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- Citrus aphids in Algarve Region (Portugal): Species, hosts, and biological controlPublication . Paiva, Paulo Eduardo Branco; Neto, Luis; Marques, Natália; Duarte, Beatriz; Duarte, AmilcarAphids affect citrus by causing leaf deformations and reducing fruit production. Additionally, aphids are a great concern due to their ability to transmit Citrus tristeza virus (CTV), the cause of tristeza, one of the main citrus diseases. In the last four years, citrus orchards in the south of Portugal (Algarve region) were sampled for aphid species identification and counting. Aphis spiraecola was the most abundant species, representing more than 80% of all identified aphids, and the damage (leaf deformation) it causes was directly proportional to its density. A. gossypii was the second most common species, followed by A. aurantii and Macrosiphum euphorbiae. The number of aphids in nymph stages was predominant over the adult stages (both wingless and winged) in all species. A. citricidus, the most efficient CTV vector, was not detected. The largest populations of A. spiraecola were observed in lemon and orange trees during spring (>100 individuals per shoot), with great damage observed in orange, lemon, and mandarin trees. A. gossypii was observed mainly in mandarin and tangor trees. There was a low activity of natural biological control agents, with the parasitism of A. spiraecola by Lysiphlebus spp. and Binodoxys spp. ranging from 0.3 to 1.5%. The numerical ratio ranged from 150 to 440 aphids per predator, and among these, syrphids were the most abundant, followed by lacewings and coccinellids (Scymnus).
- Current distribution of the African citrus psyllid Trioza erytreae in Portugal: relation to climatic conditionsPublication . Duarte, Beatriz; Poeira, Rita; Magalhães, Tomás; Paiva, Paulo; Soares, Celestino; Neto, Luís; Marques, Natália; Duarte, AmilcarThe onset of Trioza erytreae, the African citrus psyllid, in the northwest of the Iberian Peninsula (north of Portugal and northwest of Spain) caused great concern among citrus growers in Europe. This insect is a vector of the bacteria Candidatus Liberibacter spp., the causal agent of huanglongbing, one of the most devastating citrus diseases. The first report of T. erytreae presence in mainland Europe refers to an area with isolated citrus trees and no significant citrus orchards. However, it was predictable that T. erytreae could spread quickly reaching the most important citrus growing area, in the south. Therefore, the Portuguese citrus industry is the first to be threatened in Europe, but the entire European citrus industry is at risk. In addition to the containment measures taken by the Portuguese and Spanish Phytosanitary Services, several models were made to predict how the African citrus psyllid could advance through the territory of the two countries. Releases of the parasitoid Tamarixia dryi were used for psyllid control. Despite that, T. erytreae has moved south and is on the verge of reaching the most important Portuguese citrus-producing area, which is connected to the citrus-growing areas of the other Mediterranean countries. This advance took place along the coast, without reaching interior regions of the country, where, according to some models, a high-water vapor pressure deficit hinders the insect's development in warmer areas. Populations of T. erytreae dropped significantly in 2021 and 2022, making it difficult to detect even in previously infested areas. This doesn't give farmers peace of mind because the presence of T. erytreae, even in low populations, could lead to a quick spread of huanglongbing, if or when the disease arrives in Europe. Therefore, it is crucial to continue to monitor T. erytreae populations and implement the necessary containment measures for the vector.