侧沟茧蜂属二新种记述（膜翅目：茧蜂科，小腹茧蜂亚科）

记述采自辽宁、宁夏、新疆、浙江和贵州的侧沟茧蜂属Microplitis Foerster 二新种：宽背侧沟茧蜂M. amplitergius sp. nov.和内弯侧沟茧蜂M. incurvata sp. nov.。模式标本保存在浙江大学植物保护系昆虫标本室。     

侧沟茧蜂属一新种及一中国新记录种记述(膜翅目∶茧蜂科∶小腹茧蜂亚科)

本文记述采自吉林省、新疆、山东省和江苏省的侧沟茧蜂属 Microplitis Focrstcr1新种和 1中国新记录种 :方室侧沟茧蜂 Microplitis cubitellanussp.nov.和塔吉克侧沟茧蜂 Microplitistadzhica Telenga 194 9.模式标本保存在浙江大学植物保护系昆虫标本室     

侧沟茧蜂属一新种记述(膜翅目:茧蜂科:小腹茧蜂亚科)

记述采自河北省保定的侧沟茧蜂属Microplitis Foerster1新种:黑腿侧沟茧蜂Microplitis nigrifemur,sp.nov.。模式标本保存在浙江大学植物保护系寄生蜂标本室。     

黑龙江侧沟茧蜂属-新种记述（膜翅目：茧蜂科：小腹茧蜂亚科）

本记述采自黑龙江的侧沟茧蜂属Microplitis Foerster一新种,杨二尾舟蛾侧沟茧蜂Microplitis menciana Xu et He,sp nov.。     

侧沟茧蜂属二新种记述 （膜翅目：茧蜂科，小腹茧蜂亚科）

 记述采自辽宁、宁夏、新疆、浙江和贵州的侧沟茧蜂属Microplitis Foerster 二新种：宽背侧沟茧蜂M. amplitergius sp.nov.和内弯侧沟茧蜂M. incurvata s p.nov.。模式标本保存在浙江大学植物保护系昆虫标本室。     

中国侧沟茧蜂属二新种记述(膜翅目:茧蜂科:小腹茧蜂亚科)

记述采自新疆、江苏、浙江、福建和广西的侧沟茧蜂属Microplitis Foerster2新种;粘虫侧沟茧蜂Microplitis leucaniae sp.nov和祝氏侧沟茧蜂Microplitis chui sp.nov,模式标本保存在浙江大学植物保护系寄生蜂标本室。     

侧沟茧蜂属二新种记述（膜翅目：茧蜂科：小腹茧蜂亚科）

记述采自吉林省、辽宁省、新疆区和江苏省的侧沟茧蜂属Ｍｉｃｒｏｐｌｉｔｉｓ Ｆｏｅｒｓｔｅｒ２新种：北方侧沟茧蜂Ｍｉｃｒｏｐｌｉｔｉｓ ｂｏｒｅａｌｉｓ,ｓｐ．ｎｏｖ．和江苏侧沟茧蜂Ｍｉｃｒｏｐｌｉｔｉｓ ｊｉａｎｇｓｕｅｎｓｉｓ,ｓｐ．ｎｏｖ．。模式标本保存在浙江大学植物保护系昆虫标本室。     

黑龙江侧沟茧蜂属一新种记述(膜翅目:茧蜂科:小腹茧蜂亚科)

本文记述采自黑龙江的侧沟茧蜂属 Ｍ ｉｃｒｏｐ ｌｉｔｉｓ Ｆｏｅｒｓｔｅｒ 一新种,杨二尾舟蛾侧沟茧蜂 Ｍ ｉｃｒｏｐ ｌｉｔｉｓｍ ｅｎｃｉａｎａ Ｘｕ ｅｔ Ｈｅ, ｓｐ． ｎｏｖ．。     

侧沟茧蜂属一新种记述(膜翅目:茧蜂科:小腹茧蜂亚科)

