Parasitism on Eriosoma lanigerum (Homoptera: Aphididae) by Aphelinus mali (Hymenoptera: Encyrtidae) on apple orchards, in Fraiburgo county, state of Santa Catarina, Brazil

The parasitism of the woolly apple aphid (Eriosoma lanigerum Hausmann) by Aphelinus mali (Hald.) was evaluated in apple orchards cultivated with the varieties Gala and Fuji in Fraiburgo County, State of Santa Catarina, Southern Brazil. Colonies of the woolly apple aphid were evaluated during one year on 16 apple trees of each variety, starting in August 1999. The number of aphids at the mummy stage or presenting the orifice of the parasitoid emergence was recorded. Results have shown that A. mali parasitized more than 50% of the woolly apple aphids and occurred during the four seasons. It was concluded that that under these conditions no chemical control against the aphid is necessary for the apple varieties Gala and Fuji.

Características de la hoja que influyen en la incidencia de Cacopsylla pyri (L.) (Homoptera: Psyllidae) en variedades de peral

Se estudia la influencia del pH, del contenido en azúcares y del contenido en agua de las hojas de diferentes variedades de peral sobre la incidencia de la psylla del peral, Cacopsylla pyri (L.). El estudio se realizó en 2000 y 2001 en la Estación Experimental de Lleida. Se han estudiado las variedades "Harow Sweet", "William's Infel-415", "William's", "Delbard Delice", "Delbard Exquise", "Abate Fetel", "Super Cornice", "Cornice", "Sublimel", "William's Bovey", "Delferco" y "William's B.C." que en estudios anteriores presentaron diferencias en cuanto a la incidencia de C. pyri. Se han observado diferencias significativas en las características de las hojas para las distintas variedades. Las hojas de las variedades en las que la incidencia de la psylla fue mayor, presentaron mayor pH, mayor contenido en agua y menor contenido en azúcares. En conclusión, el pH y el contenido en agua y azúcares, pueden ser utilizados como indicadores de la preferencia de C. pyri en variedades de peral.

Metcalfa pruinosa (Say) (Homoptera: Flatidae), ¿una plaga potencial de plantas ornamentales en espacios verdes urbanos de Cataluña?

Se ha determinado la presencia y abundancia de Metcalfa pruinosa (Say) en espacios verdes urbanos de Cataluña. M. pruinosa es una especie ampliamente establecida en Cataluña, especialmente en la zona costera. Se ha registrado el insecto sobre más de 100 plantas distintas. La abundancia del insecto ha sido grande en parques y jardines de localidades como Figueres, Girona, Barcelona, Vilanova i la Geltrú, Tarragona o Salou, ocasionando daños estéticos de consideración. Por tanto, M. pruinosa puede considerarse ya una plaga real de los espacios verdes urbanos de Cataluña, aunque su abundancia y capacidad de daño pueden aumentar en el futuro.

Daños de Palaeococcus fuscipennis Burm (Homoptera: Margarodidae) en pinos y cipreses de los parques de Lleida

Durante el inicio de la primavera del 2001 (primera quincena de abril) se detectaron ataques muy fuertes de Palaeococcus fuscipennis Burm. en Pinus halepensis y en Pinus pinea en los parques municipales de Lleida. Algunos ejemplares de Cupressus sempervirens fueron también fuertemente atacados. Se ha estudiado la evolución del margaródido en árboles tratados contra la cochinilla y sin tratar, se ha comparado el ataque en P. pinea y P. halepensis y se ha evaluado la presencia de enemigos naturales.

Plantas hospedantes de Rhopalosiphum maidis (Fitch) (Homoptera: Aphididae) y su papel en el ciclo biológico del pulgón en Cataluña

