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International audience; BACKGROUND: Bottom-up and top-down forces are major components of biological control against pests in an agro-ecosystem. Understanding the multi-trophic interactions between plants and secondary consumers would help optimize pest control strategies. We manipulated nitrogen and/or water inputs to tomato plants (Solanum lycopersicum) to test whether these manipulations could trigger bottom-up effects on the parasitoid Necremnus tutae via host (Tuta absoluta) and/or non-host (Bemisia tabaci) exposures, and compared the control efficacy of N. tutae on T. absoluta in the presence and absence of B. tabaci. RESULTS: The results showed no cascading effects of plant nitrogen and/or water inputs on N. tutae via either host or non-host exposure. The bottom-up force was mitigated by chewing or sap-feeding insect consumers at the second energy level. By contrast, the top-down force on T. absoluta from parasitoids was enhanced by an additionally provided non-host, which could produce alternative food sources extending N. tutae longevity and enhancing the fitness of its offspring. CONCLUSION: Our results provided evidence for the combination of bottom-up and top-down approaches in tomato integrated pest management programs.

BACKGROUND The complexity of both natural and managed ecosystems involves various forms of interaction among organisms. Two or more species that exploit the same resource can engage in competitive behaviours, usually referred to as intraguild interactions. These can be direct, i.e. one species feeds directly upon the competitor (intraguild predation) or indirect, e.g. when the dominant organism competes for a food source that another organism is feeding upon (kleptoparasitism). We investigated the potential for such interactions in a biological model composed by the South American tomato pinworm, Tuta absoluta, and three of its newly associated natural enemies: the zoophytophagous predator Nesidiocoris tenuis and the two idiobiont ectoparasitoids Bracon nigricans and Necremnus tutae. RESULTS N. tenuis was shown (i) to scavenge on parasitised T. absoluta larvae and (ii) directly to attack and feed upon larvae of both parasitoid species, although at a higher percentage in the case of N. tutae. In the presence of the host plant, the predator reduced the emergence of both B. nigricans and N. tutae adults significantly. CONCLUSION This study stresses the ecological success of a generalist predator over indigenous parasitoids attacking an invasive pest. Moreover, these findings provide potential elements for better design of biological control programmes against T. absoluta. © 2017 Society of Chemical Industry.

BACKGROUND The flower bug Orius sauteri (Poppius) (Hemiptera: Anthocoridae) is widely used as a biocontrol agent against thrips and aphids infesting greenhouse vegetables in Asia. The survival and oviposition of such predators, as well as the biocontrol services they provide, may be enhanced by adding extra floral resources to the crops. In the present study we investigated the effects of the plant Calendula officinalis L., used as a floral resource, for promoting the control of Myzus persicae (Sulzer) and Frankliniella occidentalis (Pergande) by O. sauteri under laboratory and greenhouse conditions. RESULTS Results showed that the presence of C. officinalis enhanced aphid and thrips suppression via an increased O. sauteri population growth. The predator populations responded positively to the addition of C. officinalis in the system, and they also varied as a function of the temperatures tested under laboratory conditions. In a similar way, predator populations varied among seasons, with the highest densities recorded in May in the greenhouse. CONCLUSION C. officinalis can be used to increase available resources for natural enemies used in agricultural crops, notably in greenhouses. This study also provides evidence that increasing floral resources can enhance pest suppression provided by O. sauteri. © 2016 Society of Chemical Industry

Spinosyn-based products, mostly spinosad, have been widely recommended by extension specialists and agribusiness companies; consequently, they have been used to control various pests in many different cropping systems. Following the worldwide adoption of spinosad-based products for integrated and organic farming, an increasing number of ecotoxicological studies have been published in the past 10 years. These studies are primarily related to the risk assessment of spinosad towards beneficial arthropods. This review takes into account recent data with the aim of (i) highlighting potentially adverse effects of spinosyns on beneficial arthropods (and hence on ecosystem services that they provide in agroecosystems), (ii) clarifying the range of methods used to address spinosyn side effects on biocontrol agents and pollinators in order to provide new insights for the development of more accurate bioassays, (iii) identifying pitfalls when analysing laboratory results to assess field risks and (iv) gaining increasing knowledge on side effects when using spinosad for integrated pest management (IPM) programmes and organic farming. For the first time, a thorough review of possible risks of spinosad and novel spinosyns (such as spinetoram) to beneficial arthropods (notably natural enemies and pollinators) is provided. The acute lethal effect and multiple sublethal effects have been identified in almost all arthropod groups studied. This review will help to optimise the future use of spinosad and new spinosyns in IPM programmes and for organic farming, notably by preventing the possible side effects of spinosyns on beneficial arthropods.