Catch me if you can: novel foraging behavior of an egg parasitoid,Gryon gonikopalense,against the stinkbug pest,Bagrada hilaris

Journal of Pest Science - Host detection and parasitism by egg parasitoids involve host chemical recognition, spatial overlapping, and the ability to overcome physical barriers. Within the context...     

Decimation of a population of the endangered species Scutellastra mexicana (Broderip and Sowerby, 1829) (Mollusca,Gastropoda) in the Marías Island (Eastern Ocean Pacific) Biosphere Reserve

1. Scutellastra mexicana is the largest known patellid limpet species and probably is one of the most endangered marine invertebrates.
2. The species was once distributed along the American Pacific coast from Mexico to Peru, but their large size (up to 35 cm long) and easy accessibility (shallow sublittoral), made it very vulnerable to human collection and now is extinct on most of the mainland Mexican coast.
3. In August 2017, a large population of this species was found on María Cleofas island, off the coast of west‐central Mexico (Marías Archipelago, Pacific Ocean). This constitutes the only report of a population of this species since 1988.
4. A total of 808 adult individuals of up to 26 cm in length and 20 cm in width were estimated, together with the presence of juveniles, suggesting that it is a self‐sustaining population. The population was monitored in August 2017 and August 2018.
5. Although the species is under the category ‘Special Protection’ in the General Mexican Wild Law, and that María Cleofas island is a Biosphere Reserve, fishermen that operate with impunity in the area decimated the limpet population within a year of its discovery. Abundance in the shallowest area decreased significantly from 120 individuals per transect (65 m long and 2.75 m wide) in August 2017 to 48 individuals in August 2018, and the estimated adult population decreased from 808 to 304 limpets.
6. Neither passive national conservation policies nor local practices have reduced current threats to biodiversity and resource depletion in Marías Archipelago. Protected areas like this are ‘paper parks’—parks in name only—because there is no active conservation strategy or protection of marine species.

     

Prioritizing marine invasive alien species in the European Union through horizon scanning

1. The disproportionately low presence of marine species in the list of invasive alien species (IAS) of Union concern of the European Union (EU) Regulation 1143/2014 does not fully acknowledge the threat they pose to the EU marine environment.
2. In this study, the first EU‐scale Horizon Scanning (HS) focusing on marine alien species was performed, aiming to deliver a ranked list of species that should be of high priority for risk assessment (Article 5 of the EU IAS Regulation).
3. Species absent from or with a limited distribution in EU marine waters were targeted. In total, 363 alien species were initially screened for HS by a panel of experts, including a broad range of taxonomic groups. Species were scored for their likelihood of arrival, establishment, spread, and impact in EU waters.
4. A consensus workshop ranked 267 species, including a subset of 26 prioritized species. These species are considered to be mainly introduced by shipping (fouling and ballast water), via the Suez Canal, and aquaculture activities. The 26 priority species were also scrutinized in terms of feasibility of their management; 18 of them were suggested for performing risk assessments on the basis of the EU IAS Regulation.
5. Since biological invasions are dynamic and connected with accelerated globalization and diversified human activities, we recommend HS to be repeated periodically to review the species already listed and assess new ones.

     

Clinical and aetiological aspects of a summer enteritic syndrome associated with the sporulating segmented filamentous bacterium 'Candidatus Arthromitus' in farmed rainbow trout, Oncorhynchus mykiss (Walbaum)

