Drosophila suzukii (Matsumura, 1931) is an invasive pest from South East Asia that was detected for the first time in Southern Europe in 2008. This species can damage a wide range of soft-skinned fruits crops affecting ripening fruits and causing important economic losses. Since the exclusive use of chemical insecticides for controlling D. suzukii may prompt the appearance of resistance and environmental pollution, alternative methods compatible with sustainable management are required. In this study, commercial formulations of powdered sulphur and kaolin were tested as a preventive method applied to blueberry fruits under laboratory conditions. In no-choice assay, powdered sulphur had a significant effect on oviposition and adult emergency with reductions of 76% and 77%, respectively. In addition, sulphur displayed a significant toxicity on males and lethal effect with over 40% adult mortality seven days after exposure. The choice assay confirmed and improved the powdered sulphur effects, with reductions of 98% and 96% in oviposition and adult emergence, respectively. In contrast, kaolin produced no significant reduction in infestation and adult mortality during no-choice and choice assays. These outcomes suggest that preventive use of powdered sulphur could be considered for sustainable control of D. suzukii in some berry crops.
Aim of study: To determine how susceptible the most used Southern highbush blueberry (SHB) cultivars were to the spotted wing Drosophila (SWD), Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae) as well as those recently introduced to Southwestern Spain.Area of study: Southwestern Spain (Huelva province).Material and methods: Nine of the SHB cultivars which were recently introduced in Southwestern Spain and the most used ones were selected: ‘Arana’, ‘Camellia’, ‘Kirra’, ‘Mayra’, ‘Misty’, ‘O'Neal’, ‘Sharpblue’, ‘Star’ and ‘Ventura’. In order to determine how susceptible the cultivars were to SWD, no-choice tests were performed under laboratory conditions. In addition, berry size, berry firmness, ºBrix, and pH were recorded in order to assess what influence these variables had on oviposition preference by SWD.Main results: Mean clutch size and mean number of emerged adults in ‘Star’ were significantly higher than in the other tested cultivars. ‘Mayra’, ‘Camellia’ and ‘Ventura’ received the lower clutch sizes and mean number of emerged adults. Mean developmental time (egg to adult) differed significantly among tested cultivars and were highest in ‘Camellia’ than in the other tested cultivars. Only firmness and pH were correlated with SWD infestation as SWD females tend to oviposit more eggs in softer fruits than in firmer fruits. Results also showed that a higher pH increased the emergence of adults and shortened the egg to adult developmental time.Research highlights: Our results showed significant differences in the susceptibility of SHB to SWD. This information may help design IPM programs and in making recommendations for blueberry crops as planting of low-chill cultivars expands.
Frente al manejo tradicional, el cultivo ecológico proporciona una alternativa a los problemas de aparición de resistencias, residuos y contaminación ambiental, además de favorecer un aumento de la biodiversidad del ecosistema por el efecto beneficioso sobre la fauna auxiliar. En los agroecosistemas, la acción conjunta de los enemigos naturales de los fitófagos puede mantener a las poblaciones de muchos de ellos por debajo del umbral económico de daño. Uno de los grupos de depredadores menos conocidos en los estudios de control natural de las plagas del algodón son las arañas (Orden Araneae), de modo que se realizaron prospecciones en parcelas de algodón orgánico situadas en el sur de España: Córdoba, Sevilla y Cádiz. Los ejemplares se recolectaron mediante la batida directa de las plantas. La especie más abundante resultó ser Cheiracanthium sp. (Miturgidae), seguida de otras especies como Philodromus sp. (Philodromidae), los tomísidos Thomisus onustus, Runcinia grammica y Synema globosum (Thomisidae), Salticus sp. (Salticidae) y Larinia lineata (Araneidae). Además se recogieron individuos de las familias Theridiidae y Linyphiidae. Este trabajo, por tanto, es una primera aproximación en el conocimiento de las especies y su abundancia en el cultivo ecológico del algodón, lo que supone una base para futuras investigaciones en el marco del control de fitófagos mediante arañas.
Antagonist interactions such as intraguild predation (IGP) or cannibalism among predatory arthropods can reduce the impact of these invertebrates on pest limitation in agroecosystems. Here, the effects of IGP between two major natural enemies of cotton pests, the cursorial spider Cheiracanthium pelasgicum (C.L. Koch) and the common green lacewing Chrysoperla carnea (Stephens), were studied under laboratory conditions. First, a feeding preference test was carried out to determine the degree of C. pelasgicum preference for lacewing larvae, using second-instar Helicoverpa armigera larvae as alternative prey. In a second bioassay, the effects of predator interactions on potential predation of H. armigera larvae were analysed using three treatment combinations (plus a control with no predator): (1) spider alone, (2) lacewing larvae alone, (3) spider + lacewing larvae. Potential predation by C. pelasgicum on lacewing eggs was also studied. C. pelasgicum showed no significant preference for either of the two species, indicating that this spider may impact negatively on the green lacewing population. Findings revealed no additive effects and an antagonist interaction between C. pelasgicum and green lacewing larvae, which adversely affected H. armigera suppression; both predators displayed lower predation rates when kept together than either predator alone. However, presence of lacewing larvae and subsequent unidirectional IGP did not affect the predation capacity of C. pelasgicum. Finally, predation rates of C. pelasgicum on lacewing eggs were very low (mean 2.35 ± 0.71 eggs, 24 h after offering) indicating that the impact of C. pelasgicum on lacewing populations may be limited.
Drosophila suzukii es una especie exótica y plaga invasora (originaria del sudeste asiático) que afecta a varios cultivos importantes en Europa y América, entre ellos se destacan los frutos rojos. Este trabajo analiza el potencial depredador de hemípteros comerciales sobre huevos de D. suzukii en condiciones de laboratorio utilizando frutos de arándano. Se llevaron a cabo tres tipos de tratamientos: frutos con puesta + depredador, fruto sin puesta + depredador (control) y fruto sin puesta sin depredador (control). Al cabo de 72 h, se retiraron los depredadores anotando el número de hemípteros vivos y muertos. El número de adultos emergidos por fruto se comparó con el del tratamiento control. Se compararon los promedios del número de depredadores vivos y muertos en contacto con frutos con puesta con el de los depredadores vivos y muertos en contacto con fruto sin puesta. Entre los depredadores seleccionados para el estudio, sólo Anthocoris nemoralis produjo una reducción significativa del número de adultos emergidos por fruto (alrededor del 50 %). No se encontraron diferencias significativas en el número medio de adultos emergidos de D. suzukii en los tratamientos de Orius laevigatus, Macrolophus pygmaeus y Nesidiocoris tenuis, si bien este último mostró una mayor tasa de supervivencia en presencia de fruto infestado. Estudios pormenorizados, a mayor escala, son necesarios para confirmar el potencial de depredador de A. nemoralis sobre huevos de D. suzukii.
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