29 research outputs found

    Resolving cryptic species complexes of major tephritid pests

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    An FAO/IAEA Co-ordinated Research Project (CRP) on “Resolution of Cryptic Species Complexes of Tephritid Pests to Overcome Constraints to SIT Application and International Trade” was conducted from 2010 to 2015. As captured in the CRP title, the objective was to undertake targeted research into the systematics and diagnostics of taxonomically challenging fruit fly groups of economic importance. The scientific output was the accurate alignment of biological species with taxonomic names; which led to the applied outcome of assisting FAO and IAEA Member States in overcoming technical constraints to the application of the Sterile Insect Technique (SIT) against pest fruit flies and the facilitation of international agricultural trade. Close to 50 researchers from over 20 countries participated in the CRP, using coordinated, multidisciplinary research to address, within an integrative taxonomic framework, cryptic species complexes of major tephritid pests. The following progress was made for the four complexes selected and studied: Anastrepha fraterculus complex – Eight morphotypes and their geographic and ecological distributions in Latin America were defined. The morphotypes can be considered as distinct biological species on the basis of differences in karyotype, sexual incompatibility, post-mating isolation, cuticular hydrocarbon, pheromone, and molecular analyses. Discriminative taxonomic tools using linear and geometric morphometrics of both adult and larval morphology were developed for this complex. Bactrocera dorsalis complex – Based on genetic, cytogenetic, pheromonal, morphometric, and behavioural data, which showed no or only minor variation between the Asian/African pest fruit flies Bactrocera dorsalis, B. papayae, B. philippinensis and B. invadens, the latter three species were synonymized with B. dorsalis. Of the five target pest taxa studied, only B. dorsalis and B. carambolae remain as scientifically valid names. Molecular and pheromone markers are now available to distinguish B. dorsalis from B. carambolae. Ceratitis FAR Complex (C. fasciventris, C. anonae, C. rosa) – Morphology, morphometry, genetic, genomic, pheromone, cuticular hydrocarbon, ecology, behaviour, and developmental physiology data provide evidence for the existence of five different entities within this fruit fly complex from the African region. These are currently recognised as Ceratitis anonae, C. fasciventris (F1 and F2), C. rosa and a new species related to C. rosa (R2). The biological limits within C. fasciventris (i.e. F1 and F2) are not fully resolved. Microsatellites markers and morphological identification tools for the adult males of the five different FAR entities were developed based on male leg structures. Zeugodacus cucurbitae (formerly Bactrocera (Zeugodacus) cucurbitae) – Genetic variability was studied among melon fly populations throughout its geographic range in Africa and the Asia/Pacific region and found to be limited. Cross-mating studies indicated no incompatibility or sexual isolation. Host preference and genetic studies showed no evidence for the existence of host races. It was concluded that the melon fly does not represent a cryptic species complex, neither with regard to geographic distribution nor to host range. Nevertheless, the higher taxonomic classification under which this species had been placed, by the time the CRP was started, was found to be paraphyletic; as a result the subgenus Zeugodacus was elevated to genus level.Fil: Hendrichs, Jorge. Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture; AustriaFil: Vera, Maria Teresa. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia. Cátedra. Terapéutica Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: de Meyer, Marc. Royal Museum for Central Africa; BélgicaFil: Clarke, Anthony R.. Queensland University of Technology; Australi

    Historical perspective on the synonymization of the four major pest species belonging to the Bactrocera dorsalis species complex (Diptera, tephritidae)

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    An FAO/IAEA-sponsored coordinated research project on integrative taxonomy, involving close to 50 researchers from at least 20 countries, culminated in a significant breakthrough in the recognition that four major pest species, Bactrocera dorsalis, B. philippinensis, B. papayae and B. invadens, belong to the same biological species, B. dorsalis. The successful conclusion of this initiative is expected to significantly facilitate global agricultural trade, primarily through the lifting of quarantine restrictions that have long affected many countries, especially those in regions such as Asia and Africa that have large potential for fresh fruit and vegetable commodity exports. This work stems from two taxonomic studies: a revision in 1994 that significantly increased the number of described species in the Bactrocera dorsalis species complex; and the description in 2005 of B. invadens, then newly incursive in Africa. While taxonomically valid species, many biologists considered that these were different names for one biological species. Many disagreements confounded attempts to develop a solution for resolving this taxonomic issue, before the FAO/IAEA project commenced. Crucial to understanding the success of that initiative is an accounting of the historical events and perspectives leading up to the international, multidisciplinary collaborative efforts that successfully achieved the final synonymization. This review highlights the 21 year journey taken to achieve this outcome

