Natural Refuges Research Articles

Elevated Rocky Mountain elk numbers prevent positive effects of fire on quaking aspen (Populus tremuloides) recruitment

Quaking aspen (Populus tremuloides) is the most widespread tree species in North America and has supported a unique ecosystem for tens of thousands of years, yet is currently threatened by dramatic loss and possible local extinctions. While multiple factors such as climate change and fire suppression are thought to contribute to aspen’s decline, increased browsing by elk (Cervus elaphus), which have experienced dramatic population increases in the last ∼80years, may severely inhibit aspen growth and regeneration. Fires are known to favor aspen recovery, but in the last several decades the spatial scale and intensity of wildfires has greatly increased, with poorly understood ramifications for aspen growth. Here, focusing on the 2000 Cerro Grande fire in central New Mexico – one of the earliest fires described as a “mega-fire” - we use three methods to examine the impact of elk browsing on aspen regeneration after a mega-fire. First, we use an exclosure experiment to show that aspen growing in the absence of elk were 3× taller than trees growing in the presence of elk. Further, aspen that were both protected from elk and experienced burning were 8.5× taller than unburned trees growing in the presence of elk, suggesting that the combination of release from herbivores and stimulation from fire creates the largest aspen growth rates. Second, using surveys at the landscape level, we found a correlation between elk browsing intensity and aspen height, such that where elk browsing was highest, aspen were shortest. This relationship between elk browsing intensity and aspen height was stronger in burned (r=−0.53) compared to unburned (r=−0.24) areas. Third, in conjunction with the landscape-level surveys, we identified possible natural refugia, microsites containing downed logs, shrubs etc. that may inhibit elk browsing by physically blocking aspen from elk or by impeding elk’s ability to move through the forest patch. We did not find any consistent patterns between refuge elements and aspen size or canopy cover suggesting that natural refugia are not aiding in aspen recruitment and that all young aspen were susceptible to browsing. In much of their normal range, aspen are not growing to large size classes, which threatens the future of this iconic species and calls into question the ability of ecosystems to recover from mega-fires. Our results highlight the importance of considering multiple interacting factors (i.e. fire and increased elk browsing) when considering aspen management and regeneration.

Spatio‐temporal analysis of the role of faecal depositions in aggregation behaviour of the triatomine Rhodnius prolixus

AbstractSeveral triatomine species aggregate over conspecific faeces. In some domestic species, this behaviour might help individuals to find their refuges because faeces are usually deposited around such places. In the present study, the defaecation behaviour of the triatomine bug Rhodnius prolixus Stål (Heteroptera: Reduviidae) is described in detail, including the temporal pattern of aggregation of nymphs with different nutritional status to faeces of different post‐deposition times. First, using an experimental arena, the spatial distribution of faecal deposition spots released by nymphs, in relation to the position of a refuge, is recorded. The results show that a high density of faeces is deposited inside the refuge, and few and distant spots, in relation to the position of the refuge, are dropped outside. Second, whether the aggregation behaviour of nymphs is altered by the time elapsed from deposition of the faeces, and by the nutritional status of the insects, is determined. The post‐deposition time of the faeces strongly modulates the aggregation response of the insects. Differences in aggregation between fed and unfed insects are only marginally significant; however, different temporal windows of aggregation according to the post‐deposition times of the faeces are demonstrated between bugs of different nutritional status. The results are discussed with respect to the relevance of the aggregation signal in relation to the characteristics of the natural refuges used by R. prolixus.

Using Agent-Based Modelling to Predict the Role of Wild Refugia in the Evolution of Resistance of Sea Lice to Chemotherapeutants.

A major challenge for Atlantic salmon farming in the northern hemisphere is infestation by the sea louse parasite Lepeophtheirus salmonis. The most frequent method of controlling these sea louse infestations is through the use of chemical treatments. However, most major salmon farming areas have observed resistance to common chemotherapeutants. In terrestrial environments, many strategies employed to manage the evolution of resistance involve the use of refugia, where a portion of the population is left untreated to maintain susceptibility. While refugia have not been deliberately used in Atlantic salmon farming, wild salmon populations that migrate close to salmon farms may act as natural refugia. In this paper we describe an agent-based model that explores the influence of different sizes of wild salmon populations on resistance evolution in sea lice on a salmon farm. Using the model, we demonstrate that wild salmon populations can act as refugia that limit the evolution of resistance in the sea louse populations. Additionally, we demonstrate that an increase in the size of the population of wild salmon results in an increased effect in slowing the evolution of resistance. We explore the effect of a population fitness cost associated with resistance, finding that in some cases it substantially reduces the speed of evolution to chemical treatments.

