Suitability of Different Host Plants for Nymphs of The Sharpshooter Tapajosa rubromarginata (Hemiptera: Cicadellidae: Proconinii)

The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis(Germar) has become a major pest in California primarily as a vector of Xylella fastidiosa a bacteria that cause severe diseases to grapes. Owing to the uncertainty of the effectiveness of egg parasitoids native to California against GWSS, a neo-classical biological control approach is ongoing. The survey of natural enemies is conducted on leafhoppers closely related to the target pest in South America. In 2000, egg parasitoids of Tapajosa rubromarginata, a sharpshooter closely related to GWSS, were sought in regions in South America where climate types and habitats were similar to California. Nymphs and adults have different nutritional requirements, alternating host plant as a survival mechanism. Apparently, only a few host plants support the development of nymphs to maturity. We tested the viability of nymphs of T. rubromarginata reared on sweet orange, corn, bermuda grass, rescuegrass, bur clover, cowpea, and a combination of mint + oat as an attempt to determine a suitable substrate to rear this sharpshooter. We recorded high mortality of the newly emerged nymphs maintained with rescuegrass, sweet orange, corn, Bermuda grass and bur clover. Nymphs successfully reached the adult stage only eating on cowpea plants and the combination of mint + oat. Based on the observed survival rate and the number of individuals that reached the adult stage, cowpea was the most appropriate substrate for rearing in the laboratory.Fil: Virla, Eduardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Cangemi, Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Logarzo, Guillermo Alejandro. United States Department Of Agriculture. Agricultural Research Service. Overseas Biological Control Laboratories. South American Biological Control Laboratory; Argentin

Proconiini sharpshooters of Argentina, with notes on its distribution, host plants, and natural enemies

The American tribe Proconiini (Hemiptera: Cicadellidae: Cicadellinae) is one of the largest groups of xylem-feeding insects and includes the majority of the known vectors of xylem-born phytopathogenic organisms. The significance of the pathogens that this group transmits gives them an important role as pests, mostly for citrus fruit, grapes, and almonds. Knowledge of these Hemiptera in Argentina is insufficient and fragmentary. Thus one of the aims of this paper is to summarize the available information of the Proconiini sharpshooters in Argentina. In addition, 14 species are mentioned for the first time in the country, and new distributional data are given for 18 species. Thirty-four new associations between sharpshooters and host plants are recorded. New records of egg parasitoids are given for Dechacona missionum, Molomea consolida, M. lineiceps, and Tapajosa similis.Fil: Paradell, Susana Liria. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Virla, Eduardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; ArgentinaFil: Logarzo, Guillermo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. United States Department of Agriculture; Estados UnidosFil: Dellapé, Gimena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Plant bugs (Heteroptera: Miridae) associated with roadside habitats in Argentina and Paraguay: Host plant, temporal, and geographic range effects

Between November 1999 and September 2001, mirid nymphs (Hemiptera: Miridae) were collected on wild and cultivated plants in central and northern Argentina and southeastern Paraguay. In the laboratory, nymphs were reared until adult emergence. Four (Bryocorinae, Deraeocorinae, Mirinae, and Orthotylinae) of the eight mirid subfamilies were collected during the study. Twenty-two mirid species on 43 putative host plant species were collected in Argentina, and five species of mirids on eight plant species were collected in Paraguay. Eighty-five new mirid-plant associations were recorded (only 112 mirid-plant associations had been reported previously for Argentina). Most of the mirids were in the subfamily Mirinae, tribe Mirini, and most of the host plants belonged to Asteraceae. Almost all mirids were collected on plants with flower buds present. In addition to host plant records, the phenology and pattern of plant use for the most abundant mirids are reported. Mirid richness and abundance varied according to the host plant species; the highest diversity and richness of mirids occurred in the western region of Argentina (Salta, Jujuy, and Tucumán provinces). The most frequently collected mirid, Taylorilygus apicalis (Fieber) (≈87% of the 35,970 collected mirids), was usually collected on Asteraceae. This exotic species could have affected the native mirid fauna in the study area. More research on the possible interactions between T. apicalis and the native mirids of Argentina and Paraguay is needed. Our results suggest that T. apicalis exhibits regional polyphagy, i.e., uses numerous hosts throughout its geographic range.Facultad de Ciencias Naturales y Muse

