Ecological infrastructures in a vineyard of West Sicily

Abstract. Cultural methods such as excessive use of fertilizers, pesticides and monocultures have decreased agrobiodiversity and created   more favourable conditions to increase   insect pests and diseases levels in agroecosystems. Monoculture is a concentrated resource for specialized pests, which increases the attraction and accumulation of these species, the time they spend in the system and their reproductive success (Altieri, 1993). Furthermore, expansion of monocultures has decreased abundance and activity of natural enemies due to removal of food sources (i.e. nectar, pollen and often honeydew), refuges and hibernation sites. Some researchers   have proposed to increase agro-biodiversity by creating an appropriate ecological infrastructure within and around the agro-ecosystem to favour the abundance and effectiveness of natural enemies. The maintenance and management of ecological infrastructures, or ecological compensation areas (ECAs), on rural farms is considered crucial in enhancing functional biodiversity for pest suppression (Boller et al., 2004). In autumn 2006, we start cooperating with a young winery (www.funaro.it) located in Marsala area. In order to enhance biodiversity we have introduced ecological infrastructures in 2 hectares  vineyard of   Merlot variety. We have planted several plants of bramble (Rubus spp.), oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.), wild rose (Rosa canina L.), oak (Quercus pubescens Willdenow) all around Merlot vineyard. These plants should provide refuges, hibernation sites, alternate host animals, prey forthe juvenile stage of predators, resources for a successful immigration and reproduction of natural enemies of key pest in viticulture (Boller et al., 2004). The role of ecological infrastructures in vineyard is still not well understood and their use to manage vineyard pests is a controversial practice. This work aims to study the possible effects of ecological infrastructure on arthropod associated to a vineyard.
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Parasitoids

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The behaviour of parasitoids searching for patchily distributed resources has fascinated many theoretical and applied ecologists. Many models have been developed to show how parasitoids acuire information and distribute their time to the exploitation of host patches. Many recent researches show that parasitoids can allocate its foraging time between host patches in an adaptive way and that the individuals of the same species can be respond differently to the same environmental cues, depending on their genetic, phenotypic plasticity, previous experiences and the individual’s physiological state.The mating status of a parasitoid female can be considered a state variable that affects foraging behaviour. In the Chapter 1 of this thesis, effect of mating status on foraging behaviour of female parasitoids was studied, by comparing virgin and mated females of L. testaceipes Cresson (Hymenoptera:Aphidiidae) in the field and laboratory experiments. L.testaceipes is an endophagous wasp of several aphid pests on economically important crops. The results revealed that although mated females seemed to stay longer than virgin females, patch residence time did not differ statistically between mated and virgin females in both field and laboratory experiments. In the field experiments, patch residence time was affected by patch quality (the number of aphids) only for mated females in accordance with one predictions of the MTV. Furthermore, mated females attacked more aphids than virgin females and the number of aphids attacked increased with the number of aphids on patch for
mated females but not for virgin females.
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