Interprétation paléogéographique des données palynologiques du site du Paléolithique supérieur de Mezhyrich (Ukraine)

The results of palynological study of the Upper Paleolithic Mezhyrich site in central Ukraine are presented. Four local pollen zones were identified. The results of the palynological investigations allow us to hypothesize that the plant cover during Upper Paleolithic had a mosaic structure. The pollen record shows the presence of a few tree species with the predominance of herbaceous plants. We suggest that the river valleys and other local favorable sites were natural refugia where forest elements could survive even during the Last Glacial Maximum. These favorable landscapes to the existence of prehistoric hunters may have persisted during the Last Pleniglacial.

The impacts of deep-sea fisheries on benthic communities: a review

AbstractDeep-sea fisheries operate globally throughout the world's oceans, chiefly targeting stocks on the upper and mid-continental slope and offshore seamounts. Major commercial fisheries occur, or have occurred, for species such as orange roughy, oreos, cardinalfish, grenadiers and alfonsino. Few deep fisheries have, however, been sustainable, with most deep-sea stocks having undergone rapid and substantial declines. Fishing in the deep sea not only harvests target species but can also cause unintended environmental harm, mostly from operating heavy bottom trawls and, to a lesser extent, bottom longlines. Bottom trawling over hard seabed (common on seamounts) routinely removes most of the benthic fauna, resulting in declines in faunal biodiversity, cover and abundance. Functionally, these impacts translate into loss of biogenic habitat from potentially large areas. Recent studies on longline fisheries show that their impact is much less than from trawl gear, but can still be significant. Benthic taxa, especially the dominant mega-faunal components of deep-sea systems such as corals and sponges, can be highly vulnerable to fishing impacts. Some taxa have natural resilience due to their size, shape, and structure, and some can survive in natural refuges inaccessible to trawls. However, many deep-sea invertebrates are exceptionally long-lived and grow extremely slowly: these biological attributes mean that the recovery capacity of the benthos is highly limited and prolonged, predicted to take decades to centuries after fishing has ceased. The low tolerance and protracted recovery of many deep-sea benthic communities has implications for managing environmental performance of deep-sea fisheries, including that (i) expectations for recovery and restoration of impacted areas may be unrealistic in acceptable time frames, (ii) the high vulnerability of deep-sea fauna makes spatial management—that includes strong and consistent conservation closures—an important priority, and (iii) biodiversity conservation should be > balanced with options for open areas that support sustainable fisheries.

Genes of the extinct Caucasian bison still roam the Białowieża Forest and are the source of genetic discrepances between Polish and Belarusian populations of the European bison,Bison bonasus

European bison (Bison bonasus) populations from both the Polish (PL) and the Belarusian (BY) sides of the Bialowieza Forest represent the Lowland genetic line (LB line) – progeny of the Lowland bison (Bison bonasus bonasus) that inhabited western, central, and south-eastern Europe in historical times. During the species recovery, one of the founders was a descendant of the extinct Caucasian bison (Bison bonasus caucasicus) and its descendants formed the other genetic line – Lowland–Caucasian (LC). There have been justified suspicions that LB European bison in the former Soviet Union had undergone cross-mating with the LC line. We performed a comparative genetic analyses on European bison from the BY and PL parts of the Bialowieza Forest, the LC line and extinct Caucasian bison, based on a set of 19 microsatellite markers and 1512 bovine single nucleotide polymorphism (SNP) markers, polymorphic in at least one of the studied populations. Although genetic variability (mean allele number and expected heterozygosity) for both populations were similar, the FST jack-knifing and principal component analyses PCA revealed highly significant differences between PL and BY bison from the Bialowieza Forest. Examining DNA of the extinct Caucasian bison revealed that at least part of the genetic variants found in the BY, but not the PL, population were of Caucasian origin. The results indicate that the contemporary population of European bison from the BY part of the Bialowieza Forest should not be regarded as a LB line. The results also suggest that the actual global population size of the LB line European bison is only a half of its official status. Consideration of the presented results are crucial in determining management actions and policy decisions in order to conserve LB line bison within the Bialowieza Forest – its natural refuge. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 752–763.

