Kairomones from Euschistus heros egg masses and their potential use for Telenomus podisi parasitism improvement.

Telenomus podisi Ashmead (Hymenoptera: Scelionidae) is the most important egg parasitoid of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae), and its successful parasitism is related to their searching ability to find suitable hosts under a complex chemical environment using host-reliable cues. Thus, the objective of this study was to elucidate chemical substances on the external layer of E. heros eggs and report its potential kairomonal activity on T. podisi. We tested female wasps in olfactometer system to synthetic compounds obtained from a chemical identification of E. heros egg masses. The synthetic blend was also evaluated in parasitism tests under laboratory and semi-field conditions. We identified 31 substances from egg surface extracts, including monoterpenes, aldehydes and alkanes. Among those compounds, a synthetic solution including camphene, ß-pinene, limonene and benzaldehyde-induced chemotaxic behaviour on the wasps and increased the parasitism on E. heros eggs, either in laboratory or semi-field test, suggesting its potential use to T. podisi manipulation and parasitism improvement.

Taxonomic Status and Population Oscillations of Aphidius colemani Species Group (Hymenoptera: Braconidae) in Southern Brazil.

Aphidius colemani (Viereck) was reported in Brazil before the Biological Control Program of Wheat Aphids (BCPWA) when Mediterranean genotypes were introduced from France and Israel. This species was re-described as a complex called A. colemani group composed of three species. Consequently, uncertainty remains about which parasitoid of the group is occurring in southern Brazil. This study has two main objectives: (i) re-examine the species status of A. colemani group collected during the introduction of parasitoids and from a 10-year (2009-2018) monitoring program in wheat fields in northern Rio Grande do Sul (RS), Brazil; (ii) describe the variation in the population density of parasitoids and its association with meteorological factors during this period. We examined 116 specimens from the Embrapa Wheat entomological collection, and those collected in Moericke traps in Coxilha, RS. All the parasitoids of the A. colemani group from the BCPWA period were identified as Aphidius platensis (Brèthes). In traps, 6541 cereal aphid parasitoids were collected, of which 61.9% (n = 4047) were from A. colemani group and all those were identified as A. platensis. Temperature was the factor that effected population density with the highest number of parasitoids recorded in the winter months. Sex ratio changed between years varying from 0.50 to 0.97. The parasitoid A. platensis was the only species in the A. colemani group sampled during 10 years of monitoring.

Is It Possible to Manipulate Scelionidae Wasps' Preference to a Target Host?

Parasitoid host selection is mainly mediated by chemical cues, which can be adjusted by experience, changing their innate behavior. Therefore, this study evaluated if immature experience (pre-imaginal conditioning) on eggs and volatiles from different host eggs has influence on parasitism and chemotaxic behavior of Telenomus podisi Ashmead and/or Trissolcus basalis Wollaston (Hymenoptera: Scelionidae). Both wasp species were submitted to a multiple-choice parasitism test among Euschistus heros (Fabricius), Piezodorus guildinii (Westwood), and Nezara viridula L. (Hemiptera: Pentatomidae) (Hemiptera: Pentatomidae) egg masses. Eggs from these three stink bugs were equally offered to female parasitoids. After that, adults which emerged from each host were also exposed to parasitism in a multiple-choice test for up to an additional generation. Moreover, in olfactometer "Y," the behavior of innate and experienced T. podisi females to volatiles from hosts' egg extracts was tested, to study their learning and memory ability. The original host had influence on T. podisi parasitism; however, T. basalis always parasitized more N. viridula eggs independently of its last rearing host. Innate T. podisi females responded positively to E. heros and P. guildinii egg volatiles, but this behavior was not observed in N. viridula. When T. podisi females were experienced on egg volatiles from a new host, they showed significant learning and memory ability for the specific host volatile for, at least, 24 h. Experienced wasps responded positively to N. viridula and through this result we have evidences about the possibility to manipulate wasp's preferences to a specific target host.

Insect diversity in organic rice fields under two management systems of levees vegetation / Diversidade de insetos em arroz irrigado orgânico sob dois manejos da vegetação das taipas

Abstract Simplified environments characterize agroecosystems, reducing the diversity of associated plants, which are not cultivated for economic purposes, causing unbalances that can promote the emergence of cultivated plants pests, as well as the reduction of their natural enemies. Management systems that increase diversity in agroecosystems can extend the action of natural enemies of pests. Studies to understand the diversity of insects associated with rice cultivation and determine their ecological guilds can provide information about the composition and structure of such ecosystems, which can be applied to integrated pest management. Therefore, the study aimed to describe and compare groups of insects in irrigated rice fields, with organic management using two different systems of levees vegetation management, and relate them to the phenological states of rice cultivation (seedling, vegetative, and reproductive). Samples were taken in a plantation located in Águas Claras district of Viamão, RS. The total area of 18 ha was divided into two. A subarea called not cut (NC), where wild vegetation of levees was maintained, and the subarea named cut (C), where monthly cuts were made to levees vegetation, from the beginning of soil preparation until the harvest. From October 2012 to March 2013 were held weekly collections in quadrats randomly located in both the rice fields and the levees. A total of 800 insects were collected, 429 in the C subarea and 371 in the NC. There were identified 97 morphospecies in the C and 108 in NC, being 54 shared between the subareas. The captured insects were grouped into guilds: saprophages (C = 38.2%; NC = 27.5%), phytophagous (C = 28.5%; NC = 33.2%), entomophagous (grouping parasitoids and predators) (C = 29.4%; NC = 35%) and finally other insects (C = 4 %; NC = 4.3%). The peak abundance of phytophagous and entomophagous was registered in the vegetative stage of rice. At the same stage the UPGMA analysis showed that similarity in species composition was greater than 90% in the groups obtained in the paddy fields of C and NC subareas. The vegetation of levees can positively influence the presence of entomophagous in the field. Although the abundance did not change clearly, the greatest diversity in the NC areas of all the groups, may contribute to the maintenance of ecological services expanding the system resilience.

