Suchergebnisse

Xylella fastidiosa, was recently detected in Portugal (January 2019), this phytopathogenic bacterium is a threat to important crops of agricultural interest. It is transmitted by xylem-feeding insects that belong to the suborder Auchenorrhyncha. However, the knowledge about these insects in Portugal is scarce. In this context, the goal of this work was to identify the frequency and biodiversity of Auchenorrhyncha in Trás-os-Montes region, Portugal. For that, in 2018, in Trás-os-Montes region, five olive groves, five almond orchard and five vineyards with ground cover were sampled for adults of Auchenorrhyncha, during three distinct periods (beginning of July, midSeptember and mid-October). Sampling was performed in the ground and in the aerial part of the plants. In each sampling date, 10 samples of 10 sweepings were collected on the ground in each orchard and vineyard. On the aerial part of the orchards 10 samples of 4 sweeping in 6 trees were collected and in the vineyard 10 samples of 50 sweepings were collected. A total of 3741 adults of Auchenorrhyncha were recovered on the three sampling dates. From these, 949 were Fulgoromorpha and 2792 Cicadomorpha, being the highest abundance observed in the beginning of July. In general, the vineyards presented the higher number of individuals of the Cicadomorpha and the olive orchards presented the smaller number of individuals of this infraorder. However, almond orchards presented the higher abundance of confirmed vectors of X. fastidiosa, 16 individuals belonging to the genus Neophilaenus and seven individuals of the genus Philaenus in the three periods. The higher number Philaenus individuals was observed in mid-October on the vegetation cover. ; This work has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement N. 727987 "Xylella fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy XFACTORS". ; info:eu-repo/semantics/publishedVersion

The Aphrophoridae family contains important vectors of Xylella fastidiosa, a serious bacterial plant disease. In olive orchards, nymphs usually feed on the ground-cover vegetation. However, detailed information about their populations and host/non-host plants in some regions threatened by Xylella, such as the northeast of Portugal, is very limited. The goal of our work was to identify the vector species, nymphal development period, and their host and non-host herbaceous plants in olive orchards from northeastern Portugal. Ground-cover plant species hosting or not hosting nymphs were identified during the spring of 2017 to 2019 in olive orchards. Nymphal development period, nymph aggregation, and nymph's preferred feeding height of the ground-cover plants were recorded. The most abundant Aphrophoridae species was Philaenus spumarius followed by Neophilaenus sp. Nymphs developed from April to early May and showed a low number of individuals per foam (generally between one and three). They preferred the middle part of the plants. Philaenus spumarius feeds preferentially on Asteraceae and Fabaceae, and Neophilaenus sp. on Poaceae. Some abundant plants, such as Bromus diandrus, Astragalus pelecinus, Chrysanthemum segetum, Trifolium spp., Caryophyllaceae, and Brassicaceae, were barely colonized by Aphrophoridae nymphs. This knowledge is essential for the selection of the species composition of ground-cover vegetation to minimize the presence of vectors of X. fastidiosa in olive groves. ; This work was funded by European Union Horizon 2020 research and innovation program under grant agreement no. 727987 XF-ACTORS (Xylella fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy), and Foundation for Science and Technology (FCT, Portugal) the financial support by national funds FCT/MCTES to CIMO UIDB/00690/2020. ; info:eu-repo/semantics/publishedVersion

The dangerous phytopathogenic bacteria Xylella fastidiosa (Wells et al., 1987) has been recently detected in Portugal (January 2019). This disease is transmitted horizontally from infected to non-infected plants by xylem-feeders that belong to the suborder Auchenorrhyncha. The information available until now about natural enemies is reduced. In this work the potential natural enemies of Auchenorrhyncha eggs, the most susceptible stage, were studied during the autumn/winter of 2018/2019. For that, from November 2018 to February 2019 before the egg hatching, on a biweekly basis, 10 samples of 50 g of rests of the remaining vegetation in the ground cover, mainly Poaceae, were collected in an olive grove. In the laboratory, leaves, particularly the interior part of the blade which is a common oviposition location for spittlebugs, were observed under binocular stereoscope. Viable eggs were introduced in petri dishes until hatching. A total of 647 egg-laying masses and 8,222 eggs with a mean of 12.7 eggs per egg laying was recorded. Egg masses were characterised and the action of predation, parasitism and fungi were recorded. Eggs presenting signs of parasitism plus predation were more than 50%. Intact field eggs were kept in controlled conditions until hatching of nymphs and evolution. The parasitoids were identified as Paracentrobia sp. (Trichogrammatidae) being the first report for the genus in Portugal. These results constitute an important opportunity to control the main insect vectors of X. fastidiosa and containing its spread. ; This work has received funding from the European Union's Horizon 2020 research and innovation programme underGrant Agreement N. 727987 'Xylella fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy XF-ACTORS'. ; info:eu-repo/semantics/publishedVersion

