Recent emergence and worldwide spread of the red tomato spider mite, [i]Tetranychus evansi[/i]: genetic variation and multiple cryptic invasions

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699Plant biosecurity is increasingly challenged by emerging crop pests. The spider mite Tetranychus evansi has recently emerged as a new threat to solanaceous crops in Africa and the Mediterranean basin, with invasions characterized by a high reproductive output and an ability to withstand a wide range of temperatures. Mitochondrial (868 bp of COI) and nuclear (1,137 bp of ITS) loci were analyzed in T. evansi samples spanning the current geographical distribution to study the earliest stages of the invasive process. The two sets of markers separate the samples into two main clades that are only present together in South America and Southern Europe. The highest COI diversity was found in South America, consistent with the hypothesis of a South American origin of T. evansi. Among the invaded areas, the Mediterranean region displayed a high level of genetic diversity similar to that present in South America, that is likely the result of multiple colonization events. The invasions of Africa and Asia by T. evansi are characterized by a low genetic variation associated with distinct introductions. Genetic data demonstrate two different patterns of invasions: (1) populations in the Mediterranean basin that are a result of multiple cryptic introductions and (2) emerging invasions of Africa and Asia, each likely the result of propagules from one or limited sources. The recent invasions of T. evansi illustrate not only the importance of human activities in the spread of agricultural pests, but also the limits of international quarantine procedures, particularly for cryptic invasion

Test of Colonisation Scenarios Reveals Complex Invasion History of the Red Tomato Spider Mite Tetranychus evansi

The spider mite Tetranychus evansi is an emerging pest of solanaceous crops worldwide. Like many other emerging pests, its small size, confusing taxonomy, complex history of associations with humans, and propensity to start new populations from small inocula, make the study of its invasion biology difficult. Here, we use recent developments in Approximate Bayesian Computation (ABC) and variation in multi-locus genetic markers to reconstruct the complex historical demography of this cryptic invasive pest. By distinguishing among multiple pathways and timing of introductions, we find evidence for the “bridgehead effect”, in which one invasion serves as source for subsequent invasions. Tetranychus evansi populations in Europe and Africa resulted from at least three independent introductions from South America and involved mites from two distinct sources in Brazil, corresponding to highly divergent mitochondrial DNA lineages. Mites from southwest Brazil (BR-SW) colonized the African continent, and from there Europe through two pathways in a “bridgehead” type pattern. One pathway resulted in a widespread invasion, not only to Europe, but also to other regions in Africa, southern Europe and eastern Asia. The second pathway involved the mixture with a second introduction from BR-SW leading to an admixed population in southern Spain. Admixture was also detected between invasive populations in Portugal. A third introduction from the Brazilian Atlantic region resulted in only a limited invasion in Europe. This study illustrates that ABC methods can provide insights into, and distinguish among, complex invasion scenarios. These processes are critical not only in understanding the biology of invasions, but also in refining management strategies for invasive species. For example, while reported observations of the mite and outbreaks in the invaded areas were largely consistent with estimates of geographical expansion from the ABC approach, historical observations failed to recognize the complex pathways involved and the corresponding effects on genetic diversity

Climate of origin influences how a herbivorous mite responds to drought-stressed host plants

Drought associated with climate change can stress plants, altering their interactions with phytophagous arthropods. Drought not only impacts cultivated plants but also their parasites, which in some cases are favored by drought. Herbivorous arthropods feeding on drought-stressed plants typically produce bigger offspring and develop faster. However, it is unclear how much responses to drought stress differ among populations of herbivore species. Here, we evaluate variability among populations of a major agricultural pest, the two spotted spider mite, Tetranychus urticae, in response to drought stress. We compare key life history parameters of twelve populations that originate from climates ranging from wet and cool Atlantic locations to medium to dry hot Mediterranean locations. We evaluated how plant drought stress affects four life history traits: development time, fecundity, sex-ratio and emigration rate in an experiment comparing well-watered and drought-stressed bean plants. Mites feeding on drought-stressed plants developed faster and attempted to leave leaves less often, and young females were more fecund. The mites from wet temperate climates exhibited greater plasticity between the two water regimes than mites originating from dryer and hot climates, suggesting that the climate in the area of origin influences mite response to drought

Acarien rouge de la tomate: nouvelles observations et perspectives

Correspondance: [email protected] audienceTetranychus evansi, acarien rouge de la tomate, principalement inféodé aux solanacées, n'a pas encore d'impact sur les cultures en France. Mais ses potentialités d'expansion - qui le rapprochent de Bemisia tabaci - nécessitent de bien connaître ce ravageur potentiel, tant au niveau de sa biologie, que de ses plantes hôtes ou de son aire de répartition

Un nouvel acarien ravageur en France: Tetranychus evansi Baker et Pritchard

Correspondance : [email protected] audienceCet envahisseur sans doute originaire d'Amérique du Sud s'attaque principalement aux Solanacées. Un nouveau Tétranyque a été détecté en France dans les Pyrénées-Orientales. Il s'agit de Tetranychus evansi Baker et Pritchard (Acariens: Tetranuychidae). Cette espèce récemment ajoutée à la liste d'alerte EPPO est considérée comme une espèce invasive. C'est aussi un redoutable ravageur des tomates et autres Solanacées. Quel a été son périple ? Que sait-on de sa biologie ? Comment le détecter et le reconnaître ? Et enfin, que peut-on en craindre de son potentiel invasif dans notre pays

The Jean Gutierrez spider mite collection

International audienceThe family Tetranychidae (spider mites) currently comprises 1,275 species and represents one of the most important agricultural pest families among the Acari with approximately one hundred pest species, ten of which considered major pests. The dataset presented in this document includes all the identified spider mites composing the Jean Gutierrez Collection hosted at the CBGP (Montferrier-sur-Lez, France), gathered from 1963 to 1999 during his career at the Institut de Recherche pour le Developpement (IRD). It consists of 5,262 specimens corresponding to 1,564 occurrences (combination species/host plant/date/location) of 175 species. Most specimens were collected in Madagascar and other islands of the Western Indian Ocean, New Caledonia and other islands of the South Pacific and Papuasia. The dataset constitutes today the most important one available on Tetranychidae worldwide

Les tétranyques des bambous en France

National audienceQuelques éléments de biologie et de lutte concernant les 2 espèces de tétranyques trouvées sur les bambous en France, Stigmaeopsis celarius et Schizotetranychus bambusa

Ladybeetles (Coccinellidae)

Corresponding authors: Helen Roy ([email protected])International audienceThe majority of Coccinellidae are beneficial predators and they have received considerable research attention because of their potential as biological control agents. Indeed the role of coccinellids as predators of pest insects has been a major factor in the movement of coccinellids between countries. The commercial production of coccinellids by biological control companies and local producers led to a rapid increase in distribution thoughout the 1990’s. To date, 13 alien coccinellid species have been documented in Europe; 11 of these are alien to Europe (two are alien to Great Britain and Sweden but native within Europe). The distribution of alien coccinellids in Europe mirrors the biogeographical distribution and patterns of introduction. Some species have dispersed widely; Harmonia axyridis has spread rapidly from countries where it was deliberately introduced to many others across Europe. The ecological and economic impacts of alien coccinellids are not well documented. In this chapter we provide an overview of the temporal and spatial patterns of alien coccinellids in Europ