Identification of Torymus sinensis and T. beneficus (Hymenoptera: Torymidae), introduced and indigenous parasitoids of the chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae), using the ribosomal ITS2 region

The parasitoid wasps Torymus sinensis and T. beneficus (Hymenoptera: Torymidae) are introduced and indigenous natural enemies, respectively, of the chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae), an invasive pest of chestnuts in Japan. T. beneficus has two emergence types in spring, here tentatively designated as the early-spring strain and late-spring strain. It is very difficult to distinguish these two Torymus species accurately according to their morphological and ecological characteristics. Although the sequences of internal transcribed spacer 2 of the nuclear ribosomal DNA (ITS2) of these parasitoids are very similar, we have developed a pair of primers for amplifying a part of ITS2 that distinguishes species and emergence type. By performing high-resolution electrophoresis of PCR products amplified by this specific primer pair, we have succeeded in accurately identifying T. beneficus (early-spring strain) and some T. sinensis parasitoids. However, this technique was discovered to be inapplicable to identify other T. sinensis and T. beneficus (late-spring strain) parasitoids with the same ITS2 genotype. In spite of this problem, the ITS2 marker appears to be more powerful than any other molecular markers so far reported, since it is applicable to detection of T. beneficus, T. sinensis, and their hybrids.     

Egg parasitoids (Hymenoptera: Mymaridae and Trichogrammatidae) of Kolla paulula (Walker) (Hemiptera: Cicadellidae) in Taiwan

Pseudoligosita nephotetticum (Mani) (Hymenoptera: Trichogrammatidae) and Gonatocerus (Cosmocomoidea) sp. (Hymenoptera: Mymaridae) have been identified for the first time as egg parasitoids of the sharpshooter leafhopper Kolla paulula (Walker) (Hemiptera: Cicadellidae: Cicadellinae: Cicadellini) in Taiwan. K. paulula has been recently identified as a candidate vector of the phytopathogenic bacterium Xylella fastidiosa, the causative agent of Pierce's disease of grapes and similar diseases of other affected plants in Taiwan, and thus has become of particular economic importance. Also provided is a summary of the known records of egg parasitoids (Mymaridae and Trichogrammatidae) of other leafhoppers from the tribe Cicadellini in the world, as well as taxonomic notes on P. nephotetticum.     

The role of parasitoids in regulation of Polistes wasp population (Hymenoptera, Vespidae: Polistinae)

The study conducted in 2005–2010 analyzes the behavioral response of the parasitoids Latibulus argiolus (Rossi) (Hymenoptera, Ichneumonidae) and Elasmus schmitti Ruschka (Hymenoptera, Eulophidae) to the distribution of their host, Polistes wasps (Hymenoptera, Vespidae). Various conditions of the parasitoid-host system and conditions of regulation of the host abundance are discussed. The parasitoid females are more active in wasp colony clusters and tend to infest larger nests. If the parasitoids are abundant, infestation of host colonies starts earlier, sometimes before the worker emergence; therefore, density-dependent behavioral response of parasitoids is caused primarily by the impact of the aggregation component. Thus, the host population density factor appears to be mediated not only by the non-uniform development rates of colonies and their spatial distribution, but also by the seasonal (temporal) aspect of their development. Low density of the host population, at which the parasitoids regulate the wasp abundance, corresponds to a certain phase of the seasonal colony development, namely to the period before the emergence of workers. On the whole, we are dealing with a host-parasitoid system in which the spatial and temporal factors are closely interrelated.     

Aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) in cultivated and non-cultivated areas of Markazi Province, Iran

The fauna of aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae), as well as their diversity and tritrophic (parasitoid-host aphid-host plant) associations in cultivated and non-cultivated areas of Markazi province, was studied during 2004–2009. Thirty species of Aphidiinae belonging to 9 genera were identified. There are presented, in total, 73 associations with 32 host aphids occurring on 42 host plants. Five parasitoid-aphid associations are newly recorded from Iran. Lysiphlebus cardui (Marshall) is newly recorded for the fauna of Iran. Lysiphlebus fabarum (Marshall) and Diaeretiella rapae (M’Intosh) were the most abundant species in non-cultivated (72.96%) and cultivated (41.17%) areas, respectively. In the non-cultivated areas, L. fabarum was found on eight aphid species, while in cultivated areas it was only found on Aphis craccivora Koch. In cultivated areas, Sitobion avenae (F.) has the greatest diversity of parasitoids (Shanon-Weiner H = 0.875) whereas in non-cultivated areas the greatest diversity of parasitoids was recorded upon Acyrthosiphon pisum (Harris) (Shanon-Weiner H = 1.149). Significant differences were found between diversity of two ecosystems based on the overall diversity indices. Both species diversity and evenness were greater in cultivated ecosystems. The results are discussed in relation to the over-all parasitoid-aphid-plant associations in the area.     

Compatibility of Insect Growth Regulators with Eretmocerus eremicus (Hymenoptera: Aphelinidae) for Whitefly (Homoptera: Aleyrodidae) Control on Poinsettias: I. Laboratory Assays

The compatibility of five insect growth regulators (IGRs), buprofezin, pyriproxyfen, fenoxycarb, pymetrozine, and kinoprene, were tested in the laboratory for compatibility with the whitefly parasitoid Eretmocerus eremicus Rose and Zolnerowich (Hymenoptera: Aphelinidae). The survivorship of adult parasitoids foraging on poinsettia leaves with residues 6, 24, and 96 h of age was determined. The toxicity of Bemisia argentifolii Bellows and Perring (Homoptera: Aleyrodidae) patches treated with IGRs presented to female parasitoids 24 and 96 h posttreatment was quantified. Survivorship of immature E. eremicus developing within B. argentifolii nymphs was determined by treating whitefly nymphs with IGRs 5 and 13 days postoviposition by female parasitoids. Finally, behavioral observations of female parasitoids foraging on IGR-treated and untreated B. argentifolii patches presented simultaneously were quantified to determine whether IGR residues had a repellant effect toward E. eremicus. Averaging ranks for IGRs based on their compatibility with E. eremicus and their ability to kill B. argentifolii nymphs produced the following parasitoid compatibility order: buprofezin > fenoxycarb > pymetrozine = pyriproxyfen > kinoprene. Further work in greenhouses assessing the efficacy of buprofezin with E. eremicus for B. argentifolii control on poinsettias is recommended.     

Cardinium in Plagiomerus diaspidis (Hymenoptera: Encyrtidae)

The bacterial symbiont Cardinium (Bacteroidetes) was previously implicated in the thelytokous reproduction of the parasitoid Plagiomerus diaspidis Crawford (Hymenoptera: Encyrtidae). Horizontal transmission of the symbiont among the cactus scale Diaspis echinocacti Bouché (Homoptera: Diaspididae) and its hymenopteran parasitoids has been suggested. In this study, the bacteria associated with D. echinocacti, its parasitoids P. diaspidis and Aphytis sp. (Hymenoptera: Aphelinidae), and the hyperparasitoid Marietta leopardina Motschulsky (Hymenoptera: Aphelinidae) were characterized using molecular fingerprinting techniques, and the localization of Cardinium in P. diaspidis was studied using fluorescence in situ hybridizations (FISH). Cardinium was the only bacterium found in P. diaspidis, but it could not be detected in any of the other insects tested. The symbiont was specifically located in the reproductive tissues of its P. diaspidis host.     

