Endoparasitoids of larval Anomis privata (Lepidoptera: Noctuidae), major pest of Hibiscus syriacus (Columniferae: Malvaceae)

Endoparasitoids of Anomis privata larvae include five species in three families of two orders. In this work, two species of Hymenoptera Braconidae (Cotesia sp., Microplitis sp.), one species of Ichneumonidae (Mesochorus vittator) and two species of Diptera Tachinidae (Exorista (Podotachina) sorbillans, Timavia amoena) were investigated. Of the 261 larvae of A. privata examined, 32 had a parasite, so the rate of parasitism was 12.26%. Parasitism by taxon was the highest, at 10.35% (27 individuals), in Cotesia sp. in Hymenoptera Braconidae. Parasitoids of Braconidae and Ichneumonidae were larval parasitoids. A parasitic insect of Tachinidae was a larva–pupal parasitoid. Solitary parasitoids included Microplitis sp. in Braconidae and E. sorbillans in Tachinidae. Gregarious parasitoids included Cotesia sp. in Braconidae, M. vittator in Ichneumonidae and T. amoena in Tachinidae. There was also a multiparasitoid (T. amoena) and two superparasitoids (Cotesia sp., M. vittator). A larva of A. privata sought feed even after it was parasitized every parasitoid investigated in this study, so five species of parasitoids were all koinobiont.     

Taxonomic review and key to European Ichneumon flies (Hymenoptera, Ichneumonidae), parasitoids of gall-forming sawflies of the genera Pontania Costa, Phyllocolpa Benson, and Euura Newman (Hymenoptera, Tenthredinidae) on willows: Part I

Extensive material on parasitoids of the family Ichneumonidae reared from gall-making sawflies on Salix is identified. The general host—parasite list includes 75 species of hosts—Pontania (40 spp.), Phyllocolpa (21 spp.), Euura (14 spp.), their food plants (33 species of Salix), and their parasitoids of the family Ichneumonidae; many data on hosts and parasitoids are recorded for the first time. The complex of ichneumonids on gallforming sawflies is composed of about 45 species belonging to 15 genera of 6 subfamilies. The annotated list of about 30 species of ichneumonids (except for species of Saotis) reared from gall-making sawflies is given with data on the literature, studied material, distribution, and hosts. Two new species Anoncus gallicola sp. n. and Rhinotorus brachycerus sp. n. are described. A key to the species of the Ichneumonidae of this complex is given.     

Ozone‐induced stomatal sluggishness changes stomatal parameters of Jarvis‐type model in white birch and deciduous oak

• Stomatal ozone flux is closely related to ozone injury to plants. Jarvis‐type multiplicative model has been recommended for estimating stomatal ozone flux in forest trees. Ozone can change stomatal conductance by both stomatal closure and less efficient stomatal control (stomatal sluggishness). However, current Jarvis‐type models do not account for these ozone effects on stomatal conductance in forest trees.
• We examined seasonal course of stomatal conductance in two common deciduous tree species native to northern Japan (white birch: Betula platyphylla var. japonica ; deciduous oak: Quercus mongolica var. crispula ) grown under free‐air ozone exposure. We innovatively considered stomatal sluggishness in the Jarvis‐type model using a simple parameter, s , relating to cumulative ozone uptake (defined as POD : phytotoxic ozone dose).
• We found that ozone decreased stomatal conductance of white birch leaves after full expansion (?28%). However, such a reduction of stomatal conductance by ozone fell in late summer (?10%). At the same time, ozone reduced stomatal sensitivity of white birch to VPD and increased stomatal conductance under low light conditions. In contrast, in deciduous oak, ozone did not clearly change the model parameters.
• The consideration of both ozone‐induced stomatal closure and stomatal sluggishness improved the model performance to estimate stomatal conductance and to explain the dose–response relationship on ozone‐induced decline of photosynthesis of white birch. Our results indicate that ozone effects on stomatal conductance (i.e . stomatal closure and stomatal sluggishness) are crucial for modelling studies to determine stomatal response in deciduous trees, especially in species sensitive to ozone.

     

Aggregation in field parasitoid populations: foraging time allocation by a population of Diadegma (Hymenoptera, Ichneumonidae)

ABSTRACT.

