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Saint-Denis-d'Oléron, France

Chabirand A.,ANSES Plant Health Laboratory | Jouen E.,University of Reunion Island | Pruvost O.,University of Reunion Island | Chiroleu F.,University of Reunion Island | And 17 more authors.
Plant Pathology | Year: 2014

Efficient control of Xanthomonas axonopodis pv. dieffenbachiae, the causal agent of anthurium bacterial blight, requires sensitive and reliable diagnostic tools. The European standard EN ISO 16140:2003 has been followed to compare a nested PCR assay (N-PCR) to a reference method (isolation and serological identification of bacterial colonies) and to other alternative serological detection methods. The evaluation was performed in two steps: a comparative study and a collaborative study involving 15 European laboratories. Although inclusivity was maximal (100%) for all methods, a maximal exclusivity was obtained only with N-PCR followed by an enzymatic restriction digestion of the amplicons. Exclusivity indices of 90·6, 88·7 and 47·2% were found for indirect ELISA, immunofluorescence and double antibody sandwich ELISA, respectively. An exclusivity of 92·5% was obtained with the reference method, further increased to 100% if pathogenicity tests were performed as a supplemental assay. The best level of sensitivity (relative detection level) was obtained with the reference method followed by the N-PCR assay. The N-PCR performance in terms of relative accuracy, accordance and concordance was very similar to that of the reference method. Moreover, N-PCR had undeniable advantages compared to the reference method (less labour-intensive and less time-consuming). In addition, post-test probabilities of infection were calculated to select the most appropriate detection scheme related to the prevalence of the pathogen. The N-PCR assay has since been included in a revised version of the EPPO detection protocol. © 2013 British Society for Plant Pathology.

Marquier M.,FDGDON Reunion | Clain C.,FDGDON Reunion | Albon B.,FDGDON Reunion | Roux E.,FDGDON Reunion | Deguine J.-P.,Cirad UMR PVBMT
Cahiers Agricultures | Year: 2014

Three fruit flies (Diptera: Tephritidae) damage cucurbit crops on Reunion Island: Bactrocera cucurbitae (Coquillet), Dacus demmerezi (Bezzi) and D. ciliatus (Loew). Chemical control does not provide any satisfactory control of fly populations. The GAMOUR project aims at promoting agroecological management of these pests. The present work is aimed at studying the augmentative releases of the parasitoid Psyttalia fletcheri (Silvestri) (Hymenoptera: Braconidae) as a biological control agent. From 2010 to 2011, four trials were set up. We released between 1,600 to 3,000 parasitoid wasps according to the trial. The parasitism rate of P. fletcheri was then recorded using fruit samples collected in the field. Parasitism was almost null before the releases. After the releases, mean parasitism rates increased moderately with a maximum of 16.7%. The parasitism was moreover null on crops where no B. cucurbitae were caught. In light of a cost-benefit analysis, releases of P. fletcheri appear therefore irrelevant. On the other hand, inoculative releases of parasitoids in low altitude agrosystems (B. cucurbitae is present below 800 m) could locally increase the abundance of wasps and promote environmentally friendly methods to growers.

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