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Banks grass mite, Oligonychus pratensis (Banks), is a major pest of maize, Zea mays L., causing significant economic loss of yield of maize grown for grain. However, damage and economic loss to maize grown for silage are not well documented. This study evaluated damage associated with infestation by different numbers of mites (noninfested check, low, medium, and large) and subsequent effects on yield and quality of maize harvested for silage. Mite densities in each of the designated infested treatments steadily increased weekly, but at different level, until after Aug 10. Weekly changes in damage rating level corresponded to the increases of mite densities that occurred in each of the infested treatments. The population decline of mites after this date was associated with increasing predator densities. No significant differences in silage yields were detected between noninfested (80.21 Mt/ha), low (82.38 MT/ha), and medium (78.87 MT/ha) infestations, but significant differences occurred with the high-infested (70.43 MT/ha) treatment. Regression analysis between mite damage and yield by plot showed losses occurred after the cumulative damage was >20. Economic loss from maize infested with large numbers of mites ranged for -$97.80 to -489.00 when silage prices ranged from $10.00 to 50.00 per ha. Damage to maize by any of the mite-infested levels did not detrimentally affect the nutritional quality of maize cut for silage. The data indicated a threshold could be developed for making management decisions. Impact of predators in managing spider mites also is discussed.
Leafhoppers are efficient vectors of plant pathogens, but their diversity during the off season in perennial grasses bordering harvested fields of maize has not been studied. The objective of this study was to document the diversity of leafhoppers on grasses that grow during the winter dry season when harvested fields of maize, Zea mays L. ssp. mays, are fallow. Green perennial grasses at Jalisco, Mexico, were sampled with a sweep net every 2 weeks from November 2012 through June 2013. The Shannon-Wiener index showed a diversity of H´= 1.86 and the Pielou index showed a lack of evenness (J´= 0.58) in abundance of all species. In total, 25 taxa from 22 genera were collected, identified, and illustrated. The subfamily Deltocephalinae was most abundant and diverse, with 17 taxa in 14 genera. Greatest species diversity was found during the first 4 months of the winter dry season. The Deltocephalinae Stirellus bicolor, Graminella sonora, and Dalbulus elimatus were most abundant and found throughout the winter.
Iris yellow spot virus (family Bunyaviridae, genus Tospovirus) and its insect vector, onion thrips, Thrips tabaci Lindeman, are of economic concern worldwide in regions where onions (Allium cepa L.) are grown. Several weed species have been described as additional hosts and likely green bridges for survival of Iris yellow spot virus, however, there is little work regarding the overwintering habits and potential of onion thrips as a source of inoculum during the following season. The results of this work confirm onion thrips and Iris yellow spot virus presence near three Colorado onion fields throughout the winter, onion thrips reproduction on six non-allium plant species, and larval acquisition of Iris yellow spot virus from two non-allium plant species. Thrips were monitored by sticky traps during the winter months from 2011 to 2013. Thrips activity seemed to cease when the average temperature was cooler than 0°C and resumed once the average temperature warmed above 0°C. Onion cull piles were constructed and were apparently conducive to survival of thrips, but no live thrips were collected from the piles after onion bulbs began to decay. Iris yellow spot virus was detected by RTPCR in live adult and larval thrips from onion; common mallow, Malva neglecta Wallr.; dandelion, Taraxacum officinale Weber in Wiggers; flixweed, Descurainia sophia (L.) Webb. Ex Prantl; prickly lettuce, Lactuca serriola L.; and salsify, Tragopogon dubius Scop. during the winters from 2010 to 2013. Iris yellow spot virus was detected in prickly lettuce and flixweed. The five weed species were grown from seed in a greenhouse and exposed to viruliferous thrips to elucidate their potential as green bridges. Of the five weeds, Iris yellow spot virus was detected in eight of 15 salsify leaf samples and in three of six thrips larval samples reared on the plant. Winter annuals play a role in overwintering survival of onion thrips and Iris yellow spot virus, providing inoculum the next growing season, and weed management during the winter might be warranted.
