Can pollen provision mitigate competition interactions between three phytoseiid predators of Tetranychus urticae under future climate change conditions?

Biological control can be severely disrupted by hot and dry environmental conditions associated with climate change. These conditions may alter the food web configuration of arthropod communities through their effects on species interactions. They could disrupt the competition between the phytoseiid predators Euseius stipulatus, Neoseiulus californicus, and Phytoseiulus persimilis, which are the key natural enemies of Tetranychus urticae in citrus in Spain. Because the provision of alternative food could compensate for such a situation, we studied in laboratory conditions whether pollen supply could modify competition among these predatory species under different climatic conditions. Our results show that access to high-quality pollen may enhance the performance of E. stipulatus and N. californicus. However, when the phytoseiids considered in our study were forced to compete, pollen provision had contrasting effects depending on the competing pair. Overall, climate change did not affect predation when pollen was available. Predation, though, was lower than expected except when the competing pair was P. persimilis and E. stipulatus. Therefore, pollen provision can partially mitigate the adverse effects of climate change on some of the biological parameters of the three main predators of T. urticae when competing in the system. This has important implications for the future success of biological pest control.Funding for open access charge: CRUE-Universitat Jaume IThe authors thank M. Piquer (UJI) and Arcadi Sanz (UJI) for technical assistance, J. Calvo (KOPPERT BS, Spain) for supplying N. californicus, M.V Ibáñez-Gual (UJI) for statistical advice, and C. Rodriguez-Saona for comments on an earlier version of the manuscript. PUB received a predoctoral grant from MCINN (EEBB-I-14-08555)

Defensive plats responses induced by Nesidiocoris tenuis (Hemiptera:Miridae) on tomato plants

In the last decade, biological control programs for greenhouse tomatoes and other crops have been successfully implemented using zoophytophagous plant bugs (Miridae), which can feed on both plant tissues and insect prey. It is well known that plants respond to herbivore attacks by releasing volatile compounds through diverse pathways triggered by phytohormones. These herbivore-induced plant volatiles can alert neighboring plants, repel or attract herbivores, and attract natural enemies of these herbivores. Nevertheless, the possible benefits of induced plant responses by zoophytophagous predators that could add to their usefulness as biocontrol agents have not been studied until now. Here we show that the zoophytophagous predator Nesidiocoris tenuis activated abscisic acid and jasmonic acid (JA) signaling pathways in tomato plants, which made them less attractive to the whitefly Bemisia tabaci, a major tomato pest worldwide, and more attractive to the whitefly parasitoid, Encarsia formosa. We also found that intact tomato plants exposed to volatiles from N. tenuis-punctured plants activated the JA pathway, and as a consequence, E. formosa was also attracted to these intact plants with activated defense systems. Thus, our results demonstrate that N. tenuis not only benefits tomato plants directly by entomophagy but also indirectly by phytophagy, which induces a physiological response in the tomato plant.The research leading to these results was funded by the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 265865, the Spanish Ministry of Science and Innovation (AGL2011-30538-C03) and the Conselleria d’Agricultura, Pesca i Alimentació de la Generalitat Valenciana. The authors thank Virginia Pedroche (IVIA) and Blas Agut (UJI) for their technical assistance, Javier Calvo (KOPPERT BS) for the supply of insects, Universitat Jaume I-SCIC for technical support and two anonymous reviewers for their valuable comments on a previous version of this manuscript

Effect of pollen provision on life‐history parameters of phytoseiid predators under hot and dry environmental conditions

Biological control can be severely disrupted under climate change conditions. This is the case of the spider mite Tetranychus urticae in Spanish citrus orchards, where the omnivorous phytoseiid Euseius stipulatus, the most abundant predator in the system, was highly impacted by hot and dry conditions mimicking future warmer summers. Such a situation can often be compensated by the provision of alternative food to support generalist predators. As a first step to studying whether such a technique could be applied in this case, we studied at laboratory conditions whether pollen could mitigate the negative effects of hotter and drier conditions derived of climate change on three phytoseiids with different diet specializations. In addition to E. stipu-latus, these predators, which all together, are considered key for the biological con-trol of T. urticae in citrus, are Neoseiulus californicus and Phytoseiulus persimilis. Our results confirm the extremely fine-tuning of T. urticae to hot–dry conditions. They also provide evidence of the poor performance of E. stipulatus, especially in terms of reproduction, compared to the other two phytoseiids at these conditions, even when high-quality pollen was available. Moreover, access to pollen in combination with T. urticae eggs enhanced survival but reduced predation and oviposition relative to a T. urticae-only diet for N. californicus and P. persimilis. Therefore, whether the overall effect of pollen would justify its use in citrus to counteract the deleterious effects of a hotter and drier climate on the natural regulation of T. urticae is still controversial

Evaluación de distintas estratégias de manejo químico del piojo rojo de California, Aonidiella aurantii (Maskell)

El piojo rojo de California, Aonidiella aurantii, es una plaga clave en el cultivo de los cítricos. Por lo general, esta plaga se combate realizando una aplicación fitosanitaria en primera generación y, si es necesario, otra en segunda generación alternando los insecticidas clorpirifos y piriproxifén. En este trabajo se han evaluado diversas estrategias de control basadas en la utilización de dos insecticidas, piriproxifén y spirotetramat, aplicados en dos épocas distintas, salida del invierno y primera generación de A. aurantii. El trabajo se ha realizado en un campo de cítricos con un elevado nivel de infestación de A. aurantii en la cosecha anterior. Ambos insecticidas alcanzaron eficacias elevadas en cosecha, tanto cuando se aplicaron en primera generación, como a la salida del invierno. El porcentaje de destrío se redujo hasta un 100 % con spirotetramat y 86 % con piriproxifén en primera generación respecto al año anterior. Por otro lado, las aplicaciones a la salida del invierno también resultaron eficaces y redujeron el porcentaje de destrío en más de un 66 %. Además, la eficacia de spirotetramat aplicado en invierno redujo el número medio de escudos por fruto en un 80 %. Por lo tanto, los tratamientos en invierno aparecen como una alternativa interesante en la gestión de A. aurantii porque además de reducir significativamente sus poblaciones, pueden tener menores efectos secundarios sobre la fauna útil tan abundante y beneficiosa en nuestros cítrico

