Registros de una especie invasora de escarabajo coprófago, Digitonthophagus gazella (Fabricius, 1787) (Coleoptera: Scarabaeidae), en Perú

Digitonthophagus gazella, a dung beetle of indoafrican origin was first introduced to the Americas in the 1970s. Since then it has increased its range through deliberate introductions by national programs and by natural spread in the absence of geographical barriers. The species continues to expand its range as it invades new regions following the anthropogenic clearing of forests. We present the first reports of D. gazella in Peru and indicate that the species is now, perhaps, the most widespread dung beetle in tropical and subtropical pastures.Digitonthophagus gazella, un escarabajo coprófago de origen Indoafricano fue inicialmente introducido en el continente Americano en 1970. Desde ese momento su rango de distribución se ha incrementado debido a introducciones deliberadas en nuevas regiones y por procesos naturales de dispersión en ausencia de barreras geográficas. Esta especie ha continuado expandiendo su rango de distribución ayudado por el efecto antrópico producido por la tala de bosques. Se presenta el primer reporte de D. gazella para el Perú, indicando que esta especie se constituye en el escarabajo coprófago más ampliamente distribuido en pastizales tropicales y subtropicale

Field boundaries restrict dispersal of a tropical tiger beetle, Megacephala angustata Chevrolat 1841 (Coleoptera: Cicindelidae)

HORGAN FG,CH\uc1VEZ JC. 2004.Field boundaries restrict dispersal of a tropical tiger beetle, Megacephala angustata Chevrolat 1841 (Coleoptera;Cicindelidae). Entomotropica 19(3): 147-152. Field boundaries may divide populations of predatory invertebrates into local populations at the field scale by restricting between-field dispersalThis could reduce recolonisation rates after pesticide use or decrease the efficiency of numerical responses by natural enemies to pest outbreaks.The present study examines the impact of field boundaries on dispersal of the predatory tiger beetle, Megacephala angustata Chevrolat 1841 at a farm in coastal El Salvador. Pitfall trapping indicated that beetles occurred in most habitats on the farm. In pastures, captures were higherin open, unshaded areas than under field boundaries. Beetle dispersal was examined in a capture-mark-recapture study at the site. Movement between fields was very rare as indicated by a linear relationship between the accumulated number of marked beetles and the proportion of recaptures in each of three fields. In spite of frequent recaptures, three weeks after marking, only 2 of 401 beetles were found outside the fields where they had been originally captured and marked.HORGAN FG, CH\uc1VEZ JC. 2004. Barreras vivas como agente de restricci\uf3n para la dispersi\uf3n de un cicind\ue9lido tropical, Megacephala angustata Chevrolat 1841 (Coleoptera: Cicindelidae). Entomotropica 19(3): 147-152. Las barreras vivas pueden restringir la dispersi\uf3n de invertebrados depredadores en tierra agr\uedcola y dividir sus poblaciones en poblaciones locales a nivel de campo con consecuencias tanto para la recolonizaci\uf3n despu\ue9s del uso de plaguicidas como el control natural de plagas. En el estudio presente se investiga el efecto de barreras vivas sobre la dispersi\uf3n de Megacephala angustata Chevrolat 1841 en una granja en la costa de El Salvador.Trampas de ca\uedda indicaron una aversi\uf3n a los habitat sombreados,incluso a la sombra de barreras vivas,por la especie.Un estudio captura-marca-recaptura indic\uf3 que el movimiento entre potreros es poco com\ufan.Tres semanas despu\ue9s de marcar los escarabajos y a pesar de frecuentes recapturas, solamente 2 de 401 individuos se encontraron afuera de los potreros donde se les hab\uedan marcado

Combined effects of soil silicon and host plant resistance on planthoppers, blast and bacterial blight in tropical rice