Occurrence of the Tamarix Leafhopper, Opsius stactogalus Fieber (Hemiptera: Cicadellidae), in Argentina

The paleartic tamarix leafhopper,Opsius stactogalusFieber (Hemiptera: Cicadellidae), can reduce the growth of tamarisk due to the aggregate feeding imposed by their populations. The species was mentioned for Argentina in Metcalf´s catalogue (1967) without locality or region reference, and the contributions on Cicadellidae published by many authors after Metcalf omitted this distributional data. Populations of O. stactogalus on Tamarix sp. were found in 12 sites between 28º 48’ to 39º 17’ S and 64º 06’ to 70º 04’ W, located in both the Neotropical and Andean biogeographic regions.Facultad de Ciencias Naturales y Muse

Field host range of Apanteles opuntiarum (Hymenoptera: Braconidae) in Argentina, a potential biocontrol agent of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America

Field exploration in Argentina for cactophagous lepidopteran hosts parasitized by the recently described braconid parasitoid Apanteles opuntiarum Martínez & Berta (Hymenoptera: Braconidae) revealed a host range restricted to Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae) and C. doddi. Field collections of cactophagous larvae parasitized by the congeneric and sympatric parasitoid A. alexanderi included the host species C. bucyrus, Sigelgaita nr. chilensis, Tucumania sp., Tucumania tapiacola and Salambona sp. If a narrow host range for A.opuntiarum is confirmed in quarantine with North American cactus-feeding species, then this parasitoid could be released as a biological control agent for C. cactorum with little or no risk to non-target species.Las exploraciones de campo en Argentina de larvas hospedadoras cactófagas parasitadas por Apanteles opuntiarum Martínez & Berta (Hymenoptera: Braconidae), un bracónido recientemente descripto, revelaron un espectro de hospedadores restringido a Cactoblastis cac­torum (Berg) (Lepidoptera: Pyralidae) y C. doddi. Las colecciones de campo de larvas cactófagas parasitadas por la especie congenérica y simpátrica A. alexanderi identificaron a C. bucyrus, Sigelgaita nr. chi­lensis, Tucumania sp., Tucumania tapiacola y Salambona sp. como es­pecies hospedadoras. Si se confirma en cuarentena el estrecho rango de hospedadores de A. opuntiarum sobre especies norteamericanas que se alimentan de cactus, podría ser liberado como agente de con­trol biológico de C. cactorum, con bajo riesgo o ninguno a especies no blanco.Fil: Varone, Laura. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Logarzo, Guillermo Alejandro. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Martinez, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; ArgentinaFil: Navarro, Fernando. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; ArgentinaFil: Carpenter, James E.. United States Department of Agriculture; Estados UnidosFil: Hight, Stephen D.. United States Department of Agriculture; Estados Unido

Plant bugs (Heteroptera: Miridae) associated with roadside habitats in Argentina and Paraguay: Host plant, temporal, and geographic range effects