新疆北部棉铃虫寄主来源与庇护所评估

PDF HTML阅读 XML下载 导出引用 引用提醒 新疆北部棉铃虫寄主来源与转基因棉区庇护所评估 DOI: 10.5846/stxb201402160266 作者: 作者单位: 石河子大学,中国科学院新疆生态与地理研究所,中国科学院干旱区生物地理与生物资源重点实验室,121团农机推广站,147团农业科植保站,147团农业科植保站,石河子大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家国际科技合作专项(2011DFA33170);中国科学院院地合作专项(XBXJ-2011-029) Analysis of Larval host types of Cotton Bollworm (Helicoverpa armigera) Populations for Evaluation of Bt Refuges in Northern Xinjiang Author: Affiliation: Shihezi University,Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences,,The 121th Production and Construction Crops Agricultural Technology Extension Station,The 147th plant protection station of Agricultration Department,The 147th plant protection station of Agricultration Department,Shihezi University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:转Bt基因抗虫棉长期大规模种植后,棉铃虫对其存在抗性风险,庇护所是延缓抗性上升的策略之一。但在新疆北部转基因棉区,庇护所提供敏感棉铃虫的生态功能尚未见评估。2013年5-9月期间在新疆北部石河子地区147团、121团利用棉田边缘的智能测报灯收集棉铃虫成虫,应用碳稳定同位素技术从群体水平(混合翅膀)分析虫源性质,从个体水平(雌蛾翅膀和对应精包)确定交配类型;同时通过解剖雌性棉铃虫体内的精包数量评估交配频率。结果表明:来源于C4植物的棉铃虫主要出现在5月下旬和8-9月期间,比例占到50%左右;6-7月接近100%的棉铃虫来自于C3植物上;经测定不同寄主来源棉铃虫的有效交配比例为10%左右;两个地方的棉铃虫交配频率一般在0.9-2.1 次,但121团的第一代和第二代均高于147团。玉米是新疆北部地区重要的庇护所,但C3和C4来源棉铃虫同存的时间比较短,有效交配比例相对比较低,影响了庇护所的抗性稀释能力。在转基因棉区的抗性管理中不仅要考虑庇护所提供敏感棉铃虫数量大小,同时需要考虑有效交配比率,这将有利深刻理解庇护所生态功能。 Abstract:Transgenic cotton, expressing an insecticidal toxin from Bacillus thuringiensis (Bt cotton), has been widely cultivated for a long period in some areas of China. Therefore, there is the potential for the cotton bollworm, Helicoverpa armigera, to develop resistance to Bt cotton toxins. The United States Environmental Protection Agency (US EPA) is rethinking the requirement for some regions to delay developing natural refuge crops where Bt cotton growth has been highly successful. The policy of establishing refuges was intended to delay pest population development of Bt-toxin resistance. Bt cotton is widely grown in Xinjiang Province, which is the largest cotton-producing area in China, but no studies have been conducted on potential refuges in this region of China. In recent years, stable carbon isotope techniques (δ13C) have been used to identify the larval host-types (i.e., whether the hosts are C3 or C4 plants) of cotton bollworm. These methods have been used to evaluate the Bt refuge function of non-cotton crops. In this study, intelligent forecast light traps were established to collect adult cotton bollworms from May to September 2013, from the 147th and 121st regiments of the Shihezi reclamation area located in northern Xinjiang. The captured moths were placed into bottles and preserved in 95% alcohol until analysis. At each of the sites, 50 males and 30 females moths were selected on the day of capture, their wings combined into two bulked samples respectively to analyze their host type (C3 or C4) using δ13C analysis. At the same time, 30 female's wings and corresponding spermatophore were separated to one single sample to analyze the mating type and percentage of mating frequency between C3 and C4 host. A total of 23 bulked samples from the 147th regiment and 25 bulked samples from the 121st regiment were tested. The proportions of C3 and C4 hosts were calculated according to a standard curve constructed in 2012. Approximately 50% of cotton bollworms were derived from C4 hosts, and approximately 50% from C3 hosts in late May and from early August to September. From June to July, 100% of cotton bollworms were derived from C4 hosts. To evaluate the mating frequency of cotton bollworms at the two sites, we selected 210 anatomically adult females in the 1st and 2nd generations from the 147th and 121st regiments. The percentage of effective mating between the two larval host-types (C3 and C4) was approximately 10%. Mating frequency ranged from 0.9 to 2.1 per adult female at the two sites, and was higher at the 121st regiment site than at the 147th regiment site. Maize is considered to be the most important natural refuge for Bt-susceptible cotton bollworms in northern Xinjiang, since maize is the main C4 host plant in this area. Thus, maize may provide refuges for susceptible cotton bollworms in the autumn of one year and the spring of the following year. There is a short period in which cotton bollworms derived from C3 and C4 hosts simultaneously co-exist, and there is a very small percentage of effective mating between cotton bollworms derived from C3 and C4 hosts. This will affect the capacity to dilute the Bt-resistance in cotton bollworms, and may be related to the non-synchronization of C3 and C4 crops and male and female cotton bollworms. 参考文献 相似文献 引证文献