Resumo Os agroecossistemas se caracterizam por ambientes simplificados, com redução da diversidade de plantas associadas, que não são as cultivadas para fins econômicos, causando desequilíbrios que podem levar ao surgimento de insetos nocivos, assim como a diminuição de seus inimigos naturais. Sistemas de manejo que priorizem o aumento da diversidade no agroecossistema podem ampliar a ação de inimigos naturais de pragas. Estudos que busquem entender a diversidade de insetos associados ao cultivo de arroz irrigado, bem como determinar as guildas ou grupos ecológicos aos quais pertencem, podem trazer informações sobre a composição e estrutura dos ecossistemas que possam ser aplicadas no manejo integrado de pragas. Neste sentido, o estudo objetivou conhecer e comparar a diversidade de insetos entre áreas de cultivo orgânico de arroz irrigado, diferenciadas pelo manejo da vegetação das taipas e relacionar com os estádios fenológicos da cultura. As amostragens foram realizadas no distrito de Águas Claras, município de Viamão, RS. A área total de 18 ha foi subdividida em duas. Numa subárea, denominada não roçada (NR) a vegetação espontânea das taipas foi mantida, na outra, roçada (R), foram feitas roçadas mensais das taipas, desde o início do preparo do solo, até a colheita. Entre outubro de 2012 a março de 2013 realizaram-se coletas semanais, em quadrats, situados aleatoriamente tanto nas quadras de arroz quanto nas taipas. Foi coletado um total de 800 insetos, 429 na R e 371 na NR. Foram identificadas 97 morfoespécies na R e 108 na NR, das quais 54 foram compartilhadas entre as subáreas. As guildas registradas foram: saprófagos (R = 38,2%; NR = 27,5%), fitófagos (R = 28,5%; NR = 33,2%), entomófagos (reunindo parasitoides e predadores) (R = 29,4%; NR = 35%) e outros (R = 4%; NR = 4,3%). O pico de abundância de fitófagos e entomófagos foi registrado na fase vegetativa do arroz. Nesta mesma fase, a análise de UPGMA apontou que a similaridade na composição de espécies foi superior a 90% nos grupos obtidos nas lavouras das subáreas R e NR. A vegetação das taipas pode influenciar positivamente a presença de insetos entomófagos no campo. Embora a abundância não tenha variado significativamente entre as áreas, a maior diversidade na área não roçada em todos os grupos, pode contribuir na manutenção de serviços ecológicos aumentando a resiliência dos sistemas.

Insect diversity in organic rice fields under two management systems of levees vegetation.

Simplified environments characterize agroecosystems, reducing the diversity of associated plants, which are not cultivated for economic purposes, causing unbalances that can promote the emergence of cultivated plants pests, as well as the reduction of their natural enemies. Management systems that increase diversity in agroecosystems can extend the action of natural enemies of pests. Studies to understand the diversity of insects associated with rice cultivation and determine their ecological guilds can provide information about the composition and structure of such ecosystems, which can be applied to integrated pest management. Therefore, the study aimed to describe and compare groups of insects in irrigated rice fields, with organic management using two different systems of levees vegetation management, and relate them to the phenological states of rice cultivation (seedling, vegetative, and reproductive). Samples were taken in a plantation located in Águas Claras district of Viamão, RS. The total area of 18 ha was divided into two. A subarea called not cut (NC), where wild vegetation of levees was maintained, and the subarea named cut (C), where monthly cuts were made to levees vegetation, from the beginning of soil preparation until the harvest. From October 2012 to March 2013 were held weekly collections in quadrats randomly located in both the rice fields and the levees. A total of 800 insects were collected, 429 in the C subarea and 371 in the NC. There were identified 97 morphospecies in the C and 108 in NC, being 54 shared between the subareas. The captured insects were grouped into guilds: saprophages (C = 38.2%; NC = 27.5%), phytophagous (C = 28.5%; NC = 33.2%), entomophagous (grouping parasitoids and predators) (C = 29.4%; NC = 35%) and finally other insects (C = 4 %; NC = 4.3%). The peak abundance of phytophagous and entomophagous was registered in the vegetative stage of rice. At the same stage the UPGMA analysis showed that similarity in species composition was greater than 90% in the groups obtained in the paddy fields of C and NC subareas. The vegetation of levees can positively influence the presence of entomophagous in the field. Although the abundance did not change clearly, the greatest diversity in the NC areas of all the groups, may contribute to the maintenance of ecological services expanding the system resilience.

