Search results for "Parasitism"
showing 10 items of 200 documents
Intrinsic competition between two European egg parasitoids of the brown marmorated stink bug
2020
Following the accidental introduction and spread of the invasive polyphagous agricultural pest Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), the two European egg parasitoids Anastatus bifasciatus (Geoffroy) (Hymenoptera: Eupelmidae) and Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae) have been investigated for inundative biological control. Since the competititve outcome between the two generalist parasitoids is difficult to predict, intrinsic competition was investigated with a time-course development study. Both species readily oviposited in H. halys eggs containing eggs and early instar larvae of the competitor, but oviposition decreased when eggs contained late insta…
Co-evolution between ectoparasites and their insect hosts: a simulation study of a damselfly-water mite interaction
2001
Summary 1. A simulation model investigating the co-evolution of water mites infesting their aquatic insect hosts during emergence is presented. The model is based on field and experimental studies of the ectoparasitic water mite Arrenurus cuspidator and the damselfly Coenagrion puella. 2. Three scenarios were studied: (1) Only the host was allowed to evolve timing of emergence, while the timing of the parasites' infestation opportunity was held constant. (2) Both host and parasite were allowed to evolve. (3) Only the parasite's timing was allowed to evolve, while the host was constrained completely. 3. In the first two scenarios, parasite abundances decreased in the course of evolution and …
Differences in parasite community composition support ecological differentiation in a freshwater gadoid fish
2022
Several northern freshwater fishes have gone through rapid adaptive radiation after the last glacial period, resulting in new species or intraspecific morphs with distinct life histories. Parasite infections can promote adaptive radiations and spatiotemporal differences in patterns of infections can potentially reveal incipient or ongoing speciation processes. We investigated intraspecific differentiation in a freshwater gadoid fish, burbot (Lota lota), by exploring differences in parasite infections between two potential life-history morphs in Lake Konnevesi, Central-Finland, one reproducing species characteristically in shallow littoral waters in February and the other possibly in deep pr…
Reed Warbler Hosts Do Not Fine-Tune Mobbing Defenses During the Breeding Season, Even When Cuckoos Are Rare
2021
Hosts of brood parasitic cuckoos often employ mobbing attacks to defend their nests and, when mobbing is costly, hosts are predicted to adjust their mobbing to match parasitism risk. While evidence exists for fine-tuned plasticity, it remains unclear why mobbing does not track larger seasonal changes in parasitism risk. Here we test a possible explanation from parental investment theory: parents should defend their current brood more intensively as the opportunity to replace it declines (re-nesting potential), and therefore “counteract” any apparent seasonal decline to match parasitism risk. We take advantage of mobbing experiments conducted at two sites where reed warblers (Acrocephalus sc…
The Ecology of Hyperparasitoids.
2021
Hyperparasitoids are some of the most diverse members of insect food webs. True hyperparasitoids parasitize the larvae of other parasitoids, reaching these larvae with their ovipositor through the herbivore that hosts the parasitoid larva. During pupation, primary parasitoids also may be attacked by pseudohyperparasitoids that lay their eggs on the parasitoid (pre)pupae. By attacking primary parasitoids, hyperparasitoids may affect herbivore population dynamics, and they have been identified as a major challenge in biological control. Over the past decades, research, especially on aphid- and caterpillar-associated hyperparasitoids, has revealed that hyperparasitoids challenge rules on nutri…
Dispersal rate and parasitism by Closterocerus chamaeleon (Girault) after its release in Sicily to control Ophelimus maskelli (Ashmead) (Hymenoptera,…
2011
Abstract Spread of the exotic parasitoid Closterocerus chamaeleon (Girault) and its parasitism on the Eucalyptus gall wasp Ophelimus maskelli (Ashmead) (Hymenoptera, Eulophidae) were studied in Sicily after C. chamaeleon introduction in May 2006. Parasitoid spread was evaluated by sampling sites at increasing distances from the five release sites. C. chamaeleon quickly established and spread; within 5 months, it caused 62% parasitism at release sites and 38% parasitism at sites 2 km from release sites. One year after its introduction (spring 2007), C. chamaeleon was detected more than 50 km distant from release sites. By winter 2007–08, the parasitoid was recovered throughout Sicily and in …
Climate change effects on trematodiases, with emphasis on zoonotic fascioliasis and schistosomiasis.
2009
The capacity of climatic conditions to modulate the extent and intensity of parasitism is well known since long ago. Concerning helminths, among the numerous environmental modifications giving rise to changes in infections, climate variables appear as those showing a greater influence, so that climate change may be expected to have an important impact on the diseases they cause. However, the confirmation of the impact of climate change on helminthiases has been reached very recently. Only shortly before, helminthiases were still noted as infectious diseases scarcely affected by climate change, when compared to diseases caused by microorganisms in general (viruses, bacteriae, protozoans). Th…
Parasitism of dolfinfhishes, <i>Coryphaena hippurus</i> and <i>Coryphaena equiselis</i>, in the western Mediterranean (Balear…
1999
A total of 648 dolphinfishes were examined for internal and external parasites in western Mediterranean (Balearic Islands) and central-eastern Atlantic (Canary Islands) waters in order to make a comparative study between the two areas. The specimens studied from the Mediterranean Sea was Coryphaena hippurus, with 62 large individuals captured from May to September and 497 juveniles captured from August to December. The specimens studied from the central-eastern Atlantic were 39 adult C. hippurus and 49 adult Coryphaena equiselis. Parasites were found in 70% of the fish examined, and represented a total of nine endoparasitic taxa: six digeneans (Class Trematoda, Subclass Digenea; Dinurus tor…
Parasites in sympatric populations of native and invasive freshwater bivalves
2021
An increasing threat to local, native freshwater mussels (Unionida)—an ecologically important but globally alarmingly declining group— is the invasion by exotic bivalves. The Enemy Release Hypothesis predicts that introduced species should benefit from enemy-mediated competition because they are less likely to be harmed by natural enemies, such as parasites, than their native competitors. We investigated within-site differences in parasitism between sympatric native (tot. five spp.) and invasive (tot. three spp.) bivalves in eight northern European waterbodies, which harboured totally 15 parasite taxa. In paired comparisons using within-site averages, the mean number of parasite species in …
Spatiotemporal and gender-specific parasitism in two species of gobiid fish
2018
Parasitism is considered a major selective force in natural host populations. Infections can decrease host condition and vigour, and potentially influence, for example, host population dynamics and behavior such as mate choice. We studied parasite infections of two common marine fish species, the sand goby (Pomatoschistus minutus) and the common goby (Pomatoschistus microps), in the brackish water Northern Baltic Sea. We were particularly interested in the occurrence of parasite taxa located in central sensory organs, such as eyes, potentially affecting fish behavior and mate choice. We found that both fish species harbored parasite communities dominated by taxa transmitted to fish through …