Large-scale test of the natural refuge strategy for delaying insect resistance to transgenic Bt crops.

The 'natural refuge strategy" for delaying insect resistance to transgenic cotton that produces insecticidal proteins from Bacillus thuringiensis (Bt) relies on refuges of host plants other than cotton that do not make Bt toxins. We tested this widely adopted strategy by comparing predictions from modeling with data from a four-year field study of cotton bollworm (Helicoverpa armigera) resistance to transgenic cotton producing Bt toxin Cry1Ac in six provinces of northern China. Bioassay data revealed that the percentage of resistant insects increased from 0.93% in 2010 to 5.5% in 2013. Modeling predicted that the percentage of resistant insects would exceed 98% in 2013 without natural refuges, but would increase to only 1.1% if natural refuges were as effective as non-Bt cotton refuges. Therefore, the results imply that natural refuges delayed resistance, but were not as effective as an equivalent area of non-Bt cotton refuges. The percentage of resistant insects with nonrecessive inheritance of resistance increased from 37% in 2010 to 84% in 2013. Switching to Bt cotton producing two or more toxins and integrating other control tactics could slow further increases in resistance.

Sea-level rise and refuge habitats for tidal marsh species: Can artificial islands save the California Ridgway's rail?

Terrestrial species living in intertidal habitats experience refuge limitation during periods of tidal inundation, which may be exacerbated by seasonal variation in vegetation structure, tidal cycles, and land-use change. Sea-level rise projections indicate the severity of refuge limitation may increase. Artificial habitats that provide escape cover during tidal inundation have been proposed as a temporary solution to alleviate these limitations. We tested for evidence of refuge habitat limitation in a population of endangered California Ridgway's rail (Rallus obsoletus obsoletus; hereafter California rail) through use of artificial floating island habitats provided during two winters. Previous studies demonstrated that California rail mortality was especially high during the winter and periods of increased tidal inundation, suggesting that tidal refuge habitat is critical to survival. In our study, California rail regularly used artificial islands during higher tides and daylight hours. When tide levels inundated the marsh plain, use of artificial islands was at least 300 times more frequent than would be expected if California rails used artificial habitats proportional to their availability (0.016%). Probability of use varied among islands, and low levels of use were observed at night. These patterns may result from anti-predator behaviors and heterogeneity in either rail density or availability of natural refuges. Endemic saltmarsh species are increasingly at risk from habitat change resulting from sea-level rise and development of adjacent uplands. Escape cover during tidal inundation may need to be supplemented if species are to survive. Artificial habitats may provide effective short-term mitigation for habitat change and sea-level rise in tidal marsh environments, particularly for conservation-reliant species such as California rails.

