Filipe Madeira

Oleander is very frequently planted as an ornamental shrub in urban areas of the Mediterranean. Its most common pest is the aphid Aphis nerii, and heavy infestations produce aesthetic damage and disturbances to the citizens, and they are frequently sprayed with insecticides in order to reduce the population density. One alternative method is conservation biological control which is enhanced by the provisioning of alternative food, refuges, and reproduction sites. In this study, the usefulness of four flowering service plants (Lobularia maritima, Calendula officinalis, Coreopsis grandiflora, and Achillea millefolium) is evaluated for aphid infestation levels and aphid natural enemy abundances. Aphid levels were consistently lower in oleander plots surrounded by service plants. Natural enemy abundances tended to be higher in plots surrounded by service plants, but significant differences could not be found until the fourth year of the study, when more lacewings, total predators, and m...

Preface .................................................................................................................................. I List of participants ............................................................................................................... III

The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies

Knowledge of the specific insect densities during crop development is necessary to perform appropriate measures for the control of insect pests and to minimize yield losses. In a previous study, both spatial and temporal approaches were adopted to analyse the influence of landscape structure and field variables on herbivore and predatory insects on maize. Both types of variables influenced insect abundance, but the highest effect was found with maize phenology. Given that the field planting date could modulate the influence produced by the structure of the landscape on herbivores and predatory insects, analyses of population dynamics must be performed at both the local and landscape levels. The anterior prompted us to study these aspects in the two common planting periods (early and late) in northern Spain. The present study tests the hypothesis that the period of maize planting could have a higher effect than phenology or interannual variation on the abundance of natural enemies an...

We assess the effects of changing land use and crop management on alfalfa insect abundance by comparing it in 50 alfalfa fields when they were inserted in landscapes with different proportions of arable crops and orchards. Land use in a buffer of 500 m was assessed, and alfalfa insect abundance was estimated with sticky yellow traps. The number of catches of several herbivores and predators was related to the proportion of landscape components and several field variables. Results indicated that the proportion of orchards in the buffer negatively affected the abundance of predators on alfalfa, likely because orchards treated with pesticides are a sink for predators moving in the landscape, among other possible causes. Other landscape variables such as noncrop habitats, winter cereals, and landscape diversity analysed by the Shannon index had a minor influence. Among field variables, field size influenced positively the abundance of insects on alfalfa, whereas alfalfa growth stage and age affected positively or negatively the different herbivores and predators. Of course, abundance of predators and prey was affected by the abundance of prey and predators, respectively. These findings suggest that a high proportion of intensively managed crops (orchards) in the landscape interferes with the role of alfalfa as a reservoir of predatory insects for adjacent crops and that the responses to local and landscape structures are temporal and species-specific as previously concluded for maize. Consequently, landscape and field management strategies to improve pest control must consider both types of variables as well as their changing influence when we modify them.

The idea that noncrop habitat enhances pest control and represents a win-win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and so...

is one of the most common ladybird species in urban green areas of the Mediterranean region. We have obtained data about its prey acceptability and prey preferences. In a laboratory experiment, we investigated the acceptability of seven aphid and one psyllid species as prey for this coccinellid: the aphids,,,(on white poplar, pomegranate, false acacia, black walnut, lime, and oleander, respectively), and the psyllidon Persian silk tree. These species are abundant in urban green areas in the Mediterranean region. In addition, we tested the acceptability ofon barley, an aphid species easily reared in the laboratory. We also tested preferences of the predator in cafeteria experiments with three aphid species and one aphid and the psyllid. Adults and larvae of the coccinellid accepted all of the preys offered, except, with a clear preference for. The predator also showed preference forwhen it was offered in a cafeteria experiment with other aphid species or with the psyllid. The aphidob...

Knowledge of the insect densities during crop development is necessary for adopting appropriate measures for the control of insect pests and minimizing yield losses. Within integrated pest management programs, crop rotation has been carried out in recent years, but this current trend delays the planting period for Bt maize. The small amount of available information regarding the influence of sowing Bt maize early or late on the seasonal abundance of herbivores prompted us to study these aspects in two current common planting periods in northeastern Spain in 52 maize fields over three consecutive years. We sampled the fields planted on different dates with sticky yellow traps. Our results show that only the abundances of herbivore thrips, other than Frankliniella occidentalis, and Syrphidae were significantly different between the two planting periods. Moreover, when we performed yearly analyses, we found significant effects of the planting period on Coccinellidae and Chrysopidae in ...

Pseudaletia (Mythimna) unipuncta (Haworth) is a maize leaf feeder pest occurring every year in the Ebro Valley that causes occasional but sometimes devastating damages. The increasing cultivation of Bt maize in Spain has reduced very much the damage of corn borers, Sesamia nonagrioides (Lefebvre) and Ostrinia nubilalis (Hübner). However, is it not know how Bt maize can affect populations of P. unipuncta. It doesn�t exist published information about development and other biological parameters of P. unipuncta in the Iberian Peninsula and this information is needed to evaluate the effects of the new corn varieties on the local populations. To get it we need first to establish an adequate rearing method and then to start studying insect biology. In the present paper we study the larval development of a local population of P. unipuncta fed with leaves of two varieties of maize (Tietar and PR33P66) and two artificial diets, one made with beans, Phaseolus vulgaris, and another with flour o...

To know whether, how and when natural enemies switch between crops can help to delimitate their role as a reservoir and to manage the landscape in order to improve biological control functions. Carbon stable isotope analysis may be used for tracking predator movement because plant signature remains up in the food web and can be traced in herbivores and in their predators. This is especially true when C3 and C4 plants are compared of because the clear distinct ratio of 13C (δ13C) between both plants. In the irrigated area of northeastern Iberian Peninsula, the agricultural landscape is mainly formed by arable crops which share most of the natural enemies of pests. In spring and summer alfalfa and maize, a C3 and a C4 crop respectively, are prevalent. Aphids are common in alfalfa and maize; they are crop specific and are preyed by specific and generalist predators. So that, we hypothesize that aphids may be used as an herbivore reference for determining the movement of predators betwe...

Though genetically modified (GM) crops have been rapidly adopted in world agriculture, concern has been expressed about the environmental risks that they may involve. In order to identify and measure the effects on NTOs (non-target organisms) of transgenic traits of crops such as Bt corn, which has been designed to kill target species, a tiered approach has been proposed. When an effect is detected in laboratory or semi-field steps, it is measured in subsequent higher-tier steps with an increasing complexity and realism in field conditions. In some cases this sequential testing scheme is not applicable because potential effects are not measurable in simple laboratory conditions and the testing procedure has to be initiated with field trials. This is the case, for example, when indirect effects are expressed through the food web or when the main expected effect is a consequence of changes in agricultural technology. However, field trials have many disadvantages and, whenever possible...

Orius majusculus Reuter (Heteroptera: Anthocoridae) is the most common and abundant generalist predator in Spanish maize crops and is sensitive to drastic changes in weed density. We carried out a 2-year study in the NE Iberian Peninsula to examine the dispersal of O. majusculus in maize plots with moderately high and low weed density. Insects were collected using yellow sticky traps and/or a bug-vac aspirator. Dispersal was assessed using rubidium as a marker. Dispersal rate of O. majusculus differed between sampling periods, with a maximum between the 16 unfolded leaves (V16) to grain milky (R3) maize growth stages. However, we detected no differences in the distance moved by male and females of O. majusculus from rubidium-marked areas in plots with moderately high or low weed density suggesting that changes in weed density do not affect the dispersal of O. majusculus within a maize field.