Between November 1999 and September 2001, mirid nymphs (Hemiptera: Miridae) were collected on wild and cultivated plants in central and northern Argentina and southeastern Paraguay. In the laboratory, nymphs were reared until adult emergence. Four (Bryocorinae, Deraeocorinae, Mirinae, and Orthotylinae) of the eight mirid subfamilies were collected during the study. Twenty-two mirid species on 43 putative host plant species were collected in Argentina, and five species of mirids on eight plant species were collected in Paraguay. Eighty-five new mirid-plant associations were recorded (only 112 mirid-plant associations had been reported previously for Argentina). Most of the mirids were in the subfamily Mirinae, tribe Mirini, and most of the host plants belonged to Asteraceae. Almost all mirids were collected on plants with flower buds present. In addition to host plant records, the phenology and pattern of plant use for the most abundant mirids are reported. Mirid richness and abundance varied according to the host plant species; the highest diversity and richness of mirids occurred in the western region of Argentina (Salta, Jujuy, and Tucumán provinces). The most frequently collected mirid, Taylorilygus apicalis (Fieber) (≈87% of the 35,970 collected mirids), was usually collected on Asteraceae. This exotic species could have affected the native mirid fauna in the study area. More research on the possible interactions between T. apicalis and the native mirids of Argentina and Paraguay is needed. Our results suggest that T. apicalis exhibits regional polyphagy, i.e., uses numerous hosts throughout its geographic range.Facultad de Ciencias Naturales y Muse

Revisiting the influence of learning in predator functional response, how it can lead to shapes different from type III

Predator/parasitoid functional response is one of the main tools used to study predation behavior, and in assessing the potential of biological control candidates. It is generally accepted that predator learning in prey searching and manipulation can produce the appearance of a type III functional response. Holling proposed that in the presence of alternative prey, at some point the predator would shift the preferred prey, leading to the appearance of a sigmoid function that characterized that functional response. This is supported by the analogy between enzyme kinetics and functional response that Holling used as the basis for developing this theory. However, after several decades, sigmoidal functional responses appear in the absence of alternative prey in most of the biological taxa studied. Here, we propose modeling the effect of learning on the functional response by using the explicit incorporation of learning curves in the parameters of the Holling functional response, the attack rate (a), and the manipulation time (h). We then study how the variation in the parameters of the learning curves causes variations in the shape of the functional response curve. We found that the functional response product of learning can be either type I, II, or III, depending on what parameters act on the organism, and how much it can learn throughout the length of the study. Therefore, the presence of other types of curves should not be automatically associated with the absence of learning. These results are important from an ecological point of view because when type III functional response is associated with learning, it is generally accepted that it can operate as a stabilizing factor in population dynamics. Our results, to the contrary, suggest that depending on how it acts, it may even be destabilizing by generating the appearance of functional responses close to type I.EEA BarilocheFil: Bruzzone, Octavio Augusto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Bruzzone, Octavio Augusto. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Aguirre, María Belén. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Aguirre, María Belén. Consejo Nacional de Investigaciones Científicas y Tecnológicas. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Hill, Jorge Guillermo. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Virla, Eduardo G. Fundación Miguel Lillo. Instituto de Entomología; ArgentinaFil: Virla, Eduardo G. Consejo Nacional de Investigaciones Científicas y Técnicas. Planta Piloto de Pocesos Industriales Microbiológicos (PROIMI-Biotecnología); ArgentinaFil: Logarzo, Guillermo Alejandro. Fundación para el Estudio de Especies Invasivas; Argentin

Proconiini Sharpshooters of Argentina, with notes on its distribution, host plants, and natural enemies

The American tribe Proconiini (Hemiptera: Cicadellidae: Cicadellinae) is one of the largest groups of xylem-feeding insects and includes the majority of the known vectors of xylem-born phytopathogenic organisms. The significance of the pathogens that this group transmits gives them an important role as pests, mostly for citrus fruit, grapes, and almonds. Knowledge of these Hemiptera in Argentina is insufficient and fragmentary. Thus one of the aims of this paper is to summarize the available information of the Proconiini sharpshooters in Argentina. In addition, 14 species are mentioned for the first time in the country, and new distributional data are given for 18 species. Thirty-four new associations between sharpshooters and host plants are recorded. New records of egg parasitoids are given for Dechacona missionum, Molomea consolida, M. lineiceps, and Tapajosa similis.Facultad de Ciencias Naturales y Muse

Geographical Range and Laboratory Studies on Apanteles opuntiarum (Hymenoptera: Braconidae) in Argentina, a Candidate for Biological Control of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America

