Abstract The objective of this work was to evaluate the photosynthetic response of citrus varieties to the inoculation of isolates T30 and T3 of Citrus tristeza virus (CTV) characterized as having potential to provide cross-protection against severe CTV isolates in citrus. Citrus plants of 'Campbell' orange, 'Persian' lime, and 'Key' lime were subjected to inoculations by both isolates by patch. Noninoculated plants were used as the control. Symptom expression, photosynthetic and transpiration rates, and stomatal conductance were evaluated by IRGA. Stomatal density and size were evaluated by epidermal impressions. The CTV isolates were also evaluated and molecularly characterized by RT-PCR and Sanger sequencing. 'Campbell' orange and 'Persian' lime plants remained asymptomatic after the inoculations. The inoculation treatments with both CTV isolates did not reduce photosynthetic capacity, transpiration rate, and stomatal conductance, in comparison with the control. Stomatal density and size varied according to the citrus species. T30 and T3 do not affect the photosynthetic responses of 'Campbell' orange and 'Persian' lime; therefore, these isolates have the potential to provide cross-protection to citrus varieties against severe isolates of CTV.

Resumo O objetivo deste trabalho foi avaliar a resposta fotossintética de variedades de citros submetidas à inoculação dos isolados T30 e T3 de Citrus tristeza virus (CTV) caracterizados como tendo potencial para conferir proteção cruzada a citros contra isolados severos de CTV. Plantas de citros de laranja 'Campbell', limão 'Tahiti' e limão 'Galego' foram submetidas à inoculação de ambos os isolados por “patch”. Plantas não inoculadas foram utilizadas como controle. A expressão dos sintomas, as taxas fotossintética e de transpiração, e a condutância estomática foram avaliadas por IRGA. A densidade e o tamanho estomáticos foram avaliados por impressões epidérmicas. Os isolados de CTV também foram avaliados e caracterizados molecularmente por RT-PCR e sequenciamento de Sanger. As plantas de laranja 'Campbell' e limão 'Tahiti' permaneceram assintomáticas após as inoculações. Os tratamentos de inoculação com ambos os isolados de CTV não reduziram capacidade fotossintética, taxas de transpiração e condutância estomática, em comparação ao controle. A densidade e o tamanho estomáticos variaram de acordo com a espécie. T30 e T3 não afetam as respostas fotossintéticas de laranja 'Campbell' e limão 'Tahiti'; portanto, estes isolados têm potencial para promover proteção cruzada a variedades de citros contra isolados severos de CTV.

Resumen Diaphorina citri es una de las plagas más importantes de cítricos debido a que es el vector de Candidatus Liberibacter asiaticus, agente causal del Huanglongbing (HLB) en cítricos. Su manejo se basa en el uso de insecticidas y recientemente se ha explorado el uso de productos alternativos de manejo, como los aceites minerales, por lo que el objetivo del presente trabajo fue evaluar, en condiciones controladas, la actividad repelente e inhibitoria de la oviposición de los aceites minerales Akaroil®, Anasef-T®, Saf-T-Side® y Stylet Oil® en D. citri. La repelencia se determinó al exponer adultos a una hoja de naranja var. Valencia previamente tratada y la inhibición de la oviposición por el método de aplicación residual. Los cuatro aceites minerales causaron actividad repelente significativa ≥ 90 % a 35 mg/mL, no obstante, ésta disminuyó a concentraciones por debajo de 10 mg/mL. Como repelente sobresalió el aceite Saf-T-Side (CR50 = 0,14 mg/mL), seguido de Anasef-T, Akaroil y Stylet-Oil, con CR50 de 1,33, 1,92 y 3,32 mg/mL, respectivamente, a las 24 h. dosis de 1 mg/mL. Con todos los aceites, se inhibió hasta en 90 % la oviposición. La actividad de los aceites minerales debe validarse en condiciones de campo para determinar el potencial real de esta alternativa en el manejo integrado de D. citri.