Influence of the vegetation management of the leeves in irrigated rice organic in diversity of Hymenoptera parasitoids / Influência do manejo da vegetação das taipas em arroz orgânico irrigado na diversidade de himenópteros parasitoides

Abstract Among the natural enemies of insect pests in rice fields, parasitoids are especially notable. To better understand the space-time dynamics of these insects, the objectives of this study were to describe and compare groups of parasitoids in organic irrigated rice fields using two management approaches for levee vegetation, and to relate them to the phenological stages of rice cultivation (the seedling, vegetative, and reproductive stages). The samples were taken in a plantation located in Viamão, RS, Brazil. The total area of 18 ha was divided into two parts: a no-cut (NC) subarea in which the wild vegetation of the levees was maintained, and a cut (C) subarea in which the levee vegetation was cut monthly. In each subarea, four Malaise traps considered as pseudo-replicas were installed and remained in the field for 24 hours at each sampling location. Collections occurred twice a month from the beginning of cultivation (October 2012) until harvest (March 2013). A total of 3,184 Hymenoptera parasitoids were collected: 2,038 individuals in the NC subarea and 1,146 in the C subarea. We identified 458 morphospecies distributed in 24 families. Mymaridae was the most abundant and Eulophidae was the richest in both subareas. A total of 198 morphospecies was shared between the subareas, including Platygastridae, Eulophidae, and Mymaridae, which were the families with the highest number of shared species. The richness and abundance of parasitoids varied according to their phenological developmental stages, with peak abundance registering during the vegetative period. The Morisita index identified three groupings, indicating a similarity that was related to the three phases of rice growth and development: seedling, vegetative and post-harvest.

Resumo Entre os inimigos naturais de insetos pragas em campos de arroz, parasitoides são especialmente notáveis. Para melhor entender a dinâmica espaço-temporal destes insetos, os objetivos desse estudo foram descrever e comparar os grupos de parasitoides em campos de arroz orgânico irrigado utilizando duas abordagens de manejo da vegetação das taipas, e relacioná-los com os estádios fenológicos da cultura (plântula, vegetativo e reprodutivo). As amostragens foram realizadas em uma plantação localizada em Viamão, RS. A área total de 18 ha foi dividida em duas partes: uma subárea não roçada (NR) na qual a vegetação espontânea das taipas foi mantida, e uma roçada (R) subárea em que a vegetação das taipas foi roçada mensalmente. Em cada subárea, quatro armadilhas Malaise consideradas pseudo-réplicas foram instaladas e mantiveram-se no campo durante 24 horas, em cada local de amostragem. As coletas ocorreram duas vezes por mês, desde o início do cultivo (outubro de 2012) até a colheita (março de 2013). Um total de 3.184 himenópteros parasitoides foram coletados: 2.038 indivíduos na subárea NR e 1.146 na R. Foram identificadas 458 morfoespécies, distribuídas em 24 famílias. Mymaridae foi a mais abundante e Eulophidae a mais rica para ambas as subáreas. Um total de 198 morfoespécies foi compartilhado entre as subáreas, incluindo Platygastridae, Eulophidae e Mymaridae, que foram as famílias com o maior número de espécies compartilhadas. A riqueza e a abundância de parasitoides variou de acordo com as fases de desenvolvimento fenológico da cultura, com pico de abundância registrado no período vegetativo. O Índice de Morisita identificou três grupamentos indicando uma similaridade relacionada às fases da cultura, plântula, vegetativo e, na pós-colheita.

Influence of the vegetation management of the leeves in irrigated rice organic in diversity of Hymenoptera parasitoids.

Among the natural enemies of insect pests in rice fields, parasitoids are especially notable. To better understand the space-time dynamics of these insects, the objectives of this study were to describe and compare groups of parasitoids in organic irrigated rice fields using two management approaches for levee vegetation, and to relate them to the phenological stages of rice cultivation (the seedling, vegetative, and reproductive stages). The samples were taken in a plantation located in Viamão, RS, Brazil. The total area of 18 ha was divided into two parts: a no-cut (NC) subarea in which the wild vegetation of the levees was maintained, and a cut (C) subarea in which the levee vegetation was cut monthly. In each subarea, four Malaise traps considered as pseudo-replicas were installed and remained in the field for 24 hours at each sampling location. Collections occurred twice a month from the beginning of cultivation (October 2012) until harvest (March 2013). A total of 3,184 Hymenoptera parasitoids were collected: 2,038 individuals in the NC subarea and 1,146 in the C subarea. We identified 458 morphospecies distributed in 24 families. Mymaridae was the most abundant and Eulophidae was the richest in both subareas. A total of 198 morphospecies was shared between the subareas, including Platygastridae, Eulophidae, and Mymaridae, which were the families with the highest number of shared species. The richness and abundance of parasitoids varied according to their phenological developmental stages, with peak abundance registering during the vegetative period. The Morisita index identified three groupings, indicating a similarity that was related to the three phases of rice growth and development: seedling, vegetative and post-harvest.

