Influence of distance from adjacent forest fragments on aphids (Hemiptera: Aphididae) parasitoidism in wheat fields in Parana State, Brazil

In agricultural landscapes, non-crop habitats, such as forest fragments, may not only play an important role for natural enemies, but may also favor some pests. However, there is a lack of studies in Neotropical regions about these interactions. Thus, the aim of this study was to investigate aphid parasitoidism at two distances (25 m and 525 m) from edges of forest fragments adjacent to wheat crops. This research was carried out in four wheat fields in the north of the Parana state, Brazil, during the planting season of 2009. In total, 8,392 aphids were counted, representing two species. There were 589 total aphid-parasitized (“mummies”), represented by six species. In all four areas, aphid abundance and parasitoidism showed no clear relationship to distance from forest fragments (25 m and 525 m). In addition, inverse density dependence between aphids and parasitoidism was observed. In summary, this study does not support the hypothesis of higher parasitoidism of aphids near edges of forest fragments. However, this is the first study in the Neotropical region and more research must be done to better understand this tritrophic interaction.

Download Full-text

Regulation of nematode fecundity in the ring-necked pheasant (Phasianus colchicus): not just density dependence

Parasitology ◽

10.1017/s0031182098003886 ◽

1999 ◽

Vol 118 (4) ◽

pp. 417-423 ◽

Cited By ~ 49

Author(s):

D. M. TOMPKINS ◽

P. J. HUDSON

Keyword(s):

Density Dependence ◽

Good Predictor ◽

Phasianus Colchicus ◽

Common Pattern ◽

Infection Experiment ◽

Stunted Growth ◽

Heterakis Gallinarum ◽

Parasite Intensity ◽

Inverse Density Dependence ◽

The Common

Patterns of nematode fecundity were investigated for infections of the caecal worm Heterakis gallinarum in the ring-necked pheasant (Phasianus colchicus). Worm length was a good predictor of parasite fecundity. After controlling for worm length no other factors, including parasite intensity, were related to worm fecundity. Density dependence in worm size was detected in natural infections at parasite intensities above a threshold of 96 worms (worm size decreased with increasing parasite intensity). However, below this threshold, worm size actually decreased with decreasing parasite intensity (inverse density dependence). The interaction between density dependence and inverse density dependence in regulating the development and subsequent fecundity of H. gallinarum worms in ring-necked pheasants was demonstrated in an infection experiment. Density dependence was observed in the stunted growth of worms in heavily infected hosts, relative to worms in lightly infected hosts. Inverse density dependence in worm size was the common pattern across hosts by the end of the experiment, when parasite intensities were below the density dependence threshold. This is the first study to document both density dependence and inverse density dependence in parasite fecundity in the same host–helminth system.

Download Full-text

Natural enemies depend on remnant habitat size in agricultural landscapes

Journal of Forestry Research ◽

10.1007/s11676-015-0043-y ◽

2015 ◽

Vol 26 (2) ◽

pp. 469-477 ◽

Cited By ~ 5

Author(s):

Mainara Xavier Jordani ◽

Érica Hasui ◽

Vinícius Xavier da Silva

Keyword(s):

Natural Enemies ◽

Agricultural Landscapes ◽

Habitat Size ◽

Remnant Habitat

Download Full-text

Dynamics and Management of Rising Outbreak Spruce Budworm Populations

Forests ◽

10.3390/f10090748 ◽

2019 ◽

Vol 10 (9) ◽

pp. 748 ◽

Cited By ~ 10

Author(s):

Jacques Régnière ◽

Barry Cooke ◽

Ariane Béchard ◽

Alain Dupont ◽

Pierre Therrien

Keyword(s):