• 1 A field study was made of foraging time allocation by a population of parasitic wasps, Diadegma spp. (Ichneumonidae), to plants containing different densities of their hosts, the caterpillars of Plutella xylostella (L.).
• 2 The parasitoid population exhibited a clear aggregative response, spending more total time on higher density patches, which probably resulted from wasps making more and longer visits to these densities.
• 3 Despite this aggregation, positive density dependent parasitism was not found. The functional response of the Diadegma population exhibited an upper asymptote at high host densities, probably due to an increase in the proportion of time spent handling hosts, which countered the effect of aggregation.
• 4 While Diadegma may select and forage preferentially on plants with higher host density, they do not exhibit the tendency, predicted by some optional foraging models, to exploit progressively less profitable plants during a foraging bout. Some factors affecting patterns of parasitoid foraging in the field are discussed.

     

Morphological, palaeontological and molecular aspects of ichneumonoid phylogeny (Hymenoptera, Insecta)

Ichneumonoid phylogeny is revised on the basis of morphological, palaeontological and molecular evidence. The only previous formal cladistic study of the phylogeny of the families of the superfamily Ichneumonoidea made many assumptions about what families lower taxa belonged to and was based on a very limited set of characters, nearly all of which were uninformative at family level. We have subdivided both Ichneumonidae and Braconidae into major groups, investigated several new character systems, reinterpreted some characters, scored several character states for extinct taxa by examining impression fossils using environment chamber scanning electron microscopy, and included data for a significant new subfamily of Braconidae from Cretaceous amber of New Jersey. Sixteen different variants of the data set were each subjected to parsimony analysis without weighting and with successive approximations weighting employing both maximum and minimum values of both the retention and rescaled consistency indices. Each analysis resulted in one of seven different strict consensus trees. Consensus trees based on subsets of these trees, selected on the basis of the optimal character compatibility index (OCCI), resulted in an eighth distinct tree. All trees had the Braconidae monophyletic with the Trachypetinae as the basal clade, and also had a clade comprising various arrangements of Apozyginae, the Rhyssalinae group, Aphidiinae and 'other cyclostomes', but relationships among the remaining braconid groups varied between trees. Only one of the consensus trees had the Ichneumonidae (including Tanychorella ) monophyletic. The Eoichneumonidae + Tanychora are the sister group the Braconidae in two of the consensus trees. Paxylommatinae were basal in the clade comprising the Eoichneumonidae + Tanychora and the Braconidae. The preferred tree, based on the highest OCCI was used for interpreting character state transitions.     

Ethanol‐injection induces attacks by ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) on a variety of tree species

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Karyotypes of parasitic Hymenoptera: Diversity, evolution and taxonomic significance

Haploid chromosome numbers (n) of parasitic Hymenoptera (= traditional Parasitica + Chrysidoidea) vary from 2 to 23. However, this range can be subdivided into three intervals with n= 14–23 (less derived parasitic wasps, e.g., some Ichneumonidae and Braconidae as well as Gasteruptiidae), 8–13 (many other parasitic Hymenoptera) and 2–7 (Dryinidae, the majority of Chalcidoidea and some advanced Braconidae, e.g. Aphidiinae). The symmetric karyotype with a relatively high chromosome number (n= 14–17) and the prevalence of biarmed chromosomes must be considered as a groundplan feature of parasitic Hymenoptera. Independent reductions of chromosome numbers (n≤ 10–11) occurred in some groups of the superfamily Ichneumonoidea as well as in the common ancestor of the Proctotrupoidea sensu lato, Ceraphronoidea, Cynipoidea and Chalcidoidea. Further multiple decreases in chromosome numbers (n≤ 4–6) took place in some Braconidae, various lineages of the superfamily Chalcidoidea as well as in the family Dryinidae. Two main trends prevailed in the karyotype evolution of parasitic wasps: the reduction of chromosome numbers (mainly due to tandem fusions and less frequently due to centric ones) and karyotypic dissymmetrization (through an increase in size differentiation of chromosomes and/or in the share of acrocentrics in a chromosome set). Although karyotypic features of parasitic Hymenoptera can be used for solving taxonomic problems at various levels, this method is the most effective at the species level.     

