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|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|
|Issue Date: ||2011|
|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
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
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|
|Appears in Collections:||BISA - Dissertações de Mestrado / Master Thesis|
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