Search

Biological control programs in greenhouses increasingly resort to the release of several natural enemies simultaneously. In Uruguay, pest management in peppers is based on the release of Orius insidiosus and Amblyseius swirskii, to control Frankliniella occidentalis and Bemisia tabaci. Amblyseius swirskii can feed on both preys. Zoophytophagous predators not only feed on pests or plant food, but also on natural enemies with which they share prey (intraguild predation). Hence, the combined release of generalist predators could have a negative result in the control of the target pest. Thus, it was important to evaluate the compatibility of O. insidiosus and A. swirskii as predators of F. occidentalis. Studies carried out at Petri dishes level assessed: (1) the effect of the density and the composition of the prey on their predation by O. insidiosus, (2) the change of prey by O. insidiosus and (3) the effect of the genus of O. insidiosus on prey preference. Results show that if the relative densities of F. occidentalis and A. swirskii varied, O. insidiosus always changed to the most abundant prey. Male and female O. insidiosus preferred nymphs of F. occidentalis over A. swirskii, and females killed more prey than males. Since O. insidiosus fed on A. swirskii, it is advisable to be cautious when combining anthocorids and phytoseid mites for the F. occidentalis control. Studies at greenhouse will be necessary to clarify the final effect of both predators. Resumen: Los programas de control biológico en invernadero recurren cada vez más a la liberación de varios enemigos naturales en forma simultánea. En Uruguay, el manejo de plagas en pimiento se basa en la liberación de Orius insidiosus y Amblyseius swirskii, para controlar Frankliniella occidentalis y Bemisia tabaci. Amblyseius swirskii puede alimentarse de ambas presas. Los depredadores zoofitófagos no solo se alimentan de plagas o alimentos vegetales, sino también de enemigos naturales con quienes comparten presas (depredación intragremio). Por lo tanto, la liberación de depredadores generalistas podría dar resultado negativo en el control de la plaga objetivo. Por ello fue importante evaluar la compatibilidad entre O. insidiosus y A. swirskii como depredadores de F. occidentalis. A nivel de placas de Petri se estudió: (1) el efecto de la densidad y la composición de la presa sobre su depredación por O. insidiosus; (2) el cambio de presa por O. insidiosus, y (3) el efecto del género de O. insidiosus en la preferencia de presa. Se encontró que si las densidades relativas de F. occidentalis y A. swirskii variaban, O. insidiosus siempre cambiaba a la presa más abundante. Los machos y las hembras de O. insidiosus prefirieron las ninfas de F. occidentalis sobre A. swirskii, y las hembras mataron más presas que los machos. Dado que O. insidiosus depredó a A. swirskii, se recomienda precaución al combinar antocóridos y ácaros para el control de trips. Serán necesarios estudios en invernadero para esclarecer el efecto final de ambos depredadores. Resumo: Os programas de controle biológico com efeito de estufa dependem cada vez mais da liberação de vários inimigos naturais simultaneamente. No Uruguai, o manejo de pragas em pimentas é baseado na liberação de Orius insidiosus e Amblyseius swirskii, para o controle de Frankliniella occidentalis e Bemisia tabaci. Amblyseius swirskii pode se alimentar de ambas as presas. Predadores zoofitófagos não se alimentam apenas de pragas ou alimentos vegetais, mas também de inimigos naturais com os quais compartilham suas presas (predação intra-guilda). Portanto, a liberação de predadores generalistas pode controlar negativamente a praga alvo. Por esse motivo, foi importante avaliar a compatibilidade entre O. insidiosus e A. swirskii como predadores de F. occidentalis. Ao nível das placas de Petri, foram estudados: (1) o efeito da densidade e composição da presa na sua predação por O. insidiosus, (2) a mudança de presa por O. insidiosus e (3) o efeito -a do gênero de O. insidiosus em preferência de presa. Verificou-se que se as densidades relativas de F. occidentalis e A. swirskii variaram, O. insidiosus sempre mudou para a presa mais abundante. Machos e fêmeas de O. insidiosus preferiam ninfas de F. occidentalis a A. swirskii, e as fêmeas matavam mais presas do que os machos. Como O. insidiosus é anterior a A. swirskii, recomenda-se cautela ao combinar antocorídeos e ácaros para o controle de tripes. Estudos de estufa serão necessários para esclarecer o efeito final de ambos os predadores.

