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Contact: Fax: +33 4 9962 3345. Olivier.Bonato@ird.fr; International audience; The effect of the combined use of Encarsia formosa or Macrolophus caliginosus and one of three marketed mycoinsecticides, Mycotal® (Leucanicillium muscarium-based), Naturalis-L™ (Beauveria bassiana-based) and PreFeRal® (Isaria fumosorosea-based), on the control of the whitefly, Trialeurodes vaporariorum, was studied under laboratory and greenhouse conditions. The results of both types of tests, the bioassays and the greenhouse trials, for all combinations of E. Formosa with each of the three mycoinsecticides showed that the total mortality of larval populations of T. vaporariorum was not affected. The mortality of T. vaporariorum larvae treated in the second instar revealed the capacity for both B. bassiana- and L. muscarium-based formulations and E. formosa to kill the host either separately or in association. Because of its higher pathogenic activity (under our test conditions), L. muscarium provoked a large proportion of mycoses in larvae exposed to parasitization. In contrast, the efficacy of parasitization was higher in larvae treated with B. bassiana and exposed to E. formosa because of a lower pathogenic activity of the fungus. Bioassays carried out with third-instar larvae of T. vaporariorum showed a low susceptibility to both tested fungi. Consequently, mortalities recorded in larvae subjected to the combined treatments by consecutive exposures or at 2-4 days post-parasitization were mainly caused by the development of the parasitoid. Greenhouse trials showed that fungus-induced mortality of T. vaporariorum in plants treated with L. muscarium, I. fumosorosea, and B. Bassiana was significant compare to control. L. muscarium, B. bassiana and I. fumosorosea killed young whitefly larvae and limited parasitization to 10% or less. Second-instar larvae of M. caliginosus were not susceptible to L. muscarium and B. bassiana formulations with any mode of contamination: direct spraying of larvae, spraying on the foliar substrate or by contaminated T. vaporariorum prey. In greenhouse trials, M. caliginosus populations treated with fungi were not significantly affected compared to controls.

The aim of the present study is to propose an IPM method using decision rules for global management of greenhouse crops which are environmentally friendly, such as use of beneficial organisms, no pesticides, etc. Decision rules could be considered the good means for the implementation of IPM in greenhouse agro ecosystems. Decision rules based on the thresholds of pests could be developed as a basis to control rose and tomato crops. Global management action has to be directed against the several pests that are present simultaneously or successively. The strategy will be preventive, and makes use of pest abundance evaluation to choose the best rule. Use of beneficial organisms is the first action to be chosen in these decision rules. If the use of pesticide is necessary, its side-effects must be as low as possible. The results obtained on previous IPM studies were used to write complete sets of decision rules. The sets of decision rules to manage whiteflies that affect tomato and rose crops are presented. They answer the question asked and are written on the form "if-then"with a scale of actions if they are numerous. Applying these rules, satisfactory results were obtained to manage whiteflies e. g. Trialeurodes vaporariorum or Bemisia tabaci by using Macrolophus caliginosus and Encarsia formosa for tomato and by using Encarsia formosa and/ or Eretmocerus eremicus for rose. The pesticide use was considerably reduced.

Overall, Integrated Pest Management (IPM) is considered a success story within Controlled Environment Agriculture (CEA) systems but this assertion is strongly dependant on technology levels and crop plant species. The estimated percentage under biological and integrated control in CEA in 2007 was 5% of the total world greenhouse area. In spite of substantial advances, IPM mostly concerns popular vegetables and sophisticated greenhouses, suggesting that biological control used without the help of physical control, e. g. screen-barriers and climate management, and multi-pest resistant varieties is a major challenge to overcome. Up to now, biological control has been implemented empirically at the cost of huge experimental efforts in order to provide wide-test ranges of biological control agents (BCAs) and that, by the same token, counterbalance numerous unexplained failures at the crop level. Satisfactory answers to pest problems require a shift in understanding, such as promoting biological agents as well as more widely ecologically-sound practices. Despite being poorly biodiversified, many complex interactions can occur between biotic components in agro-ecosystems such as CEA. Understanding these interactions is a major hurdle to overcome for the development of future IPM strategies. The ecological approach, based on both theoretical and applied studies, is of major interest to describe the biotic interactions taking place between the crop, pests and BCAs, as well as to refine pest control methods, for example, through the use of multiple natural enemies. Such an approach can highlight crucial information to choose BCA species accurately with respect to their intra-specific characteristics, i.e. functional and numerical responses, and inter-specific interactions. It may also assist the design of robust, efficient and complementary BCA associations targeted to multipest control issues. Experimental evidence of unexpected pest/pest, pest/BCAs, BCAs/BCAs interactions observed on tomato and rose crops, and their respective impact on IPM, are presented.