Effect of Dipel (Bacillus thuringiensis) on the survival of immature and adult Hyposoter exiguae (Hymenoptera: Ichneumonidae)

The effects of formulations of Dipel (Bacillus thuringiensis subsp. kurstaki), on immature and adult Hyposoter exiguae (Hymenoptera: Ichneumonidae) were assessed, using Heliothis virescens (Lepidoptera: Noctuidae) as a host. H. exiguae developing in treated hosts had a significantly (p = 0.05) lower percentage of pupation and adult emergence compared to parasitoids developing in nontreated hosts. The mean durations of the pupal and adult stages for parasitoids emerging from treated hosts were not generally affected. After 2 days of exposure, the survival of adult males of H. exiguae fed suspensions containing viable B. thuringiensis spores was significantly lower (p = 0.05) than than the survival of wasps fed either control (sucrose solution), autoclaved Dipel, or inert formulation powder solutions. Survival of H. exiguae fed a low concentration of Dipel was not significantly reduced. Applications of B. thuringiensis in the field would very likely adversely affect immature H. exiguae more than adults, due to premature host death.     

Host specialization is ancestral in Torymus (Hymenoptera,Chalcidoidea) cynipid gall parasitoids

The host range of parasitoids varies greatly among species: Some only parasitize one to a few hosts (specialists), while others parasitize multiple species or a variety of host types (generalists). The direction of most host range shifts in parasitoid groups, that is from generalist to specialist or, alternatively, from specialist to generalist, is unknown. To explore the origin of host range shifts, we studied a clade within the genus Torymus (Hymenoptera, Chalcidoidea) that includes both generalist and specialist parasitoids of Cynipidae (Hymenoptera). We analysed the phylogenetic relationships of the species of Torymus on the basis of two gene fragments (cox1 and ITS2) of 246 specimens and performed an ancestral state reconstruction of the specialist/generalist trait. Our results revealed the following: (a) The ancestral state of this group of Torymus is specialist, with the generalist state evolving through a loss of specialization. (b) The species Torymus cyaneus and Torymus flavipes both have a strong genetic structure, suggesting the existence of different biological identities. (c) There has been a host plant shift in the lineage(s) leading to Torymus rubi and Torymus bedeguaris from galls on Quercus to those on Rosaceae. (d) The alien species Torymus sinensis and the native European species Torymus notatus are phylogenetically closely related. (e) Speciation within Torymus was likely associated with the diversification of their cynipid hosts, which itself was driven by the dramatic changes in climate and vegetation that occurred during the Miocene.     

Dispersion patterns of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) in citrus orchards in southeast Brazil

We studied the dispersion patterns of the exotic endoparasitoid, Diachasmimorpha longicaudata (Ahsmed) (Hymenoptera: Braconidae), in 1999 (summer) and in 2000 (winter) in a citrus orchard in southeast Brazil. Different population densities of D. longicaudata were released in the centre of the orchard, and their dispersion was determined by using yellow, sticky, rectangular traps, placed in various distances and heights around the release point. Our results suggest that during summer, climatic conditions did not affect dispersion. However, in winter, dispersion rates were positively affected by temperature, and negatively by rainfall. Both estimated dispersal distance and surface were higher in summer than in winter for all release densities. Dispersion peaked at 2000 parasitoids ha^?1 in summer and 8000 parasitoids ha^?1 in winter. The importance of our results for the biological control of fruit flies by augmented or innoculative releases of D. longicaudata in southeast Brazil is discussed.     

闭弯尾姬蜂与菜蛾盘绒茧蜂寄生菜蛾幼虫时的种间竞争

在室内25℃下,以菜蛾3龄初幼虫作寄主,研究了菜蛾盘绒茧蜂Cotesia plutellae和半闭弯尾姬蜂Diadegma semiclausum的种间竞争。当寄主供2种蜂同时产卵寄生时,2种蜂各自的寄生率与其单独寄生时无显著差异,合计寄生率比一种蜂单独存在时有所提高,但差异不显著。2种蜂均能产卵寄生已被另一种蜂寄生了的寄主幼虫。当寄主被2种蜂寄生的间隔时间很短（少于10 h）时,所育出的蜂绝大部分（80%以上）为绒茧蜂;当寄主先被绒茧蜂寄生,并饲养2天以上再供弯尾姬蜂寄生时,所育出的全为绒茧蜂;当寄主先被弯尾姬蜂寄生,并饲养2天以上再供绒茧蜂寄生时,寄主幼虫绝大部分不能存活,只有少部分能育出寄生蜂,且多为弯尾姬蜂。当2种蜂的幼虫存在于同一寄主体内时,2种蜂的发育均受到另一种蜂的抑制;绒茧蜂1龄幼虫具有物理攻击能力,能将弯尾姬蜂卵或幼虫致死。这些结果表明,菜蛾盘绒茧蜂与半闭弯尾姬蜂在同一寄主中发育时,前者具有明显的竞争优势。     

