Parasitic hymenoptera fauna on agromyzidae (diptera) colonizing weeds in ecological compensation areas in northern Italian agroecosystems

Parasitoids (Hymenoptera) associated with agromyzid leafminers (Diptera: Agromyzidae) were studied in three rural farms located in northern Italy. The parasitoids were reared from mined foliage of weeds growing in field margins. We reared 998 Hymenoptera specimens, representing five families, 23 genera, and 53 species, from leafminers infesting weeds. Eulophidae was the most abundant family (67.64%), followed by Braconidae (28.86%), Eucoilinae (1.40%), Tetracampidae (1.40%), and Pteromalidae (0.7%). Braconids was the most species rich family, accounting for 28 species; eulophids were represented by 19 species, pteromalids by four species, and eucoilins and tetracampids by one species each. The dominant parasitoid was the eulophid Pediobius metallicus (Nees), representing 18.17% of the total, followed by Diglyphus isaea (Walker) (12.73%), and Neochrysocharis formosa (Westwood) (10.82%). The most abundant braconid parasitoid was Dacnusa maculipes Thomson (9.62%). More than 80% of parasitoids were recovered from 10 plant species: Cirsium arvense (L.) Scopoli, Plantago lanceolata L., Sonchus asper (L.) Hill, Papaver rhoeas L., Picris echioides L., Lactuca serriola L., Myagrum perfoliatum L., Ranunculus velutinus Tenore, Arctium lappa L., and Medicago sativa L. The retention and the management of wild plants within field margins can be crucial tools to enhance the populations of biological control agents of agromyzids and to conserve rare parasitic wasp species.     

Hyperparasitoids of the gum leaf skeletoniser, Uraba lugens Walker (Lepidoptera: Nolidae), with implications for the selection of a biological control agent for Uraba lugens in New Zealand

Abstract  The hyperparasitoids reared from three species of primary parasitoids of the gum leaf skeletoniser, Uraba lugens Walker (Lepidoptera: Nolidae) collected in South Australia and Tasmania are recorded and discussed. Seven hyperparasitoids were reared. Diatora sp. and ? Paraphylax sp. (Ichneumonidae: Cryptinae); Tetrastichus sp. (Chalcidoidea: Eulophidae); Megadicylus dubius (Girault) (Chalcidoidea: Pteromalidae) and Elasmus sp. (Chalcidoidea: Eulophidae) were reared from Cotesia urabae Austin and Allen (Braconidae: Microgastrinae). Megadicylus dubius , Elasmus sp. and Anastatus sp. (Chalcidoidea: Eupelmidae) were reared from Dolichogenidea eucalypti Austin and Allen (Braconidae: Microgastrinae). Pediobius bruchicida (Rondani) (Chalcidoidea: Eulophidae) was reared from Euplectrus sp. (Chalcidoidea: Eulophidae). This appears to be the first record of the cryptine ichneumonid genus Diatora Förster from Australia. Of the seven hyperparasitoid species reared, only one ( P. bruchicida ) is known to be present in New Zealand. Implications for the selection of a biological control agent for U. lugens in New Zealand are discussed. Some prior misidentifications of associated hyperparasitoids are noted.     

A survey of hymenopteran parasitoids of forest macrolepidoptera in the central Appalachians

In 1995 and 1996, we conducted a study of the hymenopteran parasitoids of macrolepidopteran larvae in the George Washington National Forest (GWNF), Augusta County, Virginia, and the Monongahela National Forest (MNF), Pocahontas County, West Virginia. Macrolepidopteran larvae were collected from canopy foliage and from under canvas bands placed around tree boles. A total of 115 macrolepidopteran species and 5,235 individual larvae were reared. Forty-two percent (2,221) of the larvae were gypsy moth, Lymantria dispar (L.) (Lymantriidae). A total of 43 primary and secondary (hyperparasitoid) hymenopteran parasitoid species were reared from 46 macrolepidopteran species. Hymenopteran families represented included Ichneumonidae (23 species), Braconidae (19), Eulophidae (6), Perilampidae (1), and Trigonalidae (1). We reared 41 and 28 parasitoid species from the GWNF and the MNF, respectively, with 19 species reared from both forests. Many parasitoid species were collected infrequently, suggesting that they are relatively rare on the sampled hosts. The introduced species Cotesia melanoscela (Ratzeburg) (Braconidae), and Euplectrus bicolor (Swederus) (Eulophidae) were among the most commonly reared parasitoids, the latter reared from native hosts. The four most commonly reared native parasitoids were Meteorus hyphantriae, Riley (Braconidae), Microplitis near hyphantriae (Ashmead) (Braconidae), Aleiodes preclarus Marsh & Shaw, and Euplectrus maculiventris (Westwood) (Eulophidae). A total of 53 new hymenopteran parasitoid-macrolepidopteran host records were documented. Results from this study will be used to evaluate long-term treatment effects of regional applications of Bacillus thuringiensis kurstaki, and the gypsy moth fungus Entomophaga maimaiga Humber, Shimazu & Soper on hymenopteran parasitoids of macrolepidopteran larvae.     

