetaira ( comb.n.). This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:0AB1086F‐9F23‐4057‐B7ED‐3A3943E19C61 .     

The biology ofLophyroplectus luteator [Hym.: Ichneumonidae] onNeodiprion sertifer [Hym.: Diprionidae] in Ontario

Adult femaleLophyroplectus luteator (Thunb.) oviposit in all feeding stages ofNeodiprion sertifer (Geoff.), although they prefer the smallest of any larvae present at a given time. Females tend to distribute eggs contagiously both within and between host feeding colonies. Eclosion of eggs does not occur until after the host has spun its cocoon. Larval development then requires approximately 1 month in the laboratory. There is an obligatory eonymphal diapause which requires a minimum of 60–80 days at 2°C to fulfil, and post-diapause development requires 3–4 weeks.     

Distribution ofBathyplectes curculionis andBathyplectes anurus [Hym.: Ichneumonidae] fromHypera [Col.: Curculionidae] on alfalfa in Egypt,Iraq, and Iran

A survey forHypera postica (Gyllenhal) and their larval parasites,Bathyplectes curculionis (Thomson) andB. anurus (Thomson) was conducted from 1973 through 1975 in Egypt, Iraq, and Iran. The search was concentrated in Iraq and Iran in areas having cultivated species ofMedicago, and in Egypt onTrifolium alexandrinum L. Hypera were most abundant where mean daily temperatures were below 25°C or above 15°C.B. curculionis were widely distributed throughout all 3 countries, but were most abundant in the regions having hot, dry summers, with moderately cold winters.B. anurus were less abundant and less widely distributed geographically thanB. curculionis. B. anurus were prevalent in regions having moderately warm summers and cold, to very cold, winters. In localities containing both parasites,B. anurus reached peak levels about 2–4 weeks beforeB. curculionis. Mesochorus spp. were the predominant hyperparasites obtained fromBathyplectes spp. They were widely distributed in Egypt, Iraq, and Iran.

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Résumé La répartition géographique desHypera spp. (Col.: Curculionidae) et de ses parasites larvaires,Bathyplectes curculionis (Thomson) etB. anurus (Thomson) (Hym.: Ichneumonidae) a été étudiée de 1973 à 1975 en Irak et en Iran, dans les régions où sont cultivées les espèces deMedicago, et en égypte surTrifolium alexandrinum L. LesHypera spp. ont été trouvés en plus grand nombre là où la moyenne quotidienne des températures était inférieure à 25°C ou supérieure à 15°C.B. curculionis était largement répartie dans l’ensemble des 3 pays, mais plus abondante dans les régions à étés chauds et secs et à hivers modérément froids. B. anurus était moins abondante et moins largement répartie géographiquement queB. curculionis. B. anurus était dominante dans les régions à étés modérément chauds et à hivers froids ou très froids. Là où les 2 espèces étaient présentes,B. anurus était abondante 2 à 4 semaines avantB. curculionis. Les hyperparasitesMesochorus spp. ont été abondants surBathyplectes spp., leur répartition couvrant largement l’égypte, l’Irak et l’Iran.

     

Natural enemies ofAcraea terpsicore [Lep.: Nymphalidae] in ghana,with particular reference to the parasiteCharops diversipes [Hym.: Ichneumonidae]

The arthropod parasites and predators ofAcraea terpsicore (L.) were determined in the forest zone of Ghana. An unidentified mite was predatory on the very young larvae. The pentatomidsPlatynopus rostratus Dru. andMacrorhaphis acuta (Dall.) were also predatory on the larvae.Telenomus sp. parasitized the eggs. The tachinidCarcelia normula (Curran) and the ichneumonidCharops diversipes Roman were parasitic on the larvae.C. diversipes was hyperparasitized by the chalcididBrachymeria feae Masi and the eulophidPediobius taylori Kerrich. Laboratory tests showed that parasitism ofA. terpsicore byC. diversipes was significantly highest in the 1st instar, followed by the 2nd, 3rd and 4th. The 5th instar was not parasitized. These results seemed to reflect both host susceptibility and parasite preference. Only a singleC. diversipes larva developed in a host. The developmental period of the parasite egg and larva varied inversely with the age of the host at which it was parasitized. A femaleC. diversipes could oviposit immediately after emergence.     