Ultrastructure of the natural and factitious host eggs of Trichogramma galloi Zucchi and Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae)

The surface and structure of the chorion of eggs of Diatraea saccharalis (F.) (Lepidoptera: Crambidae), Anticarsia gemmatalis (Huebner), Heliothis virescens F., Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), Sitotroga cerealella (Oliver) (Lepidoptera: Gelechiidae), Ephestia kuehniella Zeller and Corcyra cephalonica Stainton (Lepidoptera: Pyralidae), that are hosts of Trichogramma galloi Zucchi and Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) were studied on SEM and TEM. Other characteristics of these eggs, such as changes in their color during embryonic development, size and volume were also recorded. Sculpturing and texture of the surface of the chorion greatly varied among the species studied, as well as the number of layers of the chorion and their thickness. Eggs of the factitious hosts were among the smallest and their volume was very close to each other. All these characteristics would provide basic information for a better understanding of the host selection behavior and are useful for the development of a suitable artificial host egg for the in vitro rearing of these egg parasitoids.     

Host discrimination by Elasmus schmitti (Hymenoptera, Eulophidae) and Latibulus argiolus (Hymenoptera, Ichneumonidae), parasitoids of colonies of Polistes wasps (Hymenoptera, Vespidae)

The ability to discriminate parasitized and non-parasitized hosts allows the parasitoids to avoid intraspecific and often interspecific competition. In 2005–2009, the incidence of mixed infestation of Polistes nimpha (Christ) colonies by parasitoids Elasmus schmitti Ruschka (Hymenoptera, Eulophidae) and Latibulus argiolus (Rossi) (Hymenoptera, Ichneumonidae) was analyzed. In settlements of different types, the frequencies of mixed infestation deviated from the values expected in case of random distribution. The presence or absence of discrimination ability cannot be confirmed unequivocally based on our material. The data obtained are discussed in relation to the biological features of parasitoids.     

Sensilla on antennae,ovipositor and tarsi of the larval parasitoids,Cotesia sesamiae (Cameron 1906) and Cotesia flavipes Cameron 1891 (Hymenoptera: Braconidae): a comparative scanning electron microscopy study

Two braconid parasitoids of cereal stemborers in eastern Africa, Cotesia sesamiae and Cotesia flavipes, have been shown to display a similar hierarchy of behavioural events during host recognition and acceptance. In order to understand the mechanisms underlying host recognition and acceptance, the morphology of antennal sensilla on the last antennomeres, on the ovipositor, and on the fifth tarsomere and pretarsus of the prothoracic legs tarsi were studied using scanning electron microscopy followed by selective silver nitrate staining. It appeared that female C. sesamiae and C. flavipes shared the same types and distribution of sensory receptors, which enable them to detect volatiles and contact chemical stimuli from their hosts. In both parasitoids, four types of sensilla were identified on the three terminal antennomeres: (i) non-porous sensilla trichodea likely to be involved in mechanoreception, (ii) uniporous sensilla chaetica with porous tips that have gustatory functions, (iii) multiporous sensilla placodea, which are likely to have olfactory function, and (iv) sensilla coeloconica known to have thermo-hygroreceptive function. The tarsi of both parasitoids possessed a few uniporous sensilla chaetica with porous tips, which may have gustatory functions. The distal end of the ovipositor bore numerous dome-shaped sensilla. However, there were no sensilla coeloconica or styloconica, known to have gustatory function in other parasitoid species, on the ovipositors of the two braconid wasps.     