Comment améliorer l'efficacité de la protection biologique contre les ravageurs de la tomate dans un contexte d'augmentation des contraintes sans en augmenter les coûts ? Tel est l'objectif principal recherché depuis plusieurs années à la station INRA Alénya

International audience

Correspondance: bonato@mpl.ird.fr.; International audience; A study of predation choices of Macrolophus caliginosus Wagner (Heteroptera: Miridae) late instars and adults, when offered various developmental stages (eggs and nymphs) of the recently established whiteßy Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), was made based on two preference indices. In addition, prey choices of late instars when presented with three ratios of Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) and B. tabaci at a similar developmental stage (eggs, young or late instars) were assessed.M. caliginosus preferred older nymphs of B. tabaci than any other stage. It also chose T. vaporariorum over B. tabaci, unless the latter consisted of _75% of the available prey. These results suggested that M. caliginosus might interfere with parasitoids such as Encarsia, Eretmocerus, or Amitus spp. because all three species emerge from the host pupal case. Furthermore, in mixed infestations, M. caliginosus preference for T. vaporariorum might either negatively affect the control of B. tabaci, or, contrarily, enhance the predator population, before a B. tabaci outbreak occurs in the greenhouse

A simple, small-sized penetrometer was made to investigate the tissue hardness of plant samples in relation to oviposition by the bug Macrolophus caliginosus Wagner. Depth and speed of probe penetration into the tissues were controlled and the reliability of the device was evaluated. The penetrometer was connected to a microcomputer, and force-time curves with characteristic parameters were thus immediately available. This technique allowed us to estimate the hardness of Pelargonium peltatum (L.) tissues. We showed a correlation between M. caliginosus oviposition sites and the hardness of the P. peltatum tissues (between 0.1 and 0.2 Newton), indicating that hardness should be a choice criterion in this range of values. Below 0.1 Newton, no correlation appeared: the tissues were tender enough to allow oviposition. Above 0.2 Newton, few eggs were laid.

The predaceous bug,Macrolophus caliginosus Wagner (Heteroptera: Miridae) is a biological control agent used in greenhouses in the French Mediterranean region. The egg of this mirid is embedded in plant tissues and all embryonic development occurs in this environment. In order to define an artificial substrate for egg-laying, exchanges of chemical substances between the egg and the host plant were investigated by morphological and biochemical analyses. Egg wet weight doubled throughout embryonic development, while egg dry weight did not vary. The amino acid content of the egg remained stable during embryogenesis. Only aspartic acid, serine and alanine decreased during the first five days of development. It can be concluded that exchanges mainly involved uptake of water by the egg.

Les recherches entreprises en conditions controlees de laboratoire ont permis de determiner les principales caracteristiques biologiques deMacrolophus caliginosus Wagner (Heteroptera: Miridae). Cette espece apparait assez polyphage mais est un predateur actif des stades immatures de l'Aleurode des serres. L'incubation des oeufs demande 11,4 jours a 25 °C et plus d'un mois a 15°C, le taux d'eclosion depassant 80% lorsque l'etat de la plante hote reste satisfaisant. La vitesse de developpement larvaire depend a la fois de la temperature et de l'alimentation fournie. Sur jeunes stades d'Aleurodes, il faut environ 19 jours a 25 °C et 58 jours a 15 °C de l'oeuf a l'adulte. L'evolution des larves est encore possible quoique tres lente a 10 °C alors que la temperature de 40 °C est letale. La longevite et la fecondite deM. caliginosus sont importantes puisqu'elles atteignent respectivement 232 jours et 409 oeufs pour des femelles nourries avec les oeufs d'Anagasta kuehniella pris comme alimentation de remplacement.M. caliginosus peut supporter une limitation severe de la quantite de nourriture disponible puisque developpement et ponte sont possibles avec moins de la moitie de la ration habituelle. L'implication de ces resultats sur la connaissance des performances de ce predateur en temps qu'agent de lutte biologique contre les ravageurs des cultures protegees est discutee.

La possibilite de nourrir la punaiseMacrolophus caliginosus Wagner a l'aide de milieux artificiels a ete testee. En l'absence de vegetal, les temoins nourris avec des œufs d'Ephestia kuehniella Zeller ont une survie mediocre et fournisent 33% d'adultes. Avec le meilleur milieu artificiel la survie est comparable a celle des temoins et 21 % d'adultes sont obtenus. Avec ce meme milieu, mais en presence de feuille de geranium, la production d'adultes atteint 62%. Les compositions en acides amines des punaises elevees avec le milieu montrent des ecarts inferieurs a 20% par rapport aux temoins. Le developpement complet deM. caliginosus nourri a l'aide de milieu artificiel a ete obtenu. Le vegetal joue un role important dans la biologie de ce predateur.