Melastomataceae in a continental Atlantic Forest island from southeastern Brazil

The Marambaia is an important natural refuge for preserving the genetic heritage of several rain forest plant species. In this insular region, where the vegetation types are Lower Montane Rain Forest and restingas (sandy coastal plain habitat), the impressive diversity of Melastomataceae consists of seven genera and 25 species of which 13 represent new records for the area. Miconia is best represented with 10 species, followed by Tibouchina (6 spp.), Leandra (4 spp.), Clidemia (2 spp.) and Huberia, Marcetia and Ossaea (1 sp. each). Most of the species are shrubs or trees and occur in Dense Submontane Ombrophilous Forest. Huberia ovalifolia DC., Leandra acutiflora (Naudin) Cogn. and Leandra melastomoides Raddi are cited in the list of endangered species for the municipality of Rio de Janeiro. An identification key is provided as well as descriptions, illustrations, comments on morphological peculiarities of species, and geographical and phenological data.

Predator–prey systems depend on a prey refuge

Models of near-exclusive predator–prey systems such as that of the Canadian lynx and snowshoe hare have included factors such as a second prey species, a Holling Type II predator response and climatic or seasonal effects to reproduce sub-sets of six signature patterns in the empirical data. We present an agent-based model which does not require the factors or constraints of previous models to reproduce all six patterns in persistent populations. Our parsimonious model represents a generalised predator and prey species with a small prey refuge. The lack of the constraints of previous models, considered to be important for those models, casts doubt on the current hypothesised mechanisms of exclusive predator–prey systems. The implication for management of the lynx, a protected species, is that maintenance of an heterogeneous environment offering natural refuge areas for the hare is the most important factor for the conservation of this species.

Natural History of an Introduced Population of Squirrel Treefrogs (Hyla squirella) on the Delmarva Peninsula

AbstractHyla squirella was not known to occur on Delmarva until an established population was discovered at the southernmost tip of the peninsula in the Eastern Shore of Virginia Natural Wildlife Refuge in 2005. Male vocalizations were heard periodically throughout the refuge during daytime and evening hours from 27 May to 7 September 2006. Large choruses of males were heard 27 May and 9 and 27 June 2006. A large breeding event was observed on 9 June in a temporary pond. The smallest mature male was 27 mm SVL and weighed 1.1 g and the smallest mature female was 31 mm SVL, 1.7 g, and gravid. Mean adult male SVL was significantly smaller than the mean for adult females. Metamorphs found on 19 October averaged 13.0 ± 0.21 mm SVL and weighed 0.164 ± 0.009 g. Ecological and life history parameters of the introduced population of H. squirella on Delmarva do not appear to differ from those of populations in the natural portion of its range. This established population offers opportunities to elucidate a variety of questions about northward range expansion, genetics, and tolerance limits.

Растительный покров подтаежных ландшафтов предгорной равнины правобережья реки Оби

Vegetation of the right bank of the Ob River in the limits of Novosibirsk area consists of southern taiga, subtaiga and forest-steppe elements. More over, in comparison with neighboring areas on the West Siberian Plain, it contains the significant amount of mountain elements (Kuminova, Vagina, Lapshina, 1963). Natural vegetation of the area belongs to the forest-steppe subzone of the West Siberian province (Il’ina, 1985). Low percentage of forest coverage is caused by anthropogenic deforestation and wide distribution of meadows (Lapshina, 1963). This is the most endangered vegetation in Novosibirsk area. Spatial vegetation structure was studied by using the model of the Ob River basin covered 184 square kilometers. Well-developed system of ravines and small creeks caused a presence of relatively large areas with very low anthropogenic impact which potentially could be the refuges of pristine zonal vegetation. Main vegetation type of this basin is forest which covered about 31% of the area. Forest diversity of model area consists of four syntaxa of association and subassociation ranks belonging to the Brachypodio pinnati–Betuletea pendulae class. Meadow vegetation is presented by five syntaxa from the Molinio-Arrhenatheretea class and mire vegetation — by two syntaxa from the Alneteae glutinosae class. Two subassociations and four variants are described for the first time. The ravine systems could be considered as low-level landscape structures which are the natural refuges with high level of biodiversity and habitats of rare and endangered species. The slope vegetation organized in ecological rows consists of three up to four syntaxa changing from the top to the ravine bottom. The Ob River Basin flora is characterized by insignificant amount of meadow steppe species, well-represented mire flora and a presence of mountain and taiga elements. The most specific floristic features are the presence of ephemeroid species, taiga species and Siberian tertiary nemoral relics (Polozhiy, Krapivkina, 1985). All these features allow us to refer the river basin vegetation to the low-mountain subtaiga type.

