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- Spread patterns of Trioza erytreae on citrus orchards and the potential role of natural enemies as biocontrol agentsPublication . Félix-Oliveira, Diogo; Pereira, J.A.; Benhadi Marín, JacintoCitrus production is a relevant economic activity around the world. In Portugal, Algarve is the leading citrus fruits producing region, it produces the famous and so-called “Orange of the Algarve”. Huanglongbing(HLB), also known as citrus greening disease, is the biggest problem of citrus cultivation in the world. This disease reduces citrus production, causes the loss of colors of fruits, turns them greenish, increases fruit acidity, and reduces sugars. HLB is caused by the group of bacteria Candidatus Liberibacter, being propagated by two vectors, the African Citrus Psylla Trioza erytreae (Del Guercio, 1908) (Hemiptera: Triozidae) and the Asian Citrus Psylla Diaphorina citri (Kuwayama, 1908) (Hemiptera: Psyllidae). Trioza erytreae is currently present in the Iberian Peninsula, which raises a threat to the citrus industry. Nowadays, the geographic distribution of T. erytreae ranges from the Basque Country (Spain) to Algarve (Portugal). In Portugal, T. erytreae already reached the Algarve region. Although the vector is widely dispersed, HLB was not currently detected in the Iberian Peninsula. This work aimed to study environmentally friendly alternatives to chemical control of T. erytreae. The application of kaolin clay sprayed on citrus plants was found to significantly reduce the landing and settlement of flying adults of T. erytreae on lemon plants in the field. Moreover, a kaolin film applied on lemon plants in laboratory significantly reduced the ability of T. erytreae to successfully access the floematic tissues, thus reducing the risk of infection by HLB on lemon plants. This suggests that kaolin could be an efficient tool to manage T. erytreae, especially in the context of sustainable citrus agriculture. Understanding the trophic interactions between prey and its predators is vital for both population ecology and integrated pest management (IPM). In IPM, knowledge of how an ecosystem’s trophic interactions affect prey densities is exploited to improve pest management strategies. The predatory bug Anthocoris nemoralis (Fabricius, 1794) (Hemiptera: Anthocoridae) is an abundant predator in fruit orchards. This species is considered a generalist predator, though it has been shown to prefer psyllids over other prey. To assess the potential of A. nemoralis as natural enemy in portuguese citrus orchards, field samples were collected from a lemon orchard in northwestern Portugal. Molecular gut-content analysis was performed in the laboratory to verify the presence of prey DNA. A PCR-based approach was used for detecting DNA of T. erytreae in the gut of A. nemoralis. Accordingly, 15 primer sets designed within rrnL gene (16S), the rrnS gene (12S), and the COI genes were tested for specificity, sensibility, and feasibility in detecting T. erytreae in the gut content of A. nemoralis. Overall, one primer set targeting rrnL gene (16S), pair LSU_F1/LSU_R1 showed specificity and sensitivity for T. erytreae so that this PCR-based diagnostic assay may help in the implementation of sustainable management tools aimed to limit the spread of the pathogen transmitted by the psyllid.
- Kaolin particle films disrupt landing, settling behavior and feeding of Trioza erytrae on lemon plantsPublication . Félix-Oliveira, Diogo; Benhadi-Marín, Jacinto; Neto, Joana; Sanz, Lorena; Garzo, Elisa; Aguiar, Ana; Fereres, Alberto; Pereira, J.A.BACKGROUND The citrus greening disease or Huanglongbing (HLB) is the most devastating disease of citrus crops. Trioza erytreae is a vector of HLB. Since its introduction in Europe, the insect reached the northern region of Spain and the southern region of Portugal, threatening relevant citrus production areas. Limiting the spread of HLB vectors is mandatory to prevent this disease. In this work, we assessed the effect of kaolin, a white mineral clay, on the landing, settling behavior and feeding behavior of Trioza erytreae on lemon plants. RESULTS After kaolin application, the number of plants on which the insect was found was significantly lower than on untreated plants in the laboratory and in the field. Moreover, there were significantly fewer T. erytreae and a shorter duration of phloem-related events on kaolin-treated than untreated plants. CONCLUSION The use of kaolin could be a suitable and efficient tool for inclusion into integrated pest management programs or organic production to reduce populations of T. erytreae and subsequently limit the spread of HLB in citrus crops. (c) 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
- Web architecture affects the functional response of the space web-builder Kochiura aulica against Trioza erytreae in the laboratoryPublication . Félix-Oliveira, Diogo; Pereira, J.A.; Benhadi-Marín, JacintoThe “citrus greening disease” or huanglongbing (HLB) is caused by the Gram-negative bacteria Candidatus Liberibacter spp. One vector of HLB, the African citrus psyllid Trioza erytreae (del Guercio, 1918), was recorded for the first time in 2014, in mainland Spain, and since then, it has spread throughout the Iberian Peninsula. Spiders could be natural enemies of T. erytreae. In this work, we assessed the potential of a model spider species, selected according to the most abundant guild in the field, as a natural enemy of T. erytreae. Theridiidae was the most successful family, capturing adults of T. erytreae in the field. Kochiura aulica (Theridiidae) was selected as a model for functional response assays in the laboratory. The effect of web-building plasticity on the functional response of K. aulica was investigated using two types of arena. The spiders developed tubular-like or branch-like webs according to the spatial constraints. The web architecture significantly shifted the trapping efficiency of K. aulica. Functional responses for tubular and branch webs were both Type-II, but more psyllid prey were captured and killed in the tubular webs than in branch webs. In addition, significantly more psyllids survived in branch-like webs. Our results suggest that web architecture is a key factor driving the number of captured adults of the psyllid. Space web builders could be successful natural enemies of T. erytreae, although further research is needed to clarify the influence of web-building plasticity on the functional response and trapping efficiency of spiders.