Soil silicon enhances rice defenses against a range of biotic stresses. However, the magnitude of these effects can depend on the nature of the rice variety. We conducted a series of greenhouse experiments to examine the effects of silicon on planthoppers (Nilaparvata lugens [BPH] and Sogatella furcifera [WBPH]), a leafhopper (Nephotettix virescens [GLH]), blast disease (Magnaporthe grisea) and bacterial blight (Xanthomonas oryzae) in susceptible and resistant rice. We added powdered silica gel (SiO2) to paddy soil at equivalent to 0.25, 1.0, and 4.0 t ha−1. Added silicon reduced BPH nymph settling, but the effect was negligible under high nitrogen. In a choice experiment, BPH egg-laying was lower than untreated controls under all silicon treatments regardless of nitrogen or variety, whereas, in a no-choice experiment, silicon reduced egg-laying on the susceptible but not the resistant (BPH32 gene) variety. Stronger effects in choice experiments suggest that silicon mainly enhanced antixenosis defenses. We found no effects of silicon on WBPH or GLH. Silicon reduced blast damage to susceptible and resistant (Piz, Piz-5 and Pi9 genes) rice. Silicon reduced damage from a virulent strain of bacterial blight but had little effect on a less virulent strain in susceptible and resistant (Xa4, Xa7 and Xa4 + Xa7 genes) varieties. When combined with resistance, silicon had an additive effect in reducing biomass losses to plants infested with bacterial blight (resistance up to 50%; silicon 20%). We discuss how silicon-containing soil amendments can be combined with host resistance to reduce biotic stresses in rice

Direct and indirect effects of planning density, nitrogenous fertilizer and host plant resistance on rice herbivores and their natural enemies

In rice ecosystems, seeding densities can be adjusted to compensate for lower nitrogen levels that reduce GHG emissions, or to increase farm profitability. However, density-induced changes to plant anatomy could affect herbivore-rice interactions, and alter arthropod community dynamics. We conducted an experiment that varied transplanting density (low or high), nitrogenous fertilizer (0, 60 or 150 kg added ha−1) and rice variety (resistant or susceptible to phloem-feeding insects) over two rice-growing seasons. Yields per plot increased with added nitrogen, but were not affected by variety or transplanting density. Planthopper and leafhopper densities were lower on resistant rice and in high-density field plots. Nitrogen was associated with higher densities of planthoppers, but lower densities of leafhoppers per plot. High planting densities and high nitrogen also increased rodent damage. The structure of arthropod herbivore communities was largely determined by season and transplanting density. Furthermore, two abundant planthoppers (Sogatella furcifera (Horváth) and Nilaparvata lugens (Stål)) segregated to low and high-density plots, respectively. The structure of decomposer communities was determined by season and fertilizer regime; total decomposer abundance increased in high-nitrogen plots during the dry season. Predator community structure was determined by season and total prey abundance (including decomposers) with several spider species dominating in plots with high prey abundance during the wet season. Our results indicate how rice plasticity and arthropod biodiversity promote stability and resilience in rice ecosystems. We recommend that conservation biological control, which includes a reduction or elimination of insecticides, could be promoted to attain sustainable rice production systems.info:eu-repo/semantics/publishedVersio

The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015

Factors affecting the mortality of winter moth in the lower mainland of British Columbia

Populations of winter moth, Operophtera brumata (L.), were monitored at four sites in Richmond, British Columbia, between 1989 and 1992. Populations peaked in 1990 on both blueberry and birch and declined with an eventual population crash in 1992.Parasitism by Cyzenis albicans (Fall.) fluctuated between years at each site. Parasitism reached its highest levels on both birch (ca. 55%) and blueberry (ca. 35%) in 1991. Pupa predation was the most important stage specific mortality factor throughout the four years. In 1992, the year of population crash, larval mortality was high. Trends in "death of pupae due to unknown causes" were linked to larval mortality and are suggested to result mainly from poor foliage quality. An unusually early spring in 1992, may have led to the observed increases in these two mortality factors. The incidence of viral or other diseases among the populations are low. Generally, pupal predation peaked in 1990 (ca. 90%) and then declined. Pterostichus spp., Amara spp., Harpalus affinus and subsoil beetle larvae are implicated as important predators. The levels and trends in predation were similar at sites with very different assemblages and abundances of beetles. There were no differences in the abundances of beetles at each site between 1991 and 1992. However, many of the important predatory species declined in 1992. An examination of the possible interactions between C. albi cans and generalist predators is made. The increased range of pupal sizes in the soil, due to the presence of C. albi cans may be a mechanism for inducing a numerical response among generalist predators. However, simultaneous population declines at sites with low levels of C. albicans indicate that winter moth outbreak and decline in North America may be induced by a number of different factors.Science, Faculty ofZoology, Department ofGraduat

Adaptation by the Brown Planthopper to Resistant Rice: A Test of Female-Derived Virulence and the Role of Yeast-like Symbionts

The adaptation by planthoppers to feed and develop on resistant rice is a challenge for pest management in Asia. We conducted a series of manipulative experiments with the brown planthopper (Nilaparvata lugens (Stål)) on the resistant rice variety IR62 (BPH3/BPH32 genes) to assess behavioral and bionomic changes in planthoppers exhibiting virulence adaptation. We also examined the potential role of yeast-like symbionts (YLS) in virulence adaptation by assessing progeny fitness (survival × reproduction) following controlled matings between virulent males or females and avirulent males or females, and by manipulating YLS densities in progeny through heat treatment. We found virulence-adapted planthoppers developed faster, grew larger, had adults that survived for longer, had female-biased progeny, and produced more eggs than non-selected planthoppers on the resistant variety. However, feeding capacity—as revealed through honeydew composition—remained inefficient on IR62, even after 20+ generations of exposure to the resistant host. Virulence was derived from both the male and female parents; however, females contributed more than males to progeny virulence. We found that YLS are essential for normal planthopper development and densities are highest in virulent nymphs feeding on the resistant host; however, we found only weak evidence that YLS densities contributed more to virulence. Virulence against IR62 in the brown planthopper, therefore, involves a complex of traits that encompass a series of behavioral, physiological, and genetic mechanisms, some of which are determined only by the female parent

Field boundaries restrict dispersal of a tropical tiger beetle Megacephala angustata Chevrolat 1841 (Coleoptera: Cicindelidae

Las barreras vivas pueden restringir la dispersión de invertebrados depredadores en tierra agrícola y dividir sus poblaciones en poblaciones locales a nivel de campo con consecuencias tanto para la recolonización después del uso de plaguicidas como el control natural de plagas. En el estudio presente se investiga el efecto de barreras vivas sobre la dispersión de Megacephala angustata Chevrolat 1841 en una granja en la costa de El Salvador. Trampas de caída indicaron una aversión a los habitat sombreados, incluso a la sombra de barreras vivas, por la especie. Un estudio captura-marca-recaptura indicó que el movimiento entre potreros es poco común. Tres semanas después de marcar los escarabajos y a pesar de frecuentes recapturas, solamente 2 de 401 individuos se encontraron afuera de los potreros donde se les habían marcado

Geographic and Research Center Origins of Rice Resistance to Asian Planthoppers and Leafhoppers: Implications for Rice Breeding and Gene Deployment

This study examines aspects of virulence to resistant rice varieties among planthoppers and leafhoppers. Using a series of resistant varieties, brown planthopper, Nilaparvata lugens, virulence was assessed in seedlings and early-tillering plants at seven research centers in South and East Asia. Virulence of the whitebacked planthopper, Sogatella furcifera, in Taiwan and the Philippines was also assessed. Phylogenetic analysis of the varieties using single-nucleotide polymorphisms (SNPs) indicated a clade of highly resistant varieties from South Asia with two further South Asian clades of moderate resistance. Greenhouse bioassays indicated that planthoppers can develop virulence against multiple resistance genes including genes introgressed from wild rice species. Nilaparvata lugens populations from Punjab (India) and the Mekong Delta (Vietnam) were highly virulent to a range of key resistance donors irrespective of variety origin. Sogatella furcifera populations were less virulent to donors than N. lugens; however, several genes for resistance to S. furcifera are now ineffective in East Asia. A clade of International Rice Research Institute (IRRI)-bred varieties and breeding lines, without identified leafhopper-resistance genes, were highly resistant to the green leafhopper, Nephotettix virescens. Routine phenotyping during breeding programs likely maintains high levels of quantitative resistance to leafhoppers. We discuss these results in the light of breeding and deploying resistant rice in Asia

Predatory Hypogaeic Beetles are Attracted to Buried Winter Moth (Lepidoptera: Geometridae) Pupae: Evidence Using a New Trap Design

Horgan, Finbarr G. (2005): Predatory Hypogaeic Beetles are Attracted to Buried Winter Moth (Lepidoptera: Geometridae) Pupae: Evidence Using a New Trap Design. The Coleopterists Bulletin 59 (1): 41-46, DOI: 10.1649/682, URL: http://dx.doi.org/10.1649/68