Modelo espacial de distribuição da lagarta-da-pastagem (Pseudaletia unipuncta, Haworth) (Lepidoptera: Noctuidae) na ilha Terceira

Mestrado em Engenharia Agronómica.A lagarta-da-pastagem (Pseudaletia unipuncta, Haworth) é considerada uma das pragas mais prejudiciais das pastagens, e que os agricultores mais temem, pois sendo uma praga polífaga pode também afetar outras culturas quando a sua densidade larvar é muito elevada e a sua cultura preferencial tiver sido já consumida. O seu combate é muito difícil, dado que a lagarta só é visível pelos agricultores quando atinge os últimos ínstares larvares, sendo estes os mais prejudiciais. Existem diversos produtos químicos aplicáveis no combate à lagarta-da-pastagem, de entre eles os mais eficazes são os à base de deltametrina e lambda-cialotrina. Também a luta biológica é um dos métodos de combate mais utilizados, em que os parasitóides com mais eficácia é o Apanteles militaris (Walsh). A aplicação de produtos à base de Bacillus thurigiensis (Berliner) também regista bons resultados. Um outro método eficaz e que não implica custos e desprovido de qualquer tipo de impacte ambiental nas pastagens é a adoção de meios de luta culturais, possibilitando eliminar ou prevenir o aparecimento e a instalação da lagarta tais como o maneio adequado da pastagem impedindo assim a formação de grandes populações de P. unipuncta e possibilitando uma definição atempada da frequência do pastoreio, da altura de corte e do apascentamento adequado. Neste estudo procurou-se quantificar, em campo, a densidade larvar de Pseudaletia unipuncta (Haw.) analisando as capturas de adultos nas armadilhas colocadas nas pastagens e posteriormente foi-se relacionar estes dados com os fatores climáticos, temperatura, humidade relativa e precipitação e com o tipo de coberto vegetal existente a fim concluirmos em que altitudes, tipos de pastagens e altura do ano é que esta praga se encontra em maior densidade populacional atendendo ao tipo de cobertura existente. Este estudo foi realizado no ano de 2011 entre os meses de Maio e Novembro e foram escolhidas dez pastagens a diferentes altitudes em redor de toda a ilha. Em cada parcela foi colocada uma armadilha do tipo funil para a captura de adultos de Pseudaletia unipuncta Haw. e semanalmente era feita a prospeção larvar no terreno. Foi feito o levantamento da composição de espécies vegetais presentes em cada pastagem. Podemos concluir através dos resultados obtidos que na parcela Pico Catarina Vieira existe uma dominância de espécie vegetal, Holcus lanatus L., coincidindo com o local onde se capturou uma maior quantidade de larvas, havendo uma correlação muito elevada entre a densidade da lagarta-da-pastagem com a dominância da vegetação. O clima também tem uma grande influência na densidade larvar, a lagarta desenvolve-se melhor em sítios amenos, com bons valores de humidade relativa e precipitação. Por fim, a altura do ano em que se obteve maiores capturas de Pseudaletia unipuncta Haw. foi no mês de Agosto.ABSTRACT: The armyworm (Pseudaletia unipuncta, Haworth) is considered one of the most damaging pests of pastures, and farmers fear most, because being a polyphagous pest can also affect other crops when their larval density is very high and it’s preferential culture has already been consumed. It’s a very difficult pest to combat, because farmers can only see the armyworm when it reaches the last larval states, which are the most damaging. There are many chemical products applicable in the armyworm combat, among them the most effective are those the basis is made of deltamethrin and lambda-cyhalothrin. Also the biological control is one of the most methods used in this pest prevention, wherein the more effectively parasites is Apanteles militaris (Walsh). The application of products based on Bacillus thuringiensis (Berliner) also records good results. Another method effective and that does not involve any costs and devoid of any environmental impact in pastures is the adoption of cultural methods, making it possible to eliminate or prevent the onset and installation of the armyworm, such as a proper management. This helps preventing the formation of large populations of P. unipuncta and enabling an early definition of the frequency of grazing, cutting height and adequate grazing. This study sought to quantify in the field, the density of larval Pseudaletia unipuncta (Haw.) analyzing the catches of adults in traps placed in pastures and then relate these data with climatic factors, temperature, relative humidity and rainfall and with the type of existing vegetation to conclude that altitude pasture types and time of year is that this pest is found in higher population density given the type of existing coverage. This study was accomplished in 2011 between the months of May and November, and were chosen ten pastures at different altitudes around the entire island. In each plot was placed a trap for capturing Pseudaletia unipuncta Haw. adults and were made weekly larval exploration. Afterwards was the survey made of the composition of plant species present in each pasture. We concluded that the results obtained in the parcel Pico Catarina Vieira show us that there was a dominance of plant species, Holcus lanatus L., coinciding with the location where were captured a greater amount of larvae, showing a very high correlation between the density of the caterpillar with the dominant vegetation. The climate also has a great influence on larval density, the caterpillar develops better in locations were the weather is more pleasant, with good values of relative humidity and precipitation. Finally, the time of year that showed higher catches Pseudaletia unipuncta Haw. was in August

Contribution to the study of the beneficial fauna of olive orchards in Porto Martins, Terceira Island, Azores

Proceedings of the 9th Meeting at Lisboa (Portugal) 26-29 October, 2021.The olive tree culture in Terceira Island occupies a strip in Porto Martins area whose fruit is very sought, mainly by tourists and restaurants. The olive tree is very affected by pests, such as the olive fly, which causes high losses and a drastic loss of production. Therefore, large quantities of pesticides are applied whose applications have a great impact, in particular, on beneficial organisms. In this work, the beneficial fauna present in olive groves was identified through the technique of beatings. The impact of the application of pesticides on these beneficial insects present in olive trees with different levels of treatments was also evaluated. For this, orchards with intensive applications, with less intensive applications and one organic orchard were selected to studied and monitoring. It was verified that in the olive groves with intensive and semi-intensive pesticide applications the abundance of beneficial insects was unbalanced, with a low abundance of predatory insects and still high population densities of the olive cottonweed pest. The results obtained point to the fact that chemical treatments do not destroy the target pests and worst contribute to a reduction in auxiliary organisms. In the organic orchard was observed the highest abundance of predatory insects and the lowest abundance of herbivorous insects. These results showed that this type of orchard is in a natural balance and that this is the way to follow in preserving the presence of beneficial insects in the olive parcels because these are very important to keep low pest populations and permit its better control. The conclusions of this study point to the fact that producers can further increase their yield by taking the biological option in their daily practices that will have a lower impact on the beneficial fauna present in the olive groves. At the same time will also permit to preserve the environment and the health of the applicators, producers and of the consumer by obtaining a product without any pesticide residues.To the producers involved in this study. To the agricultural development service of Terceira island (SDAT) and the regional secretary of agriculture and rural development /SRADR) for the logistic support to all the work. To the Cuarentagri project (www.cuarentagri.com) that allowed the execution of this work.info:eu-repo/semantics/publishedVersio