Gutación de las plantas: una fuente nutritiva de alimento para insectos

La gutación de las plantas es un fluido que proviene del xilema y del floema y que es secretado en el borde de las hojas de muchas especies de plantas. Hasta ahora, todos los estudios previos han considerado la gutación de las plantas como una fuente de agua para los insectos. En este trabajo, hipotetizamos que la gutación de las plantas puede servir como una fuente de alimento rico en nutrientes para los insectos, y además con efectos sobre la comunidad de insectos. En esta investigación, utilizando el arándano como sistema de estudio, demostramos que las gotas de la gutación contienen una cantidad significativa de carbohidratos y proteínas. Además, insectos con distintos hábitos alimenticios, como un herbívoro, un parasitoide y un depredador vieron incrementada su longevidad y su fecundidad cuando se alimentaron de gotas de gutación comparado con los que se alimentaron de agua

Blueberries infected with the fungal pathogen Colletotrichum fioriniae release odors that repel Drosophila suzukii

Spotted-wing drosophila, Drosophila suzukii, is a serious pest of thin-skinned fruits. Alternative methods to control this pest are needed to reduce insecticide use, including new repellents. Previous research demonstrated that D. suzukii adults use odor cues to avoid blueberries infected with the fungal pathogen Colletotrichum fioriniae, which causes the disease anthracnose. To identify novel D. suzukii repellents, we investigated the volatile emission from experimentallyinfected fruit, which were inoculated with C. fioriniae isolates in the laboratory, and from field-collected fruit, which were naturally infected and harvested from a field. We then tested the pathogen-induced volatiles on D. suzukii adult behavior.hanks to Arthur Rudolph for his help operating the GC–MS during pandemic work restrictions, Chelsea Abegg for providing field-collected blueberry fruit infected with anthracnose, to Mustafa Wasti, Robert Holdcraft, and Vera Kyryczenko-Roth for technical assistance. Authors CCR and JJB were supported by USDA ARS CRIS 6036-224300-001-000D and CR-S and AQ were supported by USDA SCRI 2020-51181-32140, The Sridhar Polavarapu Memorial Endowment for Vaccinium Research, and USDA Sustainable Agriculture Research and Education (grant no. LNE22-455R).info:eu-repo/semantics/publishedVersio

Repensar les nostres arrels: la citricultura a Borriana

Si Borriana ha estat un poble pròsper els darrers dos segles, li ho devem a la taronja. En canvi, la citricultura a Borriana actualment no gaudeix d’èxit, a conseqüència d’errades que s’han anat produint durant el temps. La pèrdua de rendibilitat, l’especulació urbanística i la devaluació de la taronja han provocat un abandonament de terres massiu i un pensament comú dels llauradors en jubilar la taronja. Per aquests motius, es plantegen diferents perspectives de futur: realitzar un bon maneig integrat del cultiu, venda de cítrics per Internet, cultius alternatius (alvocat, caqui, kiwi, hortalisses...), replantejaments estructurals dels cítrics, millorar el màrqueting i seguir amb la investigació citrícola

Efectos de las condiciones abióticas sobre las interacciones entre tres depredadores de Tetranychus urticae con distintos hábitos alimenticios

Tetranychus urticae es uno de los ácaros más perjudiciales que afectan a los huertos de cítricos en España, favorecido por altas temperaturas y baja humedad relativa. Sus principales enemigos naturales en este agro-ecosistema pertenecen a la familia Phytoseiidae entre los que destacan Euseius stipulatus, Neoseiulus californicus y Phytoseiulus persimilis. El cambio climático podría desencadenar brotes de T. urticae. Sin embargo, no se sabe cómo este fenómeno afectaría el sistema tritrófico clementina - T. urticae - fitoseidos. El objetivo principal de esta tesis ha sido evaluar cómo las condiciones abióticas afectan el rendimiento de las tres especies de fitoseidos, en diferentes módulos comunitarios bajo condiciones de campo y laboratorio. Nuestros resultados muestran que el cambio climático puede poner en peligro el control biológico de T. urticae en clementinos, favoreciendo estas condiciones abióticas a T. urticae, y causando efectos negativos sobre sus enemigos naturales clave, directamente o a través de sus interacciones.Tetranychus urticae is one of the most damaging mites affecting citrus orchards in Spain, favored by high temperatures and low relative humidity. Its main natural enemies in this agro-ecosystem belong to the Phytoseiidae family, namely Euseius stipulatus, Neoseiulus californicus and Phytoseiulus persimilis. For this reason, Climate Change could trigger outbreaks of T. urticae. However, it is not known how this phenomenon would affect the tri-trophic system clementine - T. urticae - phytoseiids. The main objective of this thesis has been to explore how abiotic conditions (temperature and relative humidity) affect the performance of the three phytoseiid species mentioned above on different community modules in field and laboratory conditions. Our results have shown that Climate Change can actually jeopardize biological control of T. urticae in clementines, because of the combined positive effect on T. urticae, partly through its host plant, and the negative effects on its key phytoseiid natural enemies, either directly or through their interactions.Programa de Doctorat en Cièncie