Habitat temporal complementation: How do beneficial ground beetles survive in a transient mosaic?

Managing agricultural landscapes to enhance biological control requires an understanding of the spatio-temporal dynamics of beneficial arthropod populations. In agricultural landscapes, functional heterogeneity results from both the spatial pattern of landscape elements and their rapidly changing of habitat suitability. This suitability dynamics results first from the within-year dynamics of vegetation growth and crop management practices, and second from the year-to-year dynamics of crop rotations. We investigated the impacts of cropped habitat dynamics on population recruitment, distribution and movements of a beneficial predatory carabid beetle (Pterostichus melanarius). Our hypothesis is that populations are sustained by the beetles mobility that enables them to exploit the temporal complementarity of different adjacent crops and boundaries. The study was conducted in a mosaic of five adjacent fields of cereals and maize (total area 30 ha) in Western France. The mosaic was surrounded by roads isolating the population. Three types of sampling were done weekly from May to September 2009: 1) the field productivity in terms of post-emerged adults with enclosed emergence arenas; 2) the overall activity-density of carabid beetles in open pitfall-traps and 3) the exchanges between fields and their field boundaries and adjacent fields, with directional barrier traps

Habitat temporal complementation: How do beneficial ground beetles survive in a transient mosaic?

Managing agricultural landscapes to enhance biological control requires an understanding of the spatio-temporal dynamics of beneficial arthropod populations. In agricultural landscapes, functional heterogeneity results from both the spatial pattern of landscape elements and their rapidly changing of habitat suitability. This suitability dynamics results first from the within-year dynamics of vegetation growth and crop management practices, and second from the year-to-year dynamics of crop rotations. We investigated the impacts of cropped habitat dynamics on population recruitment, distribution and movements of a beneficial predatory carabid beetle (Pterostichus melanarius). Our hypothesis is that populations are sustained by the beetles mobility that enables them to exploit the temporal complementarity of different adjacent crops and boundaries. The study was conducted in a mosaic of five adjacent fields of cereals and maize (total area 30 ha) in Western France. The mosaic was surrounded by roads isolating the population. Three types of sampling were done weekly from May to September 2009: 1) the field productivity in terms of post-emerged adults with enclosed emergence arenas; 2) the overall activity-density of carabid beetles in open pitfall-traps and 3) the exchanges between fields and their field boundaries and adjacent fields, with directional barrier traps

Intra-annual heterogeneity of the cultivated mosaic: impact on carabid beetle populations

Spatio-temporal heterogeneity is recognised as a key factor for biodiversity. In agricultural landscapes, landscape heterogeneity is mostly described by the amount of semi-natural elements. In addition, the heterogeneity of cover types in the cultivated matrix might also influence biodiversity (Fahrig et al. 2011). Within a year, this matrix is highly heterogeneous in space and time, due to the diversity of crop covers, to crop phenology and cultural practices. Thus, for species that use crops during their life cycle, the cultivated matrix can be viewed as a mosaic of asynchronous habitats with fast-changing suitability, which is likely to affect species distribution and survival (Vasseur et al. 2008). In this study, we tested whether intra-annual heterogeneity of the cultivated mosaic affects population distribution and dynamics of a beneficial carabid species (Pterostichus melanarius). We hypothesize that distribution of carabid populations is driven in space and time by seasonal changes in habitat suitability in crops, and by insect movements from unsuitable to suitable crops during the season. The study was conducted in a 30ha mosaic of five to six adjacent crop fields (winter cereals, maize) and their boundaries in Western France. Winter cereals and maize exhibit dense vegetation cover at different periods (May-July and July-September respectively) and were supposed to have asynchronous suitability for carabid beetles. From May to September 2009 and 2010, trapping was used to describe: 1) densities of post-emerged adults in crop fields (enclosed emergence arenas), 2) carabid activity-density in crop fields and field boundaries (open pitfall traps) and 3) carabid movements between adjacent crop fields, and between crop fields and their boundaries (directional barrier traps). In the early season (May-July), carabid activity-density was higher in cereals than in maize fields. This was partly explained by lower densities of emergent adults in maize fields due to destructive effects of spring soil tillage on larvae and pupae in maize. On the other hand, suitable vegetation cover and microclimatic conditions in cereals might also have result in higher carabid activity-density. During this period, carabid beetles moved preferentially from maize fields with bare soil, toward cereal fields with dense vegetation cover. Later in the season, cereal harvest and vegetation growth in maize were followed by a drastic increase in carabid activity-density in maize fields due to massive colonization of these crops by insects. The results suggest that the distribution and dynamics of carabid populations is driven by asynchronous suitability of cereals and maize fields, which act as complementary habitats during the season. The spatio-temporal heterogeneity of the cultivated mosaic might therefore play a crucial role for the persistence of beneficial carabid beetles