Abstract Diaphorina citri is one of the most important pests in citrus orchards and is associated with the transmission of Huanglongbing (HLB), a disease caused by the bacterium Candidatus Liberibacter asiaticus on citrus. Currently, the use of chemical insecticides is the most common control strategy for controlling D. citri; however, other alternatives such as the use of mineral oils have been considered. Based on this, we studied the repellence and oviposition inhibition activity by the commercial mineral oils Akaroil®, Anasef - T®, Saf-T - Side® and Stylet Oil® on D. citri. The repellency was determined by exposing adults to previously treated orange leaves with different concentrations of mineral oils and the inhibition of oviposition by the residual application method. All tested oils caused significant ≥ 90 % repellent activity to 35 mg/mL, however, this decreased to concentrations below 10 mg/mL. The greatest repellent activity was achieved by the Saf-T-Side oil (RC50 = 0.14 mg/mL), followed by Anasef-T, Akaroil and Stylet Oil, with CR50 of 1.33, 1.92, 3.32 mg/mL, respectively. Doses as low as 1 mg/mL were enough to inhibit oviposition in up to 90 % in all tested oils. We conclude that the activity of mineral oils should be validated under field conditions to determine if they represent a useful tool within D. citri integrated management.

Abstract Diaphorina citri is considered the most dangerous citrus pest because it transmits Candidatus Liberibacter asiaticus, the causal agent of Huanglongbing (HLB). Like other hemiptera insects, D. citri has developed mutualistic interactions with prokaryotic organisms known as endosymbionts. This symbiosis can be obligatory, when the interaction occurs with a primary endosymbiont, or facultative, when it is a secondary endosymbiont. Symbiosis is essential for various physiological functions, but some endosymbionts can adversely affect the psyllid's abilities. D. citri is associated with a great diversity of endosymbionts, with Candidatus Carsonella ruddii, Candidatus Profftella armatura, Candidatus Wolbachia spp. and Candidatus Liberibacter spp standing out. The aim of this review was to explore the importance and function of endosymbionts associated with D. citri, as well as their role in the transmission of Candidatus Liberibacter asiaticus.

Resumen Diaphorina citri se considera la plaga más peligrosa de los cítricos debido a que transmite a Candidatus Liberibacter asiaticus, agente causal del Huanglongbing (HLB). Al igual que otros insectos hemípteros, D. citri ha desarrollado interacciones mutualistas con organismos procariontes conocidos como endosimbiontes. Esta simbiosis puede ser de tipo obligatoria, cuando la interacción se da con un endosimbionte primario, o no obligatoria, cuando se trata de un endosimbionte secundario. La simbiosis es indispensable para diversas funciones fisiológicas, pero algunos endosimbiontes pueden afectar de manera adversa las capacidades del psílido. D. citri se asocia a una gran diversidad de endosimbiontes, en donde sobresale Candidatus Carsonella ruddii, Candidatus Profftella armatura, Candidatus Wolbachia spp. y Candidatus Liberibacter spp. El objetivo de la presente revisión fue explorar la importancia y función de los endosimbiontes asociados a D. citri, así como su papel en la transmisión de Candidatus Liberibacter asiaticus.

Regional Control Areas (RCAs) have been implemented in Mexico as a strategy to delay the spread of Candidatus Liberibacter asiaticus, the causal bacterium of the disease known as Huanglongbing (HLB). The implementation of an effective management of the vector insect, Diaphorina citri in the RCAs requires the knowledge, acceptance and coordinated engagement of small agricultural producers. This research assessed the perception and knowledge of 62 citrus growers regarding the operational, sociocultural and environmental factors influencing chemical control of D. citri in four RCAs within Veracruz State. According to their responses, the following factors have been identified as the operational factors with the highest influence on the effectiveness of insecticides against D. citri within RCAs: the lack of knowledge about the use of surfactants, application speed, poor calibration of sprayers and incorrect water quality. The most significant sociocultural factors are the general unawareness of the pest and the safe and proper application of pesticides. The most relevant environmental factors during application: temperature, relative humidity, and wind speed. Sociocultural index correlated with the perception of effectiveness. Therefore, it becomes necessary to consider differences among citrus growers in each region and setting out the most appropriate strategies for vector and disease management.

México ha establecido Áreas Regionales de Control (ARCO) como estrategia para retrasar la dispersión de Candidatus Liberibacter asiaticus, bacteria causante de la enfermedad llamada Huanglongbing (HLB). El manejo efectivo de D. citri en las ARCO depende del conocimiento, aceptación y participación coordinada de los pequeños productores. Esta investigación evaluó la percepción y el conocimiento de 62 citricultores sobre los factores operacionales, socioculturales y ambientales que inciden en el control químico de D. citri de cuatro ARCOs, en el estado de Veracruz. Con base en la respuesta de estos pequeños productores, los factores operacionales que más inciden en la efectividad de insecticidas contra D. citri en las ARCO son: desconocimiento sobre uso de adherentes, velocidad de avance del aplicador, deficiente calibración de equipos y calidad de agua utilizada; entre los factores socioculturales destacan: desconocimiento general sobre la plaga, y sobre el buen uso y manejo de plaguicidas, además, los factores ambientales más relevantes al momento de la aplicación son: temperatura, humedad relativa y velocidad de viento. El índice sociocultural se correlacionó con la percepción de la efectividad; por tanto, es necesario considerar las diferencias entre productores de cada región para establecer las estrategias más apropiadas de manejo del vector y la enfermedad.