An enteritic syndrome affecting farmed rainbow trout and occurring predominantly in summer has recently been described and related to the massive accumulation of a segmented filamentous bacterium (SFB), ‘Candidatus Arthromitus’, in the digestive tract of fish. Details of the clinical manifestations, the characteristics of the bacterium and the possible aetiology of the disease are presented in this paper. No other bacterial pathogen than ‘Candidatus Arthromitus’ was characterized in trout undergoing the enteritic syndrome. From clinical and histopathological observations, a toxin or toxic product accumulation was suspected in affected trout, and could account for the massive destruction of the intestinal mucosa. However, the origin and aetiological role of the SFB could not be clearly elucidated, although most of the filaments appeared to beviable and to produce and release strings of endospores in the lumen of the gut. The organism could not be cultured in the conditions tested, shared several morphological and structural characteristics with related bacteria described in the intestinal microflora of different vertebrate species, but no attachment structure was definitively recognized. All attempts to detect similar SFB in the fish diet orin the environment of affected fish farms were unsuccessful. It is unclear whether this organism represents a normal and not previously detected inhabitant of the intestine of trout stressed after environmental perturbation, or whether it results directly from external sources of contamination.     

Cortisol,glucose and hematocrit changes during acute stress,cohort sampling,and the diel cycle in diploid and triploid brook trout (Salvelinus fontinalis Mitchill)

In this study, groups of diploid (control) and triploid brook trout were subjected to a 5 min acute handling/confinement stress. Blood samples were collected from equal numbers of diploid and triploid fish at regular predetermined intervals, beginning prior to confinement and continuing for up to 3h after confinement. These blood samples were used for the measurement of hematocrit and plasma cortisol and glucose concentrations. The effects of cohort sampling and the diel cycle on these variables were also analysed. Except for minor differences, both groups responded similarly to the acute stress, with short-term elevations in plasma cortisol and hematocrit levels, and a more sustained increase in plasma glucose levels. No significant differences were found between diploid and triploid fish in their reactions to cohort sampling. However, the act of removing an individual from a tank caused significant changes in plasma cortisol levels in cohorts remaining in that tank (p < 0.001). Significant diel effects were observed for both ploidy groups in plasma cortisol (p < 0.05) but not in plasma glucose or hematocrit. To whom correspondence should be addressed     

Modification of marine habitats by trawling activities: prognosis and solutions

Fishing affects the seabed habitat worldwide on the continental shelf. These impacts are patchily distributed according to the spatial and temporal variation in fishing effort that results from fishers' behaviour. As a consequence, the frequency and intensity of fishing disturbance varies among different habitat types. Different fishing methodologies vary in the degree to which they affect the seabed. Structurally complex habitats (e.g. seagrass meadows, biogenic reefs) and those that are relatively undisturbed by natural perturbations (e.g. deep‐water mud substrata) are more adversely affected by fishing than unconsolidated sediment habitats that occur in shallow coastal waters. These habitats also have the longest recovery trajectories in terms of the recolonization of the habitat by the associated fauna. Comparative studies of areas of the seabed that have experienced different levels of fishing activity demonstrate that chronic fishing disturbance leads to the removal of high‐biomass species that are composed mostly of emergent seabed organisms. Contrary to the belief of fishers that fishing enhances seabed production and generates food for target fish species, productivity is actually lowered as fishing intensity increases and high‐biomass species are removed from the benthic habitat. These organisms also increase the topographic complexity of the seabed which has been shown to provide shelter for juvenile fishes, reducing their vulnerability to predation. Conversely, scavengers and small‐bodied organisms, such as polychaete worms, dominate heavily fished areas. Major changes in habitat can lead to changes in the composition of the resident fish fauna. Fishing has indirect effects on habitat through the removal of predators that control bio‐engineering organisms such as algal‐grazing urchins. Fishing gear resuspend the upper layers of sedimentary seabed habitats and hence remobilize contaminants and fine particulate matter into the water column. The ecological significance of these fishing effects has not yet been determined but could have implications for eutrophication and biogeochemical cycling. Simulation results suggest that the effects of low levels of trawling disturbance will be similar to those of natural bioturbators. In contrast, high levels of trawling disturbance cause sediment systems to become unstable due to large carbon fluxes between oxic and anoxic carbon compartments. In low energy habitats, intensive trawling disturbance may destabilize benthic system chemical fluxes, which has the potential to propagate more widely through the marine ecosystem. Management regimes that aim to incorporate both fisheries and habitat conservation objectives can be achieved through the appropriate use of a number of approaches, including total and partial exclusion of towed bottom fishing gears, and seasonal and rotational closure techniques. However, the inappropriate use of closed areas may displace fishing activities into habitats that are more vulnerable to disturbance than those currently trawled by fishers. In many cases, the behaviour of fishers constrains the extent of the impact of their fishing activities. Management actions that force them to redistribute their effort may be more damaging in the longer term.     