Although native to North America, the invasion of the aphid-like grape phylloxera Daktulosphaira vitifoliae across the globe altered the course of grape cultivation. For the past 150 years, viticulture relied on grafting-resistant North American Vitis species as rootstocks, thereby limiting genetic stocks tolerant to other stressors such as pathogens and climate change. Limited understanding of the insect genetics resulted in successive outbreaks across the globe when rootstocks failed. Here we report the 294-Mb genome of D. vitifoliae as a basic tool to understand host plant manipulation, nutritional endosymbiosis, and enhance global viticulture.Using a combination of genome, RNA, and population resequencing, we found grape phylloxera showed high duplication rates since its common ancestor with aphids, but similarity in most metabolic genes, despite lacking obligate nutritional symbioses and feeding from parenchyma. Similarly, no enrichment occurred in development genes in relation to viviparity. However, phylloxera evolved 2700 unique genes that resemble putative effectors and are active during feeding. Population sequencing revealed the global invasion began from the upper Mississippi River in North America, spread to Europe and from there to the rest of the world.The grape phylloxera genome reveals genetic architecture relative to the evolution of nutritional endosymbiosis, viviparity, and herbivory. The extraordinary expansion in effector genes also suggests novel adaptations to plant feeding and how insects induce complex plant phenotypes, for instance galls. Finally, our understanding of the origin of this invasive species and its genome provide genetics resources to alleviate rootstock bottlenecks restricting the advancement of viticulture.

Background: Although native to North America, the invasion of the aphid-like grape phylloxera Daktulosphaira vitifoliae across the globe altered the course of grape cultivation. For the past 150 years, viticulture relied on grafting-resistant North American Vitis species as rootstocks, thereby limiting genetic stocks tolerant to other stressors such as pathogens and climate change. Limited understanding of the insect genetics resulted in successive outbreaks across the globe when rootstocks failed. Here we report the 294-Mb genome of D. vitifoliae as a basic tool to understand host plant manipulation, nutritional endosymbiosis, and enhance global viticulture. Results: Using a combination of genome, RNA, and population resequencing, we found grape phylloxera showed high duplication rates since its common ancestor with aphids, but similarity in most metabolic genes, despite lacking obligate nutritional symbioses and feeding from parenchyma. Similarly, no enrichment occurred in development genes in relation to viviparity. However, phylloxera evolved > 2700 unique genes that resemble putative effectors and are active during feeding. Population sequencing revealed the global invasion began from the upper Mississippi River in North America, spread to Europe and from there to the rest of the world. Conclusions: The grape phylloxera genome reveals genetic architecture relative to the evolution of nutritional endosymbiosis, viviparity, and herbivory. The extraordinary expansion in effector genes also suggests novel adaptations to plant feeding and how insects induce complex plant phenotypes, for instance galls. Finally, our understanding of the origin of this invasive species and its genome provide genetics resources to alleviate rootstock bottlenecks restricting the advancement of viticulture., This work has been funded by INRAE (France) and by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 764840 for the ITN IGNITE project. Rosa Fernandez was funded by a Juan de la Cierva-Incorporación Fellowship (Government of Spain, IJCI-2015-26627) and a Marie Skłodowska-Curie Fellowship (747607). Angela Douglas was supported by the US National Institute of Food and Agriculture Grant 12216941. Honglin Feng was supported by a University of Miami Maytag Fellowship, William H. Evoy Graduate Research Support Fund, and a Molecular Biosciences Graduate Research Award from the Department of Biology.