Abstract Background and Aims: Xylella fastidiosa subsp. fastidiosa, the causal agent of Pierce’s disease, is a γ-proteobacterium, native to America and present in Mexico in wine-growing areas of the Valle de Guadalupe, Baja California, Parras de la Fuente, Coahuila and Ezequiel Montes in Querétaro. This pathogen has numerous hosts, in some of them without causing disease but representing an important source of inoculum, while in others, it causes decay, chlorosis, wilting and even death of the plant. Despite the potential damage it can cause, there are no reports of the quantification of losses, presence and distribution of hosts in Mexico, which is essential to develop management strategies. The objective of this work was to determine by means of Geographic Information Systems, the presence and regional and altitudinal distribution of host wild plants in Mexico. Methods: A base of 7695 georeferenced data of plants reported in the literature as hosts of X. fastidiosa subsp. fastidiosa obtained from herbalized specimens was developed. The information was analyzed using Geographic Information Systems to determine the distribution of species by state, physiographic regions, altitudinal, latitudinal, and longitudinal ranges. Key results: Twenty six reported wild plant species were identified as wild hosts of X. fastidiosa subsp. fastidiosa, widely distributed in the 32 states of the Mexican Republic. The largest number of sites with species presence was recorded in the states of Mexico, Veracruz, and Sonora. The plants inhabit an altitudinal gradient of 0 to 4146 m a.s.l. and are concentrated in the physiographic province of the Trans-Mexican Volcanic Belt. Conclusions: In Mexico, there are conditions for the development of species of wild host plants of X. fastidiosa subsp. fastidiosa, especially in the area of transition of the Trans-Mexican Volcanic Belt, in the State of Mexico, Mexico City, Durango, Michoacán and Veracruz.

Resumen Antecedentes y Objetivos: Xylella fastidiosa subsp. fastidiosa, agente causal de la enfermedad de Pierce, es una γ-proteobacteria nativa de América y presente en México en zonas vitivinícolas del Valle de Guadalupe, Baja California, Parras de la Fuente, Coahuila y Ezequiel Montes en Querétaro. Este patógeno cuenta con numerosos hospedantes, en algunos de ellos sin causar enfermedad, aunque representa una fuente importante de inóculo, y en otros, causa decaimiento, clorosis, marchitez e inclusive la muerte de la planta. A pesar del daño potencial que puede causar, no hay reportes de la cuantificación de pérdidas, presencia y distribución de hospedantes en México, lo cual es esencial para desarrollar estrategias de manejo. El objetivo de este trabajo fue determinar, mediante sistemas de información geográfica, la presencia y distribución regional y altitudinal de plantas silvestres hospedantes en México. Métodos: Se elaboró una base de 7695 datos georreferenciados de plantas reportadas en la literatura como hospedantes silvestres de X. fastidiosa subsp. fastidiosa, obtenidos de ejemplares herborizados. La información se analizó mediante Sistemas de Información Geográfica para determinar la distribución de especies por estado, regiones fisiográficas, rangos altitudinales, latitudinales y longitudinales. Resultados clave: Se identificaron 26 especies de plantas silvestres reportadas como hospedantes de X. fastidiosa subsp. fastidiosa, ampliamente distribuidas en los 32 estados de la República Mexicana. En los estados de México, Veracruz y Sonora se registró el mayor número de sitios con presencia de especies. Las plantas habitan en un gradiente altitudinal de 0 a 4146 m s.n.m. y se concentran en la provincia fisiográfica del Eje Neovolcánico. Conclusiones: En México existen las condiciones para el desarrollo de plantas silvestres hospedantes de X. fastidiosa subsp. fastidiosa, en especial en la zona de transición del Eje Neovolcánico, en el Estado de México, Ciudad de México, Durango, Michoacán y Veracruz.