Native saltbush (Rhagodia spp.; Chenopodiaceae) as a potential reservoir for agromyzid leafminer parasitoids on horticultural farms

Australia has to date been spared the introduction of highly polyphagous invasive pest agromyzid leafminers; however, their arrival and spread should be considered imminent. To develop a pre-emptive control strategy to deal with exotic leafminer outbreaks the first step is to identify Australian leafmining flies, their plant hosts and their parasitoids to gain an understanding of their population dynamics. Native vegetation may be providing resources for beneficial parasitic wasps plus access to alternative hosts and refuge from disturbance. Here, two Australian endemic saltbushes ( Rhagodia candolleana and R. parabolica , Caryophyllales: Chenopodiaceae) have been investigated for their potential to act as reservoirs for endemic agromyzid hosts and their key parasitoids. Mined leaves of the two Rhagodia species were sampled on two commercial horticultural properties in the Virginia horticulture area on the Northern Adelaide Plains between September 2007 and April 2008. Leaf mines on both Rhagodia species were caused by an endemic leafminer species, putatively Phytoliriomyza praecellens Spencer (Diptera: Agromyzidae). Ten species of parasitoids (all Hymenoptera) emerged from R. candolleana mines and seven different species from R. parabolica mines, mainly from the family Eulophidae and with some Pteromalidae and Braconidae. Trigonogastrella Girault sp. (Pteromalidae), Zagrammosoma latilineatum Ubaidillah and Hemiptarsenus varicornis Girault (both Eulophidae) were the most abundant species on R. candolleana , whereas two Opius Wesmael spp. (Braconidae) were the most abundant species on R. parabolica . Findings from this survey suggest an opportunity to plant purpose-designed refuges that could play a role in conservation biological control as part of an Integrated Pest Management strategy developed prior to incursion of pest leafminers such as Liriomyza species.     

Preliminary inventory of parasitoids associated with fruit flies in mangoes,guavas, cashew pepper and wild fruit crops in Benin

Fruit flies are pests of great economic importance due to their quarantine pest status and losses recorded in West Africa. An inventory of parasitoids associated with fruit flies in mangoes, guavas, cashew, pepper and major wild fruit crops was carried out in northern-central Benin in 2005, 2006, and 2008. Tephritid parasitoids reared from field-collected fruits belonged to three families: Braconidae (97.2%), Eulophidae (1.6%) and Pteromalidae (1.2%). Fopius caudatus (Szépligeti) accounted for 73.8% of all the parasitoids and therefore was the most abundant and widely distributed parasitoid. The parasitism rate was 7.7%, with the highest recorded in wild fruit crop habitat. Ceratitis cosyra (Walker) (77%) was the fly host most commonly reared from fruits that produced F. caudatus. The recently introduced pest Bactrocera invadens Drew Tsuruta and White was rarely parasitized and only by Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae) at this time. This is the first report of the inventory of one native parasitoid species from B. invadens in Africa, especially in West Africa.     