Two new egg parasitoids (Hymenoptera: Encyrtidae) of the wood borer Agrianome spinicollis (Macleay) (Coleoptera: Cerambycidae), a pest of pecans in eastern Australia

Abstract Baeoanusia xanthopleuron sp. n. and Avetianella coombsi sp. n. (Hymenoptera: Encyrtidae) are described from New South Wales and Queensland. Photomicrographs are provided to illustrate morphological characters of both species, and their systematic position is discussed on the basis of their morphology and biology. Both species are egg parasitoids of the wood borer Agrianome spinicollis (Macleay), an important pest of pecans in eastern Australia.     

Male antennal gland of Amitus spiniferus (Brethes) (Hymenoptera : Platygastridae), likely involved in courtship behavior

The functional anatomy of integumentary adjacent glands of the 4th male antennomere, termed male sex-antennomere (MSA4), of Amitus spiniferus (Brethes) (Hymenoptera : Platygastridae), is described. Externally, the lateral side of the MSA4 presents an elliptical, glabrous, and elevated plate with about 20 scattered pores. Internally, there is a glandular area consisting of some 20 isolated, 2-celled secretory units beneath the elevated plate. Each gland has a secretory cell, forming a cuticular receiving canal, and a canal cell, forming the conducting canal, which connects the receiving canal to the external glandular opening. The abundant secretion appears on the cuticular surface in cylindrical forms and as droplets, and probably acts as a recognition and/or an aphrodisiac pheromone during mating. This hypothesis is discussed with regard to behavioral observations reported for only 3 other known cases of similar glands in parasitoids. Modified antennomeres with specialized structures are briefly reviewed, and their secretory function and taxonomic importance in parasitic Hymenoptera, suggested.     

Single-step PCR differentiation of Cotesia sesamiae (Cameron) and Cotesia flavipes Cameron (Hymenoptera: Braconidae) using polydnavirus markers

Cotesia sesamiae (Cameron) and Cotesia flavipes Cameron (Hymenoptera: Braconidae) are the main larval parasitoids of cereal stemborers in sub-Saharan Africa. Cotesia sesamiae is endemic to eastern and southern Africa, while C. flavipes was introduced into the region for biological control against the exotic lepidopteran Chilo partellus (Swinhoe) (Lepidoptera: Crambidae). The two are sibling parasitoids, difficult to distinguish morphologically. The introduced insect could potentially lead its African biotype to extinction because of their similar ecological niche. In order to distinguish the two species, multiplex primer-specific and PCR-RFLP tests were developed. Rapid identification of the two species was possible using primer-specific tests on DNA extracts as well as on pieces of tissue in a single PCR step followed by gel electrophoresis. The CRV1 gene of the polydnavirus, a symbiont to the wasps, was used as the marker. The results show that the morphological identifications, validated by molecular tests, are accurate in 93% of cases.     

Pupal parasitoids (Hymenoptera: Pteromalidae) of muscoid filth flies in Israel

Pupal parasitoids of muscoid flies were collected monthly on three farms in southern Israel in preparation for an IPM programme for the control of filth-breeding flies. 50% and 25.5% of viable puparia collected during 1985 and 1986/87, respectively, were parasitized. Three species of Spalangia Latreille and two species of Muscidifurax Girault & Saunders (Hymenoptera: Pteromalidae) accounted for 82.0% and 94.2% of parasitoids recovered in the two seasons. Variation in the seasonal abundance and distribution of the leading parasite species are discussed in connection with their conservation and possible use for augmentative releases within IPM projects.     

