Search results for "BASAL"

Intraguild interactions between two egg parasitoids exploring host patches

2010

Intraguild interactions between two egg parasitoids, Trissolcus basalis (Hymenoptera: Scelionidae) and Ooencyrtus telenomicida (Hymenoptera: Encyrtidae), exploring egg masses of the Southern Green Stink Bug (SGSB) Nezara viridula (Heteroptera: Pentatomidae), were investigated in laboratory conditions by single, simultaneous and sequential host attack experiments. Mortality of N. viridula eggs was higher in simultaneous and sequential releases compared to single species releases. In simultaneous host exploitations, T. basalis females displayed an aggressive behavior against O. telenomicida females. The outcome of multiparasitism showed that interspecific larval competition was dominated by O…

Host chemical footprints induce host sex discrimination ability in egg parasitoids

2013

Trissolcus egg parasitoids, when perceiving the chemical footprints left on a substrate by pentatomid host bugs, adopt a motivated searching behaviour characterized by longer searching time on patches were signals are present. Once in contact with host chemical footprints, Trissolcus wasps search longer on traces left by associated hosts rather than non-associated species, and, in the former case, they search longer on traces left by females than males. Based on these evidences, we hypothesized that only associated hosts induce the ability to discriminate host sex in wasps. To test this hypothesis we investigated the ability of Trissolcus basalis, T. brochymenae, and Trissolcus sp. to disti…

The response of Trissolcus basalis to footprint contact kairomones from Nezara viridula females is mediated by leaf epicuticular waxes.

2009

Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula's cuticular hydrocarbons (CHC) and furthermore that the wasp's ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane (nC(19)). In this study, the effect of epicuticular waxes of leaves…

Attuning to a changing ocean

2020

The ocean is a lifeline for human existence, but current practices risk severely undermining ocean sustainability. Present and future social−ecological challenges necessitate the maintenance and development of knowledge and action by stimulating collaboration among scientists and between science, policy, and practice. Here we explore not only how such collaborations have developed in the Nordic countries and adjacent seas but also how knowledge from these regions contributes to an understanding of how to obtain a sustainable ocean. Our collective experience may be summarized in three points: 1) In the absence of long-term observations, decision-making is subject to high risk arising from na…

Time at risk: individual spatial behaviour drives fitness and marine protected area effectiveness

2021

The effectiveness of Marine Protected Areas (MPAs) depends on the mobility of the populations that are the target of protection, with sedentary species likely to spend more time under protection even within small MPAs. However, little is understood about how individual variation in mobility may influence the risk of crossing an MPA border, as well as the fitness costs associated with being exposed to spillover fisheries. Here we investigated the repeatability of spatial behaviour, its role in determining the probability of being at risk (i.e. exposed to the fishery) and the fitness consequences for the individuals. We acoustically tracked the movements and fate of 282 individuals of three f…

Spatial patterns of pathogen prevalence in questing Ixodes ricinus nymphs in southern Scandinavia

2020

Salmon lice (Lepeophtheirus salmonis) in the stomach contents of lumpfish (Cyclopterus lumpus) sampled from Norwegian fish farms: Relationship betwee…

2023

Cleaner fish are commonly used as a control measure against salmon lice infestations in salmonid farms. Lumpfish (Cyclopterus lumpus) is the most common cleaner fish species used in Norwegian farms. However, little is known about how different operational, including environmental, conditions affect the salmon lice grazing efficacy by lumpfish. In this paper, we analyse salmon lice (Lepeophtheirus salmonis) in the stomach contents of a large sample of more than 20,000 lumpfish from 80 different Norwegian farms. We investigate the proportion of lumpfish with salmon lice and the mean number of salmon lice in the stomach contents of the lumpfish. We further explore how the salmon lice contents …

Attraction of cod Gadus morhua from coastal spawning grounds to salmon farms

2022

Wild fish aggregate at aquaculture net-pens, but the underlying mechanisms are not fully understood. This study examined how salmon farms attract coastal Atlantic cod Gadus morhua from their inshore spawning grounds. Acoustic receivers were deployed at 5 known cod spawning grounds and 6 salmon Salmo salar farms located at varying distances from these grounds in a mid-Norway study site. Cod were caught at each spawning ground annually from 2017-2019, fitted with acoustic transmitters and released (n = 535). A total of 289 tagged cod (54%) were detected at the salmon farms, with more cod detected at farms closest to the focal spawning grounds and at operational farms. The latter result is lik…

Genomic analysis of anadromous brown trout (Salmo trutta) reveals new insights into connectivity patterns and population divergence

2018

Master's thesis Aquatic Ecology BIO500 - University of Agder 2018 A large body of studies on brown trout genetics currently exists. However, fewer of these studies have been conducted on anadromous brown trout (sea trout) and have been limited to only a few genetic markers like allozymes, mtDNA or microsatellites. Here we analyzed population structure and connectivity in sea trout applying a modern genomic approach, analyzing 503 single nucleotide polymorphic variants (SNP’s) by next generation sequencing. We studied four streams along the Skagerrak coast and found an overall significant population structure (FST = 0.0161; P<0.01) which further seemed to constitute of three genetically dist…

Kopepoder langs Skagerrakkysten - En oversikt basert på morfologisk og molekylærgenetisk identifisering

2018

Masteroppgave akvatisk økologi BIO500 - Universitetet i Agder 2018 Konfidensiell til / confidential until 01.07.2023