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Simple Summary: Competition arises for the monopolization of host resources when multiple parasitoid species attack the same host. This study focused on the competition between Chouioa cunea Yang and Tetrastichus septentrionalis Yang (Hymenoptera: Eulophidae), two pupal parasitoid species of the fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Erebidae). Experiments were conducted to investigate extrinsic and intrinsic competition. The results showed that both parasitoid species were capable of parasitizing hosts that were already parasitized by the competitor, with the first released species demonstrating superiority as an intrinsic competitor in multiparasitized hosts across various parasitoid release orders and time intervals between oviposition. These findings contribute to a better understanding of the interactions between the two parasitoids within the host pupae and offer insights into the biological control of H. cunea and other leaf-eating pests. The endoparasitoids Chouioa cunea Yang and Tetrastichus septentrionalis Yang (Hymenoptera: Eulophidae) are both gregarious pupal parasitoids of the fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Erebidae). In order to analyze the competitive interactions between both parasitoids exploiting H. cunea, we assessed both extrinsic and intrinsic competition. The search time, oviposition duration, and oviposition frequency were used as evaluation criteria for extrinsic competition. The number of survival days, female ratio, and number of parasitoids emerging from the host were used as evaluation criteria for intrinsic competition. The results indicated that both parasitoid species were able to parasitize hosts that were already parasitized by competitors. The first released species consistently emerged as the superior competitor in multiparasitized hosts. Both parasitoid release orders and time intervals between oviposition affect the competition of parasitoids and the parasitic efficiency. The results emphasize the parasitic abilities of both parasitoid species and provide a basis for future research on competition mechanisms and biological control of H. cunea. [ABSTRACT FROM AUTHOR]

For parasitoids, host foraging is the most significant activity for their reproductive success, as it directly translates into offspring production. Therefore, foraging behaviour and patch‐use decisions by parasitoids still attract research interest, especially when the studied species are biological control agents.In laboratory conditions, we studied the patch exploitation behaviour of Megarhyssa nortoni (Hymenoptera: Ichneumonidae), a larval–pupal parasitoid of several woodwasps (Hymenoptera: Siricidae), exposed to intra‐ and interspecific interactions.It is known that M. nortoni females are attracted to the symbiotic fungus carried by its hosts, which support host larval development inside the wood. Additionally, in the introduced range where the species has been released in biocontrol programs aimed at managing invasive Sirex noctilio populations, Megarhyssa nortoni coexists with the egg–larval parasitoid Ibalia leucospoides.First, we investigated whether host–fungal symbiont cues and direct presence of conspecific females affected patch time allocation and oviposition behaviour of M. nortoni, as both stimuli could provide information on concealed hosts. Second, we studied the influence of prior parasitism by I. leucospoides on patch time allocation decisions and oviposition behaviour.The main results showed that females modulated their responses to the fungal cues when foraging simultaneously with conspecifics. Also, patch‐leaving tendencies and patch residence times were not affected when females foraged patches previously exploited by I. leucospoides; indeed, they probed these patches more frequently.Our study contributes to the understanding of patch‐use decisions made by parasitoids and their impact on the biological control of damaging insect populations, particularly in a context of two parasitoid species and one host. [ABSTRACT FROM AUTHOR]

Trissolcus spp. are egg parasitoids of sunn pest, Eurygasterintegriceps Puton (Hemiptera: Scutelleridae). Direct (extrinsic) competition between female T.grandis and T.vassilievi was investigated in the laboratory by releasing different numbers (from one to 16) of one or both species into a multi-patch environment consisting different numbers of E.integriceps egg masses. Larval (intrinsic) competition was examined in host eggs multiparasitized at intervals ranging from 0 to 48 h. Survival of females was also assayed when stored at 4 °C. Trissolcusgrandis reduced the searching efficiency of congeneric rivals more than did T.vassilievi, and was a superior intrinsic competitor within multiparasitized eggs, although both species benefited from a significant 'first attack' advantage. Trissolcusvassilievi was more efficient than T.grandis when parasitizing host eggs at high conspecific densities. Mortality at 4 °C was lower in groups ≥ 10 than in groups ≤ 5, and T.grandis survived longer than T.vassilievi. [ABSTRACT FROM AUTHOR]