In vitro rearing ofPimpla instigator [Hym.: Ichneumonidea] 2. Completion of development in semi-artificial conditions

When eggs ofPimpla instigator F. collected artificially are sterilized and put on a solid agar medium, they hatch and give living 1 st instar larvae. Hatchability can be higher than 80% when the laying females are young. Time of hatching can be regulated by temperature modulation. The larvae obtained under these conditions give fertile imagos either when implanted into pupae ofPieris brassicae L. or when fed a sterilised homogenate of pupae.

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Résumé Des œufs dePimpla instigator F., collectés artificiellement, stérilisés et placés sur un milieu gélosé solide, ont éclos et donné des larves vivantes du 1 er stade. Le taux d'éclosion peut être supérieur à 80% quand les femelles sont jeunes. Le délai de l'éclosion peut être réglé par une modulation de la température. Les larves obtenues dans ces conditions donnent des imagos fertiles si elles sont implantées dans des chrysalides dePieris brassicae L. ou si elles sont alimentées avec un broyat stérile de ces pupes.

     

Predators ofBathyplectes curculionis [Hym.: Ichneumonidae], a parasite ofHypera postica [Col.: Curculionidae]

Invertebrate predation was shown to be the greatest mortality factor on diapausing larvae ofBathyplectes curculionis (Thomson) in Illinois. Feeding tests were conducted in which specific predators were determined by exposingB. curculionis larvae to various surface dwelling invertebrates found in alfalfa fields. In addition, field plantings of parasite larvae in modified cages were used to determine the size of predators, and also, if litter density affected predation. Seasonal activity ofB. curculionis predators was also measured from 4 April 1975 to 18 November 1975 via 15 pitfall traps located in 3 alfalfa fields. Results from feeding studies showed that spiders,Cicindelidae, Formicidae and smallStaphylinidae never preyed uponB. curculionis larvae in cocoons. The 2 groups of predators which consumed the larvae were field crickets,Gryllus pennsylvanicus Burm., and various species ofCarabidae. Predation on the parasite larvae planted in the field was mainly caused by moderately sized invertebrates, and was not significantly affected by litter density. The greatest number of total predators (G. pennsylvanicus plus Carabids) caught/day/pitfall trap, and the greatest predation on field-plantedB. curculionis larvae, occurred concurrently during September and October. These data suggest that predation during September and October may be significant in reducing field populations of diapausing parasite larvae. Based on feeding studies and pitfall trap catches,Gryllus pennsylvanicus and the carabids,Abacidus permundus (Say),Evarthrus sodalis LeConte,Harpalus pennsylvanicus DeGeer andScarites subterraneus Fab., were the most important predators onB. curculionis larvae.

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Résumé Il a été montré que les prédateurs invertébrés sont le plus grand facteur de mortalité des larves en diapause deBathyplectes curculionis (Thomson) en Illinois. On a fait des essais alimentaires dans lesquels on a déterminé des prédateurs spécifiques en exposant les larves deB. curculionis à divers invertébrés trouvés dans les champs de luzerne. De plus, des larves du parasite, dans des cages modifiées implantées dans les champs, ont été employées pour vérifier la taille des prédateurs et aussi pour savoir si la densité de la litière a influencé les prédateurs. L'activité saisonnière des prédateurs deB. curculionis a été mesurée du 4 avril 1975 au 18 novembre 1975 au moyen de 15 pièges placés dans 3 champs de luzerne. Les résultats des essais alimentaires montrent que les araignées,Cicindelidae, Formicidae et de petitsStaphylinidae n'ont jamais utilisé comme proie les larves en cocon deB. curculionis. Deux groupes de prédateurs ont consommé les larves: les grillons,Gryllus pennsylvanicus Burm., et des espèces variées deCarabidae. Pour la plupart ce sont des invertébrés de taille modérée qui ont utilisé comme proie les larves implantées dans les champs, la densité de litière n'étant pas significative. Le plus grand nombre de prédateurs au total (G. pennsylvanicus plusCarabidae) attrapés par jour et par piège et la plus grande consommation de larves deB. curculionis se sont produits concurremment en septembre et en octobre. Ces données indiquent que les prédateurs en septembre et octobre peuvent être très importants pour réduire le nombre de larves parasites en diapause. Si l'on juge selon les essais alimentaires et selon ce qu'on a attrapé dans les pièges,Gryllus pennsylvanicus et lesCarabidae, Abacidus permundus (Say)tEvarthrus sodalis LeConte,Harpalus pennsylvanicus DeGeer,et Scarites subterraneus Fab., on, constitué les prédateurs spécifiques les plus importants des larves deB. curculionis.