- Effect of physicochemical characteristics of lamb meat on its microbiological deteriorationPublication . Félix-Oliveira, Diogo; Coelho-Fernandes, Sara; Lorenzo Rodriguez, Jose Manuel; Cadavez, Vasco; Gonzales-Barron, UrsulaA common strategy to improve the tenderness of lamb meat of autochthonous Portuguese breeds is to mature vacuum-packed (VP) meat for ~7 days. Nonetheless, the extent to which microbial spoilage is delayed by VP depends upon the meat intrinsic properties. The objective of this study was to appraise how the growth rate of deteriorating bacteria in VP lamb meat is affected by the initial microbial load and physicochemical characteristics.
- Evolution of spoilage microorganisms in vacuum-packed lamb meat from two portuguese breedsPublication . Gonzales-Barron, Ursula; Félix-Oliveira, Diogo; Coelho-Fernandes, Sara; Santos-Rodrigues, Gisela; Lorenzo Rodriguez, Jose Manuel; Cadavez, VascoAlthough meat ageing at cold storage is essential to improve meat tenderness (Prates, 2000), the natural process of microbial spoilage takes place at the same time due to the proliferation of psychrotrophic bacteria, lactic acid bacteria, Pseudomonas spp. and Clostridium spp. (Berruga et al., 2005). A known strategy to moderately extend the shelf-life of meat is vacuum packaging. However, the spoilage retardation rate mainly depends on the initial microbiological quality of meat as well as its initial pH. The objective of this study was to evaluate the evolution of lactic acid bacteria and spoilage microorganisms (i.e., mesophiles, psychrotrophic bacteria and Pseudomonas spp.) in vacuum-packed lamb meat during cold storage at 4ºC. The microbial spoilage in meat originating from two Portuguese ovine breeds, Bordaleira- de-Entre-Douro-e-Minho (BEDM) and Churra-Galega-Bragançana (CGB), was compared.
- Presence and distribution of the African citrus psyllid in São Tomé islandPublication . Benhadi-Marín, Jacinto; Félix, Diogo; Carvalho, Miclay dos Reis Pereira; Mendes, José Luis; Baptista, Paula; Pereira, J.A.The African citrus psyllid, Trioza erytreae (Hemiptera: Triozidae), is a natural vector of Candidatus Liberibacter spp., the causal agents of the citrus greening disease or Huanglongbing (HLB). Despite the global losses of the Citrus industry due to HLB, the vector is rapidly spread to new areas threatening citrus crops and raising con-cern for stakeholders. Until now, there was a single old register of T. er y treae from the São Tomé island (Bulletin of the British Museum of Natural History, Entomology, 49, 1–102). In this work, we provide up-to-date occurrence data on the presence of T. er y treae throughout the isle of São Tomé. The identity of the captured adults was assessed and confirmed through molecular identification by sequencing a portion of the mitochondrial COI. The psyllid was found in lemon, orange and tangerine or-chards. Further monitoring is advisable to manage potential outbreaks
- Microbial contamination of lamb carcasses and meat from autochthonous portuguese breedsPublication . Coelho-Fernandes, Sara; Félix-Oliveira, Diogo; Gonzales-Barron, Ursula; Cadavez, VascoDespite the high consumption of lamb meat in Portugal, there is limited information on its microbiological safety. The objective of this study was to evaluate the levels of hygiene indicator microorganisms and occurrence of pathogens on lamb carcasses and meat from two autochthonous Portuguese breeds, Bordaleira-de-Entre-Douro-e-Minho (BEDM) and Churra-Galega-Bragançana (CGB); and evaluate possible associations among these bacterial groups within slaughter batches.