Biogeographic patterns on Kimberley islands, Western Australia

– Australia’s islands play a significant role in the conservation of its biota. The near-pristine islands along the Kimberley coast of north-western Australia are important natural refuges that have been relatively isolated from many of the threatening processes affecting the adjacent mainland.

Mosquito Resistance to Bacterial Larvicidal Toxins

Insecticide resistance to the microbial insecticides Bacillus thuringiensis subsp. israelensis (Bti) and Bacillus sphaericus (Bs) represents a serious threat to their success. Available evidence indicates that the risk for resistance to Bti is low due to the makeup of its parasporal crystal, which contains Cyt1A, Cry4A, Cry4B, and Cry11A toxic proteins. Disrupting the toxin complex in Bti enables resistance to evolve, especially in the absence of the key factor, the cytolytic toxin, Cyt1A. Cross-resistance is widespread among mosquitocidal Bacillus thuringiensis Cry toxins and the mechanisms of Cry resistance in mosquitoes are not known. Bacillus sphaericus (Bs) is at higher risk for resistance due to its single- site action and field cases have been reported from a number of locations worldwide. Cross-resistance is reported among the various Bs isolates, although some isolates produce additional toxic proteins that can reduce cross-resistance and slow resistance evolution. Field and lab evolved resistant populations consistently show recessive and monofactorial inheritance of resistance. Resistant populations, however, have evolved a variety of molecular mechanisms causing that resistance. Traditional resistance management strategies with promise include rotations and mixtures of Bti and Bs, as well as untreated areas that provide natural refuges for susceptible alleles. Promising new strategies include genetic engineering to increase the toxin complexity targeted toward mosquito larvae, to enhance the host range of the mosquito control product, and to avoid the evolution of insecticide resistance. Regardless of the control strategy, a resistance- monitoring program alongside an integrative pest management approach is the best strategy to delay insecticide resistance.

Towards a resistance management strategy for Helicoverpa armigera in Bt-cotton in northwestern China: an assessment of potential refuge crops

Transgenic Bt-cotton now dominates the cotton-growing belt in northwestern China where there are few natural plant refuges to act as sources of moths susceptible to Bt toxin. As an initial step towards developing an insect resistance management (IRM) plan for the pest moth, Helicoverpa armigera, on Bt-cotton in this part of China, we assessed the potential of six crops grown in two configurations to act as refuge hosts for susceptible moth production in both broad-acre and small-holder farms. Egg and larval abundance indicated that H. armigera had a preference for chickpea, pigeon pea, and corn, over cotton, sorghum, and benne (sesame). There were no significant differences in egg or larval abundance between plot and strip configurations of these crop hosts. We found that sorghum was not attractive to H. armigera, contrary to the findings in other cotton production areas. Moreover, chickpea, pigeon pea, and corn were determined to be potential refuge hosts based on egg and larval abundance over the growing season. From the adult moth population dynamics in broad-acre and small-holder farms, the efficiency of alternative refuge crops, and local agricultural practices, we recommend that spring corn be grown as a strip crop as part of an IRM strategy to improve the probability of Bt-susceptible moth production and mating with resistant moths in broad-acre farms. In small-holder farms where current agricultural practices are entrenched, wheat and summer corn should be evaluated as refuge crops in the future.

OCORRENCE OF <i>MISCHOCYTTARUS ROTUNDICOLLIS</i> (VESPIDAE) IN MANGROVE SWAMPS ATTRACTED BY FISH IN DECOMPOSITION

Vespidae is an important insect family that is among the largest predators of other insects in natural environments. This study in mangrove swamps was carried out in order to know if social wasp, Mischocyttarus (Mischocyttarus) rotundicollis could be attracted by fish (sardine) in decomposition. The insects were collected in mangrove swamps in Itaborai, every two weeks, totaling 72 samples from August 2008 to July 2011. Over a 36 months period 69 individuals were caught. The abiotic factors (season and tidal variations) that could influence the occurrence of these wasps in mangrove swamps were recorded. The abundance of wasps was only affected by the spring season and the highest tides (spring-tides). The presence of the M. rotundicollis, in the mangrove swamps caught with fish in decomposition, may indicate that the studied forest area still represents a natural preserved refuge and reveals the importance of understanding of ecology these wasps and provides much information that will contribute greatly to environmental sciences.