Andropogon bicornis (Poales, Poaceae): a hibernation site for Pentatomoidea (Hemiptera: Heteroptera) in a rice-growing region of Southern Brazil.

Tussocks of Andropogon bicornis (Poaceae) make up a significant part of the landscape of the rice-growing region of south Brazil. However, little is known about their role in maintaining insect diversity in anthropized regions. We tested the hypothesis that A. bicornis is a hibernation site for Pentatomoidea (Hemiptera: Heteroptera) by analyzing the composition, structure, and diversity of pentatomoid assemblages over the course of a year. A total of 208 tussocks were removed at fortnightly intervals from April 2010 to March 2011. We collected 3,423 pentatomoid specimens belonging to 22 species distributed in 13 genera of three families, Pentatomidae, Scutelleridae, and Thyreocoridae. The most common species was Tibraca limbativentris Stål, the main rice pest in southern Brazil, followed by Oebalus ypsilongriseus (De Geer) and Edessa meditabunda (Fabricius). Abundance and species richness were the lowest in January, February, and March and the highest in July, August, and September. A combination of high species diversity observed during the colder months, including several unrelated to rice, and the absence of immature specimens in the tussocks strengthens the hypothesis that A. bicornis is a hibernation site for pentatomoids in the region.

Diapause initiation and alterations in the life cycle of Grapholita molesta (Busck) (Lepidoptera: Tortricidae) as induced by photoperiodic conditions.

Grapholita molesta (Busck) is one of the major pests of Rosaceae, causing significant damage to buds and fruits. In Southern Brazil, its population density is reduced during Rosaceae dormancy months. The present study evaluated the influence of different photoperiods (L:D) (10:14, 11:13, 12:12, 13:11, 14:10 and 16:8) at 25 ± 1ºC and 60 ± 10% RH on diapause induction of G. molesta eggs, larvae, prepupae, and pupae. The effects of the photoperiod on the life cycle of non-diapausing insects and on the second generation were also assessed. Prepupal diapause was observed only when eggs and neonates (≤ 12h-old larvae) were exposed to photophases from 10h to 14h long. Development of non-diapausing individuals and those from the second generation tended to be longer in photophases between 10h and 14h long.

Morphometry and distribution of sensilla on the antennae of Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae).

Antennal sensilla of Anastrepha fraterculus (Wied.) were examined using scanning electron microscopy. In the flagellum, there are trichoid, basiconic, clavate type I and II, and styloconic sensilla and microtrichia. Only microtrichiae and chaetica sensilla were observed in the scape and pedicel. The number of sensilla in the flagellum was similar between sexes. At the apex there was a higher density of trichoid and an absence of clavate sensilla, while basiconic sensilla were more abundant in the proximal region.

Caracterização morfológica dos órgãos internos de reprodução de Spartocera dentiventris (Berg, 1884) (Hemiptera: Coreidae) em diferentes idades / Reproductive organs of Spartocera dentiventris (Berg, 1884) (Hemiptera: Coreidae) at different ages

Nesse estudo foi descrita, mensurada e ilustrada, a genitália interna de machos e fêmeas de Spartocera dentiventris considerando distintas idades. As alterações mais evidentes no sistema reprodutivo foram observadas na largura e no comprimento dos ovários que permitem a distinção entre os estágios imaturo e reprodutivo. As medidas dos órgãos de reprodução de machos não apresentam diferenças significativas nas diferentes idades.

In this work, the internal reproductive organs of Spartocera dentiventris males and females with different ages are described, measured and illustrated. The most significant changes in the reproductive organs were found in the length and width of ovaries, which permit the distinction between immature and reproductive stages. No significant difference was found among the measurements of the reproductive structures of males at the different ages.

Morfometria de Anastrepha fraterculus (Wied) (Diptera: Tephritidae) relacionada a hospedeiros nativos, Myrtaceae / Morphometry of Anastrepha fraterculus (Wied) (Diptera: Tephritidae) related to native Myrtaceae hosts

A mosca-das-frutas, Anastrepha fraterculus, tem, como principais hospedeiros primários, frutos de Myrtaceae. O tamanho do inseto pode ser indicador de aptidão e fecundidade, sendo os estudos morfométricos utilizados para auxiliar nestas identificações. Este trabalho objetivou verificar a associação entre peso dos frutos, pupários e tamanho das asas das moscas-das-frutas que se desenvolveram em diferentes mirtáceas. Foram amostrados frutos de araçazeiro-amarelo, araçazeiro-vermelho, goiabeira e goiabeira-serrana em cinco árvores de cada espécie. Os frutos foram pesados e os pupários oriundos destes pesados e individualizados. Registrou-se o número, sexo e área total da asa direita das moscas. Comparou-se o peso médio dos frutos, dos pupários e o tamanho de asas. O peso médio dos pupários foi maior em goiaba e araçá-vermelho. A maior área média de asa foi registrada nos indivíduos emergidos de goiabas e a menor, nos de araçá-amarelo. O peso dos frutos e dos pupários em araçá-amarelo, vermelho e goiaba-serrana não apresentaram associação significativa. Nas goiabeiras, a correlação entre o peso dos frutos e o dos pupários foi negativa. O peso dos frutos e a área da asa das moscas provenientes das espécies de mirtáceas não evidenciaram correlação. Os resultados indicam que a mosca é capaz de desenvolver-se de forma semelhante nas espécies de mirtáceas amostradas.