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This publication was supported by the Illinois Natural History Survey, The Illinois Agricultural Experiment Station, National Science Foundation, and the U.S. Environmental Protection Agency, through a grant (NSF GB-34718) to the University of California. The findings, opinions and recommentations expressed herein are those of the author(s) and not necessarily those of the University of California, the National Science Foundation and the Environmental Protection Agency.     

Biologie d'un thrips prédateurAeolothrips intermedius [Thys.: Aeolothripidae]

Résumé élevé à 26°C, 80% HR et sous une photopériode de 16 h, la durée des stades d'Aeolothrips intermedius Bag. est la suivante lorsque la proie estThrips tabaci: L1 2 jours, L2 6 jours, pronymphe 16 jours, nymphe 3, 4 jours. Les larves sont d'excellentes prédatrices, elles piquent leur proie au thorax puis la vident par une piq?re à l'abdomen. Elles tuent plus de proies qu'elles n'en consomment. 3 jours après la 1^re mue la larve tisse un cocon soyeux, sécrétion probable des tubes de Malpighi. L'adulte sort du cocon et doit consommer des tissus floraux pour atteindre sa maturité sexuelle. La fécondité moyenne de la femelle est de 29 œufs avec un maximum de 70. Ceux-ci, généralement isolés, sont insérés dans le tissu des nervures foliaires. Les proies peuvent être des thysanoptères, des acariens, des aleurodes, des psylles mais pas des aphides. On observe 3 ou 4 générations dans la région de Montpellier.

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Summary Aeolothrips intermedius Bag. when reared at 26°C. 80% RH. 16/24 photoperiod, on larvae ofThrips tabaci Lind. has the following duration of the various instars: 1st instar larva 2 days, 2nd 6 days, prepupa 1,6 days, pupa 3,4 days. The 2nd instar larva spins its cocoon alongside the foliar rib of the plant. Adults hatch and need to feed on flowers to reach sexual maturity. The average fecundity of the females is 29 eggs with a maximum of 73. Eggs are laid into the tissues of the foliar rib. Young larvae kill more prey than they feed upon. Three or 4 generations were observed in the field near Montpellier. Parthenogenesis may occur.

     

Genetic variability in arrhenotokous and thelytokous forms ofMesochorus nigripes [Hym.: Ichneumonidae]

Electrophoresis of isozymes was carried out to determine the degree of genetic variability in arrhenotokous and thelytokous forms ofMesochorus nigripes. Although the over-all heterozygosity (H_a) for 12 loci in 10 enzyme systems was 0.187 for the arrhenotokous form and 0.103 for the thelytokous form, a paired comparison t-test showed no significant difference. Nei's coefficient of genetic identity between these 2 forms I=0.982.

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Résumé Afin de déterminer le degré de variabilité génétique chez les formes arrhénotoques et thélytoques deMesochorus nigripes, les isozymes ont été étudiés par électrophorèse. Bien que le taux d'hétérozygotie (H_a), calculé à partir de 12 loci appartenant à 10 systèmes enzymatiques, soit de 0,187 chez la forme arrhénotoque et de 0,103 chez la forme thélytoque, aucune différence significative n'existe selon le test ≪t≫. Le coefficient d'identité génétique de Nei entre ces deux formes est: I=0,982.

     

Biological comparisons between arrhenotokous and thelytokous biotypes ofMesochorus nigripes [Hym.: Ichneumonidae]

The host preferences and sex ratios ofMesochorus biotypes from Sweden and Colorado (U.S.A.) were studied in the field and laboratory. TheseMesochorus are secondary parasites ofBathyplectes spp., parasites ofHypera postica (Gyllenhal). The Colorado biotype is 100% thelytokous, and clearly prefersBathyplectes stenostigma (Thomson) as a host. Only an arrhenotokous biotype was positively detected in Sweden, and it appeared to preferB. curculionis (Thomson). However, some of the data suggest that the thelytokous biotype was probably also present in Sweden, at least inB. stenostigma. The behavioral differences and reproductive isolation of the thelytokous and arrhenotokous biotypes indicate that they are separate sibling species, even though they cannot yet be separated morphologically, and isozyme analyses were inconclusive (possibly due to a mixture of biotypes in Sweden).      