Parasitoid Wasps in Flower Heads of Asteraceae in the Brazilian Cerrado: Taxonomical Composition and Determinants of Diversity

This study provides the first survey of the parasitoid fauna reared in flower heads of Asteraceae in the Brazilian cerrado. We investigated the relative importance of herbivore richness and plant species commonness to differences in parasitoid species richness among the plant species. A total of 15,372 specimens from 192 morphospecies belonging to 103 genera of Hymenoptera were reared from the flower heads of 74 Asteraceae species. Chalcidoidea and Ichneumonoidea were the most common superfamilies, with Eulophidae and Braconidae as the main families of parasitoid wasps. Singletons and doubletons accounted for 45% of total parasitoid species richness. The number of parasitoid species per plant species ranged from 1 to 67, and the variation in parasitoid species richness among plants was mainly explained by the number of sites in which the plants were recorded. This study shows that there is a highly diversified fauna of Hymenoptera parasitoids associated with flower heads of Asteraceae in the Brazilian cerrado. Our findings suggest that the accumulation of parasitoid species on plants is mainly determined by the regional commonness of plant species rather than the number of herbivore species associated with the plants.     

Parasitic wasp assemblages associated with native and weedy plant species in an agricultural landscape

Abstract  The establishment and maintenance of suitable habitat on-farm or in the surrounding landscape can enhance the survival of beneficial parasitic Hymenoptera, thus improving the control of pest species. Both endemic and weedy non-crop plant species across a highly modified agricultural landscape supported species-rich and abundant parasitic wasp assemblages with diverse biology and host associations. It was also shown that isolated, recently planted, single-species stands of plants can rapidly accumulate diverse assemblages of parasitoids. Chalcidoidea was the most species-rich and abundant group, egg and larval parasitoids were the most speciose and abundant guilds, and parasitoids of herbivorous insects feeding on and inside plant tissue were the most species-rich and abundant functional groups. The hymenopteran assemblages associated with the majority of plant species were dominated by three parasitoid species: a Trichogrammatidae, a Scelionidae ( Telenomus sp.) and a Eulophidae ( Ceranisus sp.), all genera that contain many important biocontrol agents of pest Lepidoptera, Hemiptera and Thysanoptera. Results show that both native and weedy plant species may potentially provide an important reservoir of mobile parasitic wasps of benefit to crop protection.     

Sunflower stem weevil and its larval parasitoids in the Central and Northern Plains of the USA

The sunflower stem weevil, Cylindrocopturus adspersus (LeConte) (Coleoptera:Curculionidae), is apest of cultivated sunflower (Helianthusannuus L) from the southern to the northernGreat Plains. The incidence of weevilinfestation in fields from the six differentstates sampled during 1996 and 1997 ranged from33% (Minnesota) to 100% (Kansas, Colorado,Nebraska). Weevil populations in the fieldssampled were statistically greater in thecentral Plains (Colorado, Kansas, Nebraska)with a mean of 12.3 and 19.5 larvae per stalkcompared with the northern Plains (North andSouth Dakota, Minnesota) of 0.7 and 1.3 larvaeper stalk in 1996 and 1997, respectively.Parasitization of weevils varied from field tofield ranging from 1 to 100%, but was usuallyless than 20%. The nine species oflarval parasitoids recovered were allHymenoptera and included: Nealioluscurculionis (Fitch), N. collaris(Brues), Bracon sp. (Braconidae); Neocatolaccus tylodermae (Ashmead), Chlorocytus sp., Pteromalus sp.(Pteromalidae); Quadrastichus ainslieiGahan (Eulophidae), Eurytoma tylodermatisAshmead (Eurytomidae); and Eupelmus sp.(Eupelmidae). Nealiolus curculionis wasthe most prevalent parasitoid reared from C. adspersus, and it was recovered from allstates sampled. Parasitoid species richness wasgreatest in the central Plains. Thereduced number of parasitoid species foundattacking C. adspersus in the northernPlains may be caused by low host populationlevels, slow migration by parasitoids into theregion, or lack of adaptation to climaticconditions. Additional work to understandthe population dynamics of the parasitoidcomplex associated with C. adspersus mayresult in improved biological control of thesunflower stem weevil in cultivatedsunflower.     