The fruit-fly Anastrepha fraterculus uses the myrtacean fruits as its main primary hosts. The insect size might be an indicator of aptitude and fecundity, and morphometric studies are used to help in those identifications. This study aimed to verify the association among fruit weight, puparial weight and wing size of fruit-flies that developed in different myrtacean species. Yellow strawberry guava, cattle guava, guava and feijoa fruits were sampled from 5 trees of each species. The fruits were weighed, and the puparia originated from them were also weighed and individualized. The number, gender and total right-wing area of the flies were registered. Mean fruit and puparial weights and wing sizes were compared. Mean puparial weight was higher in guava and cattle guava. The largest mean wing area was recorded for individuals from guavas; the smallest, for those from yellow strawberry guava. The fruit and puparial weights did not present a significant association in yellow strawberry guava, cattle guava and feijoa. In guavas, the correlation between fruit and puparial weights was negative. The fruit weight and wing area in all myrtacean species did not show any correlation. These results indicate the fly is able to develop similarly in all sampled myrtacean species.

Spatial distribution of parasitism on Phyllocnistis citrella Stainton, 1856 (Lepidoptera: Gracillariidae) in citrus orchards / Distribuição espacial do parasitismo Phyllocnistis citrella Stainton, 1856 (Lepidoptera: Gracillaridae) em pomares de citros

Many species of microhymenopterous parasitoids have been registered on Phyllocnistis citrella, the citrus leafminer. The present study aimed to identify the spatial distribution pattern of the native and introduced parasitoids of P. citrella in two citrus orchards in Montenegro, RS. The new shoots from 24 randomly selected trees in each orchard were inspected at the bottom (0-1.5 m) and top (1.5-2.5 m) stratum and had their position relative to the quadrants (North, South, East and West) registered at every 15 days from July/2002 to June/2003. The leaves with pupae were collected and kept isolated until the emergence of parasitoids or of the leaf miner; so, the sampling was biased towards parasitoids that emerge in the host pupal phase. The horizontal spatial distribution was evaluated testing the fitness of data to the Poisson and negative binomial distributions. In Montenegrina, there was no significant difference in the number of parasitoids and in the mean number of pupae found in the top and bottom strata (χ2 = 0.66; df = 1; P > 0.05) (χ2 = 0.27; df =1; P > 0.05), respectively. In relation to the quadrants, the highest average numbers of the leafminer pupae and of parasitoids were registered at the East quadrant (χ2 = 11.81; df = 3; P < 0.05), (χ2 = 10.36; df = 3; P < 0.05). In the Murcott orchard, a higher number of parasitoids was found at the top stratum (63.5 percent) (χ2 = 7.24; df =1 P < 0.05), the same occurring with the average number of P. citrella pupae (62.9 percent) (χ2 = 6.66; df = 1; P < 0.05). The highest number of parasitoids and of miners was registered at the North quadrant (χ2 = 19. 29; df = 3; P < 0.05), (χ2 = 4.39; df = 3; P < 0.05). In both orchards, there was no difference between the numbers of shoots either relative to the strata as well as to the quadrants. As the number of shoots did not varied much relative to the quadrants, it is possible that the higher number...

Vários microimenópteros parasitóides têm sido registrados em populações de Phyllocnistis citrella (minador-dos-citros). Este estudo objetivou identificar o padrão de distribuição espacial de parasitóides nativos de P. citrella e do introduzido Ageniaspis citricola em dois pomares de citros em Montenegro, RS. Em amostragens quinzenais de julho de 2002 a junho de 2003, todos os brotos de 24 plantas sorteadas aleatoriamente em cada pomar foram inspecionados no estrato inferior (0-1,5 m) e superior (1,5-2,5 m) e registrada a localização destes em relação aos quadrantes (Norte, Sul, Leste e Oeste). As folhas com pupas foram coletadas e individualizadas até a emergência dos parasitóides ou do minador, assim, a amostragem foi focada em parasitóides que emergem na fase pupal do hospedeiro. A distribuição espacial horizontal foi avaliada testando-se os ajustes dos dados à distribuição Poisson e binomial negativa. Em Montenegrina não houve diferença significativa no número de parasitóides e no número médio de pupas encontrados no estrato superior e inferior, (χ2 = 0,66; gl = 1; P > 0,05) e (χ2 = 0,27; gl = 1; P > 0,05), respectivamente. Em relação aos quadrantes, o maior número médio de pupas do minador e de parasitóides encontra-se no quadrante Leste (χ2 = 11,81; gl = 3; P < 0,05), (χ2 =10,36; gl = 3; P < 0,05). No pomar de Murcott, um maior número de parasitóides foi constatado no estrato superior (63,5 por cento) (χ2 = 7,24; gl = 1 P < 0,05), o mesmo ocorrendo com o número médio de pupas de P. citrella (62,9 por cento) (χ2 = 6,66; gl =1; P < 0,05). O maior número de parasitóides e de minadores foi registrado no quadrante Norte (χ2 = 19,29; gl = 3; P < 0,05), (χ2 = 4,39; gl = 3; P < 0,05). Em ambos os pomares, não houve diferença entre o número de brotos nos dois estratos ou entre os quadrantes. Como o número de brotos não variou muito em relação aos diferentes quadrantes, é possível que a presença maior...