Experimental bases for a chemical control of Coquillettidia mosquito populations

Coquillettidia mosquitoes are not efficiently controlled by the conventional chemical practices which are known to be satisfactory against the larvae of other mosquito species. A research project was undertaken to conceive a new management strategy using plants as pesticide vectors to reach the Coquillettidia aquatic larvae. Therefore, larval mortality was measured in the presence of plants treated with phloem-translocated pesticides. The herbicide glyphosate at sub-lethal concentrations induced root epidermal cell lyses in maize plantlets cultivated in aqueous media, which clearly decreased larval fixation. Therefore, such herbicide strategy might operate through disturbing the larval physiological activities depending on fixation. The dimethoate insecticide did not affect root viability but at low concentrations seemed to disturb the plant–insect interactions. Larvae showed a lower attraction for roots and a considerable decrease in the root fixation rate. These larval behavior modifications were sufficient to induce mortality, probably due to a lack of fixation on plant roots. The effectiveness of plant foliar treatment with glyphosate or dimethoate under laboratory conditions suggested that it might be the basis for an efficient control strategy for Coquillettidia larvae and mosquitoes having the same living conditions in ponds and for which fixation on macrophyte roots is an absolute requirement (e.g.Mansonia, Mimomyia).     

Pyrethroid resistance monitoring in European populations of pollen beetle (Meligethes spp.): a coordinated approach through the Insecticide Resistance Action Committee (IRAC)

BACKGROUND: Pollen beetle (Meligethes spp.) is a major pest of European oilseed rape crops. Its resistance to pyrethroid insecticides has been recorded in samples of beetles collected in Europe since at least 1999, and problems with the control of the beetle in the field have been widely reported. In 2007, a Pollen Beetle Working Group was formed through the Insecticide Resistance Action Committee (IRAC) in order to coordinate efforts for surveying pyrethroid resistance development. RESULTS: The results of the first 3 years of the pollen beetle pyrethroid susceptibility survey using a laboratory test are presented in this paper. Resistant beetle samples were collected from 20 of the 21 countries surveyed, with a general trend of increasing frequency and spread of resistant samples in European oilseed‐rape‐growing regions. CONCLUSION: Pyrethroid‐resistant beetles dominate in Western and Central Europe and are becoming established in the North and East, the main oilseed‐rape‐growing areas of Europe. The development and spread of pyrethroid‐resistant pollen beetles highlights the need for effective management strategies for oilseed rape insect pests. Copyright © 2011 Society of Chemical Industry     

Stabilization and plant uptake of N from N-labelled pea residue 16.5 years after incorporation in soil

The decline of N from ¹⁵N-labelled mature pea residues was followed in unplanted soil over 16.5 yr. Eight years after residue incorporation, 24% of the residue ¹⁵N input was still present in the soil and, after 16.5 yr, 16% of the residue ¹⁵N input remained. A double exponential model successfully described the decay of N from ¹⁵N-labelled pea residues. The total residual ¹⁵N declined with average decay constants of 1.45 yr⁻¹ for the 30 d to 1 yr period and of 0.07 yr⁻¹ for the 1-16 yr period. Sixteen years following incorporation of the residues, indicator plants growing in residues-amended soils were obtaining 1.7% of their N from residue N. This is, to our knowledge, the longest study on decay of N in soils from ¹⁵N-labelled crop residues. The current study thus provides a unique data set for our empirical understanding of N-dynamics in agricultural systems, which is a prerequisite to parameterize and validate N-simulation models.