Plant hosts and parasitoid associations of leaf mining flies (Diptera: Agromyzidae) in the Canberra region of Australia

Abstract  Many leaf mining flies (Diptera: Agromyzidae) are important economic pests of agricultural crops and ornamental plants, and species-rich hymenopteran parasitoid complexes are important in their control. Australian agromyzids are poorly studied, and little is known about their host plants, ecology or natural enemies. We surveyed native and naturalised species of leaf mining flies in Tallaganda National Park, New South Wales and the Australian Capital Territory. Malaise and emergence trapping in Tallaganda yielded 70 agromyzid specimens from six species in four genera: Cerodontha Rondani, Liriomyza Mik, Phytoliriomyza Hendel and Phytomyza Fallen. Of the six species collected, three are Australasian species, two are naturalised species introduced from Europe and one could not be determined to species. The Australian Cerodontha ( Cerodontha ) milleri Spencer represented most of the individuals caught in both Malaise and emergence traps. A total of 163 agromyzid and 98 parasitic wasp specimens were reared from plant samples with agromyzid mines in the Canberra region. Most agromyzids and parasitoids were reared from the weed Sonchus oleraceus L. (Asteraceae). All the agromyzids reared belonged to two introduced species of the genera Phytomyza and Chromatomyia Hardy. The biodiversity of parasitic wasps reared was high with 14 species from seven genera and three families. Hemiptarsenus varicornis (Girault) (Eulophidae), a widespread Old World agromyzid parasitoid, was the most numerous parasitoid reared in our survey.     

Parasitoids ofPlutella xylostella (Lep.: Plutellidae) in South Africa: An annotated list

Larvae and pupae of diamondback moth,Plutella xylostella (L.) (Lepidoptera: Plutellidae), were collected weekly for two years on unsprayed cabbage plots. Samples were taken to the laboratory and parasitoids that emerged were identified and their incidence determined. Parasitoids were active throughout the year and parasitism was high (reaching 90–100%) except in the winter months of June–August when it was low. Twenty one species were reared: the egg-larval parasitoidsChelonus curvimaculatus Cameron and Chelonus sp. (Braconidae); the larval parasitoidsApanteles eriophyes Nixon,Cotesia plutellae (Kurdjumov),Habrobracon brevicornis (Wesmael) (Braconidae) andPeribaea sp. (Tachinidae); the larvalpupal parasitoidsDiadegma sp.,Itoplectis sp. (Ichneumonidae) andOomyzus sokolowskii (Kurdjumov) (Eulophidae); the pupal parasitoidsBrachymeria sp.,Hockeria sp. (Chalcididae),Diadromus collaris Gravenhorst (Ichneumonidae) andTetrastichus howardi (Olliff) (Eulophidae); and the hyperparasitoidsAphanogmus fijiensis (Ferrière) (Ceraphronidae),Brachymeria sp.,Hockeria sp.Proconura sp. (Chalcididae),Mesochorus sp. (Ichneumonidae),Pteromalus sp. (Pteromalidae),Eurytoma sp. (Eurytomidae) andTetrastichus sp. (Eulophidae).     

Native primary parasitoids and hyperparasitoids attacking an invasive aphid Uroleucon nigrotuberculatum in Japan

Since the invasion of Uroleucon nigrotuberculatum from North America we searched for parasitoids of this aphid on Solidago altissima in Japan to determine what species of native parasitoids attack the newly invasive aphid. We found three primary parasitoid species: Ephedrus plagiator and Praon yomenae (Braconidae, Aphidiinae) and Aphelinus albipodus (Aphelinidae). We also found eight hyperparasitoid species: Syrphophagus sp. (Encyrtidae), Dendrocerus carpenteri (Megaspilidae), Asaphes suspensus (Pteromalidae) and Pachyneuron aphidis (Pteromalidae) through both E. plagiator and A. albipodus; Phaenoglyphis villosa (Figitidae, Charipinae), Aprostocetus sp. (Eulophidae, Tetrastichinae) and D. laticeps through E. plagiator, and Alloxysta sp. nr brevis (Figitidae, Charipinae) through A. albipodus. Uroleucon nigrotuberculatum is usually attacked by rather polyphagous primary parasitoids, E. plagiator and A. albipodus, in Japan, where an oligophagous parasitoid specialized to allied aphid species is probably absent. The hyperparasitoid community of U. nigrotuberculatum is common to those of the aphids occurring in open field‐type habitats in Japan.     

Determinants of species richness in southern African fig wasp assemblages

Summary We investigated the species richness of 24 fig wasp (Hymenoptera) assemblages associated with southern African fig trees (Ficus species, Moraceae). Assemblage sizes ranged between 3 and 30 species on different host tree species, with parasitoids slightly outnumbering gall-forming phytophages. Ten potential taxonomic, geographic and ecological determinants of assemblage richness were examined. Galler richness differed significantly between taxonomic sub-groups of Ficus and was significantly correlated with several ecological characteristics of the host trees, but there was no species-area effect. Parasitoid richness was strongly correlated with galler richness. We conclude that both ecological and historical factors have combined to determine the numbers of species that form fig wasp assemblages.     