Discrimination of Spartocera dentiventris (Berg, 1884) (Hemiptera: Coreidae) eggs by Gryon gallardoi (Brèthes, 1913) (Hymenoptera: Scelionidae).

This paper aimed to evaluate the stimuli that orient Gryon gallardoi females to the eggs of Spartocera dentiventris and allow their discrimination. Using a four-arm olfactometer connected to four odor sources--S. dentiventris eggs; hexane washed eggs; tobacco leaves; and tobacco leaves with eggs--the arrestment of female parasitoids with previous oviposition experience and without was individually verified. The time of permanence in each odor field was registered for a period of 15 minutes. Host discrimination, regarding age and previous parasitism, was tested using arenas, where females were exposed for 30 minutes, individually, to egg groups with different treatments. To evaluate age discrimination, three groups of eggs, previously washed with hexane, were employed in the following conditions: one day-old eggs; one-day brushed with 12-days-old egg extract; 12-days-old eggs with extract of one day-old eggs; and control (washed eggs, one day-old). The same procedure was done using five and eight days-old eggs jointly with control. Age-dependent egg discrimination was verified exposing four egg groups in the following treatments: parasitized, parasitized and washed with hexane, not parasitized, and not parasitized with extract of parasitized eggs. Olfactometer tests showed that inexperienced females remained more time next to tobacco leaves when compared to experienced ones. Experienced females responded to odors that emanated from eggs. Egg extracts did not promote age discrimination; however, non parasitized eggs, with extract of parasitized eggs were partially avoided. The results obtained indicate that G. gallardoi females might modify their responses upon contact with host. This fact suggests learning occurs; however, the acceptance and discrimination of host may be influenced by a complex array of stimuli, difficult to evaluate in isolation.

Spatial distribution of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) larvae in three scales.

The spatial distribution of larvae of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), the citrus leaf miner, in leaves, shoots, and tree crowns of Montenegrina tangerine (Citrus deliciosa Tenore) and Murcott tangor (Citrus sinensis L. Osbeck x Citrus reticulata Blanco) was determined. Fortnightly samplings from July/2001 to June/2003, in orchards located in Montenegro (29 degrees 68' S and 51 degrees 46' W), RS, Brazil, were carried out. At each sampling occasion eighth shoots randomly selected were collected. The spatial distribution pattern of P. citrella larvae between tree crowns and in the shoots was aggregated in most sampling occasions in both citrus species. Nevertheless, on the leaves, this pattern followed a random distribution, as indicated by the indices I, Idelta and k parameter.

Discrimination of Spartocera dentiventris (Berg, 1884) (Hemiptera: Coreidae) eggs by Gryon gallardoi (Brèthes, 1913) (Hymenoptera: Scelionidae)

This paper aimed to evaluate the stimuli that orient Gryon gallardoi females to the eggs of Spartocera dentiventris and allow their discrimination. Using a four-arm olfactometer connected to four odor sources - S. dentiventris eggs; hexane washed eggs; tobacco leaves; and tobacco leaves with eggs - the arrestment of female parasitoids with previous oviposition experience and without was individually verified. The time of permanence in each odor field was registered for a period of 15 minutes. Host discrimination, regarding age and previous parasitism, was tested using arenas, where females were exposed for 30 minutes, individually, to egg groups with different treatments. To evaluate age discrimination, three groups of eggs, previously washed with hexane, were employed in the following conditions: one day-old eggs; one-day brushed with 12-days-old egg extract; 12-days-old eggs with extract of one day-old eggs; and control (washed eggs, one day-old). The same procedure was done using five and eight days-old eggs jointly with control. Age-dependent egg discrimination was verified exposing four egg groups in the following treatments: parasitized, parasitized and washed with hexane, not parasitized, and not parasitized with extract of parasitized eggs. Olfactometer tests showed that inexperienced females remained more time next to tobacco leaves when compared to experienced ones. Experienced females responded to odors that emanated from eggs. Egg extracts did not promote age discrimination; however, non parasitized eggs, with extract of parasitized eggs were partially avoided. The results obtained indicate that G. gallardoi females might modify their responses upon contact with host. This fact suggests learning occurs; however, the acceptance and discrimination of host may be influenced by a complex array of stimuli, difficult to evaluate in isolation.

