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Universitat de Barcelona (2012)

Gestión del hábitat y papel de los recursos vegetales en el control biológico por conservación

Pumariño Romero, Lorena

Titre : Gestión del hábitat y papel de los recursos vegetales en el control biológico por conservación

Habitat management and the use of plant-based resources for conservation biological control

Auteur : Pumariño Romero, Lorena

Université de soutenance : Universitat de Barcelona

Grade : Doctoral Tesis 2012

Résumé
Modern agriculture has been focused on very intensive agricultural systems that depend on external inputs such as fertilizers or pesticides. These practices have lead to a simplification of the landscape and a decline of abundance of natural enemies. Nevertheless in the last years there has been an increasing interest in the application of more environmentally friendly techniques in agriculture, such as biological control (BC). Specifically, conservation biological control (CBC) involves the manipulation of the environment to enhance natural enemy’s effectiveness, which can be achieved by means of reducing harmful conditions or improving favourable ones. Habitat management, a part of the CBC approach, consists of selecting plants that provide natural enemies with resources such as non-host foods including pollen or nectar, alternative preys or hosts or shelter from adverse conditions. There are several forms of habitat manipulation approaches that may enhance natural enemy’s numbers in crops ; of all those different strategies, the use of insectary plants to conserve beneficial insects has been greatly used. The main objective of this work is to investigate the extent to which the use of vegetal resources may improve the CBC by means of habitat manipulation. This main objective has been developed in six specific objectives that have been carried out in sex chapters. In chapter 1, the potential of the Mediterranean plant Lobularia maritima to be used as an insectary plant for the conservation of the omnivorous predator Orius majusculus has been evaluated. This predator effectively preys on thrips in crops such as lettuce as its conservation in the Mediterranean area is very important. The results have shown that L. maritima provides the predator enough resources to survive in the absence of prey, which would allow the survival of the predator during periods of prey scarcity. In chapter 2, both O. majusculus and O. laevigatus have demonstrated that they prey on thrips in L. maritima plants and they are able to control these pest populations on this insectary plant. At the same time, O. majusculus effectively reproduces on L. maritime with thrips as prey. Therefore, L. maritima can be considered a good insectary plant for the conservation of O. majusculus that does not enhance thrips populations. Results in chapter 3 have demonstrated that different plant species affect very differently the survival, reproduction and nutrient status of the predatory bug O. insidiosus. These observed differences are in part due to the levels of access to the floral and extrafloral resources. Moreover, the predator reproduction is enhanced by an increase in biodiversity. These results show that it is very important to choose the most appropriate plant species for each specific situation and each specific CBC program. In chapter 4 the interactions of two important predators have been evaluated. It has been observed that O. insidiosus and N. americoferus are able to detect one another when they share the same habitat and in fact, they change their reproductive decisions depending on if they are exposed to the other species or they are only exposed to conspecifics. In chapter 5 tomato specific DNA markers have been designed. They allow the tomato DNA identification within the guts of three different species with different feeding habits in the laboratory. Moreover, these markers allow the tomato DNA identification within field collected insects. In chapter 6 is has been demonstrated that the use of mulches in vineyards not only enhance the arthropods abundance on the vineyard soil but also they improve several ecosystem services such as soil temperature and moisture and earthworm populations. On the other hand they improved some harvest parameters and they reduce pest and diseases on the vineyard canopy. Overall it can be concluded that the results of this work have demonstrated that the use of several vegetal resources can noticeably improve CBC programs despite the fact the vegetal species must be selected carefully and depending on every specific CBC program

Mots clés : Control biológico, Depredadores omnívoros, Gestión del hábitat, Plantas insectario

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Page publiée le 20 octobre 2015, mise à jour le 13 février 2019