Importance of long-term research in classical biological control: an analytical review of a release against the cabbage seedpod weevil in North America

Abstract:  Cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (Col., Curculionidae), is an invasive alien pest that is spreading in North America. To aid with planning for introductions of European parasitoids in North America, we examined the status of the only classical biological control release against this pest in North America, which in 1949 introduced Mesopolobus morys , Stenomalina gracilis and Trichomalus perfectus (Hym., Pteromalidae). Weevils and parasitoids were reared in 2005 from mass collections of seedpods of Brassica napus , Brassica rapa and Raphanus raphanistrum (Brassicaceae) from 18 sites in the Fraser Valley, near Vancouver, British Columbia, Canada. Of the three European parasitoid species that were originally released, only S. gracilis was found. The predominant hymenopterous parasitoid species were Trichomalus lucidus , S. gracilis , Mesopolobus moryoides (Pteromalidae), Necremnus tidius (Eulophidae) and Eupelmus vesicularis (Eupelmidae). These constituted over 97% of the parasitoids reared, although overall parasitism was low. Only M. moryoides is clearly North American in distribution; other than S. gracilis , the remaining species were either accidentally introduced or are Holarctic in distribution. Based on these results, re-releases of M. morys and T. perfectus in North America should be considered as part of a classical biological control programme. However, redistribution of S. gracilis is not recommended at present because of potential conflicts with biological control programmes against weeds. Ongoing re-examination of classical biological control programmes can further our understanding of failure of release programmes, particularly when re-examination can be made in the light of improved taxonomy and systematics of the target and agent species.     

Significance of parasitoids in the reduction of oak bark beetle Scolytus intricatus Ratzeburg (Col., Scolytidae) in Serbia

Abstract:  As the vector of vascular fungi of the genus Ophiostoma the oak bark beetle, Scolytus intricatus , is one of the significant links in the chain of agents of oak forest decline in Serbia. It is known that the adults of this bark beetle, which develop under the bark of the trees infected by fungi of the genus Ophiostoma , transport the spores of these fungi. During the maturation feeding, the spores are transmitted to healthy tree crowns, where they germinate and cause infection. In period 1992–96 at 27 localities in Serbia, the significance of parasitoids in the reduction of this bark beetle was examined, as the intensity of spore transmission depends upon the number of oak bark beetle adults in nature. In the research of parasitoids of S. intricatus 20 species were identified in five families of Hymenoptera: Braconidae (six species), Eurytomidae (one), Pteromalidae (10), Eupelmidae (one) and Eulophidae (two). Among these parasitoids the greatest influence on the abundance of oak bark beetle was the species Ecphylus silesiacus . It was identified in 90.91% of study samples, its domination was 39.15% and the percentage of oak bark beetle parasitism was 5.66%. In addition, the species Entendon ergias , Dendrosoter protuberans and Cheiropachus quadrum were significant in reduction of S. intricatus . The average percentage of parasitism of oak bark beetle by E. ergias was 2.74%, by D. protuberans it was 2.63% and by Ch. quadrum 1.63%. The significance of other parasitoids in the reduction of oak bark beetles was low. In the study period the total parasitism of oak bark beetle varied between a minimum of 8.64% in 1992 and a maximum of 19.64% in 1996. The average for the whole study period was 14.49%.     

Parasitons of non-target tephritid flies in hawaii: Implications for biological control of fruit fly pests