Intra-annual heterogeneity of the cultivated mosaic: impact on carabid beetle populations

 Spatio-temporal heterogeneity is recognised as a key factor for biodiversity. In agricultural landscapes, landscape heterogeneity is mostly described by the amount of semi-natural elements. In addition, the heterogeneity of cover types in the cultivated matrix might also influence biodiversity (Fahrig et al. 2011). Within a year, this matrix is highly heterogeneous in space and time, due to the diversity of crop covers, to crop phenology and cultural practices. Thus, for species that use crops during their life cycle, the cultivated matrix can be viewed as a mosaic of asynchronous habitats with fast-changing suitability, which is likely to affect species distribution and survival (Vasseur et al. 2008). In this study, we tested whether intra-annual heterogeneity of the cultivated mosaic affects population distribution and dynamics of a beneficial carabid species (Pterostichus melanarius). We hypothesize that distribution of carabid populations is driven in space and time by seasonal changes in habitat suitability in crops, and by insect movements from unsuitable to suitable crops during the season. The study was conducted in a 30ha mosaic of five to six adjacent crop fields (winter cereals, maize) and their boundaries in Western France. Winter cereals and maize exhibit dense vegetation cover at different periods (May-July and July-September respectively) and were supposed to have asynchronous suitability for carabid beetles. From May to September 2009 and 2010, trapping was used to describe: 1) densities of post-emerged adults in crop fields (enclosed emergence arenas), 2) carabid activity-density in crop fields and field boundaries (open pitfall traps) and 3) carabid movements between adjacent crop fields, and between crop fields and their boundaries (directional barrier traps). In the early season (May-July), carabid activity-density was higher in cereals than in maize fields. This was partly explained by lower densities of emergent adults in maize fields due to destructive effects of spring soil tillage on larvae and pupae in maize. On the other hand, suitable vegetation cover and microclimatic conditions in cereals might also have result in higher carabid activity-density. During this period, carabid beetles moved preferentially from maize fields with bare soil, toward cereal fields with dense vegetation cover. Later in the season, cereal harvest and vegetation growth in maize were followed by a drastic increase in carabid activity-density in maize fields due to massive colonization of these crops by insects. The results suggest that the distribution and dynamics of carabid populations is driven by asynchronous suitability of cereals and maize fields, which act as complementary habitats during the season. The spatio-temporal heterogeneity of the cultivated mosaic might therefore play a crucial role for the persistence of beneficial carabid beetles

Bees, honey and pollen as sentinels for lead environmental contamination.

International audienceThree beehive matrices, sampled in eighteen apiaries from West France, were analysed for the presence of lead (Pb). Samples were collected during four different periods in both 2008 and 2009. Honey was the matrix the least contaminated by Pb (min = 0.004 μg g(-1); max = 0.378 μg g(-1); mean = 0.047 μg g(-1); sd = 0.057). The contamination of bees (min = 0.001 μg g(-1); max = 1.869 μg g(-1); mean = 0.223 μg g(-1); sd = 0.217) and pollen (min = 0.004 μg g(-1); max = 0.798 μg g(-1); mean = 0.240 μg g(-1); sd = 0.200) showed similar levels and temporal variations but bees seemed to be more sensitive bringing out the peaks of Pb contamination. Apiaries in urban and hedgerow landscapes appeared more contaminated than apiaries in cultivated and island landscapes. Sampling period had a significant effect on Pb contamination with higher Pb concentrations determined in dry seasons

Polycyclic aromatic hydrocarbons: bees, honey and pollen as sentinels for environmental chemical contaminants.