Conserving natural enemies with flowering plants: Estimating floral attractiveness to parasitic Hymenoptera and attraction’s relationship to flower and plant morphology

Flowering plants in agricultural landscapes can provide ecological services, such as nectar-provision for adult parasitic Hymenoptera. Various flowering native, introduced/established and cultivated potted plants were used to bait interception traps along the wooded margins of fields planted seasonally with either feed-corn or rye. Depending on circumstances, controls consisted of traps baited with the same species of plant without flowers, a pot/area without plants, or both. In most cases pots were rotated among trap-sites. Of the 19 plant species tested, 10 captured significantly more summed ichneumonoids and chalcidoids, seven more Braconidae, two more Ichneumonidae and six more Chalcidoidea than controls. Among Braconidae, traps baited with certain plants captured significantly more individuals of specific subfamilies. “Attractive” and “unattractive” plant species tended to cluster in a principal components vector space constructed from plant morphological characteristics (flower width, flower depth, flower density and plant height). Flower width and plant floral-area (flower width² * flower density) were the variables that most often explained the variance in capture of the different parasitoid taxa. Our study identified particular plants that could be incorporated into regional conservation biological control programs to benefit parasitoid wasps In addition, the results indicate that morphological characteristics might help identify further suitable plant candidates for agricultural landscape modification.     

Diversity of Microgastrinae (Hymenoptera: Braconidae) in apple orchards of southern Quebec,Canada

This study reports the Microgastrinae (Hymenoptera: Braconidae) species collected from two blocks of apple trees from 1993 to 1994 in southern Quebec, Canada. The habitat management block (HMB) had companion flowering plants within the block, whereas the control had no flowering plants. Thirty-six Microgastrinae species were identified including three new records for Canada: Apanteles tischeriae Viereck, Cotesia crambi Weed, Diolcogaster bakeri Muesebeck. The number of microgastrine varied considerably between the two blocks and years. Species numbers were similar between the two blocks, but the Shannon diversity and Evenness similarity indices indicated that HMB had a more diverse and balanced population of Microgastrinae. Matching our microgastrine identifications with literature records showed that the wasps could potentially parasitize over one-third of the lepidopteran pests of apples and/or other lepidopteran species recorded within this agro-ecosystem. The inclusion of four Asteraceae companion plant species in the HMB enhanced the diversity of Microgastrinae.     

Plant richness and blooming cover affect abundance of flower visitors and network structure in Colombian orchards

1. Pollination is essential to fruit production. How plant diversity and blooming events in and around orchards affect the pollinator community and the plant-flower-visitor network in neotropical systems remains largely unknown.
2. We surveyed the flower visitors in deciduous fruit trees and alternative blooming resources (other crops, hedgerows and weeds) in Colombia across 6 orchards over 12 months. We evaluated whether plant species richness and blooming cover influenced abundance and richness of flower visitors, as well as network-level connectance and specialization. We also assessed the role of alternative blooming resources for the flower visitors of deciduous fruit trees.
3. Overall, we found 66 taxa of flower visitors, 35 of which visited deciduous fruit trees. There was a greater abundance of flower visitors when there was higher richness of weedy species and greater blooming cover of deciduous fruit trees. Networks were less connected when there was lower crop and weedy species richness. Finally, flower visitor abundance and specialization increased when there were multiple hedgerow species in bloom with a high blooming cover.
4. We highlight the importance of maintaining alternative blooming resources in and around the orchards to support deciduous fruit tree pollinators and diversity in the plant flower-visitor network.

     

An account of the Chalcidoidea (Hymenoptera) parasitising leaf-mining insects of deciduous trees in Britain

Data on the distribution and frequency of hymenopterous parasites of leaf-mining insects on deciduous trees show that Chalcidoidea of the family Eulophidae are the chief component of the parasite faunas. The regular parasite complement of a leaf-mining species is in the order of 10 to 20 species of parasitic Hymenoptera. Many of these are polyphagous, but in almost all instances a preference for a particular type of host is evident. The parasite faunas of tree leaf-mining Lepidoptera, Coleoptera and Hymenoptera are shown to be qualitatively similar, but those of Diptera are rather different. The parasite faunas of tree leaf-miners are different also from those of leaf gall-forming insects on trees and, to a lesser degree, from those of leaf-miners on herbaceous plants. The parasite fauna associated with a tree genus is quantitatively and qualitatively characteristic and, in general, it most resembles that found on allied tree genera. Congeneric leaf miners attacking the same tree species are attacked by very similar parasite faunas, although mine situation and season of development may exert some influence. These latter factors are considered especially in relation to leaf-miners of the genus Phyllonorycter for which most data are available.     