We surveyed the parasitoid complex associated with four non-pest tephritid flies in Hawaii,Procecidochares alani Steyskal (on the Island of Hawaii), andEutreta xanthochaeta Aldrich,Phaeogramma lortnocoibon Asquith, andTrupanea dubautiae (Byran) (on the island of Kauai). The former two tephritids are deliberatelyintroduced biological control agents of weeds; and the latter two are endemic to the Hawaiian Islands. Ten species of hymenopterous parasitoids in six families were recovered from these four non-pest tephritids. Among these species of parasitoids, six were inadvertently introduced to Hawaii, includingEurytoma tephritidis Fullaway (Eurytomidae),Bracon terryi (Bridwell) (Braconidae),Habrocytus elevatus (Walker) (Pteromalidae),Euderus metallicus (Ashmead) (Eulophidae),Torymus advenus (Osten Sacken) (Torymidae), andEupelmus allynii (French) (Eupelmidae); and three were purposely introduced to Hawaii for classical biological control of economically important pests, includingEupelmus cushmani (Crawford),Diachasmimorpha tryoni (Cameron), (Braconidae), andDiachasmimorpha longicaudata (Ashmead). The relative abundance of parasitoid species and percent parasitism varied with the tephritid hosts. Our findings indicate that future development and implementation of biological control programs against frugivorous tephritids or other pests should consider the potential impact of some of the parasitoids on deliberately-introduced weed control agents. Before we can fully assess the potential impacts of some of the purposely-introduced parasitoids on non-target tephritids, however, effects of the many vagrant parasitoids associated with the non-targets should be thoroughly investigated     

The parasitoid complex (Hymenoptera, Eulophidae) of the leafminer Phyllonorycter issikii (Kumata) (Lepidoptera, Gracillariidae) from the Middle Volga Basin

In the Middle Volga Basin, Phyllonorycter issikii, an invasive species new to Europe, is attacked by many native parasitoids of the family Eulophidae (the percentages of infestation are given in parentheses): Sympiesis gordius (42), Minotetrastichus frontalis (20), Chrysocharis laomedon (11), Pnigalio soemius (10), S. sericeicornis (8), Apanteles sp. (4), Hissopus geniculatus (4), Entedon sp. (0.4), Aprostocetus sp., Cirrospilus lyncus, C. diallus, C. viticola, and Pteromalidae (0.2). Six species of parasitoids: Aprostocetus sp., C. lyncus (Walker 1838), C. diallus (Walker 1838), C. viticola (Rondani 1877), H. geniculatus (Hartig 1838), and Apanteles sp. (Braconidae), are recorded for the first time. The number of ectoparasitoids is 5.5 times that of endoparasitoids. The second generation of Ph. issikii is reduced by 22% due to parasitoids, and its propagation rate also decreases. However, the climate warming may level the pressure of parasitoids and promote development of the third generation in Ph. issikii.     

Parasites of grass flies (Diptera, Chloropidae) from the order hymenoptera in the Holarctic region

Hymenopterous parasitoids of grass flies of the family Chloropidae from the Palaearctic and Nearctic regions are reviewed. These parasitoids belong to four superfamilies and 16 families of Hymenoptera and were reared from 39 species of Chloropidae in the Palaearctic (less than 6% of the fauna) and only from 10 species in the Nearctic Region. The majority of parasitoids are oligo-or polyphagous species. To a certain degree, the parasitoids are specialized on one of the three host groups: (1) species developing in shoots of cereal and meadow grasses; (2) forest species developing in cones of coniferous trees; and (3) species associated with the common reed, Phragmites australis. In the Palaearctic Region, the majority of parasitoids (91 species) were reared from Oscinella frit L. s. 1.; a significantly smaller number of these parasites is known from this host in the Nearctic Region, nearly half of the parasitoids being common for both regions. The next large group of parasitoids is associated with gall-inducing species of the genus Lipara Meigen (59 species) developing in the common reed. By contrast with two other groups of parasitoids, this one includes many species of the family Ichneumonidae. It should be noted that taxonomic diversity at the third trophic level is markedly greater than at the second level.     

Interactions among three trophic levels and diversity of parasitoids: a case of top-down processes in Mexican tropical dry forest

The objective of this study was to analyze the relationship between plant hosts, galling insects, and their parasitoids in a tropical dry forest at Chamela-Cuixmala Biosphere Reserve in western Mexico. In 120 transects of 30 by 5 m (60 in deciduous forest and 60 in riparian habitats), 29 galling insects species were found and represented in the following order: Diptera (Cecidomyiidae, which induced the greatest abundance of galls with 22 species; 76%), Homoptera (Psylloidea, 6.9%; Psyllidae, 6.9%; Triozidae, 3.4%), Hymenoptera (Tanaostigmatidae, 3.4%; which were rare), and one unidentified morphospecies (3.4%). In all cases, there was a great specificity between galling insect species and their host plant species; one galling insect species was associated with one specific plant species. In contrast, there was no specificity between parasitoid species and their host galling insect species. Only 11 species of parasitoids were associated with 29 galling insect species represented in the following families: Torymidae (18.2%), Eurytomidae (18.2%), Eulophidae (18.2%), Eupelmidae (9.1%), Pteromalidae (9.1%), family Braconidae (9.1%), Platygastridae (9.1%), and one unidentified (9.1%). Most parasitoid species parasitized several gall species (Torymus sp.: 51.1%, Eurytoma sp.: 49.7%, Torymoides sp.: 46.9%). Therefore, the effects of variation in plant defenses do not extend to the third trophic level, because a few species of parasitoids can determine the community structure and composition of galling insect species in tropical plants, and instead, top-down processes seem to be regulating trophic interactions of galling insect species in tropical gall communities.     