The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a key pest of sweet pepper cultivation, where it causes feeding damage, excretes phytotoxic substances, and transmits important viruses. Control with chemical insecticides often is ineffective because endophytic oviposition and the cryptic habits of the pest provide protection. In Uruguay, the biological control program of this pest in sweet pepper crops is at risk due to the low settlement rate and high dispersal of releases of predator Orius insidiosus (Say) (Hemiptera: Anthocoridae). Previous studies have ruled out an antibiosis effect as the cause of dispersal; therefore, we hypothesized antixenosis (non-preference) for the sweet pepper plants as the cause of poor biological control by O. insidiosus. The effect of olfactory stimuli from different structures of strawberry, corn, and sweet pepper plants (lamuyo and blocky type) on the behavior of O. insidiosus was evaluated in olfactometry and free-choice cage experiments. Since Orius tristicolor (White) (Hemiptera: Anthocoridae) occurs naturally in the area, it was included also in the study with the aim of assessing whether there are differences in behavior between the species. Orius tristicolor may act as a complementary biocontrol agent or competitor on sweet pepper. Y-tube experiments showed no preference for plant volatiles in any combination, and response to volatile stimuli generally was poor. However, in the free-choice cage experiment, females of both species of Orius preferred the flowering strawberry plants over the flowering sweet pepper plants, which could explain the low establishment of O. insidiosus when released on pepper with neighboring strawberry fields. Given that horticultural greenhouses in Uruguay and in many other countries are open, this information can be very useful in designing the spatial and temporal management of different crops on a production field, which enhances the effectiveness of these predatory species. Resumen El trips occidental de las flores, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), es una plaga clave para el cultivo de pimiento dulce, donde causa danos al alimentarse, excreta sustancias fitotoxicas y transmite importantes virus. El control con insecticidas quimicos no resulta efectivo, debido que la oviposicion endofitica y los habitos cripticos le brindan proteccion. En Uruguay, el programa de control biologico de esta plaga en el cultivo de pimiento dulce esta en riesgo debido a la baja tasa de establecimiento y la alta dispersion de las liberaciones del depredador Orius insidiosus (Say) (Hemiptera: Anthocoridae). Estudios previos permiten descartar un efecto de antibiosis como causa de la dispersion, por lo cual se planteo como hipotesis la existencia de antixenosis o no preferencia por la planta de pimiento dulce como la causa de un control biologico deficiente por parte de O. insidiosus. Se evaluo el efecto de estimulos olfativos provenientes de diferentes estructuras de plantas de frutilla, maiz y pimiento dulce (tipo lamuyo y california) sobre el comportamiento de O. insidiosus en experimentos de olfatometria, y de libre eleccion en microparcela. Dado que Orius tristicolor (White) (Hemiptera: Anthocoridae) tambien esta presente en el area, se incluyo en el estudio con el objetivo de evaluar si existen diferencias en el comportamiento entre ambas especies. Orius tristicolor podria actuar como un agente controlador complementario o competidor en pimiento dulce. Los experimentos con tubo en Y no mostraron preferencia por los compuestos volatiles de las plantas en ninguna combinacion, y la respuesta a los estimulos volatiles en general fue pobre. Sin embargo, en el experimento de libre eleccion en microparcela, las hembras de ambas especies de Orius prefirieron las plantas con flores de frutilla sobre las plantas con flores de pimiento dulce, lo que podria explicar el bajo establecimiento de O. insidiosus cuando se libera en pimiento dulce con los campos de frutilla cercanos. Dado que los invernaderos horticolas en Uruguay y en muchos otros paises estan abiertos, esta informacion puede ser muy util para disenar el manejo espacial y temporal de diferentes cultivos en un campo de produccion, lo que mejora la efectividad de estas especies depredadoras. Key Words: thrips; antixenosis; plant volatile; sweet pepper; strawberry View this article in BioOne

The rice crop and associated ecosystems constitute a rich mosaic of habitats that preserve a rich biological diversity. Spiders are an abundant and successful group of natural predators that are considered efficient in the biocontrol of the major insect pests in agroecosystems. Spider diversity in different stages of the rice crop growth from eastern Uruguay was analysed. Field study was developed on six rice farms with rotation system with pasture, installed during intercropping stage as cover crop. Six rice crops distributed in three locations were sampled with pitfall and entomological vaccum suction machine. Sixteen families, representing six guilds, were collected. Lycosidae, Linyphiidae, Anyphaenidae and Tetragnathidae were the most abundant families (26%, 25%, 20% and 12%, respectively) and comprised more than 80% of total abundance. Other hunters (29%), sheet web weavers (25%) and ground hunters (24%) were the most abundant guilds. Species composition along different crop stages was significantly different according to the ANOSIM test. The results showed higher spider abundance and diversity along the crop and intercrop stages. This study represents the first contribution to the knowledge of spider diversity associated with rice agroecosystem in the country.

