Survey of natural enemies of spider mites (Acari: Tetranychidae) in citrus orchards in eastern Spain

Field surveys were conducted from 2004 to 2007 to determine the species composition and relative abundance of natural enemies associated with colonies of either the citrus red mite, Panonychus citri, or the two spotted spider mite, Tetranychus urticae, in Valencian citrus orchards (eastern Spain). Fourteen species were recorded, six phytoseiid mites and eight insect predators. Two of them are reported for the first time on citrus in Spain and two more are first reports as predators associated with T. urticae. The community of predators associated with T. urticae and P. citri was almost identical, and the Morisita-Horn index of similarity between both natural enemy complexes was close to one, suggesting that predators forage on both pest species. Quantifying the presence of many known spider mites predators in Valencian citrus orchards is an important first step towards spider mite control. A challenge for future studies will be to establish conservation and/or augmentation management strategies for these predators, especially to improve T. urticae biological control

Drift reduction of low drift nozzles in spraying citrus orchards

Drift is especially critical when spraying fruit, vine and citrus orchards where pesticides are intensively used. In this context, cone low drift nozzles (LDN) intended for spraying tree crops, have been evaluated relating to cone standard nozzles (STN) in laboratory and deciduous fruit orchards (Van de Zande et al. 2012); (Planas et al., 2013)

Efecto de boquillas de baja deriva y convencionales sobre la deriva y el control de Aonidiella aurantii (Maskell) en cítricos

La deriva es la mayor fuente de contaminación durante los tratamientos fitosanitarios en cultivos arbóreos. Una de las tecnologías efectivas para su reducción es el uso de boquillas de baja deriva (LDN). Sin embargo, su uso podría afectar la eficacia de control. El objetivo de este trabajo fue estudiar el efecto de LDN sobre la deriva y la eficacia de los tratamientos fitosanitarios en el control de Aonidiella aurantii en cítricos frente a boquillas convencionales (STN). Para evaluar la deriva se realizó un ensayo siguiendo la metodología de la norma ISO 22866 en una parcela comercial de Clemenules. Para evaluar la eficacia se llevó a cabo un ensayo en una parcela comercial de Clemenules y se emplearon los siguientes productos: Reldan® E + Atominal® 10 EC, Reldan® E y aceite parafínico contra la primera, segunda y tercera generación respectivamente. En ambos casos las aplicaciones se realizaron con un volumen de caldo de aproximadamente 2500 L ha-1, empleando un turboatomizador. Se aplicó un tratamiento con boquillas STN Teejet de disco y núcleo, y otro con boquillas LDN Albuz modelo TVI, seleccionando en cada ensayo el diámetro adecuado para ajustar el volumen aplicado a las características de cada parcela. En el ensayo de eficacia también hubo un tratamiento Control (sin insecticidas). Los resultados mostraron que la boquilla LDN redujo en un 22.7% la deriva depositada. No se encontraron diferencias significativas de eficacia entre los tratamientos con LDN y STN, pero si entre estos y el Control. Por lo tanto, se deduce de este trabajo que las boquillas LDN son la solución para reducir la deriva en tratamientos contra A. auranti en cítricos sin comprometer la eficacia

Intraguild predation between 'Euseius stipulatus 'and the phytoseiid predators of 'Tetranychus urticae' in clementines, 'Neoseiulus californicus and 'Phytoseiulus persimilis

The current management of the two spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) in clementines is based primarily on applications of acaricides. In recent years, emphasis has been placed on implementing more environmentally safe measures to control T. urticae in Spain. To this end, inoculative releases of the predator phytoseiids Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot are currently being implemented. Indeed, phytoseiid releases have demonstrated to be successful in controlling T. urticae on clementine under laboratory and semi-field conditions. Both phytoseiids are naturally present in the citrus agro-ecosystem although at low levels. However, Euseius stipulatus Athias-Henriot is the most abundant phytoseiid in citrus and its conservation is a key component in the citrus IPM, due to its positive action on different pests. Therefore, before using N. californicus and P. persimilis to control T. urticae in inoculative releases in commercial orchards, we need to clarify the relationship between these phytoseiid species. With this aim, we conducted two experiments of intraguild predation between E. stipulatus and N. californicus, and between E. stipulatus and P. persimilis. First, we tested the aggressiveness (propensity of an individual to attack and kill another individual) of adult females on hetero-specific larvae. Second, we assessed survival and development of immature individuals in presence and absence of intraguild adult predators and alternative food