Numbers of Phyllophaga vetula (Horn) (Coleoptera: Melolonthidae) larvae killed after application of nematodes Steinernema glaseri Steiner, Heterorhabditis bacteriophora Poinar, and Steinernema feltiae Filipjev at five concentrations (50, 100, 200, 500, and 1,000 nematodes per larva) in aqueous suspension were compared. Lethal concentrations and times for each species were determined. The difference between the treatments was very significant. The nematode most effective for pest control was S. glaseri at a dose of 1,000 per larva that killed 97.5%. H. bacteriophora at the same dose killed 87.5%, and S. feltiae killed 60.0%. With 500 per larva, all three nematodes were statistically the same. S. glaseri at any concentration had the lowest lethal concentration (LC50 and LC95) and lethal time (LT50 and LT95), followed by H. bacteriophora and S. feltiae. The three species of nematodes showed a positive dose-response relationship.
The Orange County Vector Control District treats infestations of red imported fire ants, Solenopsis invicta Buren, with two granular baits, Amdro Pro and Distance, at residences with the ant. Some treatments are subcontracted to pestmanagement professionals who received red imported fire ant certification by the Orange County Vector Control District. During this study, we compared four treatment protocols and assessed their efficacy at suppressing red imported fire ants. At the first post-treatment survey at 3 months, homes in three of the protocols received a single treatment of Amdro Pro. Homes in two of the protocols subsequently received either one follow-up treatment with Distance at 3 months or two follow-up treatments with Distance at 3 and 6 months, respectively. Homes in the fourth protocol received a single treatment of a 50:50 mixture of Amdro Pro and Distance. Most reinfestation by red imported fire ants occurred within the first 3 months after the initial treatment, with failure ranging from 29–40%. Although the failure rate was slightly higher for the treatment with the mixture compared to Amdro Pro alone (40 versus 33%, respectively), failure rates did not differ significantly between these treatments. Thereafter and until 9 months later, treatment failures were <10% among residences without red imported fire ants at 3 months. The differences among the protocols were not significant for any of the time periods. At 9 months, there was a small increase in failures compared to 6 months, indicating more red imported fire ants had moved in from surrounding areas or the original colonies were starting to recover. Additional treatments would be necessary to maintain a low level of infestation. We also recorded the identification and frequency of other ant species seen at homes inspected for red imported fire ants.
Biotic and abiotic factors affect the species richness and abundance of ants inhabiting arid and semiarid zones. We evaluated how soil surface temperature, texture, percentage of surface coarse fragments, and vegetation affected the composition, diversity, and distribution of ants inhabiting a mosaic of environmental conditions in a semiarid zone in central Mexico. We captured 22 ant species at five sites studied, with the top of Cutac hill (1,750 m altitude) and Terrace 2 (1,376 m altitude) the richest sites with 10 species each. Based on redundancy analyses, the percentage of clay followed by the percentage of coarse fragments at the surface of the soil were the variables most related to the composition of ants in these communities. Percentage of clay ranged from 16 to 26 and was positively related to abundance of Pheidole sp. 1 and negatively related to abundance of Dorymyrmex bureni Trager (R2 = 0.76, P = 0.04; R2 = 0.86, P = 0.02, respectively), whereas percentage of soil surface coarse fragments ranged from 0.8 to 59 and were negatively correlated to Pheidole sp. 1 (R2 = 0.76, P = 0.05), but positively correlated to abundance of Brachymyrmex sp. (R2 = 0.86, P = 0.06). When ants were analyzed by functional group, vegetative structure (ranging from 109 to 246 hits with vegetation) and percentage of coarse fragments in the soil were most correlated with their distribution. Although results of the redundancy analyses were not statistically significant, preliminary analysis of variables might explain the composition and distribution of an ant community. We suggested that soil characteristics might be important for explaining ant distribution and community composition.
A second Nearctic species of the recently erected fungus gnat genus Acomopterella Zaitzev was discovered in the eastern United States. The only currently recognized Nearctic congener of the new species occurs in the far western United States and Canada. One adult male flew to a Malaise trap in an ecotone between swamp and second-growth forest dominated by black ash (Fraxinus nigra Marshall), paper birch (Betula papyrifera Marshall), red maple (Acer rubrum L.), and black cherry (Prunus serotina Ehrhart).