ABSTRACT Diaphorina citri Kuwayama (Hemiptera: Liviidae) is an invasive species in America and is the main vector of the pathogen associated with Huanglongbing, a deadly disease of citrus plants in the world. The management of such a problem includes the intensive use of insecticides to reduce vector populations and risk of pathogen transmission. As an alternative to synthetic insecticides to control D. citri, the present study determined the chemical composition of diverse plant essential oils and assessed the toxicity and repellency of oil extracts against D. citri. Their chemical composition and abundance were determined by gas chromatography coupled to mass spectrometry. Adults and nymphs were exposed to leaf citrus discs treated by spraying or immersion with different oil extract concentrations. Repellency was assessed by exposing adults to treated leaves in experimental arenas and determining the number of insects remaining on the leaf after different time periods compared with the control. The main oil compounds in the tested plants were anethole, verbenone, 4-ethyl-4-methyl-1-hexene, 4-allylanisole, and trans-tagetone. Oils from Rosmarinus officinalis L. and Schinus molle L. caused no repellent or insecticide effects on D. citri. In contrast, oil extracts from the Foeniculum vulgare Mill. and Tagetes species were toxic and/or repellent for both adults and nymphs. There was a positive relationship between toxicity and concentration. Oil extracts from Tagetes lucida, T. coronopifolia, and T. terniflora were repellent (> 92%) at 40 mg mL-1; this was correlated with the concentration and decreased over time. Essential oils extracts from the Tagetes species could represent a potential defense that could be integrated into the management of D. citri.

Abstract: In order to determine the diversity of thrips species associated with Chrysanthemum [Dendranthema grandiflorum (Ramat.) Kitamura] var. Harman, at four locations in the municipality of Texcoco, State of Mexico, larvae and adults were collected biweekly in the periods from March to June and August to November 2011. The collected individuals were subjected to clarification techniques and mounted for identification. Seventeen species of thrips were identified, included in the genera Frankliniella with 13 species and Anaphothrips, Chrirothrips, Neohydatothrips and Leptothrips with one species each. Most abundant species were F. occidentalis and F. brunnescens (88.6%). The diversity and abundance of thrips was similar in the four localities. The ecological relevance of our findings is discussed.

Resumen: Con el objetivo de estimar la diversidad de especies de tisanópteros asociados al cultivo de crisantemo [Dendranthema grandiflorum (Ramat.) Kitamura] var. Harman en cuatro localidades en el municipio de Texcoco, Estado de México, se realizaron recolectas quincenales de larvas y adultos, en los periodos de marzo a junio y agosto a noviembre de 2011. Los individuos recolectados se sometieron a técnicas de aclaración y montaje para su identificación. Se identificaron 17 especies de trips, incluidas en los géneros Frankliniella con 13 especies; Neohydatothrips, Anaphothrips, Chrirothrips y Leptothrips con una especie cada uno. Las especies más abundantes fueron F. occidentalis y F. brunnescens (88.6%). La diversidad y abundancia de tisanópteros fue similar en las cuatro localidades estudiadas. Se discute la relevancia ecológica de nuestros hallazgos.

Abstract: In this study it was standardized and validated the nested PCR test for rapid, sensitive and reliable detection of species of the genus Xyleborus using external “primers” CI-J-2183 and TL2-N-3014 and internal primers J2210 and N2739 that amplify a band of 500 bp in the region of the gene mitochondrial Cytochrome Oxidase subunit 1(CO1). Also, DNA extraction from 26 specimens of Xyleborus was realized with kit Qiagen DNeasy ® mericom Food (DMF), not previously reported its use for their application in insects, which resulted in enough DNA and high-quality for amplification by PCR reactions. The method allowed to process a single insect by extraction, and obtain genetic material from specimens preserved in alcohol of up to eight years old. The detection limit was defined up to a concentration of 780 pg/μL. The PCR was optimized in a final volume of 15 µL without compromising quality of amplification. The standardized test allowed quality DNA, which ensured high reproducibility and sensitivity in the detection of species of Xyleborus and partial sequencing of the CO1 gene to the seven species studied; consensus sequences were analyzed by homology and deposited in the GenBank.

