Molecular phylogeny and host use evolution of the genus Exorista Meigen (Diptera: Tachinidae)

Members of the genus Exorista are parasitoids of a diverse array of insect hosts in the orders, Lepidoptera, Hymenoptera, Mantodea and Orthoptera. Phylogenetic relationships among subgenera and species of Exorista were inferred using four nuclear (Tpi, white, 18S and 28S) and four mitochondrial DNA (16S, 12S, ND5 and CO1) genes in maximum parsimony (MP), maximum likelihood (ML) and Bayesian Markov chain Monte Carlo (MCMC) analyses. Separate trees based on different sets of genes (mt DNA, nuclear, ribosomal, etc.) were compared and found to be nearly concordant. According to the molecular tree generated from the concatenated sequence data, the genus Exorista is paraphyletic. The phylogenetic analyses indicate the existence of two major clades of Exorista, including two genera Parasetigena and Phorocera. Morphological traits supporting clades indicated by molecular analyses within this genus are evaluated. Evolutionary patterns of the host use and host shifts are examined by optimizing host information using maximum likelihood on the molecular phylogeny. The ancestral host group of the tribe Exoristini (excluding Ctenophorinia and Phorinia) appears to be the order Lepidoptera, although hosts of some species are unknown. A major host shift to the Hymenoptera occurred in the clade of subgenus Adenia, and the ancestral state of subgenus Spixomyia is equivocal because there is little information available on the hosts in members of a subclade of this group (subclade A: Exorista hyalipennis group).     

Ocimum gratissimum Linn. (Lamiaceae) essential oil for the management of Exorista sorbillans Wiedemann (Diptera: Tachinidae) menace of silkworm in seriecosystem

Although they act as biocontrol agents, Tachinid parasitoids attack economically beneficial insects, inviting the adoption of control measures against them. The uzi fly, Exorista sorbillans, infests silkworms incurring heavy loss. It is difficult to control such parasitoids as the larval stage is endoparasitic, and insecticides cannot reach them without subjecting the silkworms to potential risks. We selected the leaves of Ocimum gratissimum L. for testing their toxicity potential against E. sorboillans because of its low selective toxicity to Antheraea assamensis Helfer larvae. Assay for adulticidal efficacy of the leaf extracts showed the petroleum ether extract to be the most effective. But the essential oil (LC50 of 0.42%) was even more effective. GC–MS analysis of the oil revealed the presence of twenty-seven compounds with a high percentage of thymol (26.17%), indicating the plant oil as thymol rich chemotype. Thymol was the dominant constituent in the active fraction. The oil and constituents caused rapid death on topical application, indicating a higher penetration rate. We propose the exploration of the essential oil and its constituents as a sustainable solution for controlling E. sorbillans infestation of silkworms in the future.     

Learning in the Generalist Tachinid Parasitoid Exorista Mella Walker (Diptera: Tachinidae)

Many parasitoids have been shown to learn visual and/or olfactory cues associated with hosts. In contrast to the Hymenoptera, learning in dipteran parasitoids is relatively unstudied. This study explores the ability of a polyphagous tachinid, Exorista mella, to learn to associate visual and olfactory cues with hosts. In an experiment involving colored host models, flies trained on models of one color were subsequently attracted more strongly to models of the color that they had not experienced. The unsuitability of these models as hosts suggested that the flies may have engaged in avoidance learning. Flies demonstrated the ability to learn to associate colored disks with hosts. A separate experiment demonstrated that flies responded to volatile plant compounds but failed to find evidence for odor learning. Learning of host-associated cues by E. mella may allow this generalist parasitoid to take advantage of locally abundant host populations and maintain host-searching efficiency in an environment.     