El género Theope Doubleday es de los de mayor riqueza en la familia Riodinidae, hasta ahora con 73 taxones descritos. Varias especies son raras, por la densidad baja de sus poblaciones y hábitos poco comunes, resultando en una representación deficiente en las colecciones científicas. Como T. villaiBeutelspacher, 1981, que es una especie endémica del occidente de México, descrita a partir de un solo ejemplar y de la que se desconocen aspectos de su biología; se distribuye en la parte media del occidente de México, en los bosques subperennifolio y mesófilo de montaña; en intervalos altitudinales bien acotados. Se describe la variación morfológica de los imagos, sus aspectos ecológicos (microhábitat, estacionalidad, tipo de vegetación), y de distribución (latitudinal y altitudinal) con base en 28 ejemplares. Se encontraron diferencias entre el holotipo y la descripción original, que habían pasado desapercibidas. Las autapomorfías en los machos de T. villai son los octavos tergito y esternito (saccus) modificados. Manifiesta dimorfismo sexual en tamaño, coloración, y diseño alar; los genitales de ambos sexos comparten características con otras especies del género. Esta información contribuirá a entender mejor las relaciones interespecíficas. Debido a su rareza y a la presión ejercida por el uso del suelo en su hábitat, T. villai debería considerarse para su protección.
Se describe y compara el corion de siete especies del género LeptophobiaButler, 1870: L. eleusis eleusis (Lucas, 1852); L. tovaria maruga Fruhstorfer, 1907; L. cinerea cinerea (Hewitson, 1867); L. caesia caesia (Lucas, 1852); L. eleone luca Fruhstorfer, 1907; L. philoma subargentea (Hewitson, 1870); y L. aripa elodia (Boisduval, 1836). Su descripción e ilustración considera los siguientes rasgos estructurales: número y disposición de ejes (cortos y largos), cuantificación de costillas, descripción de la trama y la distinción de protuberancias en la región perimicropilar. También se describe el color del huevo y su tamaño (longitud y su proporción con el diámetro máximo). Se tipifican tres formas de huevo: elipsoidal oblonga, barrilete, y obovada. Se hacen comparaciones entre los caracteres presentes en las diferentes especies; se comentan implicaciones taxonómicas y filogenéticas. Los caracteres del corion están correlacionados con los caracteres alares y el ambiente de vuelo de los imagos, esto lleva a reconocer dos subgrupos de especies en el género (hipótesis de Klots).
Se describe e ilustra la anatomía del sistema reproductor en las hembras de 12 especies mexicanas de Melolonthidae; se comparan con otros miembros de cada subfamilia, así como otras familias de Scarabaeoidea. El sistema está formado por dos ovarios, dos oviductos laterales y el oviducto común que desemboca a la cámara genital con sus placas genitales, donde llegan el conducto de la espermateca procedente de la espermateca y su glándula, la bolsa copulatriz y dos glándulas accesorias. Se observaron diferencias anatómicas importantes en Melolonthidae con respecto a Scarabaeidae (s.s.), Geotrupidae, Passalidae, y Lucanidae, que se relacionan con patrones biológicos y conductuales, y tal vez representen caracteres con valor filogenético.
Using molecular and traditional taxonomy there was corroborated that the Caryedon species introduced to Mexico in 1966 was C. gonagra (Fabricius) instead of C. serratus (Olivier). Drawings and photographs of male and female genitalia, and a key to identify species in the Serratus subgroup are presented.