本文记述采自福建福州的侧沟茧蜂属ＭｉｃｒｏｐｌｉｔｉｓＦｏｅｒｓｔｅｒ１新种：暗翅侧沟茧蜂Ｍｉｃｒｏｐｌｉｔｉｓｏｂｓｃｕｒｉｐｅｎｎａｔｕｓ,ｓｐ．ｎｏｖ．。模式标本保存在浙江大学植物保护系昆虫标本室。     

侧沟茧蜂属一新种及一中国新记录种记述（膜翅目∶茧蜂科∶小腹茧蜂 …

本文记述采自吉林省、新疆、山东省和江苏省的侧沟茧蜂属Ｍｉｃｒｏｐｌｉｔｉｓ Ｆｏｃｒｓｔｃｒ１新种和１中国新记录种∶方室侧沟茧蜂Ｍｉｃｒｐｌｉｔｉｓ ｃｕｂｉ９ｔｅｌｌａｎｕｓ ｓｐ．ｎｏｖ．和塔吉克克侧沟茧峰Ｍｉｃｒｏｐｌｉｔｉｓ ｔａｄｚｈｉｃａ Ｔｅｌｅｎｇａ １９４９．模式标本保存在浙江大学植物保护系昆虫标本室。     

TWO NEW SPECIES OF MICROPLITIS FOERSTER (HY‐MENOPTERA: BRACONIDAE) FROM CHINA*

Abstract The present paper describes two new species of Microplitis Fcerster 1862, viz: Microplitis zhaoi Xu et He sp. nov. and Microplitis choui Xu et He sp. nov. The type specimens are deposited in Zhejiang University, Hangzhou, China. 1. Microplitis zhaoi sp. nov. is described from Fujian and Zhejiang Provinces in China closely related to Microplitis malimba Papp, but differs from the latter in the combination of the following features: 1) l‐R1 shorter than stigma; 2) sternites 1–3 yellowish white; 3) submarginal cell of hind wing 2 times as long as basal width and 4) r as long as 2‐SR. 2. Microplitis choui sp. nov. is described from Shaanxi and Gansu Provinces in China closely related to Microplitis zhaoi sp. nov. but differs from the latter in the combination of the following features: 1) r shorter than 2‐SR; 2) sternites 1–3 blackish: 3) tergites 2–3 black; 4) cu‐a of hind wing strongly sloped outward and 5) antenna shorter than body.     

With or without you: Effects of the concurrent range expansion of an herbivore and its natural enemy on native species interactions

Global climatic changes may lead to the arrival of multiple range‐expanding species from different trophic levels into new habitats, either simultaneously or in quick succession, potentially causing the introduction of manifold novel interactions into native food webs. Unraveling the complex biotic interactions between native and range‐expanding species is critical to understand the impact of climate change on community ecology, but experimental evidence is lacking. In a series of laboratory experiments that simulated direct and indirect species interactions, we investigated the effects of the concurrent arrival of a range‐expanding insect herbivore in Europe, Spodoptera littoralis, and its associated parasitoid Microplitis rufiventris, on the native herbivore Mamestra brassicae, and its associated parasitoid Microplitis mediator, when co‐occurring on a native plant, Brassica rapa. Overall, direct interactions between the herbivores were beneficial for the exotic herbivore (higher pupal weight than the native herbivore), and negative for the native herbivore (higher mortality than the exotic herbivore). At the third trophic level, both parasitoids were unable to parasitize the herbivore they did not coexist with, but the presence of the exotic parasitoid still negatively affected the native herbivore (increased mortality) and the native parasitoid (decreased parasitism rate), through failed parasitism attempts and interference effects. Our results suggest different interaction scenarios depending on whether S. littoralis and its parasitoid arrive to the native tritrophic system separately or concurrently, as the negative effects associated with the presence of the parasitoid were dependent on the presence of the exotic herbivore. These findings illustrate the complexity and interconnectedness of multitrophic changes resulting from concurrent species arrival to new environments, and the need for integrating the ecological effects of such arrivals into the general theoretical framework of global invasion patterns driven by climatic change.     