Resumen: En este estudio se estandarizó y validó la técnica de PCR anidada para la detección rápida, sensible y confiable de especies del género Xyleborus mediante el uso de los “primers” externos CI-J-2183 y TL2-N-3014 e internos J2210 y N2739, que amplifican una banda de 500 pb de la región del gen mitocondrial Citocromo Oxidasa subunidad 1(CO1). Asimismo, se realizó la extracción de ADN de 26 ejemplares de Xyleborus con el kit Qiagen DNeasy® mericom Food (DMF), no reportado previamente su uso para su aplicación en insectos, que resultó en ADN suficiente y de alta calidad para reacciones de amplificación por PCR. El método permitió procesar un solo insecto por extracción, y obtener material genético de muestras conservadas en alcohol de hasta ocho años de antigüedad. El límite de detección se definió hasta una concentración de 780 pg/μl. Se optimizó la PCR en un volumen final de 15 µL sin comprometer calidad de la amplificación. La técnica estandarizada permitió la obtención de ADN de calidad, lo que aseguró alta reproducibilidad y sensibilidad en la detección de especies de Xyleborus y la secuenciación parcial del gen CO1 para las siete especies estudiadas; las secuencias consenso fueron analizadas por homología y depositadas en el GenBank.

Abstract Milpa Alta, in the south of Mexico City, is the most important production zone of nopal (Opuntia ficus-indica) in the world, and is consumed as a vegetable. In this location, there are symptoms known as nopal cacarizo, related to the presence of red chinch bug (Hesperolabops nigriceps), and despite the importance of the crop, there are no studies about the distribution of nopal cacarizo. To determine the distribution, incidence and severity of the disease, samplings were made in vegetable nopal plantations in different geographic points of Milpa Alta. A logarithmic diagram scale was constructed to evaluate its severity, and correlated to nopal cacarizo with H. nigreceps. Aggregation and dispersal indices of Morisita and Lloyd were also estimated. Nopal cacarizo is distributed throughout Milpa Alta with some aggregation in the west (Morisita=1.768; Lloyd=2.535), as is H. nigriceps (Morisita=1.003; Lloyd=1.006). Furthermore, there was a close relationship between nopal cacarizo and H. nigriceps (r=0.765). Damage to individual plants is concentrated in the basal, second and third cladodes. Using the logarithmic diagrammatic scale, with acceptable precision (r2=0.988) and exactness (b1=1.012), an incidence of 56.4±18.5 % was established along with a severity of 10.5±6.4 % of nopal cacarizo in Milpa Alta. This is evidence of the importance of the symptoms in plants of Opuntia, the need to know the phenomenon and the conditions that favor its dispersion.

Resumen Milpa Alta, al sur de la Ciudad de México, es la zona productora de nopal (Opuntia ficus-indica) más importante en el mundo y es consumido como verdura. En este lugar, hay una sintomatología denominada cacarizo del nopal relacionada con la presencia de la chinche roja (Hesperolabops nigriceps) y, a pesar de la importancia del cultivo, no hay estudios de la distribución del cacarizo del nopal. Para determinar la distribución, incidencia y severidad de la sintomatología se realizaron muestreos en huertas de nopal verdura en diferentes puntos geográficos de Milpa Alta, se construyó una escala logarítmica diagramática para evaluar la severidad, se correlacionó el cacarizo del nopal con H. nigriceps y se estimaron los índices de agregación y dispersión de Morisita y Lloyd. El cacarizo del nopal se distribuye en todo Milpa Alta con alguna agregación en el oeste (Morisita=1.768; Lloyd=2.535), igual que H. nigriceps (Morisita=1.003; Lloyd=1.006). Además hubo una relación estrecha entre cacarizo del nopal y H. nigriceps (r=0.765). El daño a las plantas individuales se concentra en el cladodio basal, segundo y tercero. Con la escala logarítmica diagramática, con precisión (r2=0.988) y exactitud (b1=1.012) aceptables, se estableció una incidencia de 56.4±18.5 % y una severidad de 10.5±6.4 % del cacarizo del nopal en Milpa Alta. Esto evidencia la importancia de la sintomatología en plantas de Opuntia, la necesidad de conocer el fenómeno y las condiciones que favorecen su dispersión.