International audienceThree beehive matrices, sampled in six different apiaries from West France, were analyzed for the presence of four polycyclic aromatic hydrocarbons (PAH4: benzo[a]pyrene, benzo[a]anthracene, benzo[b]fluoranthene and chrysene). Samples were collected during four different periods in both 2008 and 2009. Honey samples showed the lowest levels of PAH4 contamination (min=0.03 μg kg(-1); max=5.80 μg kg(-1); mean=0.82 μg kg(-1); Sd=1.17). Bee samples exhibited higher levels of PAH4 contamination (min=0.32 μg kg(-1); max=73.83 μg kg(-1); mean=7.03 μg kg(-1); Sd=17.83) with a great dispersion of the concentrations due to four main events of high concentrations. Pollen samples showed only one major episode with the highest PAH4 concentration found (min=0.33 μg kg(-1); max=129.41 μg kg(-1); mean=7.10 μg kg(-1); Sd=22.28). The PAH4 concentrations found were significantly influenced by the landscape context for all beehive samples

Correlating the pollens gathered by Apis mellifera with the landscape features in western France

Honey bee health depends on various factors, including the availability of food resources and chronic exposure to toxins in the foraging area.These parameters can be evaluated using indicators based on either pollen gathered to the hive or landscape features of the foraging area, including the structure, land use, or density of such specific landscape elements as hedgerows.This study examines the correlation between the diversity of pollens gathered and the landscape features in a 3-km radius using Geographic Information System technology. Palynological analyses were performed on pollen pellets collected from sixteen apiaries in western France during one year. Richness, diversity and similarity indices were calculated for land-cover features and palynological data and then compared. The land-cover analyses permitted the identification of three different landscape contexts (hedgerow, cultivated, and urban landscapes). Although the palynological profiles were highly diverse, some taxa were conserved between hives. The flower richness was greater in the apiaries from urban landscapes than in apiaries from rural landscapes, regardless of the dominant land-cover.The statistical analysis did not associate a specific flora with a specific landscape. However, it was possible to distinguish the pollen gathered by bees in urban landscapes and from pollen collected in rural area

Reprint of: Genetic parameters of in-vivo prediction of carcass, head and fillet yields by internal ultrasound and 2D external imagery in large rainbow trout [i](Oncorhynchus mykiss)[/i]

Voir aussi : Pierrick Haffray, Jérome Bugeon, Quentin Rivard, Benjamin Quittet, Sophie Puyo, Jean Michel Allamelou, Marc Vandeputte, Mathilde Dupont-Nivet. 2013. Genetic parameters of in-vivo prediction of carcass, head and fillet yields by internal ultrasound and 2D external imagery in large rainbow trout (Oncorhynchus mykiss). Aquaculture (410–411), 236-244Selection to improve processing yields relies on sib selection, in which live candidates are ranked according to their family breeding value. This approach limits genetic progress, as it only exploits genetic variability between families and not within them. Indirect criteria measured on live candidates could overcome this limitation. The present study (1) proposes a procedure to identify indirect criteria to predict processing yields in rainbow trout (head, carcass and fillet yields), (2) estimates genetic parameters of these indirect criteria, and (3) predicts relative genetic gains in processing yields using full-sib selection or indirect individual selection on those indirect criteria. DNA-pedigreed all-female rainbow trout Oncorhynchus mykiss (n = 2029, 1631.0 ± 355.6 g) from 600 families produced from 100 sires and 60 dams were characterized by external and internal non-lethal morphological measures using digital pictures and real time ultrasound tomography. Nineteen landmarks were recorded on the digital pictures to define the outline of the body, head and lateral line. Their coordinates were used to calculate different lengths, heights and areas. Five different internal thicknesses were measured by ultrasound tomography. In the first phase of this study, processing yields were predicted using multiple linear regressions including both external and internal morphometric variables. In a second phase, the heritability of the predicted values and their genetic correlations with real processing yields were estimated using animal models. Predicted yields exhibited intermediate heritabilities (0.25–0.28) that were half the value of heritabilities for real processing yields (0.47–0.55), but had high genetic correlations with these real yields (0.87–0.90). The relative efficiency of indirect selection (IS) on these indirect criteria was compared to theoretical mass selection (MS) or sib selection (FS) with different family sizes (10 or 100) and two different selection pressures (10% or 40%). At the same selection pressure (10%, with 100 sibs per family %), full-sib selection created genetic progress 49.6% to 60.5% higher than indirect selection according to the processing yield targeted. However, when sib-selection pressure was limited to a more realistic between family selection pressure (40% and 10 sibs per family), indirect selection with 10% selection pressure was 21.9% to 32.7% more efficient than sib selection

Widespread occurrence of chemical residues in beehive matrices from apiaries located in different landscapes of Western France.