Potential for classical biological control of the potato bug Closterotomus norwegicus (Hemiptera: Miridae): description, parasitism and host specificity of Peristenus closterotomae sp. n. (Hymenoptera: Braconidae)

The potato bug, Closterotomus norwegicus (Gmelin) (Hemiptera: Miridae) is an introduced pest of lucerne, white clover and lotus seed crops in New Zealand and a key pest of pistachios in California, USA. Efforts were made to identify potential biological control agents of C. norwegicus in Europe. A total of eight parasitoids, including six primary parasitoids from the genus Peristenus (Hymenoptera: Braconidae) and two hyperparasitoids from the genus Mesochorus (Hymenoptera: Ichneumonidae), were reared from C. norwegicus nymphs collected in various habitats in northern Germany. With a proportion of more than 85% of all C. norwegicus parasitoids, Peristenus closterotomae (Hymenoptera: Braconidae), a new species, was the most dominant parasitoid, whereas other parasitoid species only occurred sporadically. Peristenus closterotomae did not fit in the keys to any described species and is described as new to science. Parasitism caused by P. closterotomae was on average 24% (maximum 77%). To assess the host specificity of parasitoids associated with C. norwegicus, the parasitoid complexes of various Miridae occurring simultaneously with C. norwegicus were studied. Peristenus closterotomae was frequently reared from Calocoris affinis (Herrich-Schaeffer), and a few specimens were reared from Calocoris roseomaculatus (De Geer) and the meadow plant bug, Leptopterna dolobrata (Linnaeus) (all Hemiptera: Miridae). The remaining primary parasitoids associated with C. norwegicus were found to be dominant in hosts other than C. norwegicus. Whether nymphal parasitoids may potentially be used in a classical biological control initiative against the potato bug in countries where it is introduced and considered to be a pest is discussed.     

Parasitism of obliquebanded leafroller (Lepidoptera: Tortricidae) in commercially managed Michigan apple orchards

The obliquebanded leafroller, Choristoneura rosaceana (Harris), is one of the major arthropod pests of apple in the United States. In 1999 and 2000, a survey of the obliquebanded leafroller parasitoid complex in commercially managed apple orchards in Michigan's two largest fruit production regions was conducted to determine the species present and their importance to obliquebanded leafroller population management. In total, 8,961 obliquebanded leafroller larvae were collected of which 2,174 were parasitized. Parasitism increased from the overwintering generation to the summer generation for both regions and both years. In 1999, 11% of the 1,126 overwintering obliquebanded leafrollers collected were parasitized, whereas 28% of the 3,669 summer generation were parasitized. In 2000, 8% of the 489 overwintering obliquebanded leafrollers collected were parasitized, whereas 26% of the 3,677 summer generation obliquebanded leafrollers collected were parasitized. In total, 20 species of hymenopteran and dipteran parasitoids from seven families were recovered from obliquebanded leafroller larvae over the course of the study. The most abundant hymenopteran parasitoids were Bassus dimidiator Nees (Braconidae) comprising 48% of the total parasitoids, followed by Colpoclypeus florus (Walker) (Eulophidae) (8% of the total) and Macrocentrus linearis (Nees) (Braconidae) (2% of the total). Dipteran parasitoids (Tachinidae) accounted for 36% of the parasitism and were largely comprised of Nilea erecta (Coquillett) (5%) and Actia interrupta Curran (13%). These collections represent new host records for B. dimidiator, Bassus annulipes (Cresson) Hyphantrophaga blanda (Osten Sacken), and Compsilura concinnata (Meigen). The parasitoid C. florus is also reported from Michigan for the first time.