Population Growth ◽

Density Dependence ◽

Natural Enemies ◽

Choristoneura Fumiferana ◽

Regional Scale ◽

Adult Emergence ◽

Spruce Budworm ◽

Migration Activity ◽

Larval Stages ◽

The Impact

Management of spruce budworm, Choristoneura fumiferana (Clem.), outbreak spread requires understanding the demographic processes occurring in low, but rising populations. For the first time, detailed observations were made in the early stages of outbreak development. We sampled populations over a three-year period in both treated and untreated populations in the Lower St-Lawrence region of Quebec, Canada, and measured the density-dependence of survival and population growth rates, and the impact of natural enemies and insecticides. Insecticides tested were Bacillus thuringiensis (Berliner 1915) and tebufenozide. We recorded strong density-dependence of survival between early larval stages and adult emergence, explained largely by the variation of natural enemy impacts and overcrowding. We also observed inverse density-dependence of apparent fecundity: net immigration into lower-density populations and net emigration from the higher, linked to a threshold of ~25% defoliation. Because of high migration rates, none of the 2013 treatments reduced egg populations at the end of summer. However lower migration activity in 2014 allowed population growth to be reduced in treated plots. This evidence lends support to the conclusion that, for a budworm population to increase to outbreak density, it must be elevated via external perturbations, such as immigration, above a threshold density of ~4 larvae per branch tip (L4). Once a population has increased beyond this threshold, it can continue growing and itself become a source of further spread by moth migration. These findings imply that populations can be brought down by insecticide applications to a density where mortality from natural enemies can keep the reduced population in check, barring subsequent immigration. While we recognize that other factors may occasionally cause a population to exceed the Allee threshold and reach outbreak level, the preponderance of immigration implies that if all potential sources of significant numbers of moths are reduced on a regional scale by insecticide applications, a widespread outbreak can be prevented, stopped or slowed down by reducing the supply of migrating moths.

Download Full-text

The potential of different semi-natural habitats to sustain pollinators and natural enemies in European agricultural landscapes

Agriculture Ecosystems & Environment ◽

10.1016/j.agee.2019.04.009 ◽

2019 ◽

Vol 279 ◽

pp. 43-52 ◽

Cited By ~ 8

Author(s):

Agustín M. Bartual ◽

Louis Sutter ◽

Gionata Bocci ◽

Anna-Camilla Moonen ◽

James Cresswell ◽

...

Keyword(s):

Natural Enemies ◽

Agricultural Landscapes ◽

Natural Habitats

Download Full-text

Morpho (Morpho) helenor (Cramer) (Lepidoptera, Nymphalidae, Morphinae) in Bolivia: Geographical distribution and ecological plasticity, with a description of a new subspecies

Zootaxa ◽

10.11646/zootaxa.3130.1.2 ◽

2011 ◽

Vol 3130 (1) ◽

pp. 30 ◽

Cited By ~ 2

Author(s):

YUVINKA GARECA ◽

PATRICK BLANDIN

Keyword(s):

Geographical Distribution ◽

Field Studies ◽

Neotropical Region ◽

New Subspecies ◽

Transition Zones ◽

Ecological Plasticity ◽

North East ◽

The North ◽

Intermediate Phenotypes ◽

Wide Range

The geographical distribution of Morpho helenor (Cramer) in Bolivia is mapped from the study of specimens preserved in Bolivian and foreign collections, and from recent field studies in various ecoregions. One subspecies, M. h. theodorus Fruhstorfer, inhabits Amazonian moist forests in the western and northern parts of the country. Another subspecies, M. h. coelestis Butler, is common in moist cloud forests (Bolivian Yungas), but also occurs to the North and North-East. We describe a new subspecies, M. h. prometa ssp. nov., from Southern Andean Yungas. Transition zones between theodorus and coelestis are highlighted, where specimens exhibiting intermediate phenotypes were collected. The pattern of geographic transition from M. h. coelestis to M. h. prometa needs to be documented. M. h. prometa inhabits sub-humid, semideciduous forests, whereas M. h. theodorus and M. h. coelestis live in rainforests. M. h. coelestis populations are found from less than 100 m to more than 1600 m a.s.l.; M. h. theodorus has been collected at more than 1000 m a.s.l.; and M. h. prometa between 500 m and 1400 m a.s.l.. Therefore, Bolivian M. helenor populations are distributed throughout a wide range of ecological contexts: we discuss the habitat plasticity of the species in light of available knowledge of its geographical distribution and habitats in the Neotropical Region.

Download Full-text

Population trend status of Ontario’s forest birds

The Forestry Chronicle ◽

10.5558/tfc85184-2 ◽

2009 ◽

Vol 85 (2) ◽

pp. 184-201 ◽

Cited By ~ 16

Author(s):

Peter J Blancher ◽

R. Dean Phoenix ◽

Debra S Badzinski ◽

Michael D Cadman ◽

Tara L Crewe ◽

...

Keyword(s):

Agricultural Landscapes ◽

Forest Birds ◽

Population Trend ◽

Individual Species ◽

Population Declines ◽

Breeding Bird ◽

The North ◽

Aerial Insectivore ◽

Monitoring Reliability ◽

Wide Scale

Recent population trends of Ontario’s forest birds were assessed by integrating results across 8 bird surveys to provide an estimate of trend status for all of Ontario, and for 2 forested regions of Ontario separately. Surveys with mid- and longterm trends were relied on most extensively in this assessment. Comparison of the first and second Breeding Bird Atlases was especially important for estimating trends in northern forests, but overall reliability of status assessments in the north was considered poor due to limited coverage and significant potential for bias. Trends of most forest birds were stable or positive at the Ontario-wide scale, with trends at least as positive as forest birds elsewhere in North America, and showing more positive trends overall than birds of agricultural landscapes. Nevertheless, individual species trends ranged from large declines to large increases, and several forest birds have been added to Species at Risk lists largely because of population declines. There were few differences in trend status among forest birds grouped by habitat association or migratory guild, although all 5 aerial insectivore species have declined. Better monitoring coverage of the boreal will be needed if improved reliability of trends is desired in the near future. Key words: Ontario, forest birds, boreal forest, population trend, bird surveys, monitoring reliability

Download Full-text

Ichneumonids (Hymenoptera) and Tachinid Flies (Diptera) Associated to Leptidopterans in Soybean Crops

Journal of Agricultural Science ◽

10.5539/jas.v10n7p167 ◽

2018 ◽

Vol 10 (7) ◽

pp. 167 ◽

Cited By ~ 1

Author(s):

Angélica Massarolli ◽

Ana Regina Lucena Hoffmann ◽

Bruna Magda Favetti ◽

Alessandra Regina Butnariu

Keyword(s):

Biological Control ◽

New Species ◽

Natural Enemies ◽

Management Strategies ◽

Neotropical Region ◽

The State ◽

Pest Species ◽

Mato Grosso ◽

Control Programs ◽

Lepidopteran Pest

Studies on natural enemies are important to find new species and to develop management strategies to preserve them to help control pests in biological control programs. For the state of Mato Grosso, Brazil, which comprises the Amazon, Cerrado, and Pantanal biomes, few studies have been conducted on the diversity of these parasitoids, possible endemic and/or new species, as well as their potential as natural enemies. Thus, the present study was aimed at describing the diversity of parasitoids of the families Ichneumonidae (Hymenoptera) and Tachinidae (Diptera) associated with pest lepidopterans in soybean crops. Weekly sampling of pest lepidopterans was carried out during four soybean seasons (2009/2010, 2010/2011, 2011/2012 and 2012/2013). Parasitoid larvae were observed in the main lepidopteran pest species of soybean during the four soybean seasons. Three genera of the Ichneumonidae family, belonging to the genera Microcharops Roman, Ophionellus Westwood, and Podogaster Brullé. Six genera of the Tachinidae family occur in the state of Mato Grosso in soybean fields. The following genera were recorded: Archytas spp. Jaennicke, Phorocera spp. Robineau-Desvoidy, Gymnocarcelia spp. Townsend, Lespesia spp. Robineau-Desvoidy, Eucelatoria spp. Townsend, Chetogena spp. Rondani. These parasitoids were found parasitizing caterpillars of the Noctuidae (Lepidoptera), in species that had not yet been reported as hosts for the Neotropical region. Further studies are needed on the beneficial entomofauna and their preservation in agricultural environments.

Download Full-text