The honey bee, Apis mellifera, is frequently used as a sentinel to monitor environmental pollution. In parallel, general weakening and unprecedented colony losses have been reported in Europe and the USA, and many factors are suspected to play a central role in these problems, including infection by pathogens, nutritional stress and pesticide poisoning. Honey bee, honey and pollen samples collected from eighteen apiaries of western France from four different landscape contexts during four different periods in 2008 and in 2009 were analyzed to evaluate the presence of pesticides and veterinary drug residues.A multi-residue analysis of 80 compounds was performed using a modified QuEChERS method, followed by GC-ToF and LC-MS/MS. The analysis revealed that 95.7%, 72.3% and 58.6% of the honey, honey bee and pollen samples, respectively, were contaminated by at least one compound. The frequency of detection was higher in the honey samples (n = 28) than in the pollen (n = 23) or honey bee (n = 20) samples, but the highest concentrations were found in pollen. Although most compounds were rarely found, some of the contaminants reached high concentrations that might lead to adverse effects on bee health. The three most frequent residues were the widely used fungicide carbendazim and two acaricides, amitraz and coumaphos, that are used by beekeepers to control Varroa destructor. Apiaries in rural-cultivated landscapes were more contaminated than those in other landscape contexts, but the differences were not significant. The contamination of the different matrices was shown to be higher in early spring than in all other periods.Honey bees, honeys and pollens are appropriate sentinels for monitoring pesticide and veterinary drug environmental pollution. This study revealed the widespread occurrence of multiple residues in beehive matrices and suggests a potential issue with the effects of these residues alone or in combination on honey bee health

Genetic parameters of in-vivo prediction of carcass, head and fillet yields by internal ultrasound and 2D external imagery in large rainbow trout (Oncorhynchus mykiss)

Selection to improve processing yields relies on sib selection, in which live candidates are ranked according to their family breeding value. This approach limits genetic progress, as it only exploits genetic variability between families and not within them. Indirect criteria measured on live candidates could overcome this limitation. The present study (1) proposes a procedure to identify indirect criteria to predict processing yields in rainbow trout (head, carcass and fillet yields), (2) estimates genetic parameters of these indirect criteria, and (3) predicts relative genetic gains in processing yields using full-sib selection or indirect individual selection on those indirect criteria. DNA-pedigreed all-female rainbow trout Oncorhynchus mykiss (n = 2029, 1631.0 +/- 355.6 g) from 600 families produced from 100 sires and 60 dams were characterized by external and internal non-lethal morphological measures using digital pictures and real time ultrasound tomography. Nineteen landmarks were recorded on the digital pictures to define the outline of the body, head and lateral line. Their coordinates were used to calculate different lengths, heights and areas. Five different internal thicknesses were measured by ultrasound tomography. In the first phase of this study, processing yields were predicted using multiple linear regressions including both external and internal morphometric variables. In a second phase, the heritability of the predicted values and their genetic correlations with real processing yields were estimated using animal models. Predicted yields exhibited intermediate heritabilities (0.25-0.28) that were half the value of heritabilities for real processing yields (0.47-0.55), but had high genetic correlations with these real yields (0.87-0.90). The relative efficiency of indirect selection (IS) on these indirect criteria was compared to theoretical mass selection (MS) or sib selection (FS) with different family sizes (10 or 100) and two different selection pressures (10% or 40%). At the same selection pressure (10%, with 100 sibs per family %), full-sib selection created genetic progress 49.6% to 60.5% higher than indirect selection according to the processing yield targeted. However, when sib-selection pressure was limited to a more realistic between family selection pressure (40% and 10 sibs per family), indirect selection with 10% selection pressure was 21.9% to 32.7% more efficient than sib selection