Abstract Chemical insecticides to control Trialeurodes vaporariorum West. have been virtually the only tool used, however the global problem of environmental pollution and insecticides selective pressure, has fostered a change in the way of handling pest to more environmentally friendly and efficient. Nim of Neem Azadirachta indica is an option as botanical insecticides, as its metabolites have already been marketed in different formulations; however it is necessary to evaluate its insecticide and insectistatic action. The objective of this research was to compare the effect on mortality, repellency and oviposition of formulated products of A. indica. In this study four formulations based on neem oil in adults of T. vaporariorum were tested. The products that showed the highest mortality were Neem Oil Spray and PHC Neeem, at a concentration of 0.6 mg mL-1. The best repellent effect was Neem Oil Spray (82.6%), PHC Neeem (72.3%), Biosave Neem (70.8%), and Neemix 4.5 (59.9%); the first two show greater persistence with similar effect the 3 days of evaluation. The best inhibitor of oviposition was Neem Oil Spray (99.6% using 1 mg mL-1), Biosave Neem (92.8%), PHC Neeem (82.6%), and Neemix 4.5 (57%). In contrast, Biosave Neem and Neemix 4.5 stimulated oviposition at concentrations of 0.01 to 0.3 mg mL-1 and PHC Neeem 0.035 mg mL-1. The oil concentration in the formulation is crucial in effect, as to larger proportion, the formulation becomes more persistent, otherwise makes it more polar and its systemic capacity increases.

Resumen Los insecticidas químicos para controlar Trialeurodes vaporariorum West. han sido prácticamente la única herramienta utilizada, sin embargo la problemática global de contaminación ambiental y presión selectiva a insecticidas, ha fomentado un cambio en la forma de manejar las plagas más ecológicas y eficaces. El nim o neem Azadirachta indica es una opción como insecticidas botánicos, sus metabolitos ya se han comercializado en diferentes formulaciones, sin embargo es necesario evaluar su acción insecticida e insectistática. El objetivo de esta investigación fue comparar el efecto en la mortalidad, repelencia y oviposición de productos formulados de A. indica. En este estudio se probaron cuatro formulaciones a base de aceite de nim en adultos de T. vaporariorum. Los productos que mostraron la mortalidad más alta fueron Neem Oil Spray y PHC Neeem, a una concentración de 0.6 mg mL-1. El mejor efecto repelente fue de Neem Oil Spray (82.6%), PHC Neeem (72.3%), Biosave Neem (70.8%), y Neemix 4.5 (59.9%); los dos primeros muestran mayor persistencia con efecto similar a los 3 días de evaluación. El mejor inhibidor de la oviposición fue Neem Oil Spray (99.6% utilizando 1 mg mL-1), Biosave Neem (92.8%), PHC Neeem (82.6%), y Neemix 4.5 (57%). En contraste, Biosave Neem y Neemix 4.5 estimularon la oviposición en concentraciones de 0.01-0.3 mg mL-1 y PHC Neeem a 0.035 mg mL-1. La concentración de aceite en la formulación es determinante en el efecto, pues a mayor proporción, la formulación se hace más persistente, lo contrario la hace más polar y aumenta su capacidad sistémica.

Abstract The management of the citrus bacterial disease Huanglongbing (HLB) is more effective when focused on the control of the insect vector in Regional Control Areas (RCA). To support the regional management strategy of insecticides, susceptibility of two Diaphorina citri populations to the insecticides endosulfán, dimethoate, imidacloprid, malathion, methomyl, abamectin and lambda-cyhalothrin was determined. Imidacloprid formulated as a commercial product was evaluated by systemic absorption in orange seedlings (Citrus sinensis L.) cv. Valencia. The other technical grade formulated products were evaluated by topical application in dilutions with acetone. Mortality was registered 24 һ after applying the insecticides. For each product the LD50 or LC50 was obtained through Probit analysis and the resistance factor was calculated. Cazones colony was susceptible to the seven insecticides evaluated, thus these values are proposed as a baseline for monitoring resistance. Martinez population also showed susceptibility to abamectin, endosulfán, lambda-cyhalothrin, imidacloprid and malathion, and resistance to dimethoate (87.52 X) and methomyl (83.58 X).

Resumen El manejo de la enfermedad bacteriana de los cítricos Huanglongbing (HLB) es más efectivo si se enfoca al control del insecto vector en Áreas Regionales de Control (ARCO). Para apoyar la estrategia de manejo regional de insecticidas se determinó la susceptibilidad de dos poblaciones de Diaphorina citri a los insecticidas endosulfán, dimetoato, imidacloprid, malatión, metomilo, abamectina y lambda-cialotrina. El imidacloprid formulado como producto comercial se evaluó por absorción sistémica en plántulas de naranja (Citrus sinensis L.) cv. Valencia. Los demás productos formulados en grado técnico se evaluaron por aplicación tópica en diluciones con acetona. La mortalidad se registró 24 h después de aplicar los insecticidas. Para cada producto se obtuvo la DL50 o CL50 mediante análisis Probit y se calculó el factor de resistencia. La colonia Cazones fue susceptible a los siete insecticidas evaluados, por lo que estos valores se proponen como base para la vigilancia de la resistencia. La población de Martínez también mostró susceptibilidad a abamectina, endosulfán, lambda-cialotrina, imidacloprid y malatión, y resistencia a dimetoato (87.52 X) y metomilo (83.58 X).