Combined use of herbivore‐induced plant volatiles and sex pheromones for mate location in braconid parasitoids

Herbivore‐induced plant volatiles (HIPVs) are important cues for female parasitic wasps to find hosts. Here, we investigated the possibility that HIPVs may also serve parasitoids as cues to locate mates. To test this, the odour preferences of four braconid wasps – the gregarious parasitoid Cotesia glomerata (L.) and the solitary parasitoids Cotesia marginiventris (Cresson), Microplitis rufiventris Kokujev and Microplitis mediator (Haliday) – were studied in olfactometers. Each species showed attraction to pheromones but in somewhat different ways. Males of the two Cotesia species were attracted to virgin females, whereas females of M. rufiventris were attracted to virgin males. Male and female M. mediator exhibited attraction to both sexes. Importantly, female and male wasps of all four species were strongly attracted by HIPVs, independent of mating status. In most cases, male wasps were also attracted to intact plants. The wasps preferred the combination of HIPVs and pheromones over plant odours alone, except M. mediator, which appears to mainly use HIPVs for mate location. We discuss the ecological contexts in which the combined use of pheromones and HIPVs by parasitoids can be expected. To our knowledge, this is the first study to show that braconid parasitoids use HIPVs and pheromones in combination to locate mates.     

Response of females of the braconid parasitoid Microplitis demolitor to frass of larvae of the Noctoids, Heliothis zea and Trichoplusia ni and to 13-methylhentriacontane

Microplitis demolitor Wilkinson, a solitary larval parasitoid of several species of Noctuidae, has been imported into the United States from Australia. A closely related species, Microplitis croceipes (Cresson), is native to the United States. The host-selection behavior of M. demolitor females is similar to that of M. croceipes in that it is stimulated by kairomones (including 13-methylhentriacontane) in the frass of Heliothis zea (Boddie) larvae, larval diet affects the kairomonal activity of the frass, and exposure to frass prior to release stimulates host-selection behavior. M. demolitor females also respond to frass from Trichoplusia ni (Hübner) larvae that had fed on Pink Eye Purple Hull Cowpea cotyledons.

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Réponse de femelles de Microplitis demolitor sur la nourriture de chenilles de noctuelles et sur 13-methylhentriacontane

Résumé Microplitis demolitor, un parasitoïde solitaire de plusieurs espèces de chenilles de noctuelles, a été introduit d'Australie aux Etats-Unis comme agent potentiel de contrôle biologique. Les fèces des chenilles d'Heliothis zea et Trichoplusia ni élevées sur des cotyledons de pois (Pink Eye Purple Hull Cowpea) stimulent les femelles à sélectionner un hôte, mais les fèces des chenilles des deux espèces élevées sur diète CSM ne possèdent pas cette activité. Un extrait hexanique des fèces des chenilles de H. zea élevées sur cotyledons de pois stimule également ce comportement, de même que le 13-methylhentriacontane, substance présente dans les fèces des chenilles de H. zea (Jones et al., 1971). Les femelles de M. demolitor exposées immédiatement avant leur lâcher en serre aux fèces des chenilles de H. zea, nourries de cotyledons de pois, parasitent un plus fort pourcentage (41.7%) de chenilles de H. zea que cells qui n'ont pas été exposées aux fèces (13.9%).Le comportement de sélection de l'hôte des femelles de M. demolitor est donc semblable à celui des femelles de Microplitis croceipes, un parasitoïde étroitement apparenté indigène des Etats-U-nis. La femelle, par exemple, est stimulée par une kairomone des fèces des larves de H. zea nourries sur des cotyledons de pois (incluant le 13-methyl-hentriacontane), la diète affecte l'activité kairomonale des fèces, et une exposition préalable aux fèces avant le lâcher stimule le comportement de sélection de l'hôte.La stimulation du comportement de sélection de l'hôte, au moment du lâcher peut être utilisée pour améliorer l'efficacité des lâchers des parasitoïdes dans les programmes de contrôle biologique.

     

Intrinsic competition and its effects on the survival and development of three species of endoparasitoid wasps

In natural systems, pre‐adult stages of some insect herbivores are known to be attacked by several species of parasitoids. Under certain conditions, hosts may be simultaneously parasitized by more than one parasitoid species (= multiparasitism), even though only one parasitoid species can successfully develop in an individual host. Here, we compared development, survival, and intrinsic competitive interactions among three species of solitary larval endoparasitoids, Campoletis sonorensis (Cameron) (Hymenoptera: Ichneumonidae), Microplitis demolitor Wilkinson, and Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), in singly parasitized and multiparasitized hosts. The three species differed in certain traits, such as in host usage strategies and adult body size. Campoletis sonorensis and M. demolitor survived equally well to eclosion in two host species that differed profoundly in size, Pseudoplusia includens (Walker) and the larger Heliothis virescens (Fabricius) (both Lepidoptera: Noctuidae). Egg‐to‐adult development time in C. sonorensis and M. demolitor also differed in the two hosts. Moreover, adult body mass in C. sonorensis (and not M. demolitor) was greater when developing in H. virescens larvae. We then monitored the outcome of competitive interactions in host larvae that were parasitized by one parasitoid species and subsequently multiparasitized by another species at various time intervals (0, 6, 24, and 48 h) after the initial parasitism. These experiments revealed that M. croceipes was generally a superior competitor to the other two species, whereas M. demolitor was the poorest competitor, with C. sonorensis being intermediate in this capacity. However, competition sometimes incurred fitness costs in M. croceipes and C. sonorensis, with longer development time and/or smaller adult mass observed in surviving wasps emerging from multiparasitized hosts. Our results suggest that rapid growth and large size relative to competitors of a similar age may be beneficial in aggressive intrinsic competition.     

Foraging Efficacy of a Larval Parasitoid in a Cotton Patch: Influence of Chemical Cues and Learning

Plant-herbivore chemical signals and behavioral plasticity may enhance parasitoid host-foraging efficacy in the field; however, no studies have quantified the potential benefits from these factors under field-type conditions. The effect of plant-herbivore signals and learning on the foraging efficacy of Microplitis croceipes was quantified by directly observing and recording total and sequential duration of various foraging behaviors relative to 5 randomly placed herbivore-damaged and host-infested cotton plants and 20 undamaged and non-host-infested plants. Microplitis croceipes spent significantly more time searching (flying and antennation) on host infested versus uninfested plants. Antennation time was significantly and negatively correlated with successive host stings. Contrary to expectations of increased duration, flight time remained constant throughout the foraging bout, which may indicate that there was some learning associated with flight. These results suggest that plant-herbivore chemical signals and learning enhances the foraging efficacy of M. croceipes.     

Intraspecific host discrimination and larval competition inMicroplitis croceipes,Microplitis demolitor,Cotesia kazak (HYM.: Braconidae) andHyposoter didymator HYM: Ichneumonidae), parasitoids ofHeliothis virescens (LEP.: Noctuidae)