Mating behavior ofBathyplectes curculionis [Hym.: Ichneumonidae] a parasitoid of the alfalfa weevil,Hypera postica Col.: Curculionidae]

We describe the courtship behavior of male and femaleBathyplectes curculionis (Thomson). FemaleB. curculionis are polygamous and sexually receptive for up to 2 days after eclosion. The high activity levels of virgin females combined with their polygamy and long period of sexual receptivity allow for post-dispersal mating which may facilitate maximum gene flow between localB. curculionis populations. This high genetic diversity may be partially responsible for the widespread occurrence ofB. curculionis in North America.

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Résumé Nous décrivons le comportement sexuel deBathyplectes curculionis (Thomson) male et femelle. Les femelles deB. curculionis sont polygames et réceptives 2 jours après l'éclosion. L'activité des femelles vierges et leur polygamie associées à la longue période de réceptivité sexuelle permettent un maximum d'échanges génétiques entre les populations locales. Cette grande diversité génétique peut être en partie responsable de l'étendue de la distribution deB. curculionis en Amérique du Nord.

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Partially supported by funds from both the Department of Entomology and the Graduate School of The Ohio State University.

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Submitted to the Graduate School of The Ohio State University in partial fulfillment of the requirements of the degree of Doctor of Philosophy. Present address: Agricultural Research Center, University of Florida, 3205 S. W. 70th Avenue, Ft. Lauderdale, Florida, U.S.A., 33314.     

Effects ofBathyplectes curculionis andBathyplectes anurus [Hym.: Ichneumonidae] on the growth and development ofHypera postica [Col.: Curculionidae]

Observations, linear measurements, dissections, and histological preparations were made of parasitized and nonparasitized larvae of the alfalfa weevil,Hypera postica (Gyllenhal), on a daily basis. The observed developmental period lasted from 24 h after oviposition byBathyplectes curculionis (Thomson) orBathyplectes anurus (Thomson) until parasite larvae emerged from their hosts. Adult and larval parasites significantly altered growth and development ofH. postica larvae.B. curculionis andB. anurus caused 24 and 29% greater premature mortality in young host larvae than that observed in the unparasitized controls. Rate of development for parasitized larvae during the 1st 12 days was essentially the same as for nonparasitized larvae. Nonparasitized larvae reached maximum size in 17–18 days, whereas larvae parasitized byB. curculionis andB. anurus required 14–21 and 19–22 days, respectively. Larvae parasitized byB. curculionis are smaller in overall lengths, widths and head capsule widths than nonparasitized larvae and those parasitized byB. anurus.     

A taxonomic contribution to the genus Dolichomitus Smith (Hymenoptera,Ichneumonidae, Pimplinae) from?Brazil

In the present study, two new species of Pimplinae, Dolichomitus jatai sp. n. and Dolichomitus moacyri sp. n. are described, and the distribution range of Dolichomitus annulicornis (Cameron, 1886) is extended. The specimens were collected using Malaise traps in areas of Atlantic forest and Brazilian savannah (cerrado) in southeastern Brazil and are deposited in a Brazilian collection (DCBU).     

Seasonal history ofMacrocentrus grandii [Hym.: Braconidae] andEriborus terebrans [Hym.: Ichneumonidae], two parasitoids of the European corn borer,Ostrinia nubilalis [Lep.: Pyralidae]

The seasonal histories and phenological relationships of European corn borer,Ostrinia nubilalis (Hübner), and its 2 parasitoids,Macrocentrus grandii (Goidanich) andEriborus terebrans (Gravenhorst) were studied in southcentral Minnesota. Both parasitoids overwintered in mature borer larvae, broke diapause, completed development, and emerged at the same time as did borer adults. Thus the 1st generation parasitoids coincided with the peak abundance of their preferred larval instars of the 1st host generation. Both parasitoids had a 2nd generation, matching the bivoltinism ofO. nubilatis in Minnesota. The activity of 2nd generationE. terebrans was before the peak 2nd generation borer moth flight and was not synchronized with the peak abundance of 2nd generation borer larvae. The peak activity of 2nd generationM. grandii occurred after the peak 2nd generation borer moth flight and was fully synchronized with the peak abundance of 2nd generation borer larvae. Thus,M. grandii has both generations synchronized with the host seasonal history, and was the more effective of the 2 parasitoids.