En el presente estudio se determinó la actividad tóxica y repelente del aceite de Tagetes coronopifolia contra Diaphorina citri(Hemiptera: Liviidae). El aceite de T. coronopifolia se obtuvo de la parte área de un ecotipo de Texcoco, México, la cual se procesó mediante hidrodestilación. La toxicidad se evaluó mediante la exposición de adultos y ninfas a diferentes concentraciones del aceite mediante aspersión e inmersión de discos de hoja de Citrus sinensis cv Valencia. La repelencia se determinó al exponer adultos, confinados en un dispositivo, a una hoja tratada, a las 4, 5, 6 y 24 h post- aplicación. Los adultos y ninfas resultaron significativamente susceptibles al aceite de T. coronopifolia (P < 0,05), la mortalidad se incrementó con la concentración y el tiempo de exposición. La toxicidad del aceite > 40% se presentó a partir de 0,01 mg mL-1 en ninfas, mientras que en adultos fue a partir de 10 mg mL-1. El aceite de T. coronopifolia mostró el máximo efecto repelente (92%) con 40 mg mL-1 a 4 h posteriores al tratamiento, aunque disminuyó a las 24 h.

In this study the toxicity and repellent activity of Tagetes coronopifolia essential oil was determined against Diaphorina citri(Hemiptera: Liviidae). T. coronopifolia oil was obtained from the aerial part of an ecotype from Texcoco, Mexico, and processed by hydrodistillation. Nymphs and adults were sprayed with several oil concentrations, and also exposed to Citrus sinensis cv. Valencia leaf discs treated by immersion. Mortality was assessed in both bioassays. Repellency was evaluated by exposing adults to a treated leaf confined in a device at 4, 5, 6 and 24 hours after application. Adults and nymphs were significantly susceptible to T. coronopifolia oil (P < 0.05), mortality increased with concentration and time of exposure. In nymphs, oil toxicity > 40% was observed starting at 0.01 mg mL-1, while in adults, it started at 10 mg mL-1. T. coronopifolia oil caused maximum repellency (92%) with 40 mg mL-1, 4 hours after treatment, but decreased at 24 hours.

In a search for sustainable options of greenhouse whitefly Trialeurodes vaporariorum (Westwood) management, the toxic and/or repellent potential of water, ethanolic, and acetonic extracts of Ambrosia artemisiifolia L. (Asteraceae), Comocladia engleriana Loes (Anacardiaceae), Piper auritum Kunth (Piperaceae), Raphanus raphanistrum L. (Brassicaceae), and Taraxacum officinale F.H. Wigg. aggr.* (Asteraceae) were evaluated. Repellency was assessed by the cylinder method (olfactometer), while toxicity and oviposition inhibition were assessed by the leaf immersion method. Acetonic extracts did not cause any repellent or insecticidal effect. In contrast, 200 mg mL-1 water and ethanolic extracts of R. raphanistrum and ethanolic extract of A. artemisiifolia had the highest repellent activity (76%, 72%, and 69%, respectively) although their activity decreased gradually over time. Ethanolic extracts of P. auritum (66%) and R. raphanistrum (56%) at 200 mg mL¹ were highlighted as being toxic, while the most effective in inhibiting oviposition were water extracts of R. raphanistrum (76.1%) and P. auritum (72.0%) and ethanolic extract of P. auritum (69.5%); however, concentrations lower than 60 mg mL-1 caused oviposition stimulation. Our results suggest that water and ethanolic extracts of R. raphanistrum and P. auritum represent a useful tool in integrated whitefly management.

Seasonal abundance of the "Asian Citrus Psyllid", Diaphorina citri Kuwayama, was evaluated on citrus groves in the region of Cazones, Veracruz, Mexico. For the period from February 2010 to February 2012, biweekly records for adult specimens were made using yellow sticky cardboard traps, as well as the presence of eggs, nymphs, adults, and natural enemies on the flush shoots were also registered. Psyllid populations occurred throughout the period of study, detecting population peaks on February, March, April and July in the citrus plantations. Increases of psyllid infestations were positively related to the abundance of new shoot flushes, and these in turn, were related to the temperature and rainfall. Natural enemies were not a decisive factor in regulating liviid populations,while the abundance of shoot flushes produced by citrus treescould play an important role in integrated psyllid management.