Este trabalho objetivou avaliar os estímulos que direcionam as fêmeas Gryon gallardoi aos ovos de Spartocera dentiventris e promovem discriminação deles. Através de um olfatômetro de quatro braços conectado a quatro fontes de odor (ovos de S. dentiventris não lavados, ovos lavados com hexano, folhas de fumo e folhas de fumo com ovos) verificou-se, individualmente, o arrestamento dos parasitóides, experientes em oviposição e não experientes, registrando-se o tempo de permanência em cada campo de odor por 15 minutos. Para avaliar a discriminação do hospedeiro, em relação à idade e parasitismo prévio, utilizaram-se arenas, onde as fêmeas foram expostas por 30 minutos, individualmente, a grupos de ovos com diferentes tratamentos. Para a avaliação da idade, utilizaram-se três grupos de ovos, lavados com hexano, nas seguintes condições: ovos de um dia de idade pincelados com extrato de ovos de 12 dias, ovos de 12 dias com extrato de ovos de um dia e controle (ovos lavados de um dia). O mesmo procedimento foi feito utilizando-se ovos de cinco e oito dias de idade, juntamente com o controle. A discriminação de ovos previamente parasitados foi verificada expondo quatro grupos de ovos com os seguintes tratamentos: parasitados, parasitados e lavados com hexano, não parasitados e não parasitados com extrato de ovos parasitados. Testes em olfatômetro demonstraram que as fêmeas inexperientes permaneceram mais tempo junto às folhas de fumo que as experientes. As fêmeas experientes responderam aos odores oriundos dos ovos. Os extratos de ovos não promoveram a discriminação da idade, porém ovos não parasitados, impregnados com extrato de parasitados, foram parcialmente evitados. Os resultados deste trabalho apontam que as fêmeas de G. gallardoi podem modificar suas respostas diante do contato prévio com o seu hospedeiro, sugerindo aprendizagem, porém a aceitação e a discriminação do hospedeiro podem ser influenciadas por uma complexa combinação de estímulos,...

Spatial distribution of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) larvae in three scales

The spatial distribution of larvae of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), the citrus leaf miner, in leaves, shoots, and tree crowns of Montenegrina tangerine (Citrus deliciosa Tenore) and Murcott tangor (Citrus sinensis L. Osbeck x Citrus reticulata Blanco) was determined. Fortnightly samplings from July/2001 to June/2003, in orchards located in Montenegro (29º 68’ S and 51º 46’ W), RS, Brazil, were carried out. At each sampling occasion eighth shoots randomly selected were collected. The spatial distribution pattern of P. citrella larvae between tree crowns and in the shoots was aggregated in most sampling occasions in both citrus species. Nevertheless, on the leaves, this pattern followed a random distribution, as indicated by the indices I, Idelta and k parameter.

Com o objetivo de determinar a distribuição espacial das larvas de Phyllocnistis citrella Stainton, (Lepidoptera: Gracillariidae), o minador-dos-citros, nas folhas, nos brotos e nas copas das plantas de tangerineira ‘Montenegrina’ (Citrus deliciosa Tenore) e de tangor ‘Murcott’ (Citrus sinensis L. Osbeck x Citrus reticulata Blanco), foram realizadas amostragens quinzenais de julho de 2001 a junho de 2003 em pomares localizados em Montenegro (29º 68’ S e 51º 46’ W), RS, Brasil. Em cada ocasião de amostragem foram coletados aleatoriamente oito brotos. Através da análise, pelos índices de dispersão I e Idelta, o padrão de distribuição espacial das larvas de P. citrella entre as plantas e nos brotos de ‘Montenegrina’ e ‘Murcott’ foi agregado na maioria das ocasiões de amostragem. O padrão de distribuição espacial das larvas do minador-dos-citros nas folhas mostrou-se diferente do registrado em copas das plantas e brotos, os índices I, Idelta e o parâmetro k indicaram distribuição aleatória.

Spatial distribution of parasitism on Phyllocnistis citrella Stainton, 1856 (Lepidoptera: Gracillariidae) in citrus orchards.

Many species of microhymenopterous parasitoids have been registered on Phyllocnistis citrella, the citrus leafminer. The present study aimed to identify the spatial distribution pattern of the native and introduced parasitoids of P. citrella in two citrus orchards in Montenegro, RS. The new shoots from 24 randomly selected trees in each orchard were inspected at the bottom (0-1.5 m) and top (1.5-2.5 m) stratum and had their position relative to the quadrants (North, South, East and West) registered at every 15 days from July/2002 to June/2003. The leaves with pupae were collected and kept isolated until the emergence of parasitoids or of the leaf miner; so, the sampling was biased towards parasitoids that emerge in the host pupal phase. The horizontal spatial distribution was evaluated testing the fitness of data to the Poisson and negative binomial distributions. In Montenegrina, there was no significant difference in the number of parasitoids and in the mean number of pupae found in the top and bottom strata (chi2 = 0.66; df = 1; P > 0.05) (chi2 = 0.27; df =1; P > 0.05), respectively. In relation to the quadrants, the highest average numbers of the leafminer pupae and of parasitoids were registered at the East quadrant (chi2 = 11.81; df = 3; P < 0.05), (chi2 = 10.36; df = 3; P < 0.05). In the Murcott orchard, a higher number of parasitoids was found at the top stratum (63.5%) (chi2 = 7.24; df =1 P < 0.05), the same occurring with the average number of P. citrella pupae (62.9%) (chi2 = 6.66; df = 1; P < 0.05). The highest number of parasitoids and of miners was registered at the North quadrant (chi2 = 19. 29; df = 3; P < 0.05), (chi2 = 4.39; df = 3; P < 0.05). In both orchards, there was no difference between the numbers of shoots either relative to the strata as well as to the quadrants. As the number of shoots did not varied much relative to the quadrants, it is possible that the higher number of miners and parasitoids in the East and West quadrants would be influenced by the higher solar exposure of these quadrants. The data of the horizontal spatial distribution of the parasitism fit to the negative binomial distribution in all sampling occasions, indicating an aggregated pattern.