- Ocurrencia de microorganismos indicadores de higiene y patogénicos en canales de cordero de razas autóctonas portuguesasPublication . Coelho-Fernandes, Sara; Félix-Oliveira, Diogo; Gonzales-Barron, Ursula; Cadavez, VascoSe estima que el consumo de carne ovina producida en Portugal es elevado, aunque se dispone de poca información sobre su calidad microbiológica.
- Microbial deterioration of lamb meat of portuguese origin as affected by its intrinsic propertiesPublication . Cadavez, Vasco; Gonzales-Barron, Ursula; Félix-Oliveira, Diogo; Coelho-Fernandes, Sara; Rodrigues, GiselaIn Portugal, sheep and goat meat production constitutes 2.8% of the total meat production, with a self-sufficiency of ~82%. The main autochthonous sheep breeds exploited for meat production are Churra-Galega-Bragançana (CGB) and Bordaleira-de-Entre-Douro-e-Minho (BEDM), whose quality must be optimised in order to ensure adequate income levels for sheep producers. The study aimed to characterise the evolution of spoilage microorganisms in refrigerated vacuum-packed (VP) lamb meat from BEDM and CGB breeds; and elucidate how intrinsic properties of meat can affect its microbial spoilage. Meat from BEDM breed presented higher (p<.0001) populations of mesophiles, lactic acid bacteria, Pseudomonas spp. and psychrotrophic bacteria, since its higher ultimate pH (means: 5.77 for BEDM vs. 5.58 for CGB) accelerated spoilage rate (p<.0001). While water activity and protein content were not found to modulate microbial deterioration (p>0.05), the growth of spoilage bacteria was found to be exacerbated by higher moisture (p<.0001) and higher ash content (p<0.001). By contrast, a higher fat content retarded (p<.0001) the growth of spoilage bacteria in VP lamb meat. In order to extend the shelf-life of Portuguese-origin lamb meat, animal handling must be enhanced to minimise pre-slaughter stress, and a carcass classification system should be adopted towards the selection of fatter animals and chilled carcasses of optimal ultimate pH.
- Evolución de los microorganismos de dterioro en carne de cordero envasada al vacío de origen portuguésPublication . Félix-Oliveira, Diogo; Coelho-Fernandes, Sara; Gonzales-Barron, Ursula; Cadavez, VascoEn la Unión Europea, existen un conjunto de marcas de calidad asociadas a la carne, las cuales tienen por finalidad no sólo certificar su calidad sino también aumentar el rendimiento de los productores, en vista a que sus intereses confluyen con los intereses del consumidor moderno que procura garantías de calidad y sanidad. En Portugal, el Decreto Ley 147/2006 aprobó las condiciones higiénicas y técnicas a ser observadas en la distribución y venta de las carnes y sus productos, estableciendo 7ºC como la temperatura máxima de distribución y conservación de carnes frescas. Por otro lado, la maduración de la carne, que ocurre durante almacenamiento refrigerado a 0 - 4ºC, es esencial para mejorar la ternura de la misma. En el caso de la carne de cordero, a los 7 días de maduración se alcanza casi el 80% de su máximo potencial de ternura (Prates, 2000). Sin embargo, durante esta maduración – favorable a la calidad sensorial – también se da a cabo el deterioro microbiano debido a la proliferación de bacterias psicrotróficas, ácido-lácticas, Pseudomonas, Clostridium, etc. (Berruga et al., 2005). Una de las estrategias para prolongar el tiempo de vida de la carne es la aplicación de envasado al vacío, la cual puede retardar moderadamente el deterioro microbiano. Sin embargo, se debe tener en cuenta que la tasa de retardo depende principalmente de la calidad microbiológica inicial de la carne y su pH. El objetivo de este estudio fue evaluar la evolución de microorganismos indicadores de deterioro (mesófilos, psicrotróficos, bacterias ácido-lácticas y Pseudomonas spp) en carne de cordero envasada al vacío, durante almacenamiento refrigerado a 4º±1ºC. El deterioro microbiano en carnes provenientes de dos razas portuguesas, Bordaleira-de-Entre-Douro-e-Minho (BEDM) y Churra-Galega-Bragançana (CGB), fue comparado.