Se evaluó la abundancia estacional del "Psílido Asiático de los Cítricos" Diaphorina citri Kuwayama, en plantaciones de cítricos en la región de Cazones, Veracruz, México. Durante el período de Febrero de 2010 a Febrero de 2012 se realizaron registros quincenales de adultos de D. citri en trampas amarillas, así como la presencia de huevos, ninfas, adultos y enemigos naturales en los brotes. Las poblaciones del psílido se presentaron durante todo el periodo de estudio, detectando picos poblacionales en Febrero, Marzo, Abril y Julio en las plantaciones. Los incrementos en las infestaciones del psílido mostraron una relación positiva con respecto a la abundancia de brotes, y éstos a su vez, con la temperatura y precipitación. Durante el periodo de estudio, los enemigos naturales no fueron un factor determinante en la regulación de las poblaciones del psílido, mientras que la abundancia de brotes en los árboles de cítricos, representa un factor clave en el manejo integrado de esta plaga.

Se identificaron enemigos naturales asociados a escamas armadas en aguacate Hass, y el porcentaje de parasitoidismo en ramas y frutos. Los muestreos se realizaron en huertas certificadas para exportación en Michoacán, México. De julio de 2009 a septiembre de 2010 se colectaron quincenalmente escamas armadas y sus entomófagos en cinco huertos, mientras que en nueve se realizaron muestreos bimestrales (mayo a septiembre) para determinar niveles de parasitoidismo. En cada muestreo se contó por especie el total de escamas vivas y parasitadas por estadio. Se identificaron tres especies de escamas armadas Hemiberlesia lataniae, Abgrallaspis aguacate y Hemiberlesia rapax, las cuales infestan hojas, ramas y frutos, que se presentaron en diez, seis y dos huertas, respectivamente. Los entomófagos identificados fueron: Encarsia citrina, presente en diez huertas y la más abundante con 108 especímenes, Encarsia juanae en cuatro huertas, y con 69 especímenes colectados, Plagiomerus nr. diaspidis con cuatro huertas, y 65 especímenes, Signiphora nr. borinquensis con seis huertas y 23 especímenes, Marietta mexicana en una huerta con cinco especímenes, Aphytis sp. presente en una huerta con dos especímenes y Chilocorus cacti en dos huertas con cinco especímenes. El porcentaje de parasitoidismo fue mayor en ramas que en frutos y aumentó en los meses de julio y septiembre de 2010, influenciado posiblemente por mayores temperaturas y humedad relativa. Encarsia citrina es el parasitoide con mejor perspectiva en manejo de escamas armadas debido a que parasita las tres especies de escamas armadas, tiene mayor distribución, abundancia, y está presente la mayor parte del año.

Natural enemies associated to armored scales on avocado Hass, and the percentage of parasitoidism on branches and fruits were recorded. The study was conducted on 14 avocado Hass orchards certified for exportation in the State of Michoacan, Mexico. From July 2009 to September 2010, armored scales and their entomophagous were collected in five orchards biweekly; meanwhile, in nine different orchards, levels of parasitoidism on armored scales were assessed bimonthly (from May to September 2010). The totals of scales species alive and parasitized scales per stage were recorded for each sample. The armored scales Hemiberlesia lataniae, Abgrallaspis aguacatae and Hemiberlesia rapax were found infesting avocado leaves, branches and fruits. These armored scales were collected in ten, six, and two orchards respectively. The entomophagous insects recognized were Encarsia citrina present in 10 orchards and the most abundant with 108 specimens, Encarsia juanae in four orchards, 69 specimens collected, Plagiomerus nr. diaspidis four orchards, 65 specimens, Signiphora nr. borinquensis six orchards, 23 specimens, Marietta mexicana one orchard, five specimens, Aphytis sp. one orchard, two specimens and Chilocorus cacti two orchards, five specimens. The percentage of parasitoidism in armored scales infecting branches was bigger than in infested fruits; the number of parasitized scales increased between July and September 2010, possibly influenced by higher recorded temperatures and the relative humidity of the orchards. Encarsia citrina, which parasitizes the three armored scale species, has the best distribution and abundance, and it was present most of the year, therefore, it could be the parasitoid with better potential in management of armored scales.