La polilla de la tuna, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), es una plaga que amenaza las Opuntia spp. nativas de América del Norte. Se han implementado varias estrategias para su control, erradicándola de México pero no de los Estados Unidos, donde ha continuado incrementando su distribución geográfica con éxito. Por lo tanto, se propone un enfoque integrado que incluya al control biológico para regular las poblaciones de C. cactorum en América del Norte. Se realizaron relevamientos de campo del parasitoide recientemente descrito, Apanteles opuntiarum Martínez & Berta, dentro del área de distribución nativa de C. cactorum en Argentina, y se realizaron estudios de laboratorio para desarrollar un protocolo de cría del parasitoide. Apanteles opuntiarum fue el parasitoide más común de C. cactorum y sus distribuciones en el campo coincidieron ampliamente. En el laboratorio, el éxito reproductivo del parasitoide se maximizó cuando una o dos avispas estuvieron expuestas a 30 larvas dentro de un recipiente de 500 ml. Hembras criadas en laboratorio fueron menos exitosas parasitando hospedadores que hembras provenientes del campo. A pesar del éxito logrado en la cría de los parasitoides, obtuvimos una proporción de sexos sesgada hacia machos en los experimentos. Como este sesgo podría estar relacionado a la presencia del parásito reproductivo Wolbachia, tanto la colonia de laboratorio como individuos provenientes del campo fueron analizados y poseían Wolbachia. El presente estudio proporcionó información útil de campo y laboratorio para (1) estandarizar una técnica de cría en laboratorio; (2) realizar estudios de especificidad de hospedadores en condiciones de cuarentena; y (3) seleccionar las poblaciones de parasitoides que mejor coinciden con el clima de las áreas invadidas por C. cactorum en América del Norte.The cactus moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), is a pest that threatens native Opuntia spp. in North America. Control tactics developed and implemented against this invasive pest successfully eradicated the moth in Mexico and on barrier islands in the United States. However, with the cancellation of the regional management program in the United States, no control tactics are being implemented to mitigate the expansion of the moth's geographical range. Hence, an integrated approach including biological control is proposed to regulate the population of C. cactorum in North America. Field surveys of the recently described parasitoid, Apanteles opuntiarum Martínez & Berta, were carried out within the C. cactorum native range in Argentina, and laboratory studies were conducted to develop a parasitoid rearing protocol. Apanteles opuntiarum was the most common parasitoid of C. cactorum and their field distributions were similar. In the laboratory, the parasitoid's reproductive success was maximized when one or two female wasps were exposed to 30 host larvae within a 500 ml container. Laboratory reared females were less successful at parasitizing hosts than field collected females. In spite of the success achieved with laboratory rearing, male bias was observed throughout the experiments. Because this bias might be related to the presence of the reproductive parasite Wolbachia, both laboratory colony and field collected individuals were screened and Wolbachia was detected. This study provides useful field and laboratory information on (1) laboratory rearing techniques for A. opuntiarum; (2) developing host specificity test protocols for studies under quarantine conditions; and (3) selecting parasitoid populations that best match the climatic conditions present in the C. cactorum invaded areas of North America.Fil: Mengoni Goñalons, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Varone, Laura. Fundación para el Estudio de Especies Invasivas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Logarzo, Guillermo Alejandro. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Guala, Mariel. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Rodriguero, Marcela Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Hight, Stephen D.. United States Department Of Agriculture. Agriculture Research Service; Estados UnidosFil: Carpenter, James E.. United States Department Of Agriculture. Agriculture Research Service; Estados Unido

Structure and composition of a thrips community in the Chihuahua Desert, New Mexico, U.S.