Vectores de la leishmaniasis tegumentaria en el valle del Rímac

Objetivo: Determinar la composición de especies de Lutzomyia en el valle del Rímac. Material y métodos: El área estudiada fue el anexo de Ullupampa (2000 msnm), ubicado a 1 kilómetro de Surco, distrito de San Jerónimo de Surco, provincia de Huarochirí, Lima. Para la captura de flebotominos se utilizó trampa Shannon, trampas de luz CDC y captura directa con aspirador manual, en ambientes intra y peridomiciliarios y refugios naturales extradomiciliarios. Resultados: Se identificó 1742 flebotominos del género Lutzomyia, de las cuales 52,6% corresponden a Lutzomyia verrucarum, 28,2% a Lutzomyia peruensis y 19,2% a Lutzomyia noguchi, las primeras abundantes en intra y peridomicilio y la última en medios extradomiciliarios. La densidad de Lutzomyia presenta variaciones estacionales, siendo mayor entre los meses de marzo y mayo. La actividad hematófaga horaria presenta un pico entre las 20 y 21 horas. Conclusiones: Las viviendas rodeadas de cultivos de plantas frutales separadas por “pircas” y animales domésticos en el intradomicilio, favorecen la actividad hematófaga domiciliaria de L. peruensis y L. verrucarum, principales vectores de la leishmaniasis en el valle del Rímac.

Risk Assessment for <I>Helicoverpa zea</I> (Lepidoptera: Noctuidae) Resistance on Dual-Gene Versus Single-Gene Corn

Recent Environmental Protection Agency (EPA) decisions regarding resistance management in Bt-cropping systems have prompted concern in some experts that dual-gene Bt-corn (CrylA.105 and Cry2Ab2 toxins) may result in more rapid selection for resistance in Helicoverpa zea (Boddie) than single-gene Bacillus thuringiensis (Bt)-corn (CrylAb toxin). The concern is that Bt-toxin longevity could be significantly reduced with recent adoption of a natural refuge for dual-gene Bt-cotton (CrylAc and Cry2Ab2 toxins) and concurrent reduction in dual-gene corn refuge from 50 to 20%. A population genetics framework that simulates complex landscapes was applied to risk assessment. Expert opinions on effectiveness of several transgenic corn and cotton varieties were captured and used to assign probabilities to different scenarios in the assessment. At least 350 replicate simulations with randomly drawn parameters were completed for each of four risk assessments. Resistance evolved within 30 yr in 22.5% of simulations with single-gene corn and cotton with no volunteer corn. When volunteer corn was added to this assessment, risk of resistance evolving within 30 yr declined to 13.8%. When dual-gene Bt-cotton planted with a natural refuge and single-gene corn planted with a 50% structured refuge was simulated, simultaneous resistance to both toxins never occurred within 30 yr, but in 38.5% of simulations, resistance evolved to toxin present in single-gene Bt-corn (CrylAb). When both corn and cotton were simulated as dual-gene products, cotton with a natural refuge and corn with a 20% refuge, 3% of simulations evolved resistance to both toxins simultaneously within 30 yr, while 10.4% of simulations evolved resistance to CrylAb/c toxin.

Artificial burrows with basal chambers are preferred by pygmy bluetongue lizards, Tiliqua adelaidensis

Natural refuges are sometimes supplemented with artificial refuges to enhance populations of endangered species, or to improve the success of translocation and relocation programs. The design and structure of these artificial structures should incorporate key features of natural refuges. We aimed to improve the design of artificial burrows currently used in the conservation of the pygmy bluetongue lizard, Tiliqua adelaidensis, by comparing burrows with or without a basal chamber. We found that lizards chose burrows with chambers significantly more often, but that neither the size of the chamber, nor the substrate lining the chamber influenced the choice. Incorporating a basal chamber into the design of artificial burrows should provide more favourable artificial refuges for these lizards and should be incorporated into future conservation management programs.