    Evaluating mating compatibility within fruit fly cryptic species complexes and the potential role of sex pheromones in pre-mating isolation

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    The study of sexual behavior and the identification of the signals involved in mate recognition between con-specifics are key components that can shed some light, as part of an integrative taxonomic approach, in delimitating species within species complexes. In the Tephritidae family several species complexes have received particular attention as they include important agricultural pests such as the Ceratitis fasciventris(Bezzi), Ceratitis anonae (Graham) and Ceratitis rosa Karsch (FAR) complex, the Bactrocera dorsalis(Hendel) complex and the Anastrepha fraterculus (Wiedemann) complex. Here the value and usefulness of a methodology that uses walk-in field cages with host trees to assess, under semi-natural conditions, mating compatibility within these complexes is reviewed, and the same methodology to study the role of chemical communication in pre-mating isolation among Anastrepha fraterculus populations is used. Results showed that under the same experimental conditions it was possible to distinguish an entire range of different outcomes: from full mating compatibility among some populations to complete assortative mating among others. The effectiveness of the methodology in contributing to defining species limits was shown in two species complexes: Anastrepha fraterculus and Bactrocera dorsalis, and in the case of the latter the synonymization of several established species was published. We conclude that walk-in field cages constitute a powerful tool to measure mating compatibility, which is also useful to determine the role of chemical signals in species recognition. Overall, this experimental approach provides a good source of information about reproductive boundaries to delimit species. However, it needs to be applied as part of an integrative taxonomic approach that simultaneously assesses cytogenetic, molecular, physiological and morphological traits in order to reach more robust species delimitations.Fil: Juárez, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Devescovi, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Brízová, Radka. Institute Of Organic Chemistry And Biochemistry; República ChecaFil: Bachmann, Guillermo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Segura, Diego Fernando. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kalinova, Blanka. Institute Of Organic Chemistry And Biochemistry; República ChecaFil: Fernandez, Patricia Carina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Ruiz, María Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Yang, Jianquan. Fujian Agriculture and Forestry University; ChinaFil: Teal, Peter E. A.. No especifíca;Fil: Cáceres, Carlos. No especifíca;Fil: Vreysen, Marc J.B.. No especifíca;Fil: Hendrichs, Jorge. No especifíca;Fil: Vera, María Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; Argentin

    Integrative taxonomy versus taxonomic authority without peer review: the case of the Oriental fruit fly, Bactrocera dorsalis(Tephritidae)

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    1. Major global horticultural and food security tephritid fruit fly pests,Bactrocera papayae(papaya fruit fly) andB. invadens(invasive fruit fly), weresynonymised withB. dorsalis(Oriental fruit fly) by Schutzeet al.(2015a) based onextensive integrative taxonomic evidence from multiple sources. This synonymy waspeer reviewed by eight independent experts.2. Drew & Romig (2016) withdrewB.papayaeandB.invadensfrom synonymy based onopinion drawn primarily from disparate geographical distribution, morphological, andhost use information. This reversal was not subjected to peer review.3. We consider the withdrawal from synonymy as invalid due to significant errors andmisrepresentations of the literature provided in the arguments of Drew & Romig (2016)that we propose would not have withstood peer scrutiny.4. This case reflects a broader issue of individual taxonomic authorities using opinionto challenge extensive evidence generated via scientific hypothesis-testing methods bydiscipline specialists.5. We recommend that taxonomic acts not subjected to peer review, especially of pestspecies, be actively discouraged by the broader scientific and regulatory community

    Conceptual framework and rationale

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    The sterile insect technique (SIT) has been shown to be an effective and sustainable genetic approach to control populations of selected major pest insects, when part of area-wide integrated pest management (AW-IPM) programmes. The technique introduces genetic sterility in females of the target population in the field following their mating with released sterile males. This process results in population reduction or elimination via embryo lethality caused by dominant lethal mutations induced in sperm of the released males. In the past, several field trials have been carried out for mosquitoes with varying degrees of success. New technology and experience gained with other species of insect pests has encouraged a reassessment of the use of the sterility principle as part of integrated control of malaria vectors. Significant technical and logistic hurdles will need to be overcome to develop the technology and make it effective to suppress selected vector populations, and its application will probably be limited to specific ecological situations. Using sterile males to control mosquito vector populations can only be effective as part of an AW-IPM programme. The area-wide concept entails the targeting of the total mosquito population within a defined area. It requires, therefore, a thorough understanding of the target pest population biology especially as regards mating behaviour, population dynamics, dispersal and level of reproductive isolation. The key challenges for success are: 1) devising methods to monitor vector populations and measuring competitiveness of sterile males in the field, 2) designing mass rearing, sterilization and release strategies that maintain competitiveness of the sterile male mosquitoes, 3) developing methods to separate sexes in order to release only male mosquitoes and 4) adapting suppression measures and release rates to take into account the high reproductive rate of mosquitoes. Finally, success in area-wide implementation in the field can only be achieved if close attention is paid to political, socio-economic and environmental sensitivities and an efficient management organization is established taking into account the interests of all potential stakeholders of an AW-IPM programme