Rosalba Quiñones-Valdez, Jesús Ricardo Sánchez-Pale, Ana Karen Pedraza-Esquivel, Alvaro Castañeda-Vildozola, A. T. Gutierrez-Ibañez, José Francisco Ramírez-Dávila
Los Thrips spp., son la principal plaga que afecta al cultivo de gladiolo en las diversas regiones del Estado de México. Su manejo ha sido poco satisfactorio debido al desconocimiento de su distribución espacial. El objetivo del presente trabajo fue determinar la distribución espacial de Thrips spp., con técnicas geoestadísticas que permitan su visualización a través de los mapas generados. Se determinó que las poblaciones de Thrips spp. presentaron una distribución espacial de tipo agregada en todo el ciclo fenológico del cultivo de gladiolo. El modelo gaussiano, indicó agregaciones de forma continua, ésto favorece el avance de las infestaciones de los insectos a plantas aledañas, posiblemente debido a la preferencia por la variedad. Con el modelo esférico, las agregaciones fueron de forma aleatoria dentro de la parcela lo que propició infestaciones en zonas específicas, que permitirá direccionar las diferentes medidas de control sobre los puntos de agregación de los insectos. Los mapas obtenidos reflejaron la estructura agregada de las poblaciones en puntos específicos de las parcelas.
Rhagoletis zoqui Bush es una especie endémica de la región central de México, que en el estado de Puebla se alimenta del “Nogal de Castilla” (Juglans regia L.) ocasionando daños en los frutos y pérdidas económicas a escala regional. Durante dos ciclos de fructificación del hospedero (2011 y 2012) se realizaron muestreos semanales para evaluar las poblaciones de adultos de R. zoqui, utilizando nueve trampas Multilure cebadas con proteína hidrolizada. En total se recolectaron 3,657 especímenes, de los cuales el 23.5% correspondieron al ciclo 2011, con los mayores índices mosca/trampa/día registrados a finales de Junio; mientras que en el ciclo 2012 se capturó el 76.5% de los especímenes totales, con su mayor incidencia a principios de Julio. La comparación entre los índices mosca/trampa/día de ambos ciclos, indicó que las capturas del ciclo de fructificación 2012 fueron significativamente mayores que en el ciclo anterior. Los análisis de correlación entre los índices de captura semanal y los factores climáticos para el ciclo 2011, mostraron una relación significativa del incremento poblacional con la precipitación pluvial, en cambio, el incremento de la temperatura media semanal fue correlacionado con la disminución de los índices de captura.
Verónica Ávila-Rodríguez, Urbano Nava-Camberos, José Luis Reyes-Carrillo, Cristina García de la Peña, Cándido Márquez-Hernández, José Luis García-Hernández
El nogal pecanero, Carya illinoinensis (Wang.) K. Koch, es un cultivo de gran importancia económica en el norte de México. En la Comarca Lagunera en los últimos tres años se han detectado infestaciones y daños al follaje del nogal por un micro lepidóptero del género Coptodisca Walsinham (Lepidoptera: Heliozelidae), denominado localmente como “minador de aretes del nogal”. Este minador de estuche fue identificado como Coptodisca lucifluella (Clemens), la única especie de Coptodisca que se ha reportado atacando al nogal. Este es el primer reporte de una especie de Coptodisca en México. En el 2012, muestreos de este micro lepidóptero a fines del ciclo del cultivo en ocho huertas de nogal de la Comarca Lagunera, indicaron que estuvo presente en todas las huertas con una gran variación en sus niveles de infestación y daños foliares. En el 2013, muestreos quincenales de la plaga a lo largo del ciclo del cultivo en cuatro huertas de la región mostraron que durante la mayor parte del ciclo del nogal las infestaciones y daños foliares fueron bajos, los cuales se incrementaron notablemente a partir de principios de agosto. Los porcentajes de parasitismo variaron de 0 a 23.3%, dependiendo de la localidad y fecha de muestreo. Los parasitoides obtenidos de esta plaga pertenecieron a ocho géneros, siendo Baryscapus y Quadrastichus (Hymenoptera: Chalcidoidea: Eulophidae) los más abundantes.
Hyblaea puera Cramer (Lepidoptera: Hyblaeidae) was reported in commercial teak (Tectona grandis L. f.) plantations in the states of Campeche and Tabasco in southeastern Mexico, from 2011 to 2013. By 2013, more than 1,000 and 4,000 ha of teak were attacked by H. puera in Tabasco and Campeche, respectively. It is necessary to monitor and detect of the arrival of the epicentic phase of H. puera to take action and prevent the epidemic phase and defoliation of large areas.
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