We examined plant used versus plant availability by a thysanopteran community on 13 woody and perennial native plants in the Chihuahua Desert. Individual plants were sampled with sticky-traps on 8 dates from May 1997 to August 1998. We sampled 5,040 adult thrips from 26 species in 19 genera, of which 16 could be identified to species. Four families were represented, Thripidae (17 species comprised 98.2 % of the collected specimens), Phlaeothripidae (5 species comprised 1.6%), Aeolothripidae (2 species comprised 0.1%) and Heterothripidae (1 species comprised 0.1%). A total of 16 species (84.2%) were phytophagous on flowers and leaves, 2 (10.5%) were predators, one (5.2%) was mycophagous. Feeding habits for 7 species are unknown. Thrips abundance was positively correlated with plant volume, but not with insect richness. Strikingly for a natural area, Frankliniella occidentalis accounted for 73.6% of the total collection of the sampled thrips, which together with Chirothrips falsus, Microcephalothrips abdominalis, Frankliniella gossypiana, and Neohydatothrips signifier, comprised 94.0% of the total number of collected thrips. Main abundances, considering all thrips species, occurred in fall and spring; no thrips were collected during winter. This seasonal pattern of occurrence was observed for the most abundant thrips species. In summary, the results of this study were: 1) few thrips species were found to be specialists; only 2 thrips species out of 12 studied, showed strong preference for host plants, 2) presence of a high percentage of positive associations, and a low percentage of negative associations, 3) the role of plant volume explained more than 80% of variance of thrips abundance. These results suggest that the studied thrips community has low plant specificity and the pattern of plant use observed could be the consequence of generalist feeding diets.Examinamos el uso de plantas versus la disponibilidad de plantas de una comunidad de Thysanoptera sobre 13 plantas nativas (leñosas y perennes) en el desierto de Chihuahua. Se muestrearon plantas individuales con trampas pegajosas en 8 fechas desde de mayo de 1997 hasta agosto de 1998. Se obtuvieron 5.040 trips adultos pertenecientes a 26 especies en 19 géneros, de los cuales 16 se pudo identificar hasta especie. Cuatro familias están representadas, Thripidae (17 especies que representaron el 98,2% de los especímenes recolectados), Phlaeothripidae (5 especies que constituyeron 1,6%), Aeolothripidae (2 especies que constituyeron el 0,1%) y Heterothripidae (1 especie que correspondió al 0,1%). Un total de 16 especies (84,2%) fueron fitófagos (en flores y hojas), 2 (10,5%) fueron depredadores, uno (5,2%) fue micófago. De 7 especies se desconocen sus hábitos alimentarios. La abundancia de trips se correlacionó positivamente con el volumen de las plantas, no así con la riqueza. Sorprendentemente para un área natural, Frankliniella occidentalis representó el 73,6% de la recolección total de los trips, que junto con Chirothrips falsus, Microcephalothrips abdominalis, Frankliniella gossypiana, y Neohydatothrips signifer, representaron 94,0% del total recogido. La mayor abundancia de trips se produjo en otoño y primavera, y no se recolectaron trips en el invierno. Este patrón estacional de ocurrencia se observó para las especies de trips más abundante. En resumen, los resultados de este estudio fueron: 1) presencia de pocas especies de trips fueron especialistas, sólo dos especies de trips de los 12, mostraron una clara preferencia por sus plantas hospedantes, 2) presencia de un alto porcentaje de asociaciones positivas, y un bajo porcentaje de asociaciones negativas, 3) el rol del volumen de plantas que explica más del 80% de la varianza de la abundancia de trips. Estos resultados sugieren que la comunidad trips estudiado tiene una baja especificidad y el patrón de utilización de las plantas es consecuencia de una dieta alimentaria generalista.EEA BarilocheFil: Logarzo, Guillermo Alejandro. USDA-ARS South American Biological Control Laboratory; ArgentinaFil: Zamar, María Inés. Universidad Nacional de Jujuy. Instituto de Biología de la Altura; ArgentinaFil: Richman, David. New Mexico State University. Department of Entomology, Plant Pathology and Weed Science; Estados UnidosFil: Bruzzone, Octavio Augusto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin