High Levels Of Parasitism Research Articles

Immune responses of bumblebee workers as a function of individual and colony age: senescence versus plastic adjustment of the immune function

Senescence may evolve in response to externally imposed schedules of survival and reproduction. It may result from cumulative damage to several tissues and organs leading to the progressive malfunction of somatic defences including the immune system, which is a relevant and accessible trait to study the evolution and the mechanisms of senescence.In social insects, reproduction of workers is negligible and their fitness relies on the colony reproductive success, which depends on workers’ longevity. Consequently, evolution of senescence in workers will rely on age‐dependent survival rate and the residual reproductive value of the colony. Using the bumblebee, Bombus terrestris, as model system, we investigated changes in constitutive and inducible immune defences. Such changes were monitored in relation to worker age and colony age and as well under a high, persistent level of parasitism. The results show that the inducible production of antibacterial peptides was not affected by the age of individual worker or the age of their colony. In contrast, constitutive defences such as haemocyte density and phenoloxidase (PO) activity decline with individual worker age and potential accumulation of physiological defects due to high and persistent levels of parasitism did not explain this pattern of immunosenescence. Interestingly, levels of worker constitutive defences were found to increase with colony age. We found antibacterial activity was strongly traded‐off against PO activity. Such a relationship was not caused by resource shortage. Overall, these data suggest that patterns of variation of immune defences with worker age and colony age are likely the result of plastic temporal adjustments of immune responses in accordance with life history predictions. Hence, control of pathogenic threat in a social system may involve optimal adjustments of immune defences at both the individual and colony levels.

Larger olive fruit size reduces the efficiency of Psyttalia concolor, as a parasitoid of the olive fruit fly

The larval parasitoid, Psyttalia concolor (Szépligeti), has been released for biological control of the olive fruit fly, Bactrocera oleae (Rossi), in California. The effect of olive ( Olea europaea L.) fruit size on parasitism efficiency was quantified within one cultivar (Sevillano) and across four different sized cultivars (in order of decreasing size: Sevillano, Ascolano, Manzanillo, and Mission). Parasitism was examined under two different host distributions: (a) variable distribution in which host density increased with fruit size; and (b) uniform distribution in which host density was similar across all fruit sizes. Regardless of host distribution and cultivar, parasitism by P. concolor was consistently higher on smaller fruit. Field cage studies also showed that olive fruit fly parasitism by P. concolor was lower within fruit of the largest olive cultivar (Sevillano) compared to fruit of the smallest cultivar (Mission). Results suggest larval B. oleae were protected in large fruit due to the relatively short ovipositor of P. concolor. By rearing P. concolor on the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), adult females had a larger body size and ovipositor length than when female wasps were reared on B. oleae. In turn, P. concolor females with longer ovipositors had higher levels of parasitism in similar sized olive fruit. We discuss the potential implications of these findings for biological control of B. oleae.

Influência da competição intra-específica entre fêmeas e da ausência de hospedeiro no parasitismo de Telenomus remus Nixon (Hymenoptera, Scelionidae) sobre ovos de Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae)

A competição intraespecífica e a ausência de hospedeiros podem comprometer o sucesso de programas de controle biológico. Assim, este trabalho objetivou avaliar o efeito de diferentes densidades de fêmeas (1, 3, 6 e 9 fêmeas/ 100 ovos) e da ausência de hospedeiro no parasitismo de Telenomus remus Nixon (Hymenoptera, Scelionidae) em ovos de Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae). Observou-se aumento no parasitismo de ovos de S. frugiperda por T. remus a partir da densidade 3 fêmeas/ 100 ovos tanto em condições de laboratório (18%) quanto em campo (32%), embora o parasitismo causado por densidades maiores que 1 fêmea/100 ovos não foi significativamente diferente. Todavia, isso não causou superparasitismo. Por outro lado, o número de fêmeas produzidas na progênie diminuiu (39%) com a maior densidade de fêmeas sob condições de laboratório. Contudo, não verificou-se diferença significativa sob condições de campo. Mesmo após 9 dias de ausência de hospedeiro não houve redução nos índices de parasitismo, permanecendo em torno de 95 ovos parasitados/fêmea/dia. Todavia, no décimo dia pode-se observar redução (40%) no número médio de ovos parasitados. Desse modo, a liberação de três fêmeas por 100 ovos é adequada para se obter elevados níveis de parasitismo.

The impact of exotic parasitoids on populations of a native Hawaiian moth assessed using life table studies

The impact of alien species on native organisms is a cause for concern worldwide, with biological invasions commonplace today. Suppression efforts targeting many invasive species have included introductions of biological control agents. The numerous releases of biological control agents in the Hawaiian archipelago have resulted in considerable concern for non-target impacts, due to high levels of non-target parasitism observed to occur in some cases. This study investigated the impact of introduced Hymenoptera parasitoids on a Hawaiian moth. The endemic Hawaiian moth Udea stellata (Butler) has seven alien parasitoids associated with it, two purposely introduced, three adventive, and two of uncertain origin. The objective of this study was to determine the relative contribution of the seven parasitoid species to the population dynamics of U. stellata by constructing partial life tables. Marginal attack rates and associated k-values were calculated to allow comparison of mortality factors between experimental sites. Sentinel larvae were deployed on potted host plants and left in the field for 3-day intervals in open and exclusion treatments. The factors that contributed to total mortality in the open treatment were: disappearance (42.1%), death due to unknown reasons during rearing (16.5%) and parasitism (4.9%). The open treatment incurred significantly higher larval disappearance compared to the exclusion treatment (7.8%), which suggests that in large part disappearance is the result of predation. Adventive parasitoids inflicted greater total larval mortality attributable to parasitism (97.0%) than purposely introduced species (3.0%).

Short Note: Increase in feeding by the tick, Ixodes uriae, on Adélie penguins during a prolonged summer

Ixodes uriae White is the only tick species found in Antarctica, and in our research area at Palmer Station it feeds predominantly on Adélie penguins. At the beginning of the summer the ticks leave their off-host aggregation sites, feed on penguins, then subsequently return to their off-host habitats, where they remain until the next summer (Benoit et al. 2007). These ticks have been implicated as a competent vector for Borrelia spirochetes (Olsen et al. 1993) and tick-borne viruses (Nuttall 1984), and are thought to impact development, cause anaemia, alter the thermoregulation, and even lead to the death of penguins (Gauthier-Clerc et al. 1998, Mangin et al. 2003). In this report, we note a striking increase in the number of fed ticks found near Adélie penguin rookeries in 2007 compared to 2006, suggesting that the longer and warmer summer of 2007 may have permitted more ticks to find their hosts. High levels of parasitism could be detrimental to the already declining Adélie penguin populations near Palmer Station (Fraser & Patterson 1997).

Community regulation by herbivore parasitism and density: Trait-mediated indirect interactions in the intertidal

The abundant herbivorous mud-snail Hydrobia ulvae is an ecosystem engineer in soft-bottom intertidal habitats due to its grazing and bioturbation activity. However, mud snails are commonly infected by trematodes that reduce their overall activity, which in turn may affect their impact on the surrounding benthic community. To test this hypothesis, we performed field experiments manipulating both the abundance of uninfected snails (0, 7500 and 15.000 ind. m - 2 ) and the level of snail parasitism (0, 33 and 100% trematode prevalence) on a Danish mud-flat. The results showed that increasing snail abundance and parasitism generally had opposite effects on the community of microphytobenthos and zoobenthos. Increasing snail density increased the chlorophyll- a concentration in the substrate (enhancement), whereas increasing parasitism decreased it. In accordance, the benthic primary producers were generally less nutrient limited at high snail density and mostly so at high levels of snail parasitism. Moreover, epipsammic diatoms were favoured over epipelic diatoms at increasing snail density, whereas the opposite was evident at increasing snail parasitism. At the community level, increasing snail density increased evenness among epipelic diatoms, whereas increasing snail parasitism decreased evenness and species diversity. Probably through the action of trophic cascades and varying levels of disturbance, the zoobenthic community was influenced by experimental treatments as well. The indirect effects of snail parasitism influenced significantly the abundance of more faunal species (seven) than did snail density (two). At the community level, increasing snail density decreased evenness and lowest species richness coincided with intermediate snail density. In contrast, increasing snail parasitism resulted in increasing evenness and peaking species richness at intermediate level of parasitism. Together, the results show that parasites solely through their impact on the behaviour of a single community member can be significant indirect determinants of community organisation and function.

Variability of growth, health, and population turnover within mussel beds of Perna canaliculus in northern New Zealand

The growth and health of intertidal mussel (Perna canaliculus) populations were investigated along an exposed coastline at Ninety Mile Beach, northern New Zealand. A marked and recaptured experiment of young mussels (15–35 mm in shell length) over a year at three sites resulted in significant differences in recovery rates, shell growth, condition indices, age, and degree of shell parasitism. A high recovery rate of fast growing mussels coincided with a high condition index and low shell parasitism. Conversely, a low recovery rate of slow growing populations was associated with a low condition index and a high level of shell parasitism. Anomalous shell conditions included bored shells, wear and sloughing of periostracum, shell erosion, and nacre pits and bulges. Aging of adult mussels (70–80 mm) indicates that in areas of fast population turnover rates, mussels reach adulthood in only 1.1 years compared to the 2.5-year-old mussels found in low turnover areas. These differences are attributed to variations in environmental conditions (e.g., food availability, sediment load) throughout the study area, and highlight the importance of site-specific variability for intertidal populations.

Reproductive Biology and Development of Lixadmontia franki (Diptera: Tachinidae), a Parasitoid of Bromeliad-eating Weevils

Abstract The biology and development of Lixadmontia franki Wood and Cave (Diptera: Tachinidae), an endoparasitoid of bromeliad-eating weevils in the genus Metamasius, are described. Embryonic development is completed within 8 d post-mating while the egg is held inside the female reproductive system. Neonate larvae actively search for a host and initiate parasitism by penetrating the host’s cuticle. Larval developmental time and pupation at 20°C averaged 17 and 25 d, respectively, with no significant differences observed between genders. Adult males live on average 9 d compared to 17 d for females. Females are capable of parasitizing third to sixth instars of Metamasius quadrilineatus Chevrolat, but the highest levels of parasitism were observed when third and fourth instars were exposed to flies.

The parasitoid Praon volucre (Hymenoptera: Braconidae: Aphidiinae) as a potential biological control agent of the aphid Uroleucon ambrosiae (Hemiptera: Aphididae) on lettuce in Brazil

The aphid Uroleucon ambrosiae (Thomas) is one of the principal pests found on greenhouse lettuce crops, and there is no efficient biological control agent of this pest in Brazil. This work evaluates the aphid U. ambrosiae as a host for the parasitoid Praon volucre (Haliday), aimed at using P. volucre as a potential biological control agent of U. ambrosiae on lettuce. As Macrosiphum euphorbiae (Thomas) is a common host of P. volucre in the field, the development of the parasitoid was compared on these two aphid species. Twenty nymphs of the 2 nd instar were kept with P. volucre for one hour at 22 ± 1°C, 70 ± 10% RH and a 12 h photo- phase. The size of the aphid's tibiae at the moment of oviposition indicated that there was no significant size difference between U. ambrosiae (0.6 ± 0.02 mm) and M. euphorbiae (0.7 ± 0.03 mm). When mummies were formed, M. euphorbiae had significantly longer tibia (1.5 ± 0.03 mm) than U. ambrosiae (1.4 ± 0.02 mm). No significant differences were detected in the percentage emer- gence (74.9 ± 7.92 and 87.5% ± 3.31 for U. ambrosiae and M. euphorbiae, respectively), or proportion of female offspring (56.2 ± 7.62 and 44.2 ± 7.14%). The development time from oviposition to adult and longevity of females and males of P. volucre reared on the two host species were not different. High parasitism levels were recorded for both host aphid species, but the percentage para- sitism of M. euphorbiae (54.4 ± 4.40) was higher than of U. ambrosiae (35.6 ± 5.30). Female parasitoids reared on M. euphorbiae had longer tibiae (0.78 ± 0.01 mm) than those reared on U. ambrosiae (0.72 ± 0.01 mm). Our results demonstrate that the alternative host species U. ambrosiae, compared to the natural host species M. euphorbiae, affects the female's size, but did not affect parasitoid development time, longevity, emergence or sex ratio. The parasitoid P. volucre seems to be a good candidate for using as a bio- logical control agent of U. ambrosiae on lettuce in Brazil.

Testing the impact of laboratory reared indigenous leafroller (Lepidoptera: Tortricidae) parasitoids (Hymenoptera: Ichneumonidae, Braconidae) on sentinel hosts in controlled orchard releases

Leafrollers can experience high levels of indigenous parasitism in organically managed apple orchards and the augmenta- tive release of specific parasitoid species to suppress these secondary pests may be advantageous in orchards converting to non- chemical pest management. Caged and uncaged releases of two ichneumonid (Apophua simplicipes (Cresson) and Glypta variegata Dasch) and two braconid (Macrocentrus linearis Nees and Apanteles polychrosidis Viereck) koinobiont endoparasitoids of the obliquebanded leafroller, Choristoneura rosaceana (Lepidoptera: Tortricidae) on host-infested potted apple trees were conducted to assess the parasitoids' abilities to find and successfully parasitize sentinel hosts under orchard conditions. Seasonal timing of the trials varied for each parasitoid species, based on their relative performance under simulated summer/fall conditions in laboratory tri- als. After the release of five or fifty parasitoid females, the mean percent parasitism of leafroller larvae collected from infested trees ranged from 0 to 75% depending on the parasitoid species involved. Although caged releases tended to increase the percentage of live parasitized hosts in release treatments, uncaged releases provided a more realistic assessment of the parasitoid's ability to seek and find hosts within an infested area over a longer period. Release of the large, solitary A. simplicipes, had the most significant impact on the host population density.

Factors influencing parasitism of Sirex noctilio (Hymenoptera: Siricidae) by the nematode Deladenus siricidicola (Nematoda: Neotylenchidae) in summer rainfall areas of South Africa

Control of the invasive wasp, Sirex noctilio Fabricius using the parasitic nematode Deladenus siricidicola Bedding is a well known example of a successful classical biological control program. Despite its wide-scale success, this control method has recently had poor success in the summer rainfall areas of South Africa. Data from previous studies showed variation in nematode parasitism from inoculated trees (inoculation success) between different tree sections and among inoculation times. They also pointed to moisture content of the wood or virulence of the nematode as the most likely underlying factors influencing variations in inoculation success. The results from our study showed that the highest levels of parasitism was obtained from early inoculations and from the bottom sections of trees, where moisture content of the wood was highest, supporting the hypothesis that moisture content influences parasitism. However, even when moisture content was adequate, average inoculation success remained below 25% and was often 0%, suggesting that there are other barriers to inoculation success. Different sources from which the nematodes were produced did not influence inoculation success, indicating that nematode virulence is most likely not the cause of the low success. Another interesting finding was that parasitized wasps were larger than unparasitized wasps. Background parasitism was present despite the poor success with past inoculations, but the data also suggest that the natural build-up of this population could be constrained by the same factors that influence inoculations.

Parasite levels in blue-black grassquits correlate with male displays but not female mate preference

The handicap principle proposes that male sexual ornaments and displays provide honest indicators of quality. Female preference for high-quality males, however, may be driven not only by genetic benefits but also by indirect benefits. We investigated the impact of parasitism on morphological, ornamental, and behavioral characteristics of male and female blue-black grassquits (Volatinia jacarina) in captivity. First, we tested whether male displays and morphology were influenced by parasitism. Second, we assessed if females were attentive to variation in male morphology and displays linked to parasitism. Third, we tested whether parasitism in females influenced health and mate preferences. We maintained 2 groups of birds in captivity: nonmedicated birds developed high levels of coccidian parasitism, whereas medicated birds were free of parasitism. Parasitized males developed, relative to nonparasitized males, lower weight/tarsus indices and mass. They also showed relative deficiencies in their displays, with less persistence and lower rates. Despite the negative effects of parasitism on males, females did not prefer nonparasitized males. This held for both parasitized and nonparasitized females. Our data suggest that coccidian parasitism has adverse effects on morphological condition and expression of displays. These effects, however, appear not to be attended to by females; moreover, female mate preferences appear not to be impacted by the threat of parasitism. It thus seems that female mate preferences may not depend only on sexual characters affected by parasitism in this species.

Risk taking by singing males

The distance at which an individual flees from a potential predator represents a measure of risk taking. If individuals are engaged in another activity that might affect fitness, trade-offs between the fitness benefits of flight and the other activity should determine the nearest distance of approach by a predator. In a comparative analysis of birds, flight distance represented a reliable measure of risk of predation by the sparrowhawk Accipiter nisus that increased with decreasing flight distance across species. To test the hypothesis that singing males adjusted their risk taking to the costs and benefits of early flight, we compared the flight distance of singing and nonsinging birds to an approaching human observing with a binocular. Singing birds on average fled at a greater distance than nonsinging birds, implying that singing birds took small risks. We used a standardized measure of difference in flight distance between singing and nonsinging individuals to investigate factors affecting interspecific variation in risk taking. Species that used more exposed song posts (sites used for singing) took smaller risks than species with less exposed song posts. Species that suffered from higher levels of parasitism as reflected by the prevalence of Plasmodium, but not by 3 other genera of blood parasites, took greater risks during singing compared with nonsinging activities. Likewise, species with high circulating levels of natural antibodies, and hence a history of natural selection caused by bacteria took relatively greater risks during singing than species with few natural antibodies. These findings suggest that risks taken by singing birds have been molded by natural and sexual selection, and that risk taking represents a compromise between the costs and benefits of flight from a potential predator.

Southwestern Willow Flycatchers (Empidonax Traillii Extimus) in a Grazed Landscape: Factors Influencing Brood Parasitism

AbstractBrood parasitism by Brown-headed Cowbirds (Molothrus ater; hereafter “cowbirds”) is an important factor contributing to the endangered status of the Southwestern Willow Flycatcher (Empidonax traillii extimus, hereafter “flycatcher”). We report on factors that influence brood parasitism on the flycatcher using seven seasons of nest data (n = 491 nests) collected in riparian patches comprising cottonwood (Populus fremontii), willow (Salix spp.), and boxelder (Acer negundo) along the Gila River in southwest New Mexico. We quantified habitat and landscape characteristics that might be associated with higher levels of parasitism and assessed the correlation between those and the observed incidence of nest parasitism. Given that cowbirds associate with cattle, we were particularly interested to determine whether the distance to active summer grazing would influence the frequency of brood parasitism. We found an apparent negative trend between the distance to grazing and brood parasitism, but this trend was not statistically significant. Rather, brood parasitism was more strongly correlated with characteristics of the habitat. Specifically, nests in larger patches, and nests built near the patch edge adjacent to the river, were more susceptible to parasitism, which suggests that these areas are preferred nesting habitat for cowbirds because of a potentially greater abundance of hosts. Parasitism was significantly lower within the core of large patches, but the insulating effect was not evident in small and medium-sized patches. Higher nest height was strongly correlated with lower probability of parasitism, most notably for nests in boxelders. Nests in boxelders were less susceptible to parasitism, whereas nests in willows were more susceptible to parasitism. We discuss the results in the context of other studies. We recommend that management efforts to recover the flycatcher should focus on increasing quality habitat, and we suggest that cattle management should focus on eliminating the adverse effects of grazing on riparian health as a more feasible option than removing cattle far enough from riparian corridors so as to preclude parasitism.Empidonax traillii extimus en un Paisaje con Pastoreo: Factores que Influyen sobre el Parasitismo de la Nidada