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is one of the most significant pests of commercial vegetables, fruits, and ornamental crops worldwide, causing both direct and indirect damage. Chemical control is the most common methodology for dealing with F. occidentalis, but this pest lays its eggs inside plant tissues, and adults and larvae feed in concealed locations, which can make chemical control of this pest difficult. As an alternative to chemical control, research attention has been focused on biological control through inoculative augmentation using anthocorid flower bugs of the genus Orius (Hemiptera: Anthocoridae). Although Orius insidiosus (Say) (Hemiptera: Anthocoridae) is an effective predator used worldwide for suppressing populations of western flower thrips, its use on pepper crops in Uruguay (Salto) has not achieved favorable results to date. Taking into account that O. insidiosus can supplement its diet by feeding on pollen and plant tissues, the aim of this study was to assess the effects of pepper fruits compared to bean pods, a vegetable substrate widely used for multiplying this predator, on the duration of the embryonic and nymph developmental stages, survival, fertility, and longevity of this species. Since Orius tristicolor (White) (Hemiptera: Anthocoridae) is present also in the horticultural region of Salto, this species was incorporated into the study in order to evaluate if significant differences exist between these 2 species. When biological parameters were measured, pepper fruits proved to be a more appropriate substrate than bean for the 2 Orius species studied. We reject the hypothesis that an antibiosis effect would explain the difficulties for the establishment of O. insidiosus in the greenhouses of Salto. These results show the need to examine other factors contributing to low establishment of these predatory bugs in greenhouses in Uruguay. Resumen El trips occidental de las flores, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), es una de las plagas mas importantes de hortalizas comerciales, frutas y cultivos ornamentales en todo el mundo, causando dano tanto directo como indirecto. El control quimico es la metodologia mas comun para el control de F. occidentalis, pero esta plaga pone sus huevos dentro de los tejidos vegetales y los adultos y las larvas se alimentan en lugares ocultos, lo que puede dificultar el control quimico de esta plaga. Como una alternativa al control quimico, mucha de la atencion de la investigacion se ha enfocado en el control biologico a traves del aumento inoculativo usando insectos antocoridos del genero Orius (Hemiptera: Anthocoridae). Aunque Orius insidiosus (Say) (Hemiptera: Anthocoridae) es un depredador eficaz utilizado en todo el mundo para suprimir poblaciones de trips occidental de las flores, su uso en cultivos de pimiento en Uruguay (Salto) no ha dado buenos resultados hasta la fecha. Teniendo en cuenta que O. insidiosus puede complementar su dieta alimentandose de polen y de tejidos vegetales, el objetivo de este estudio fue evaluar los efectos de los frutos de pimiento, en comparacion con las vainas de frijol (un sustrato vegetal ampliamente utilizado para multiplicar este depredador), en la duracion de las etapas de desarrollo embrionario y ninfal, supervivencia, fertilidad y longevidad de esta especie. Como Orius tristicolor (White) (Hemiptera: Anthocoridae) esta presente tambien en la region horticola de Salto, esta especie se incorporo al estudio para evaluar si existian diferencias significativas entre estas dos especies. Cuando se midieron los parametros biologicos, los frutos de pimiento probaron ser un sustrato mas apropiado para las dos especies de Orius estudiadas que las vainas de frijol. Rechazamos la hipotesis de que un efecto de antibiosis explicaria las dificultades para el establecimiento de O. insidiosus en los invernaderos de Salto. Estos resultados muestran la necesidad de examinar otros factores que contribuyen al bajo establecimiento de estos insectos depredadores dentro de los invernaderos en Uruguay. Key Words: biological control; omnivory; plant-feeding predators; pepper; Frankliniella occidentalis; oviposition substrates View this article in BioOne https://doi.org/10.1653/024.102.0216

Grapevine phylloxera, Daktulosphaira vitifoliae (Fitch) (Hemiptera: Phylloxeridae) is a worldwide pest of Vitis species. It has forms that feed on leaves and roots. Root forms predominate on Vitis vinifera (L.) cultivars, while leaf forms predominate on Vitis species from its native American range. Recently, high densities of D. vitifoliae infestations in leaves of V. vinifera in Brazil, Peru, and Uruguay have been reported. The aims of this study were to determine the seasonal development of grape phylloxera, quantify infestation levels on V. vinifera leaves, and compare them with infestation levels on leaves of a rootstock of American origin. Studies were conducted in two vineyards in Uruguay from 2004–2007. Terminal shoots of 3309 C and Cabernet Sauvignon, Chardonnay, Tannat, Viognier, grafted onto resistant rootstock, were sampled weekly and leaves examined for gall presence and insect life stage. First galls were detected in early October; eggs began to appear within two weeks. Two oviposition peaks occurred by the end of December, and they coincided with bursts of shoot growth. On 3309C rootstock, oviposition peaks were more frequent than on the European cultivars. Based on thermal accumulation, D. vitifoliae could complete eight generations a year in Uruguay. Rootstock 3309C suffered the greatest damage but in some cases was similar to the European cultivars. Damage to Chardonnay, Cabernet Sauvignon and Viognier were also high. There were no galls on Tannat. The 2005–2006 season was characterized by low infestation rates caused by a prolonged drought that affected vegetative growth. There were also differences between vineyards, where the vigorous plants suffering more damage. Leaf galling phylloxera incidence and damage were mainly associated to the cultivar but plant vigor and environmental factors also contributed to increase the incidence.