    Small Sample Size for Test of Training Time by Augmented Reality: An Aeronautical Case

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    Augmented Reality works for learning (growing tendency) in aeronautical sector demand an evaluation that requires experimental sampling, and this is often an expensive process. Usually, sample size is determined by resources availability constraint, which does not guarantee the level of significance (α) and the margin of error (E) required. This paper introduces a congruent sequence of statistical procedures to determine the estimated work sample size for traineeship in assembly operations. Sample size estimations for an aeronautical case are presented considering various scenarios. A minimum necessary sample size is calculated with statistical rigor via formulation and Operating Characteristic Curves. © 2015 The Authors

    Application of Nuclear Techniques to Improve the Mass Production and Management of Fruit Fly Parasitoids

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    The use of irradiated hosts in mass rearing tephritid parasitoids represents an important technical advance in fruit fly augmentative biological control. Irradiation assures that fly emergence is avoided in non-parasitized hosts, while at the same time it has no appreciable effect on parasitoid quality, i.e., fecundity, longevity and flight capability. Parasitoids of fruit fly eggs, larvae and pupae have all been shown to successfully develop in irradiated hosts, allowing a broad range of species to be shipped and released without post-rearing delays waiting for fly emergence and costly procedures to separate flies and wasps. This facilitates the early, more effective and less damaging shipment of natural enemies within hosts and across quarantined borders. In addition, the survival and dispersal of released parasitoids can be monitored by placing irradiated sentinel-hosts in the field. The optimal radiation dosages for host-sterility and parasitoid-fitness differ among species, and considerable progress has been made in integrating radiation into a variety of rearing procedures

    Resolution of Cryptic Species Complexes of Tephritid Pests to Enhance SIT Application and Facilitate International Trade.Vol. 540.

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    Tephritid fruit flies (Diptera: Tephritidae) are considered by far the most important group of horticultural pests worldwide. Female fruit flies lay eggs directly into ripening fruit, where the maggots feed causing fruit loss. Each and every continent is plagued by a number of fruit fly pests, both indigenous as well as invasive ones, causing tremendous economic losses. In addition to the direct losses through damage, they can negatively impact commodity trade through restrictions to market access. The quarantine and regulatory controls put in place to manage them are expensive, while the on-farm control costs and loss of crop affect the general well-being of growers. These constraints can have huge implications on loss in revenues and limitations to developing fruit and vegetable-based agroindustries in developing, emergent and developed nations. Because fruit flies are a global problem, the study of their biology and management requires significant international attention to overcome the hurdles they pose. The Joint Food and Agriculture Organisation / International Atomic Energy Agency (FAO/IAEA) Programme on Nuclear Techniques in Food and Agriculture has been on the foreground in assisting Member States in developing and validating environment-friendly fruit fly suppression systems to support viable fresh fruit and vegetable production and export industries. Such international attention has resulted in the successful development and validation of a Sterile Insect Technique (SIT) package for the Mediterranean fruit fly. Although demands for R&D support with respect to Mediterranean fruit fly are diminishing due to successful integration of this package into sustainable control programmes against this pest in many countries, there were increasing demands from Member States in Africa, Asia and Latin America, to address other major fruit fly pests and a related, but sometimes neglected issue of tephritid species complexes of economic importance. Any research, whether it is basic or applied, requires a taxonomic framework that provides reliable and universally recognized entities and names. Among the currently recognized major fruit fly pests, there are groups of species whose morphology is very similar or identical, but biologically they are distinct species. As such, some insect populations that are grouped taxonomically within the same pest species, display different biological and genetic traits and show reproductive isolation which suggest that they are different species. On the other hand, different species may have been taxonomically described, but there may be doubt as to whether they actually represent distinct biological species or merely geographical variants of the same species. This uncertain taxonomic status has practical implications on the effective development and use of the SIT against such complexes, particularly at the time of determining which species to mass-rear, and significantly affects international movement of fruit and vegetables through the establishment of trade barriers to important agricultural commodities which are hosts to these pest tephritid species..
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