Se evaluó el papel de las distintas plantas hospedantes de Rhopalosiphum maidis (Fitch) en el ciclo biológico anual de los dos cariotipos más comunes en Cataluña (2n = 8 y 2n = 10 cromosomas) mediante el seguimiento de poblaciones de pulgones en cereales de invierno y verano y en gramíneas espontáneas. Asimismo se registró la densidad de R. maidis en parcelas comerciales de maíz y se determinó el periodo de colonización mediante la instalación de una trampa de succión. Las gramíneas espontáneas juegan un papel fundamental en el ciclo biológico anual de ambos cariotipos. Los pulgones de cariotipo 2n = 10 pueden vivir sobre cebada durante el otoño, invierno y primavera, y sobre gramíneas adventicias, como Setaria sp. y Echinochloa crus-galli ((L.) P. Beauv.), en verano e inicios de otoño; la superposición del ciclo de estas gramíneas permite a los pulgones con este cariotipo cerrar su ciclo anual en ellas. En el caso de los pulgones de cariotipo 2n = 8, el sorgo es el principal hospedante de verano; la cañota constituye un hospedante básico en primavera y otoño, pudiendo actuar como hospedante en inviernos extremadamente cálidos. El periodo primaveral de colonización del maíz por R. maidis se produjo principalmente en mayo y duró hasta mediados de junio. El número de alados capturados en la trampa de succión, así como el de individuos hallados sobre plantas, fue muy bajo tanto en mayo como en junio. Los resultados obtenidos sugieren que el maíz no juega un papel relevante en el ciclo de R. maidis. Se analizan algunas de las posibles causas de este fenómeno.

Relación Cacopsylla pyri (L.) (Homoptera: Psyllidae) - Peral. Influencia de la variedad

Se estudian algunas de las características morfológicas y fisiológicas de diferentes variedades de peral que pueden influir sobre la instalación y desarrollo de las poblaciones de Cacopsylla pyri. Se realizaron recuentos de puesta, ninfas, adultos y enemigos naturales de C. pyri en lamburdas y posteriormente en hojas de brotes del año en una colección de selección de variedades de peral de la "Estació Experimental de Lleida". El año 1997 se muestrearon 40 variedades. Los resultados obtenidos pusieron de manifiesto que existian diferencias significativas debidas a la variedad en los niveles de ocupación por el fitófago. Las variedades se agruparon en 3 categorias en función de la presencia de psylla: elevada, media y baja. De las plantadas los años 1994 y 1995 se muestrearon las 16 variedades correspondientes a los grupos anteriores. Las características de la planta estudiadas fueron: altura, diámetro del tronco, peso de la madera de poda, contenido en clorofila, macro y micronutrientes. Se han observado diferencias significativas entre las distintas variedades en las características de la planta estudiadas, relacionadas con las diferencias en los niveles de ocupación.

Ensayo de preferencia de individuos alados de Rhopalosiphum maidis (Fitch) (Homoptera: Aphididae) sobre siete gramíneas cultivadas

Se evaluó en laboratorio la preferencia de dos poblaciones leridanas de Rhopalosiphum maidis (Fitch) en la colonización de siete gramíneas cultivadas. Una de las poblaciones fue recogida sobre cañota (Sorghum halepense C. (L.) Pers.) y su cariotipo era 2n = 8. Los individuos de la otra población presentaban un cariotipo 2n = 10 y procedían de cebada. Las gramíneas testadas fueron: sorgo, maíz, trigo, trigo duro, cebada, triticale y avena. Los individuos alados de ambas poblaciones colonizaron los siete cereales aunque de distinta manera. El sorgo fue preferentemente colonizado por los pulgones con cariotipo 2n = 8 y el número de ninfas producidas en 48 horas fue mayor que en el resto de las gramíneas testadas. Los pulgones con cariotipo 2n = 10 mostraron preferencia por la cebada. Los alados de ambas poblaciones fueron incapaces de reproducirse sobre las plantas de maíz.

Presencia en Valencia de Rhizoecus cacticans (Hambl.) (Homoptera, pseudococcidae)

En el presente artículo se advierte de la presencia del pseudococcino Rhizoecus cacticans (HAMBLETON) en la zona de Valencia, atacando a raíces de cactáceas. Se dan algunas características del género y se describe la especie, así como algunos datos sobre los daños que causa. Se indican procedimientos posibles de control.