The olive tree (Olea europaea L.) is among the oldest and most widespread crops in the Mediterranean basin. Portugal is the third olive producer in the European Union, and Trás-os-Montes region, located in northeastern Portugal, is the second Portuguese producing olive region. The olive moth, Prays oleae (Bernard) (Lepidoptera: Praydidae) is a key olive pest in Trás-os-Montes. This pest is a natural host/prey of several organisms which include larvae of generalist and specialist parasitoids as well as generalist predators and entomopathogens. Its most abundant parasitoid is the specialist Ageniaspis fuscicollis (Dalman) (Hymenoptera: Encyrtidae) and this, in Trás-os-Montes region, is commonly followed by the facultative hyperparasitoid Elasmus flabellatus (Fonscolombe) (Hymenoptera: Eulophidae). Spiders represent a relevant group of generalist predators in olive agroecosystems and encompass an important predatory action in agroecosystems as well as an ability to reduce the populations of various insect pests. In this context, a mathematical model, considering the population of the olive moth, the two parasitoids populations and the spider population as the variables in our system, was constructed. The ecosystem steady states for feasibility and stability were assessed. The possible pesticide effects, that represent essentially extra mortality rates for each one of the insect populations, and potential abundance variations on their populations under a climate change scenario were included. Results indicate that the most important natural control agent is A. fuscicollis but in certain conditions E. flabellatus or spiders may be relevant contributors for the pest reduction. This approach may provide a useful tool to assist the field researchers on this pest system and its management. ; info:eu-repo/semantics/publishedVersion

The olive tree (Olea europaea L.) is among the oldest and most widespread crops in the Mediterranean basin. Portugal is the third olive producer in the European Union, and Trás-os-Montes region, located in northeastern Portugal, is the second Portuguese producing olive region. The olive moth, Prays oleae (Bernard) (Lepidoptera: Praydidae) is a key olive pest in Trás-os-Montes. This pest is a natural host/prey of several organisms which include larvae of generalist and specialist parasitoids as well as generalist predators and entomopathogens. Its most abundant parasitoid is the specialist Ageniaspis fuscicollis (Dalman) (Hymenoptera: Encyrtidae) and this, in Trás-os-Montes region, is commonly followed by the facultative hyperparasitoid Elasmus flabellatus (Fonscolombe) (Hymenoptera: Eulophidae). Spiders represent a relevant group of generalist predators in olive agroecosystems and encompass an important predatory action in agroecosystems as well as an ability to reduce the populations of various insect pests. In this context, a mathematical model, considering the population of the olive moth, the two parasitoids populations and the spider population as the variables in our system, was constructed. The ecosystem steady states for feasibility and stability were assessed. The possible pesticide effects, that represent essentially extra mortality rates for each one of the insect populations, and potential abundance variations on their populations under a climate change scenario were included. Results indicate that the most important natural control agent is A. fuscicollis but in certain conditions E. flabellatus or spiders may be relevant contributors for the pest reduction. This approach may provide a useful tool to assist the field researchers on this pest system and its management ; info:eu-repo/semantics/publishedVersion

The olive grove is a key landscape across the Mediterranean basin. This agroecosystem is threatened by Xylella fastidiosa, the causal agent of the olive tree quick decline syndrome, Philaenus spumarius being the main vector. A way to limit pest populations relies on the use of biological control agents such as arthropods. Among them, spiders are generalist predators with di erent hunting strategies that feed mostly on insects and can contribute to limit pests. In this work, field and laboratory data were used to provide a protocol aiming to facilitate the selection of species of spiders among di erent guilds that could represent potential natural enemies of P. spumarius. Sampling of spiders was conducted in olive groves in northeastern Portugal. Two species, namely the orb-weaver Araniella cucurbitina and the ambusher Synema globosum, were selected according to the dominant guilds of spiders inhabiting the olive crop. We tested the di erences of potential predatory e ciency using classical functional response tests with P. spumarius as prey. A type-II functional response was found for A. cucurbitina, whereas a type-I response was found for S. globosum. This di erence uncovers a di erent potential e ciency among the two species as natural enemies of P. spumarius with relevant implications at high prey density in the field. A conceptual workflow to follow the fieldwork and selection of species for further work (i.e., laboratory assays) is provided and discussed. Standardized methods regarding the assessment of the suitability and e ciency of potential natural enemies are essential for the integration of results at di erent geographical extents and crops. Selecting functional counterparts such as di erent species of predators occurring at di erent locations that use the same prey (e.g., a pest) in the same way (e.g., hunting strategy) would facilitate developing biological control schemes. ; This research was funded by the European Union's Horizon 2020 research and innovation programme under Grant Agreement N. 727987 "Xylella fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy XF-ACTORS", the Spanish Ministry of Innovation and Science under the RETOS programme grant AGL2017-89604R and strategic project PEst-OE/AGR/UI0690/2019 – CIMO, funded by national funds through FCT/MCTES (PIDDAC). ; info:eu-repo/semantics/publishedVersion

X. fastidiosa is one of the most destructive pathogens of olive orchards. Its recent arrival to Europe can cause important losses, with possible drastic consequences for the sector. Philaenus spumarius (Linnaeus 1758) was identified as vector of X. fastidiosa in Europe and finding candidate natural enemies of P. spumarius is essential to design environmentally friendly control strategies against X. fastidiosa. Generalist predators, such as spiders, arise as important potential biocontrol agents. In this context, a set of species-specific primers for detecting the presence of P. spumarius DNA in the gut of predatory arthropods is being developed. All primers will be tested for checking cross-reactive amplification of arthropods DNA and evaluated in heterospecific mixes of nucleic acids. Subsequent feeding trials will be conducted using Synemaglobosum (Fabricius 1775), an important spider species in olive groves from Mirandela, Portugal. These trials will allow determining the detection efficiency of the primers designed and also they will be the starting point to detect predation in field trials. These primers therefore provide a very useful tool for screening the gut contents of potential predators of P. spumarius, and can thus reveal candidate species for this species biological control. ; This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement N. 727987 "Xylella fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy XF-ACTORS". ; info:eu-repo/semantics/publishedVersion