Étude du potentiel biotique du parasitoïde Encarsia sophia dans des conditions contrôlées

Bemisia tabaci Gennedius (1889) est un ravageur phytophage affectant diverses cultures partout dans le monde. La lutte biologique contre B. tabaci se base sur l’utilisation de ses ennemis naturels surtout les parasitoïdes et les prédateurs.  Dans ce contexte, plusieurs espèces parasitoïdes du genre Eretmocerus et Encarcia et des prédateurs (comme Nesidiocoris tenuis) dont l’efficacité a été prouvée, sont utilisées dans la lutte contre cette mouche blanche.  L’évaluation des potentialités du parasitoïde indigène Encarsia sophia a montré une performance à limiter les populations de B. tabaci dans les serres géothermiques dans le Sud Tunisien. Cependant à 25°C et à une humidité relative variable entre 55 et 75%, le taux de parasitisme d’E. sophia des larves L2, L3 et L4 de B. tabaci sur culture d’aubergine est de 14,72 ± 5,60%. Il est conclu que l’usage cet ennemi indigène de B. tabaci peut remédier la multiplication de ce ravageur

A review of the management of Aphis fabae Scopoli (Hemiptera: Aphididae)

The black-bean aphid Aphis fabae Scopoli is a serious agricultural threat spreaded almost worldwide. It threatens more than 200 host plant species and causes several damages through sucking sap, injuring leaves, the excretion of honeydew -inducing the development of sooty mould- and the transmission of plant viruses. Chemical aphicides are the most approach used to control A. fabae. Nevertheless, their extensive use has led to serious problems concerning human health and environment. These drawbacks led to apply eco-friendly strategies based on entomopahtogenic fungi, natural enemies and plants to manage the pest. In this paper, we review the biological control of A. fabae with special reference to management using plant extracts. Many plants belonging to several families are opted to control A. fabae. Several parts of these plants in particular leaves, stems and peels are used to eradicate it. Aqueous and alcoholic extracts are the most used forms. The mode of action of the major compounds of botanicals is through stomach or/and nerve poisoning

Oligonychus afrasiaticus (Mcgregor) : Problématiques d’infection du palmier dattier et son contrôle : Révision de littérature

Oligonychus afrasiaticus constitue l’un des acariens les plus destructifs du palmier dattier. Il est très répandu dans le monde. Diverses stratégies sont utilisées dans sa lutte sans qu’elles réussissent, toutefois, à l’éliminer. On décrit dans cet article la biologie de l’espèce ainsi que les méthodes chimiques et biologiques utilisées dans son contrôle et on finit par poser certaines problématiques relatives à la cause de son émergence et les refuges qui abritent cet acarien durant tous les mois de l’année

Effectiveness of pheromone traps against Tuta absoluta

International audienceIn the Tunisian south, the heated greenhouses are an important axis of development of agriculture thanks to the big geothermal potential of this zone. Currently, this sector suffers from several phytosanitary problems. In the last years, a new insect, Tuta absoluta, threaten the cultures of cultivated tomatoes in heated greenhouses. To improve control of T. absoluta, the effectiveness of pheromone traps (associated or not with a source of light) and luminous traps (associated or not with water, with limed buckets for limed covers) were compared. The results show that the traps with pheromones significantly catch more adults of T. absoluta compared to all the other types of traps (average number of trapped adults of T. absoluta = 73.4 (± 142)). The luminous traps associated with water, with limed buckets as with limed covers show, as for them, an intermediate effectiveness. In spite of this slightly less effectiveness, the luminous traps have the advantage of low costs of production as well as the advantage of simultaneously capturing males and females of T. absoluta. ; Peer reviewe

Comparison of the effectiveness of the most used chemicals against Tuta absoluta in Tunisia

Control failures with several chemicals have prompted research into the resistance status of Tuta absoluta and the effectiveness of certain active ingredients against this pest. In this context, a comparison was made of the effectiveness of the most widely used chemicals against T. absoluta in Tunisia. The results show that the L1 larval stage of Tuta absoluta is very sensitive to all of the chemicals tested. Stage L2 is sensitive to Spinosad, indoxacarb and emactin, while Bacillus thuringiensis, martine do not cause 50% mortality. L3 stage mortality fluctuates between 20% and 80% mortality. The L4 stage is more affected by the treatment with Bacillus thuringiensis which can go to 100%. Based on these results, chemical treatments should be directed according to the dominant larval stage in the plants