Discovery of an oak gall wasp (Hymenoptera: Cynipidae) inducing galls on deciduous oak trees in India

We report for the first time the occurrence of an oak gall wasp Andricus mukaigawae (Mukaigawa) (Hymenoptera: Cynipidae) on the deciduous oak Quercus griffithii Hook. F & Thomson ex Miq. in India. Andricus mukaigawae is the only cynipid species that has been observed to induce galls on deciduous oak species in India to date. In addition, this is the first record of a gall wasp species with a distribution extending all the way from the eastern Palearctic region to the Indian subcontinent, suggesting the existence of a close relationship between cynipid faunas on deciduous oak trees in the two regions.     

On the taxonomic position of <Emphasis Type="Italic">Palaeonothrus</Emphasis> Krivolutskii et Sidorchuk 2003 (Insecta: Hymenoptera: Ichneumonoidea,non Acariformes,Oribatida)

The taxonomic position of the genus Palaeonothrus Krivolutskii et Sidorchuk, 2003 described from the Holocene of Arkhangelsk oblast is reconsidered. The fossils, which were originally attributed to moss mites (Acariformes: Oribatida), turned out to be isolated mesonota of some Ichneumonidae or Braconidae wasps, which were impossible to identify more precisely. Consequently, it is proposed to treat the genus Palaeonotrus as Ichneumonoidea incertae sedis until the source insects are identified.     

Effects of the emerald ash borer invasion on the community composition of arthropods associated with ash tree boles in Maryland,U.S.A.

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The effects of foraging ants on arboreal insect herbivores in an undisturbed woodland savanna

ABSTRACT.

• 1 A comparison was made of the insect fauna on paired Terminalia sericea, Burkea africana and Ochna pulchra trees; one tree in each pair was treated with Formex® to exclude ants from the canopy, and the other was designated the control.
• 2 Treatment with Formex banding to exclude ants did not influence plant phenology.
• 3 Pyrethrum knockdown samples from control trees had generally more insect individuals and insect species than samples from trees where ants were excluded.
• 4 Formex-treated trees had significantly less homopterous individuals and species than the control trees.
• 5 With the exception of ants and Homoptera, there was no difference in the insect guild composition and dominance ranking of various insect taxa, sampled by pyrethrum knockdown, between the control and Formex-treated trees.
• 6 T.sericea had significantly greater populations of both sessile and mobile Homoptera on the control trees than on the Formex-treated trees. A similar trend could be seen on B.africana. There were significantly more sessile homopterans on the control trees of O.pulchra than on the Formex-treated trees. Low numbers of mobile Homoptera were recorded on both control and Formex-treated O.pulchra trees, and numbers on control trees were fewer in comparison to numbers of mobile Homoptera on control T.sericea and B.africana trees.
• 7 It is concluded that the ants have similar effects on the insect communities of trees in a natural, undisturbed savanna as has been demonstrated on trees in agro-ecosystems, and on plants that are structurally adapted for mutualistic associations with ants.
• 8 Although slight, leaf damage by some leaf-feeding insects was greater on trees where ants had been excluded than on control trees that supported foraging ant populations.

     

Body size distribution in aphids: relative surface area of specific plant structures

Abstract.

• 1 The distribution of the body sizes of British aphids is right-skewed on a logarithmic axis, as in other taxa. Over the size range 2–5 mm there is a marked decrease in numbers of species with increase in size, which on a log log scale has an exponent of -3, The exponent for the right-hand side of the size distribution of British plants is -0.7.
• 2 The sizes of sixty-eight species of the genus Aphis are weakly correlated with the size of their respective host plants.
• 3 An aphid's size is strongly correlated with the length of its proboscis, which indicates the depth to which it has to probe plant tissues in order to feed.
• 4 On average, trees host more species of aphids than either shrubs or herbaceous plants, which appears to be associated with the relative surface area of specific plant structures. The surface area of plants is mainly made of leaves and most species of aphids are leaf feeders. The largest and least numerous species of aphids feed on the branches and trunks of trees, the proportional cover of which is less than that of leaves.
• 5 Taking into account all the above observations, a functional explanation in terms of the relative surface area of specific plant structures is offered to account for the size diversity curve of aphids.