Chromosome studies in southern Brazilian wheat pest aphids Sitobion avenae, Schizaphis graminum, and Methopolophium dirhodum (Homoptera: Aphididae)

We examined the chromosome set of the aphid species Sitobion avenae, Schizaphis graminum and Methopolophium dirhodum by means of conventional staining and C, NOR, AluI and HaeIII banding methods. These species are considered important pests to several plants of economic interest in Brazil. No variation was observed in the number of chromosomes of S. avenae, whereas there was intraspecific variation in the other two species. Interspecific differences in the response to the banding treatments were observed. Whereas these techniques allowed the identification of several S. graminum chromosome pairs, only the AluI treatment was capable of inducing differential staining in the M. dirhodum chromosomes and no clear patterns emerged when the S. avenae preparations were treated

Producción de grana cochinilla del nopal Dactylopius coccus Costa (Homoptera: dactylopiidae) en dos localidades del sur del estado de Nuevo León [por] Aldo Tovar Puente

Tesis (Maestría en Ciencias Forestales) U.A.N.L. Facultad de Ciencias Forestales 2000.

Differential susceptibilities of peach-potato aphid, Myzus persicae (Homoptera: Aphididae) and its parasitoid, Aphidius matricariae (Hymenoptera: Aphidiidae) to foliar insecticides on partially resistant and susceptible potato cultivars

In a field experiment the effects of Sumicidin (super) 5EC (fenitrothion), Metasystox EC25 (oxydemeton-methyl) and Tamaron SL600 (methamidophos), applied at different dosages, were evaluated against peach-potato aphid, Myzus persicae (Sulzer) and its parasitoid Aphidius matricariae Haliday on Cardinal and Desiree (respectively partially resistant and susceptible potato cultivars to M. persicae). Sumicidin (super) 5EC was found about 30% more effective in reducing aphid populations than the other insecticides tested. The highest doses of each insecticide caused maximum aphid mortality; in general aphid mortality appeared dose dependent. Almost all the higher and lower doses of the tested insecticides were about 19% more effective on Cardinal than on Desiree. The most significant result was the synergistic interaction at the lower doses with plant resistance, so that the same level of control was recorded with second highest dose on Cardinal as with the highest dose on Desiree. Also the same control level was achieved at the lowest dosage rate on Cardinal compared with the next higher dose on the Desiree. Sumicidin (super) 5EC was found least toxic to the parasitoid, A. matricariae in terms of percent parasitism, emergence of parasitoids and number of mature eggs in the emerging female parasitoids; increase of about 22, 67 and 47% respectively were found in parasitoid performance with Tamaron SL600 which was found comparatively highly toxic. The highest doses of all insecticides were found clearly toxic to the parasitoid. In general, effects on the parasitoid were dose dependent. Maximum yield was obtained from the second highest dose of Sumicidin (super) 5EC.

Selective toxicity of different granular insecticides to the peach-potato aphid, Myzus persicae (Homoptera: Aphididae) and its parasitoid, Aphidius matricariae (Hymenoptera: Aphidiidae) in two differentially resistant potato cultivars

Field studies were conducted in Pakistan to examine the effects and the interaction of two differentially resistant potato cultivars i.e. Cardinal and Desiree (one partially resistant and one susceptible to Myzus persicae (Sulzer), respectively) with different dosage rates of granular insecticides, at different time intervals after application in relation to percent kill of M. persicae and effects on the parasitoid Aphidius matricariae Haliday (i.e. the third trophic level) within the aphid mummies, percent parasitism and Thimet 10G (phorate) was found about 30% more effective in reducing aphid population than the Furadan 3G (carbofuran). The highest doses of each insecticide caused maximum aphid mortality, in general aphid mortality appeared dose dependent. Mostly all the higher and lower doses of the tested insecticides were about 10% more effective on Cardinal than on Desiree. The most significant result was the synergistic interaction at the lower doses with plant resistance, so that the same level of control was recorded with the second highest dose on Cardinal as with the highest dose on Desiree. Also the same level of control was observed at the lowest dose on Cardinal as with the second last lowest dose on Desiree. Furadan 3G was found least toxic to the A. matricariae in terms of percent parasitism, emergence of parasitoids and number of mature eggs in the emerging females. Furadan 3G gave 13, 15 and 6% higher figures, respectively from the parasitoid characteristics than Thimet 10G. The highest doses of both insecticides were clearly toxic to the parasitoid. In general, the effects on the parasitoid were dose dependent. The second highest dose of Thimet 10G, gave the maximum yield

The role of exotic plants in the invasion of Seychelles by the polyphagous insect Aleurodicus disperses: a phylogenetically controlled analysis

