Spread patterns of Trioza erytreae on citrus orchards and the potential role of natural enemies as biocontrol agents

• Autor(a) principal: Félix-Oliveira, Diogo
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10198/24707
• topic: Huanglongbing; T. erytreae; Kaolin; Natural enemies; Domínio/Área Científica::Ciências Agrárias::Biotecnologia Agrária e Alimentar

Citrus 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.