Species composition and structure of Thysanoptera communities in different microhabitats at the Parque Estadual de Itapuã, Viamão, RS.

Although thrips are known as inhabitants of flowers, they are also abundant and diverse in other microhabitats. There is an information gap concerning them, especially related to the native fauna in southern Brazil. The structure and composition of the thysanopteran community in different microhabitats was studied at the "Parque Estadual de Itapuã" (30 degrees 22' S 51 degrees 02' W), RS, southern Brazil. Between June 1999 and May 2001, branches (n = 1,274), flowers (n = 774), grass tussocks (n = 596) and leaf litter (n = 603) were sampled systematically in 20 points of four trails (T1 - Pedreira beach, T2 - Araçá beach, T3 - Lagoinha, and T4 - Grota hill). We found 2,197 adult thrips determined in 73 species in 41 genera, of which 37 could be nominated. Four families are represented, Thripidae, Phlaeothripidae, Heterothripidae and Merothripidae, with the first the most abundant (N = 1,599) and with the highest species richness (S = 32). The highest thrips abundance occurred in flowers N = 1,224 and the highest number of exclusive species occurred in the leaf litter (27). Frankliniella rodeos Moulton, 1933, Frankliniella gemina Bagnall, 1919 and Smicrothrips particula Hood, 1952 comprise 49.4% of the total sampled. Regarding T2, we obtained the highest abundance (N = 935) and highest species richness (S = 43). The composition of the faunas in each kind of environment proved very particular.

Species composition and structure of Thysanoptera communities in different microhabitats at the Parque Estadual de Itapuã, Viamão, RS / Estrutura e composição de espécies de comunidades de Thysanoptera em diferentes micro-hábitats no Parque Estadual de Itapuã, Viamão, RS

Although thrips are known as inhabitants of flowers, they are also abundant and diverse in other microhabitats. There is an information gap concerning them, especially related to the native fauna in southern Brazil. The structure and composition of the thysanopteran community in different microhabitats was studied at the "Parque Estadual de Itapuã" (30° 22' S 51° 02' W), RS, southern Brazil. Between June 1999 and May 2001, branches (n = 1,274), flowers (n = 774), grass tussocks (n = 596) and leaf litter (n = 603) were sampled systematically in 20 points of four trails (T1 - Pedreira beach, T2 - Araçá beach, T3 - Lagoinha, and T4 - Grota hill). We found 2,197 adult thrips determined in 73 species in 41 genera, of which 37 could be nominated. Four families are represented, Thripidae, Phlaeothripidae, Heterothripidae and Merothripidae, with the first the most abundant (N = 1,599) and with the highest species richness (S = 32). The highest thrips abundance occurred in flowers N = 1,224 and the highest number of exclusive species occurred in the leaf litter (27). Frankliniella rodeos Moulton, 1933, Frankliniella gemina Bagnall, 1919 and Smicrothrips particula Hood, 1952 comprise 49.4 percent of the total sampled. Regarding T2, we obtained the highest abundance (N = 935) and highest species richness (S = 43). The composition of the faunas in each kind of environment proved very particular.

Embora os tripes sejam conhecidos como habitantes de flores, também são abundantes e diversos em outros micro-hábitats. Há uma lacuna de informações neste sentido, especialmente sobre a fauna nativa no Sul do Brasil. Entre junho de 1999 a maio de 2001, ramos (n = 1.274), flores (n = 774), touceiras de gramíneas (n = 596) e folhedo (n = 603) foram amostrados sistematicamente em 20 pontos de quatro trilhas (T1 - Praia da Pedreira, T2 - Praia do Araçá, T3 - Lagoinha, e T4 - Morro da Grota). Resultaram 2.197 tripes adultos determinados em 73 espécies de 41 gêneros, das quais 37 puderam ser nominadas. Quatro famílias estão representadas, Thripidae, Phlaeothripidae, Heterothripidae e Merothripidae, sendo a primeira mais abundante (N = 1.599) com a maior riqueza de espécies (S = 32). A maior abundância de tripes ocorreu nas flores (N = 1.224) e o maior número de espécies exclusivas ocorreu no folhedo (27). Frankliniella rodeos Moulton, 1933, Frankliniella gemina Bagnall, 1919 and Smicrothrips particula Hood, 1952 compõem 49,4 por cento do total da amostra. Na T2 foi obtida maior abundância (N = 935) e maior riqueza de espécies (S = 43). A composição das faunas de cada tipo de ambiente revelou-se muito particular.