Annotated check-list of the family Tachinidae (Diptera: Calyptratae: Oestroidea) in the Canary Islands

Summary

A commented check-list of the tachinid species inhabiting the Canary Islands (Spain) is provided, with special emphasis on hosts species and floral resources. Nine new local records are provided and Cylindromyia rufipes is reported for the first time for the Canary Islands, thus increasing the species number to 52. Zoogeographic analysis of the area revealed that there are differences in chorotype composition among islands, with the easternmost islands being richer in Mediterranean species and poorer in endemics. These differences may be due to ecological differences between the easternmost island and the remaining islands. Relevance regarding influence of tachinid as pollinators is discussed.     

A simplified artificial medium for the in vitro rearing of Exorista larvarum (Diptera: Tachinidae)

The standard artificial medium for the parasitoid Exorista larvarum, composed of skimmed milk, yeast extract, egg yolk, sucrose and gentamicin, was simplified by deleting sucrose. Fecund adults were obtained on both the standard and the simplified medium. No difference was found between them for any of the developmental parameters examined.     

有瓣蝇类分类、系统发育及演化

有瓣蝇类(Calyptratae)隶属于昆虫纲(Insecta)四大超适应辐射类群之一的双翅目(Diptera),占双翅目已知物种多样性的近20%。有瓣蝇类分布广泛,生物学习性极为多样,在维系生态系统稳定中发挥着重要作用,是媒介、法医、传粉和天敌昆虫学研究领域的热点类群,也是探究双翅目系统演化及其成功适应辐射的关键类群。为了还原有瓣蝇类的演化历史,许多著名昆虫学者先后对该类昆虫开展过不同层面的研究。有瓣蝇类的单系性得到了普遍支持,并被分为3个总科——虱蝇总科(Hippoboscoidea)、蝇总科(Muscoidea)和狂蝇总科(Oestroidea),其中单系的狂蝇总科与多系的蝇总科聚为一支,再与虱蝇总科成为姐妹群。在科级阶元水平,蝠蝇科(Streblidae)(虱蝇总科)、花蝇科(Anthomyiidae)(蝇总科)、丽蝇科(Calliphoridae)(狂蝇总科)、邻寄蝇科(Rhinophoridae)(狂蝇总科)等类群的单系性仍有待验证,且新的科仍在不断被建立［如粉蝇科(Polleniidae)、乌鲁鲁蝇科(Ulurumyiidae)］,因此,有瓣蝇类科级系统发育关系仍不十分明晰。已有研究对虱蝇总科虱蝇科(Hippoboscidae)、蝠蝇科、蛛蝇科(Nycteribiidae),蝇总科蝇科(Muscidae)、粪蝇科(Scathophagidae),狂蝇总科麻蝇科(Sarcophagidae)、狂蝇科(Oestridae)胃蝇亚科(Gasterophilinae)的演化历史进行研究,明确了起源与扩散、寄主转移、取食策略等关键生物学习性的演化历史。但由于部分关键类群生活史信息的缺失,以及尚未有效解决的系统发育关系,有瓣蝇类演化历史仍有许多待解之谜。本文综述了有瓣蝇类分类、系统发育及演化研究进展,是在系统学研究进入系统发育基因组学时代后对该类群相关研究进展的首次全面总结。     

In vitro rearing of the parasitoid Exorista larvarum (Diptera: Tachinidae) from eggs laid out of host

We evaluated the possibility of using the eggs laid out of host to rear Exorista larvarum (L.) (Diptera: Tachinidae), a larval parasitoid of Lepidoptera, on artificial media. In a first experiment, eggs oviposited on a plastic sheet (either by inexperienced or experienced females) showed the same in vitro hatching capability as those removed from the larvae of the factitious host Galleria mellonella L. Subsequently, eggs laid on the host integument or out of host, either by inexperienced or experienced females, were removed from the oviposition substrate and placed on a skimmed milkbased artificial medium. The percentages of hatched eggs, of puparia and adults, as well as the puparial weights did not differ significantly among the three treatments. These findings suggested that E. larvarum may be successfully reared in vitro with a total exclusion of the host insect. In a further test, no difference for the in vitro hatching time was found between the eggs oviposited either on a plastic sheet or on G. mellonella larvae in the same length of time (60 min). This result suggested that at oviposition the out-of-host eggs were unincubated, similarly to those that had been laid on the host larvae.     

广州南沙港蝇类(双翅目:有瓣蝇类)调查

2007年7月至2009年6月自南沙港诱捕到有瓣蝇类46750头,包括蝇科、麻蝇科、丽蝇科、花蝇科25属45种,其中宽额丽蝇Calliphora latifrons Hough为我国新记录,红头丽蝇Calliphora vicina Robineau-Desvoidy和古铜黑蝇Ophyra aenescens Wiedemann为广东省新记录种.上述3种是近年来国外输入的蝇类.大头金蝇Chrysomya megacephala Fabricius为南沙港区优势种,发生高峰出现在9～10月,4～5月出现次高峰.     

Phylogenetic relationships of subgenera of the genus Exorista Meigen,with a revision of the Japanese species (Diptera: Tachinidae)

Phylogenetic relationships of the subgenera of Exorista Meigen (Diptera: Tachinidae) are inferred from morphological data. Our results show that the genus Exorista is not monophyletic and that members of the subgenus Spixomyia Crosskey are divided into two clades. Each subgenus is redefined based on male and female morphological features. The Japanese species of Exorista are revised and classified into five subgenera: Adenia Robineau‐Desvoidy, Exorista Meigen, Podotachina Brauer and Bergenstamm, Ptilotachina Brauer and Bergenstamm, and Spixomyia Crosskey. Thirteen species are recognized, including two newly recorded species, Exorista (Adenia) cuneata Herting and Exorista (Spixomyia) lepis Chao. Exorista cantans Mesnil is transferred to the subgenus Podotachina from Spixomyia.     

Sensitivity analysis, molecular systematics and natural history evolution of Scathophagidae (Diptera: Cyclorrhapha: Calyptratae)

The 60 000 described species of Cyclorrhapha are characterized by an unusual diversity in larval life‐history traits, which range from saprophagy over phytophagy to parasitism and predation. However, the direction of evolutionary change between the different modes remains unclear. Here, we use the Scathophagidae (Diptera) for reconstructing the direction of change in this relatively small family (≈ 250 spp.) whose larval habits mirror the diversity in natural history found in Cyclorrhapha. We subjected a molecular data set for 63 species (22 genera) and DNA sequences from seven genes (12S, 16S, Cytb, COI, 28S, Ef1‐alfa, Pol II) to an extensive sensitivity analysis and compare the performance of three different alignment strategies (manual, Clustal, POY). We find that the default Clustal alignment performs worst as judged by character incongruence, topological congruence and branch support. For this alignment, scoring indels as a fifth character state worsens character incongruence and topological congruence. However, manual alignment and direct optimization perform similarly well and yield near‐identical trees, although branch support is lower for the direct‐optimization trees. All three alignment techniques favor the upweighting of transversion. We furthermore confirm the independence of the concepts “node support” and “node stability” by documenting several cases of poorly supported nodes being very stable and cases of well supported nodes being unstable. We confirm the monophyly of the Scathophagidae, its two constituent subfamilies, and most genera. We demonstrate that phytophagy in the form of leaf mining is the ancestral larval feeding habit for Scathophagidae. From phytophagy, two shifts to saprophagy and one shift to predation has occurred while a second origin of predation is from a saprophagous ancestor. © The Willi Hennig Society 2006.     

The Muscoidea (Diptera: Calyptratae) are paraphyletic: Evidence from four mitochondrial and four nuclear genes

Approximately 5% of the known species-level diversity of Diptera belongs to the Muscoidea with its approximately 7000 described species. Despite including some of the most abundant and well known flies, the phylogenetic relationships within this superfamily are poorly understood. Previous attempts at reconstructing the relationships based on morphology and relatively small molecular data sets were only moderately successful. Here, we use molecular data for 127 exemplar species of the Muscoidea, two species from the Hippoboscoidea, ten species representing the Oestroidea and seven outgroup species from four acalyptrate superfamilies. Four mitochondrial genes 12S, 16S, COI, and Cytb, and four nuclear genes 18S, 28S, Ef1a, and CAD are used to reconstruct the relationships within the Muscoidea. The length-variable genes were aligned using a guide tree that was based on the protein-encoding genes and the indel-free sections of the ribosomal genes. We found that, based on topological considerations, this guide tree was a significant improvement over the default guide trees generated by ClustalX. The data matrix was analyzed using maximum parsimony (MP) and maximum likelihood (ML) and yielded very similar tree topologies. The Calyptratae are monophyletic and the Hippoboscoidea are the sister group to the remaining calyptrates (MP). The Muscoidea are paraphyletic with a monophyletic Oestroidea nested within the Muscoidea as sister group to Anthomyiidae+Scathophagidae. The monophyly of three of the four recognized families in the Muscoidea is confirmed: the Fanniidae, Muscidae, and Scathophagidae. However, the Anthomyiidae are possibly paraphyletic. Within the Oestroidea, the Sarcophagidae and Tachinidae are sister groups and the Calliphoridae are paraphyletic.     

Larval morphology and anatomy of the parasitoid Exorista larvarum (Diptera: Tachinidae), with an emphasis on cephalopharyngeal skeleton and digestive tract

The endogenous development of the tachinid gregarious larval parasitoid Exorista larvarum L. (Diptera: Tachinidae) has been analyzed in the last larval instar of a factitious host, the wax moth Galleria mellonella L. (Lepidoptera: Pyralidae), with the use of histological techniques and scanning electron microscopy. This study has focused on the parasitoid internal body structures and their changes during the larval development. The first and second instars are enveloped by a host-derived hemocyte capsule attached to the respiratory funnel via a prominent anal hook located between 2 anal lobes. The third instar abandons the respiratory funnel and migrates free in the body cavity of the already dead host. Emphasis is given to the prominent cephalopharyngeal skeleton, highlighting the morphological aspects of its sclerotized as well as non-sclerotized components. In addition to the cephalopharyngeal skeleton, the anterior third of the larval parasitoid body is occupied by large salivary glands, massive proventriculus, and cerebral ganglia. The extensive digestive tract, which occupies the major part of the body, is differentiated into well-marked individual parts. The abdomen is predominantly filled with the extremely long mesenteron that increases in size during the larval development. The whole body is covered by an apparently thin integument, with strong spines that are especially numerous in the anterior and posterior body parts.     

Molecular phylogenetics and piercer evolution in the bug‐killing flies (Diptera: Tachinidae: Phasiinae)

Phasiinae (Diptera: Tachinidae) are endoparasitoid flies that attack Heteroptera, including a multitude of agricultural pests. A phylogenetically informed classification of Phasiinae has eluded systematists for over a century, primarily because of the conflicting character states and confusing morphology of certain taxa that indicate potential placement within other subfamilies. The unstable nature of phasiine taxonomy discourages important research into their classification, life history and potential use in biological control. In hopes of resolving several longstanding taxonomic debates and encouraging future research into this important group of parasitoids, the first molecular systematic analysis of Phasiinae is presented, including 128 worldwide taxa (80 genera) and approximately 7.6 kb of nuclear data representing four genes. Special emphasis is placed on the resolution of taxonomically ambiguous groups. The resulting robustly supported phylogenetic trees [maximum‐likelihood (ML)/Bayesian] were used to trace the evolution of significant adaptive traits within Tachinidae and test hypotheses about the classification of Phasiinae. Subfamily placements of certain taxa are confidently resolved including Eutherini, Epigrimyiini, Litophasia Girschner within Dexiinae, and Strongygastrini and Parerigonini within Phasiinae. The members of tribe Phasiini are redistributed: Cistogaster Latreille, Clytiomya Rondani, Ectophasia Townsend, Eliozeta Rondani and Euclytia Townsend transferred to Gymnosomatini; Opesia Robineau‐Desvoidy to Strongygastrini; and Xysta Meigen to Xystini. Similarly, members of Parerigonini are treated as belonging to Parerigonini (Parerigone Brauer, Zambesomima Walker), Cylindromyiini (Australotachina Curran, Pygidimyia Crosskey, Neobrachelia Townsend) or new tribe Zitini (Zita Curran, Leverella Baranov). Penthosia van der Wulp is transferred from Cylindromyiini to Hermyini. Ancestral state reconstruction suggests that piercing structures used to insert eggs directly into host tissues have evolved separately in a number of groups, but have also been lost or reduced in several lineages. A single potentially unequivocal morphological synapomorphy of Phasiinae, an elongated medial plate of the hypandrium in males, is identified. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:8BE75122‐FC7C‐4809‐AAF7‐19575596EF78 .     

寄生取食Cry1Ab杀虫蛋白的粘虫幼虫对伞裙追寄蝇寄生率及生长发育的影响

【Aim】 To demonstrate the effect of transgenic Bt-crop on the bionomics of the tachinid fly Exorista civilis Rondani, the parasitism rate and life history parameters of E. civilis developed from larvae of the oriental armyworm, Mythimna separata (Walker), fed on artificial diets with Cry1Ab toxin were investigated in laboratory. 【Methods】 M. separata larvae were fed on diets containing 0, 3.125, 6.25, 12.5 and 25 μg/g of Cry1Ab toxin, respectively, and used as the host for E. civilis. The parameters related to the parasitism and the growth and development of E. civilis on the host were observed and recorded. 【Results】 The results showed that the parasitism rate and fecundity of the fly on M. separata larvae feeding on diets containing various doses of Cry1Ab protein were insignificantly different (P≥0.05), suggesting that host selective behavior of the E. civilis is not affected by the dose of Bt-toxin in the caterpillar. The developmental period (egg-larva, pupa, adult oviposition and generation), emergence rate, sex ratio, and fecundity of E. civilis developed from M. separata larvae treated by various concentrations of Cry1Ab toxin were insignificantly different (P≥0.05). However, the survival rate of the maggots in the host feeding on diet containing 3.125 μg/g of Cry1Ab toxin was significantly greater than that of the control and the rest treatments (P<0.05), while insignificantly different among the remained 4 treatments (P≥0.05). The pupal weight significantly declined as the concentration of Cry1Ab toxin fed by their hosts increased (P<0.05). The pupal weight in the control group was 49.8 mg, while that in treatment groups of 6.25 and 25 μg/g Cry1Ab toxin was only 41.0 and 36.7 mg, respectively. 【Conclusion】 These results indicate that parasitizing host M. separata larvae fed with Cry1Ab toxin has no dramatically negative effect on parasitoid E. civilis. This study provides a basis for the evaluation of the risk of transgenic Bt-crops on the tachinid parasitoids in fields.     

The genus Campylocheta (Diptera: Tachinidae) from Japan

Seven new species of Campylocheta are described and illustrated from Japan: abdominalis from Hokkaido, Honshu and Kyushu, flaviceps from Honshu and Tsushima, grisea from Kyushu, argenticeps from Honshu, bisetosa from Hokkaido and Honshu, hirticeps from Hokkaido, Honshu and Tsushima, and suwai from Hokkaido. Campylocheta dentifera Richter and C. umbrinervis Mesnil are redescribed and a key to nine Japanese species is provided.     

A revision of the genus Trixa Meigen （Diptera： Tachinidae）

The genus Trixa Meigen, 1824 is revised. Dexiotrix Villeneuve, 1936 and Trixella Mesnil, 1980, each of which was sometimes treated as a distinct genus, are treated as junior synonyms of Trixa Meigen. Two species from Sichuan and Yunnan, China, are described as new to science, viz. Trixa chinensis sp. nov. and T. chaoi sp. nov. T. alpina Meigen is treated as a junior synonym of T. caerulescens Meigen. T. nox (Shima) and T.pubiseta (Mesnil) are newly recorded from China. Males of T. pubiseta (Mesnil) and T.longipensis (Villeneuve) are described for the first time. Diagnoses, figures and a key to twelve species in Trixa are given.