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Please use this identifier to cite or link to this item: http://hdl.handle.net/10400.5/3907

Title: Evolução das populações de Tuta absoluta (Meyrick) e meios de protecção em ambiente empresarial vocacionado para exportação
Authors: Matos, Tiago Manuel Ferreira Lopes Guerreiro de
Advisor: Mexia, António Maria Marques
Oliveira, Elisabete Tavares Lacerda de Figueiredo
Keywords: tuta absoluta
population's evolution
nesidiocoris tenuis
spinosade
mass trapping
Issue Date: 2011
Publisher: ISA/UTL
Citation: Matos, Tiago Manuel Ferreira Lopes Guerreiro - Evolução das populações de Tuta absoluta (Meyrick) e meios de protecção em ambiente empresarial vocacionado para a exportação. Lisboa: ISA, 2011
Abstract: Tuta absoluta (Meyrick) represents, nowadays, a serious threat to tomato crops, either protected or open field crops, which is a sector of vital importance in the Mediterranean basin and, therefore, in Portugal too. As it usually happens in case of exotic invasive pests, the lack of knowledge about its biology, behaviour and effective control measures generates a period of uncontrolled balance of the pest with serious outbreaks or, in many cases, the adoption by growers of highly undesirable strategies. The present work intends to partially address to the challenges presented by that lack of knowledge, exploring the pest behaviour in greenhouse tomato crops and testing different pest control measures. All the essays were carried out in a Portuguese company totally focused on growing tomatoes to the English market, one of the most demanding markets in the world. Nowadays, production companies need a lot of certification schemes to be able to sell their agricultural goods in those markets. Many of those certifications are brand specific, for each supermarket, and almost all of them are related with good agricultural practices which guarantee food security and biodiversity preservation. These subjects are growing concerns for consumers and growers must be able to reach such level of demanding, while they are also obliged to fulfil quality standards and innovation in their products. With these concerns in mind and the need for picking tomatoes every week from October to June, this company´s strategy for T. absoluta, such as for other pests, must include biological control and the use of pesticides from natural origin. When necessary, synthetic pesticides are applied but those must have a short harvest interval. The fulfilment of this and other rules will always be essential to the success of this particular company, as it will be for Portuguese agricultural companies in general if they want to successfully sell quality products in foreign markets and contribute to the increase of the country´s export revenue. T. absoluta females seemed to prefer laying their eggs in the top section of tomato plants, inducing a large number of mines in the section immediately below that area. These mines tend to be abandoned at a later stage of the larval development. Those larvae moved then to immature fruits or leaves in the bottom part of the plant. The existence of eggs and young larvae in the top of the plants justifies the presence of Nesidiocoris tenuis adults in that area, actively searching for preys and, therefore, reducing the overall T. absoluta damage. This mirid can be considered, consequently, a v good biological control agent of T. absoluta. However, in the absence of a suitable prey, N. tenuis can become a tomato plants pest himself, as it was observed. The deliberate releases of this mirid in crops must be carefully evaluated and its spontaneous presence should be regularly monitored. The use of nets at the top windows of the studied greenhouses seemed to delay the appearance of T. absoluta in the crop, especially if proper isolation measures were carried out. Net´s beneficial effect should be confronted with consequences on the greenhouse environment and significant economic effort demanded for application of this devices. Another possible way to avoid the pest residence inside greenhouse is the elimination of the falling pupae, which tend to remain in the soil or under soil covers. In situations where a pesticide application is necessary, spinosade a.i. must be considered, given the promising results presented. Its registration for the control of this pest should be considered. It will be also very useful to perform field trials with a.i. recently registered, for T. absoluta control. After reducing this pest’s populations to very low numbers, either through pesticide applications or mirid´s predation mechanisms, regular applications of Bacillus thuringiensis, a biopesticide, contributed to delay the recovery of those populations. Under such circumstances, possible development of resistance must be considered and evaluated. The application of other preventive strategies, such as the introduction of the egg parasitoid Trichogramma achaeae, could also have an interesting effect on the pest development. In this case, its real efficiency on T. absoluta will have to be studied in detail still, given the remaining doubts on its efficacy, especially if we consider the highest recommended release rates. If its effectiveness is demonstrated, a proper way of supplying this beneficial insect with good quality standards to Portuguese growers from producing companies will have to be guaranteed. Water traps for mass trapping, which combine the attractive effect of sexual pheromone and light, captured higher levels of T. absoluta adults than the traditional ones, with pheromone bait only. However, this traps seemed unable to capture females of T. absoluta, an expected event due to the light effect. This lack of female captures makes it hard to justify their use, considering its high cost compared with traditional water traps
Description: Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia
URI: http://hdl.handle.net/10400.5/3907
Appears in Collections:BISA - Dissertações de Mestrado / Master Thesis

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