Coping with habitat heterogeneity: the story of Mediterranean blue tits

A prerequisite for understanding adaptation is to understand how populations respond to environmental heterogeneity. We chose the blue tit Cyanistes caeruleus and Mediterranean habitat mosaics which exhibit a large diversity of habitats for analysing the effects of environmental heterogeneity on phenotypic variation. Three main factors of heterogeneity have been considered: (1) whether dominant tree species are deciduous or evergreen, (2) the geographic configuration of habitats and landscapes, and (3) the degree of infestation by parasites, which considerably varies in space. Several study sites equipped with nest-boxes and traps for collecting the droppings of caterpillars falling from the leaves of trees have been monitored over several decades in a series of habitats in mainland and insular (Corsica) landscapes. Depending on the geographic configuration of habitat patches within landscapes, the large phenotypic variation observed in many demographic, morphometric and behavioural traits has been shown to result either from a plastic response to habitat variation or from genetically determined specialisation to local habitats. Blue tits in deciduous habitats started to breed ca. 1 month earlier than in evergreen habitats, but patterns differed between the mainland and Corsica. On the mainland, populations may be locally maladapted because of gene flow across habitat patches, which results in a low supply/demand ratio of food, poor breeding performance and a source–sink population structure. In Corsica, higher phenotypic variation resulted from lower dispersal ranges in islands, a component of the insular syndrome. Genetically-based habitat-specific specialisation to local habitats on this island is a demonstration that adaptive responses of suites of life history traits to habitat-specific selection regimes may operate on a scale which is much smaller than the scale of potential dispersal and gene flow. Adaptive responses of blue tits to two constraints, i.e. high levels of parasitism and low amounts of food, have been studied in detail. The very small amount of measured genetic divergence between populations contrasts with the large inter-population phenotypic variation which is observed in many traits. This is one more example that natural selection can produce rapid and sometimes strongly adaptive morphological divergence in the absence of discernable differentiation at neutral DNA loci, and that weak genetic differentiation does not necessarily mean phenotypic resemblance.

Do Larvae of Species in Macrolepidopteran Assemblages Share Traits That Influence Susceptibility to Parasitism?

Research on how morphology, behavior, and life histories of insects determine their susceptibility to parasitism has primarily focused on the traits of single host species. Very little research has been conducted attempting to determine if similarities or differences in the traits of co-occurring species, on a single plant or in a habitat, influence levels of parasitism imposed on any member of an assemblage. In this study, we use categorical and regression tree analyses to determine which traits of the larvae of macrolepidopteran species are associated with highest levels of parasitism. Of a variety of morphological, behavioral, and ecological traits of 72 species (representing eight families), caterpillar color was the trait that had the greatest influence on susceptibility to parasitism. The highest levels of parasitism were associated primarily with green larvae. These results suggest that the herbivore species composition and, specifically, the traits possessed by the species may influence community or assemblagewide patterns of parasitism. That is, sharing of traits that enhance host finding and successful parasitism may result in associational susceptibility to parasitism, whereas co-occurrence with species that differ morphologically, behaviorally, or ecologically may reduce the likelihood of parasitism and thus result in associational resistance. The concepts of associational resistance and susceptibility have historically been restricted to plant-plant interactions. The extension of these concepts to herbivores is novel. If found to be widespread, these interactions can have significant impacts on our expectations of the effectiveness of biological control agents.

Seasonal patterns of parasitism and differential susceptibility among species in macrolepidopteran assemblages on Salix nigra (Marsh) and Acer negundo L.

Abstract 1. Previous research has demonstrated that parasitism of larval macrolepidoptera on Acer negundo (box elder) is greater than that of larvae on Salix nigra.2. In this study, percentage larval parasitism of species on box elder and black willow was calculated for distinct portions of the season, to determine if the higher levels of parasitism on box elder resulted from greater parasitism during a particular portion of the season.3. Larval parasitism was higher on box elder regardless of the portion of the season; however, the seasonal pattern of parasitism differed for each tree species, i.e. late‐season box elder parasitism increased and late‐season black willow parasitism decreased relative to early‐ and mid‐season parasitism.4. The degree to which higher levels of parasitism were associated with host and parasitoid traits such as average larval abundance, number of species, type of host, and parasitoid species load of macrolepidoptera, as well as average number of species of parasitoids during each portion of the season was determined.5. In addition, the possibility that differences in the pattern of parasitism on box elder and black willow were caused by the presence of a greater number of numerically dominant parasitoid species in late‐season box elder was investigated.6. None of the variables, other than type of host species, were associated with higher levels of parasitism in late‐season box elder.7. Late‐season, single‐tree species on box elder (i.e. species that occurred only on box elder) were more heavily parasitised, compared with dual‐tree species. This difference was not observed earlier in the season nor on black willow.8. Further, single‐tree species on late‐season box elder included three numerically dominant species that suffered significantly greater larval parasitism than any other type of species on either of the two trees.9. This study supported previous predictions, that suggested the importance of larval coloration: there was a higher proportion of green larvae among the most highly parasitised host species, i.e. single‐tree, numerically dominant species.