Intraspecific host discrimination and larval competition were studied forMicroplitis croceipes (Cresson),Microplitis demolitor Wilkinson,Cotesia kazak (Telenga), andHyposoter didymator (Thunberg), solitary endoparasitoids of the tobacco budworm,Heliothis virescens (F.). In ovipositional choice tests between unparasitized and parasitized hosts, the mean number of ovipositions for unparasitized hosts was significantly higher than the mean number of ovipositions for hosts parasitized once by a conspecific female forC. kazak andH. didymator, demonstrating that females of these two species discriminate against hosts recently (within a few seconds) parasitized by a conspecific female. No significant difference in oviposition occurred between these two kinds of hosts forM. croceipes andM. demolitor. Mean percent parasitization by a second conspecific female was determined at 24, 48, and 72 h delays in time between the first and second female attack, and with no delay. Except for the 0 h time delay forC. kazak andH. didymator, percent parasitization by a second conspecific female generally decreased as the delay in time between the first and second female attack increased. When the second parasitization immediately followed the first, one parasitoid larva always eliminated the other by physical combat. With a 24 or 48 h delay between the first and second parasitization, the younger larva was the victor over the older larva forM. croceipes, M. demolitor andC. kazak in at least 50% of the cases. Elimination of older larvae by younger larva was by physical attack. However, forH. didymator, the older instar was the victor, and elimination of younger larvae by older larvae was probably through physiological processes. Further, older larvae ofH. didymator apparently killed the eggs of the second female by physiological processes.      

Effects of bacterial contamination on development ofMicroplitis croceipes [Hym.: Braconidae]

Bacterial contaminants ofHeliothis virescens (F.) influenced the development ofMicroplitis croceipes (Cresson). Among the four bacterial species studied, the most virulent wasPseudomonas maltophilia Hugh and Ryschenkow followed byBacillus subtilis (Ehrenberg) Cohn. Both bacteria caused severe mortality in all stages ofMicroplitis tested.Microplitis larvae were less susceptible toEscherichia coli (Migula) Castellani and Chalmers andLeuconostoc mesenteroides (Tsenkovskii) van Thieghem than toB. subtilis andP. maltophilia. AlthoughE. coli did not affect the number of cocoons produced, adult emergence was lower than in controls. Longevity of adultMicroplitis exposed to bacterially contaminated honey-water was greatly reduced in all bacterial treatments.      

Intrinsic and extrinsic competitive interactions between two larval parasitoids of Heliothis virescens

1. Competition between parasitoid species may be a key factor in the community dynamics of plant–herbivore-parasitoid systems and is an important consideration in the selection and management of effective biological control agents. 2. Interspecific competition can occur between adult parasitoids searching for hosts (extrinsic competition) and between multiple parasitoid larvae developing within a single host individual (intrinsic competition). A model system comprising the lepidopteran pest Heliothis virescens and two key hymenopteran endoparasitoids, Microplitis croceipes and Cardiochiles nigriceps, was employed to explore parasitoid host-location strategies and the consequences of intrinsic and extrinsic competitive interactions between parasitoid species. 3. The less specialised of the two parasitoids, M. croceipes, was found to have a shorter hatching time and to dominate intrinsic competition, except when its oviposition followed that of the more specialised parasitoid, C. nigriceps, by 16 h or more. This interval corresponded to the differential in hatching time between the two species. 4. Cardiochiles nigriceps, however, displayed superior host-searching efficiency that may compensate for its disadvantage in intrinsic competition. This parasitoid was more effective at detecting host infestation sites via airborne odours and at locating and attacking early instar host larvae than was M. croceipes.     

Humidity‐terminated diapause in the tropical braconid parasitoid Microplitis demolitor

1. Microplitis demolitor, a solitary braconid parasitoid of Helicoverpa armigera and Helicoverpa punctigera, uses an increase in relative humidity to signal the end of diapause and the re‐establishment of direct development. 2. Photoperiod and temperature changes appear not to have a direct influence on the duration or termination of diapause in this species. 3. Once diapause termination is signalled, the adult parasitoids emerge approximately 38 days later. 4. The cue for diapause termination in M. demolitor is different from that used by its hosts and ensures that the parasitoid emerges to find a population of nonmigrating hosts. 5. It appears that the cocoon surrounding the diapausing parasitoid plays a role in diapause termination; parasitoids emerge earlier from diapause if the cocoon is removed but the weight of the intact cocoon does not appear to influence the length of time the parasitoid is in diapause.