Percorrer por autor "Venturino, Ezio"
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- A model for the biological control of an olive tree (Olea europaea L.) pestPublication . Villa, Maria; Santos, Sónia A.P.; Benhadi-Marín, Jacinto; Pereira, J.A.; Venturino, EzioThe olive tree (Olea europaea L.) is among the oldest and most widespread crops in the Mediterranean basin, [2]. Portugal is one important olive producer country in particular in the Tr´as-os-Montes region, in the northeastern Portugal. The olive moth, Prays oleae (Bernard) (Lepidoptera: Praydidae) is the most damaging pest in this region, [1]. Larvae of several generalist and specialist parasitoids attack the olive moth. The most abundant specialist parasitoid is Ageniaspis fuscicollis (Dalman) (Hymenoptera: Encyrtidae), [3]. In Tr´as-os-Montes region, the second most abundant parasitoid was Elasmus flabellatus (Fonscolombe) (Hymenoptera: Eulophidae) that behaves as a facultative hyperparasitoid, parasitizing some larvae of hymenopteran and larvae and pupae of lepidopteran species, [5]. Spiders are generalist predators with important predatory action in agroecosystems and ability to reduce the populations of various insect pests, [4].We construct a mathematical model considering the population of the olive moth M, juvenile (larvae) Pi and adult populations Ai of the two parasitoids, i = 1, 2 and the spiders population S as the variables in our system. We assess the ecosystem steady states for feasibility and stability. In addition, we include also the possible pesticide effects, that represent essentially extra mortality rates for each one of the insect populations.
- Modeling the interactions among phythopatogens and phyllosphere microorganisms for the biological disease control of Olea europaea L.Publication . Baptista, Paula; Bulai, Iulia Martina; Gomes, Teresa; Venturino, EzioIn this paper we formulate a model for assessing the interaction between the phytopathogen Spilocaea oleaginea and the phyllosphere microorganisms that are present in the olive tree leaves. The model describes the evolution in time of the foliage of the olive tree and the two different microorganisms, the phytopathogen fungi, that negatively affect the plant causing spots in the leaves, and the beneficial phyllosphere microorganisms, that help in keeping in check the invasion of the former. The system possesses five equilibria that are suitably analysed for feasibility and stability. The model shows interesting features: a bistable behavior, exhibited by three different pairs of equilibria. The separatrix surface of the basins of attraction of one such pair is computed. This allows the possible assessment of human intervention for control of the disease. Persistent oscillations via Hopf bifurcation are also discovered.
- A three way trees-fungi-bacteria interactions (Olea europaea, Epicoccum nigrum and Pseudomonas savastanoi pv. savastanoi (Psv)) mathematical model for the “olive knot” disease eradicationPublication . Venturino, Ezio; Berardo, C.; Bulai, Iulia Martina; Baptista, Paula; Gomes, TeresaThe bacterium Pseudomonas savastanoi pv. savastanoi [Psv), is responsible for the 'olive knot' disease producing tumorous galls mostiy on stems and branches of olive trees. This endangers olive harvest, reducing tree strength and ultimately killing them. Interaction of Psv at infection sites with other microorganisms, mainly epiphytic but in the knots as well, cause disease spread. In olive knots some of the latter either depress Psv growth or increase knot sizes. Preventíon strategies appear the better way to contrai olive knot. Naturally occurring antagonistíc microorganisms able to suppress Psv constitute biological agents, that can reduce olive knot incidence. The endophytic fungal community associated to Psv in the phyllosphere of olive tree cultivars is able to antagonize Psv following experiments in vitro. This antagonistíc activity againts Psv was particularly displayed by the fungus Epícoccum nigrum, that was showed the capacity to inhibited the Psv growth/biomass on 96%, after 48 hours ofinteraction. A nonlinear mathematical system is introduced for understanding the action of this resident fungus [E. nigrum) in Psv development. It accounts for interactions between o\ive-Psv-E. nígrum and increases our knowledge on the olive knot disease spreading.
- A tritrophic interaction model for an olive tree pest, the olive moth — Prays oleae (Bernard)Publication . Pappalardo, Sonia; Villa, Maria; Santos, Sónia A.P.; Benhadi-Marín, Jacinto; Pereira, J.A.; Venturino, EzioThe 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.