Efeito do número de adultos de Trichogramma galloi Zucchi, 1988 (Hymenoptera: Trichogrammatidae) liberados em semanas sucessivas, para o controle de Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae)

Neste trabalho, estudou-se o efeito do número de adultos de Trichogramma galloi Zucchi, 1988 liberados em semanas sucessivas, para o controle de Diatraea saccharalis (Fabricius, 1794). O experimento foi conduzido em março de 2003, com a cultivar SP 79-1011, de quatro meses de idade. Adotou-se o delineamento experimental inteiramente casualizado. Foram demarcadas quatro subáreas de 400 m² cada (20 m x 20 m), eqüidistantes 20 m. Cada parcela foi infestada artificialmente uma vez por semana com 20 casais de D. saccharalis (dois casais por gaiola, correspondendo a dez repetições por tratamento). Cada repetição correspondeu aos diferentes pontos de infestação. Repetiu-se esse procedimento por três semanas consecutivas, obtendo-se as posturas. Liberou-se T. galloi nas primeiras 24 horas após a infestação, no centro de cada uma das subáreas, nas seguintes quantidades (tratamentos): a- ausência de liberação (testemunha); b- 4.000 adultos (100.000 T. galloi/ha); c- 8.000 adultos (200.000 T. galloi/ha) e 10.000 adultos (250.000 T. galloi/ha). Com este trabalho ficou evidenciado que as liberações realizadas em áreas infestadas com ovos de D. saccharalis, em três semanas consecutivas, proporcionaram níveis elevados de parasitismoe que as melhores taxas de liberação de T. galloi para o controle de D. saccharalis, ficaram entre 150.000 e 175.000 parasitóides/ha.

Biliary ascariasis: Report of a complicated case and literature review

Invasion of the Ascaris worm into the biliary system leads to a wide variety of clinical syndromes. Most of the descriptions of the disease have originated from the developing world, where due to the environmental factors there is a high level of parasitism. An increased incidence of biliary ascariasis borne out of population migration and increased facilities for diagnosis has led to a renewal of interest in this disease in the developed world. Significant morbidity and mortality is associated with the concomitant complications, and early diagnosis and management is of utmost importance. Common disease presentations include biliary colic, obstructive jaundice, acalculous cholecystitis, choledocholithiasis, pancreatitis, and cholangitis. Although with a potential for serious mortality, pancreatitis, and cholangiocarcinoma constitute relatively less common threats. Recent advances in endoscopy have shifted the attention of this disease from the surgeon to the gastroenterologist and a consensus of opinion is arising for early intervention. We present here a patient with biliary ascariasis managed endoscopically and review the epidemiology, prevalence, clinical presentation, diagnosis, and management of this disease.

SOUTHWESTERN WILLOW FLYCATCHERS (EMPIDONAX TRAILLII EXTIMUS) IN A GRAZED LANDSCAPE: FACTORS INFLUENCING BROOD PARASITISM

Abstract Brood parasitism by Brown-headed Cowbirds (Molothrus ater; hereafter “cowbirds”) is an important factor contributing to the endangered status of the Southwestern Willow Flycatcher (Empidonax traillii extimus, hereafter “flycatcher”). We report on factors that influence brood parasitism on the flycatcher using seven seasons of nest data (n = 491 nests) collected in riparian patches comprising cottonwood (Populus fremontii), willow (Salix spp.), and boxelder (Acer negundo) along the Gila River in southwest New Mexico. We quantified habitat and landscape characteristics that might be associated with higher levels of parasitism and assessed the correlation between those and the observed incidence of nest parasitism. Given that cowbirds associate with cattle, we were particularly interested to determine whether the distance to active summer grazing would influence the frequency of brood parasitism. We found an apparent negative trend between the distance to grazing and brood parasitism, but this trend...