CHANGE - Global Change and Sustainability Institute

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Trioza erytreae (Del Guercio, 1918) and the Interaction with Its Hosts: A Review

Publication . Magalhães, Tomás; Duarte, Amílcar; Pereira, J.A.; Marques, Natália T.

The cultivation of citrus in the Mediterranean region is of considerable economic importance. The viability of this industry is contingent upon a number of factors, with adequate phytosanitary management being of particular significance. During the last decade, the geographical range of the invasive psyllid, Trioza erytreae (Del Guercio, 1918), has expanded to the mainland territories of Portugal and Spain. Trioza erytreae acts as a vector for the Huanglongbing disease (HLB). This review presents the current knowledge about the hosts of the psyllid and their attractiveness and suitability. A classification of the hosts according to their suitability, as assessed in the literature, is provided. The attributes of the hosts and the methods used to assess their suitability are described, as well as the climatic factors that affect the psyllid–host interaction. The review emphasises the importance of a comprehensive evaluation of the interactions between the psyllids and their hosts to develop and implement more effective strategies for controlling T. erytreae.

2025Journal article

Open access

Electrical impedance spectroscopy for potassium content analysis and botanical origin identification of honey

Publication . Elamine, Youssef; Inácio, Pedro M.C.; Miguel, Maria da Graça; Carlier, Jorge D.; Costa, Maria Clara; Estevinho, Leticia M.; Gomes, Henrique L.

Minerals are reported to dominate the electrical properties of honey and indicate its botanical and geographical origins. In this study, Electrochemical Impedance Spectroscopy (EIS) was used to assess the relation between mineral elements, electrical properties and botanical origin using three honey varieties - Citrus sp., Eucalyptus sp., and Erica sp. These varieties are identified through pollen analysis and market labelling. Flame atomic absorption and emission spectroscopies were used to quantify the concentrations of eight elements (potassium, sodium, calcium, magnesium, manganese, zinc, copper, and iron). Among all the mineral elements, potassium showed a consistent correlation with impedance. The potassium estimation in honey and standard solutions (calibration curve) had similar sensitivities of 153.43 nF/mM and 132.68 nF/mM, respectively. Additionally, the analysis revealed that potassium dominates the mineral composition, with the other species present in minimal quantities. The EIS technique showed high sensitivity to potassium and other ionisable species, making it possible to classify the botanical origin of these three honey types. The EIS technique proved to be both time and cost effective, yielding a classification rate higher than that achieved by analysing mineral composition.

2024Journal article

Open access

Developing epidemiological preparedness for a plant disease invasion: Modelling citrus huánglóngbìng in the European Union

Publication . Ellis, John; Lázaro, Elena; Duarte, Beatriz; Magalhães, Tomás; Duarte, Amílcar; Benhadi-Marín, Jacinto; Pereira, José Alberto; Vicent, Antonio; Parnell, Stephen; Cunniffe, Nik J.

Societal Impact Statement Huánglóngbìng (HLB) is a bacterial disease of citrus that has significantly impacted Brazil and the United States, although citrus production in the Mediterranean Basin remains unaffected. By developing a mathematical model of spread in Spain, we tested surveillance and control strategies before any future HLB entry in the EU. We found while some citrus production might be maintained by roguing, this requires extensive surveillance and significant chemical control, perhaps also including testing of psyllids (which spread the pathogen) for bacterial DNA. Our work highlights the key importance of early detection (including asymptomatic infection) and vector control for HLB management. Summary • Huánglóngbìng (HLB; citrus greening) is the most damaging disease of citrus worldwide. While citrus production in the United States and Brazil have been affected for decades, HLB has not been reported in the European Union (EU). However, a HLB vector, the African citrus psyllid, is already in Portugal and Spain. In 2023, the major vector, the Asian citrus psyllid, was first reported in Cyprus. • We develop a landscape-scale, epidemiological model, accounting for heterogeneous citrus cultivation and vector dispersal, as well as climate and disease management. We use our model to predict HLB dynamics for an epidemic vectored by the African citrus psyllid in high-density citrus areas in Spain, assessing detection and control strategies. • Without disease management, we predict large areas infected within 10–20 years. Even with significant visual surveillance, any epidemic will be widespread on first detection, making eradication unlikely. Nevertheless, increased inspection and roguing following first detection, particularly if coupled with intensive insecticide use, could sustain some citriculture for a decade or more, albeit with reduced production. However, effective control may require chemical application rates and/or active substances no longer authorised in the EU. Strategies targeting asymptomatic infection will be more successful. Detection of bacteriliferous vectors—sometimes possible long before plants show symptoms—could reduce lags before disease management commences. If detection of HLB-positive vectors were followed by intensive insecticide sprays, this may greatly improve outcomes. • Our work highlights modelling as a key component of developing epidemiological preparedness for a pathogen invasion that is, at least somewhat, predictable in advance.

2025Journal article

Open access

Prevalence, diversity and risk factors of gastrointestinal parasites in dogs housed at official shelters across Portugal

Publication . Lopes, Patrícia; Gomes, Jacinto; Lozano, João; Louro, Mariana; Carvalho, Luís Madeira de; Fonseca, Isabel Pereira da; Lobo, Ricardo; Monteiro, Fernando; Carvalho, Liliana; Afonso, Paulo; Almas, Miguel; Cunha, Mónica V.

Gastrointestinal parasites (GIP) are among the most common pathogens that affect dogs globally, with some species representing a zoonotic threat. Stray and shelter dogs are especially vulnerable to parasitism as their clinical history is often unknown, and copro-parasitological analyses are seldom performed upon animal arrival at shelters. In Portugal, official shelters play a pivotal role in sheltering and managing stray dogs; however, little is known about the GIP infection status of these animals. This study thus aimed to determine the occurrence of GIP in dogs housed at official shelters in Portugal and explore potential variables contributing to the GIP burden. Between November 2021 and October 2022, a total of 355 dog faecal samples were collected from shelters across the country. These samples were either obtained individually from dogs or pooled from groups of animals housed together, and were analysed using the Mini-FLOTAC technique with zinc sulphate flotation solution (specific gravity 1.35) to detect, identify, and quantify GIP shedding intensity. Over 16 % (57/355) of the samples were GIP-positive. The most frequently observed parasites were Trichuris vulpis (20/355), Toxocara canis (19/355), Ancylostoma spp. (13/355), and Cystoisospora canis (8/355). Co-infections with two parasitic agents were detected in three individual samples: two dogs harboured both T. vulpis and C. canis, while one dog was co- infected with T. vulpis and T. canis. Most positive samples (53/59) exhibited a moderate to high shedding intensity, with over 50 eggs or oocysts per gram of faeces – EPG or OPG, respectively. Only a few showed a low shedding intensity of less than 10 EPG or OPG. When examining individual faecal samples, the average prevalence rate of GIP in shelter dogs across sampled regions was 15.9 % (33/208). A single taeniid infection was detected and confirmed, via molecular assays, to be due to Echinococcus granulosus. The occurrence of Ancylos-toma spp. and T. vulpis were significantly correlated with the number of dogs housed in shelters. The presence of Ancylostoma spp. eggs was significantly associated with season and region, while consistency of faeces was significantly associated with the presence of T. canis eggs and GIP co-infection status. This study represents the first nationwide screening for GIP in shelter dogs in Portugal. Our findings underscore the importance of regular screening in shelters, namely upon animals' arrival, and the need for active, effective management of infections to control GIP spread within the shelter and to prevent possible occupational zoonotic transmission.

2025Journal article

Open access