Salt response in pepper (Capsicum annuum L.): components of photosynthesis inhibition, proline accumulation and K+/Na+ selectivity

Three salinity of irrigation water (control, 70, 120 and 170 mM NaCl) were applied to five cultivars of hot pepper (Capsicum annuum L.) collected from the South of Tunisia. After three weeks, relative water content, photosynthetic pigment levels, gas exchange, proline, soluble sugars and ions K+ and Na+ concentrations were measured. The results showed that the inhibition of photosynthesis was not mainly stomatal, but probably biochemical manifesting by a stability of stomatal conductance up to 120 mM NaCl and accompanied by a continuous increase in intercellular CO2 concentration under the three concentrations of salt. Proline content increased considerably as a result of stress and reaches almost double those of controls in cultivars Alaya, Shkira and Sgay and even triple in cultivars Maghraoua and Farch. Solubles sugars do not contribute effectively to the osmotic adjustment. Mineral analysis showed that until 120 mM NaCl, the highest concentration of Na+ was obtained in stems, probably reflecting the existence of a re-circulation mechanism of Na+. Meanwhile, salinity reduced the foliar K+ content. At stems level, K+ concentration does not show significantly disruptions compared to control. However, at the roots, there is a continuous increase in potassium content. For K+/Na+ shoot ratio and at 70 mM NaCl, all cultivars showed a decrease of selectivity except cv. Maghraoua. At 120 and 170 mM, the same cultivar showed the lowest reduction. In root system, at 70 mM NaCl, cv. Maghraoua showed the greater improvement of selectivity.Â

A review of the management of Aphis fabae Scopoli (Hemiptera: Aphididae)

The black-bean aphid Aphis fabae Scopoli is a serious agricultural threat spreaded almost worldwide. It threatens more than 200 host plant species and causes several damages through sucking sap, injuring leaves, the excretion of honeydew -inducing the development of sooty mould- and the transmission of plant viruses. Chemical aphicides are the most approach used to control A. fabae. Nevertheless, their extensive use has led to serious problems concerning human health and environment. These drawbacks led to apply eco-friendly strategies based on entomopahtogenic fungi, natural enemies and plants to manage the pest. In this paper, we review the biological control of A. fabae with special reference to management using plant extracts. Many plants belonging to several families are opted to control A. fabae. Several parts of these plants in particular leaves, stems and peels are used to eradicate it. Aqueous and alcoholic extracts are the most used forms. The mode of action of the major compounds of botanicals is through stomach or/and nerve poisoning

Étude du potentiel biotique du parasitoïde Encarsia sophia dans des conditions contrôlées

Bemisia tabaci Gennedius (1889) est un ravageur phytophage affectant diverses cultures partout dans le monde. La lutte biologique contre B. tabaci se base sur l’utilisation de ses ennemis naturels surtout les parasitoïdes et les prédateurs.  Dans ce contexte, plusieurs espèces parasitoïdes du genre Eretmocerus et Encarcia et des prédateurs (comme Nesidiocoris tenuis) dont l’efficacité a été prouvée, sont utilisées dans la lutte contre cette mouche blanche.  L’évaluation des potentialités du parasitoïde indigène Encarsia sophia a montré une performance à limiter les populations de B. tabaci dans les serres géothermiques dans le Sud Tunisien. Cependant à 25°C et à une humidité relative variable entre 55 et 75%, le taux de parasitisme d’E. sophia des larves L2, L3 et L4 de B. tabaci sur culture d’aubergine est de 14,72 ± 5,60%. Il est conclu que l’usage cet ennemi indigène de B. tabaci peut remédier la multiplication de ce ravageur

Oligonychus afrasiaticus (Mcgregor) : Problématiques d’infection du palmier dattier et son contrôle : Révision de littérature

Oligonychus afrasiaticus constitue l’un des acariens les plus destructifs du palmier dattier. Il est très répandu dans le monde. Diverses stratégies sont utilisées dans sa lutte sans qu’elles réussissent, toutefois, à l’éliminer. On décrit dans cet article la biologie de l’espèce ainsi que les méthodes chimiques et biologiques utilisées dans son contrôle et on finit par poser certaines problématiques relatives à la cause de son émergence et les refuges qui abritent cet acarien durant tous les mois de l’année