The accidental introduction of the spiralling whitefly, Aleurodicus dispersus Russell (Homoptera: Aleyrodidae) to Seychelles in late 2003 is exploited during early 2005 to study interactions between A. dispersus, native and exotic host plants and their associated arthropod fauna. The numbers of A. dispersus egg spirals and pupae, predator and herbivore taxa were recorded for eight related native/exotic pairs of host plants found on Mahe, the largest island in Seychelles. Our data revealed no significant difference in herbivore density (excluding A. dispersus) between related native and exotic plants, which suggests that the exotic plants do not benefit from 'enemy release'. There were also no differences in predator density, or combined species richness between native and exotic plants. Together these data suggest that 'biotic resistance' to invasion is also unlikely. Despite the apparent lack of differences in community structure significantly fewer A. dispersus egg spirals and pupae were found on the native plants than on the exotic plants. Additional data on A. dispersus density were collected on Cousin Island, a managed nature reserve in which exotic plants are carefully controlled. Significantly higher densities of A. dispersus were observed on Mahe, where exotic plants are abundant, than on Cousin. These data suggest that the rapid invasion of Seychelles by A. dispersus may largely be due to the high proportion of plant species that are both exotic and hosts of A. dispersus; no support was found for either the 'enemy release' or the 'biotic resistance' hypotheses.

Effects of UV-blocking films on the dispersal behavior of Encarsia formosa (Hymenoptera : Aphelinidae)

The parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae) has been used successfully for the control of Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae). The development of UV-blocking plastic films has added a new component to future integrated pest management systems by disrupting insect pest infestation when UV light is excluded. Because both T. vaporariorum and E. formosa are reported to have similar spectral efficiency, there was a need to identify the impact of UV-blocking films on the dispersal behavior of both the pest and the natural enemy. In field studies, using choice-chamber experiments, E. formosa showed some preference to disperse into compartments where less UV light was blocked. However, further studies indicated that the effect was primarily attributable to the different light diffusion properties of the films tested. Thus, unlike its whitefly host, when the UV-absorbing properties of the films were similar, but the light diffusion properties differed, E.formosa adults preferred to disperse into compartments clad with films that had high light diffusion properties. When the plastic films differed most in their UV-absorbing capacity and had no light-diffusion capability, the initial dispersal of E. formosa between treatments was similar, although a small preference toward the environment with UV light was observed over time. When parasitoid dispersal was measured 3 h after release, more parasitoids were found on plants, suggesting that the parasitoids would search plants for whitefly hosts, even in a UV-blocked light environment. The potential for the integration of UV-blocking films with E. formosa in an advanced whitefly management system is discussed.

Resistência de genótipos de batata, Solanum spp., a afídeos (Homoptera: Aphididae) e influência sobre parasitóides

Avaliou-se a resistência de genótipos de batata aos afídeos Myzus persicae (Sulz.), Macrosiphum euphorbiae (Thomas) e Aphis gossypii (Glover), e a influência desses genótipos sobre parasitóides, em dois ensaios em plantios de inverno (1996 e 1997), em condições de campo, em Jaboticabal, SP. Os genótipos plantados no primeiro ano foram: Achat, Baronesa, Bintje, BR-2, Contenda, Monalisa, N 140-201 e NYL 235-4, distribuídos em quatro blocos ao acaso. Dois levantamentos foram efetuados, aos 70 e 85 dias após o plantio, avaliando-se o número de pulgões/folha e pulgões parasitados, nos terços superior, médio e inferior da planta. em 1997 plantaram-se os mesmos genótipos, excetuando-se o N 140-201, com levantamentos aos 72 e 80 dias. O genótipo NYL 235-4 mostrou-se suscetível a M. euphorbiae, sob infestações médias de 2,90 (1996) e 1,19 pulgões/folha (1997); dentre as cultivares comerciais, Baronesa foi a menos atacada por M. persicae (0,12 e 0,10 pulgões/folha em 1996 e 1997), enquanto BR-2 foi bem suscetível (1,10 e 0,66 pulgões/folha). Os afídeos ocorreram em maior população nas partes média e inferior das plantas; maior número de pulgões mumificados por Aphidius ervi Hal. e Diaretiella rapae (McIntosh), com parasitismo variando de 15 a 36%, foi observado em NYL 235-4, que foi o genótipo mais infestado pelos afídeos.