     

The effect of population density on the reproduction ofTrichogramma japonicum Ashmead (Hymenoptera: Trichogrammatidae)

When a fixed number of the hosts, the eggs of the almond moth were exposed experimentally to various numbers of the parasites, Trichogramma japonicum, the following changes were observed with increasing parasite density:

1. The percentage of parasitism rises and approaches to 100 with gradually diminishing rate.
2. The number of parasite progeny increases and reaches a maximum, then decreases gradually.
3. The number of eggs laid per parasite female decreases gradually.
4. The proportion of hyperparasitized hosts progressively rises. The frequency distribution of parasite eggs in a host is of an intermediate type between random and uniform.
5. The competition among parasite larvae becomes severe. The progressive rise in mortality, the declining percentage of females in progeny and the emergence of stunted adults at the higher densities are observed.

In connection with both the nature of the parasitizing behaviour of adult and that of the competition among larvae, the nature of the density effect on the parasite population was discussed.     

Recognition of the Trachypetidae stat.n. as a new extant family of Ichneumonoidea (Hymenoptera), based on molecular and morphological evidence

The Trachypetinae (type genus Trachypetus Guérin de Méneville) comprise seven species of large-bodied wasps in three genera (Cercobarcon Tobias, Megalohelcon Turner and Trachypetus) endemic to continental Australia. Historically they have been variously treated, as members of the Helconinae in the case of Megalohelcon, or as separate subfamilies (Cercobarconinae and Trachypetinae). Some 25 years ago they were united in a single subfamily, the Trachypetinae, based on a number of characters. Although there has been conflicting evidence from morphological and molecular phylogenetic studies as to how best to treat the group, there has been a growing consensus that they fall outside the rest of the Braconidae, although taxon sampling has been a limiting factor for molecular studies. We generated a molecular dataset comprising five gene fragments (nuclear 28S ribosomal rDNA, nuclear 18S, elongation factor 1-alpha, mitochondrial 16S rDNA, and mitochondrial cytochrome oxidase subunit 1) for a taxonomically broad range of Braconidae, Ichneumonidae, trachypetines and outgroup hymenopterans including the first molecular data for the trachypetines Cercobarcon and Trachypetus obtained using specially designed internal primers. Molecular and combined molecular and morphological analyses confirm the monophyly of the Trachypetinae and robustly place them as sister to the Braconidae. Detailed morphological analysis including newly recognized characters shows that trachypetines lack several synapomorphies that define the Braconidae, and that they possess a number of symplesiomorphies absent from this family but found in some ichneumonids. We conclude that family-level status is warranted for the group based on both molecular and morphological criteria, and hence we propose the new family, Trachypetidae Schulz stat.n. (type genus Trachypetus Guérin de Méneville), for it. As a result, the remaining extant Braconidae become clearly defined based on synapomorphies not present in Trachypetidae stat.n. This published work has been registered on ZooBank, http://zoobank.org/urn:lsid:urn:lsid:zoobank.org:pub:5418F709-D724-4F14-89D8-1E054D1D27D0 .     

Can natural enemies of current insect pests provide biotic resistance to future pests?

1. Economic pests jeopardize agricultural production worldwide. Classical biological control, comprising the import of exotic natural enemies to control target pest populations, has a successful history in many countries. However, little is known about how these natural enemies contribute to the suppression of pests that are yet to arrive. Biotic resistance theory, though, posits that communities resist species invasions as a result of natural enemies.
2. We assessed the potential of the resident exotic parasitoid wasp fauna in New Zealand (intentionally‐introduced biological control agents and unintentionally‐introduced species) to provide biotic resistance against possible future pests. A dataset was generated containing resident exotic parasitoid species (Ichneumonoidea: Braconidae; Ichneumonidae) in New Zealand, as well as their known global host ranges and the pest status of host species, to infer the potential for biotic resistance.
3. The known exotic ichneumonoid fauna in New Zealand comprises 65 species. These species associate with 107 host species in New Zealand, of which 54 species are pests. However, the current exotic species could potentially suppress 442 pest species not yet occurring in New Zealand.
4. This approach could be used to inform pest management programmes worldwide. Future research should consider how biotic resistance from the established parasitoid fauna can be used to inform specific decisions with respect to classical biological control.