Fitness of Encarsia sophia (Hymenoptera: Aphelinidae) parasitizing Trialeurodes vaporariorum and Bemisia tabaci (Hemiptera: Aleyrodidae)

Abstract Fitness and efficacy of Encarsia sophia (Girault & Dodd) (Hymenoptera: Aphelinidae) as a biological control agent was compared on two species of whitefly (Hemiptera: Aleyrodidae) hosts, the relatively smaller sweetpotato whitefly, Bemisia tabaci (Gennadius) biotype ‘B’, and the larger greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Significant differences were observed on green bean (Phaseolus vulgaris L.) in the laboratory at 27 ± 2°C, 55%± 5% RH, and a photoperiod of 14: 10 h (L: D). Adult parasitoids emerging from T. vaporariorum were larger than those emerging from B. tabaci, and almost all biological parameters of E. sophia parasitizing the larger host species were superior except for the developmental times of the parasitoids that were similar when parasitizing the two host species. Furthermore, parasitoids emerging from T. vaporariorum parasitized more of these hosts than did parasitoids emerging from B. tabaci. We conclude that E. sophia reared from larger hosts had better fitness than from smaller hosts. Those from either host also preferred the larger host for oviposition but were just as effective on smaller hosts. Therefore, larger hosts tended to produce better parasitoids than smaller hosts.     

Survey for parasites ofSesamia calamistis (Lep.: Noctuidae) andEldana saccharina (Lep.: Pyralidae) in southwestern Nigeria

Field surveys were conducted during 1990–92 to document the relative abundance of different species of parasites of the lepidopterous stem borersSesamia calamistis Hampson andEldana saccharina Walker in maize fields in southwestern Nigeria. Species of parasitoids detected on both stem borers included the larvalpupal parasitoidsSturmiopsis parasitica Curran (Diptera: Tachinidae) andBrachymeria feae Masi (Hymenoptera: Chalcididae), and the larval parasitoidDolichogenidea polaszeki Walker (Hymenoptera: Braconidae). The braconidCotesia sesamiae (Cameron) was found attackingS. calamistis. The hyperparasitoidExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) was detected on a pupa ofS. parasitica. Parasitic nematodes belonging toMermis sp. and/orHexamermis sp. were found infesting larvae of both stem borers. Overall, larval/pupal parasitization levels at Ibadan were low and ranged from 4.2 to 22.8% forS. calamistis and 1.2 to 13% forE. saccharina. Of the parasites found,S. parasitica was the most common, followed by nematodes. Four hymenopteran egg parasitoids were found attackingS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, andTrichogrammatoidea eldanae Viggiani (Trichogrammatidae). Egg parasitization ranged from 13.4 to 41.5%. The only egg parasitoid detected onE. saccharina wasTelenomus applanatus Bin and Johnson, which inflicted only 5% parasitization.     

Contrasting patterns of ovarian development and oogenesis in two sympatric host-feeding parasitoids,Diglyphus isaea and Neochrysocharis formosa (Hymenoptera: Eulophidae)

Diglyphus isaea (Walker) and Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae) are common idiobiont parasitoids of leafminers attacking vegetable crops. They exhibit differing levels of synovigeny, and host feeding enhances their fecundity and longevity. The reproductive systems of these two parasitoids are typical of hymenopteran eulophids, consisting of two ovaries, each usually comprising three polytrophic meroistic ovarioles. Diglyphus isaea possesses two obvious oviduct accessory glands, which are absent in N. formosa. Both parasitoids underwent oosorption when starved, while feeding on host larvae promoted oogenesis and egg maturation. In both, oogenesis and vitellogenesis commenced on the first day of the pupal stage rather than after eclosion. Formation of ovarioles in D. isaea commenced 1 day earlier than in N. formosa. Mature eggs were rarely observed in ovaries of newly emerged D. isaea, but usually a few were present in N. formosa. When hosts (second–third instar Liriomyza sativae larvae) were provided, the number of mature eggs in D. isaea ovaries initially increased and then stabilized, while in N. formosa, the number first increased and then decreased. Diglyphus isaea had fewer but larger eggs than N. formosa did. Thus, synovigenic divergence begins at the pupal stage and may result in different life-history traits of adults.