Individual hosts are often co-infected with multiple parasite species. Evidence from theoretical and empirical studies supports the idea that co-occurring parasites can impact each other and their hosts via synergistic or antagonistic interactions. The fundamental aim of understanding the consequences of co-infection to hosts and parasites requires an understanding of patterns of species co-occurrence within samples of hosts. We censused parasite assemblages in 755 adult, male fathead minnows collected from 7 lakes/ponds in southern Alberta, Canada between 2018 and 2020. Fifteen species of endoparasites infected fathead minnows, 98% of which were co-infected with between 2 and 9 parasite species (mean species richness: 4.4 ± 1.4). Non-random pairwise associations were detected within the overall parasite community. There were particularly strong, positive associations in the occurrences and intensities of the 2 congeneric larval trematodes Ornithodiplostomum sp. and Ornithodiplostomum ptychocheilus that comprised >96% of the 100 000+ parasites counted in the total sample of minnows. Furthermore, the occurrence of Ornithodiplostomum sp. was a strong predictor of the occurrence of O. ptychocheilus, and vice versa. Positive covariation in the intensities of these 2 dominants likely arises from their shared use of physid snails as first intermediate hosts in these waterbodies. These 2 species represent a predictable and non-random component within the complex assemblage of parasites of fathead minnows in this region.

The endoparasitoids Chouioa cunea Yang and Tetrastichus septentrionalis Yang (Hymenoptera: Eulophidae) are both gregarious pupal parasitoids of the fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Erebidae). In order to analyze the competitive interactions between both parasitoids exploiting H. cunea, we assessed both extrinsic and intrinsic competition. The search time, oviposition duration, and oviposition frequency were used as evaluation criteria for extrinsic competition. The number of survival days, female ratio, and number of parasitoids emerging from the host were used as evaluation criteria for intrinsic competition. The results indicated that both parasitoid species were able to parasitize hosts that were already parasitized by competitors. The first released species consistently emerged as the superior competitor in multiparasitized hosts. Both parasitoid release orders and time intervals between oviposition affect the competition of parasitoids and the parasitic efficiency. The results emphasize the parasitic abilities of both parasitoid species and provide a basis for future research on competition mechanisms and biological control of H. cunea.

Parasites can exert a substantial influence on the ecology of wildlife populations by altering host condition. Our objectives were to estimate single and multiparasite-condition relationships for fallow deer (Dama dama) and red deer (Cervus elaphus) in Denmark and to assess potential health effects along the parasite burden gradient. Fallow deer hosted on average two endoparasite taxa per individual (min = 0, max = 5) while red deer carried on average five parasite taxa per individual (min = 2, max = 9). Body condition of both deer species was negatively related to presence of Trichuris ssp. eggs while body condition of red deer was positively related to antibodies of the protozoan Toxoplasma gondii. For the remaining parasite taxa (n = 12), we either found weak or no apparent association between infection and deer body condition or low prevalence levels restricted formal testing. Importantly, we detected a strong negative relationship between body condition and the sum of endoparasite taxa carried by individual hosts, a pattern that was evident in both deer species. We did not detect systemic inflammatory reactions, yet serology revealed reduced total protein and iron concentrations with increased parasite load in both deer species, likely due to maldigestion of forage or malabsorption of nutrients. Despite moderate sample sizes, our study highlights the importance of considering multiparasitism when assessing body condition impacts in deer populations. Moreover, we show how serum chemistry assays are a valuable diagnostic tool to detect subtle and sub-clinical health impacts of parasitism, even at low-level infestation.

Brood parasites are expected to lay only one egg per parasitized nest, as the existence of several parasitic nestlings in a brood increases competition and can lead the starvation of some of them. However, multiparasitism (laying of two or more eggs by one or more parasitic females in a single host nest) is surprisingly frequent. Here, we study multiparasitism by different females or by the same female (repeated parasitism) in the great spotted cuckoo Clamator glandarius, a non‐evictor brood parasite that mainly parasitizes the magpie Pica pica, and whose chicks may be raised together with host nestlings in the same nest. We used a total of 262 magpie nests found during four breeding seasons. Multiparasitism and repeated parasitism are very frequent because this brood parasite is less virulent than other cuckoo species and magpie hosts can successfully raise more than one parasitic nestling per nest. The total number of cuckoo chicks fledged was higher in multiparasitized nests than in single‐ or double‐parasitized magpie nests. Magpie breeding success (i.e. the proportion of eggs that produce young that leave the nest) did not differ between single‐, double‐, and multiparasitized magpie nests. These results suggest that multiparasitism is an adaptation in the great spotted cuckoo. The intensity of parasitism (number of cuckoo eggs per nest), after controlling for the potential effect of year, did not affect nest desertion or nest predation rate, neither during the incubation nor the nestling periods. This implies that nest concealment does not affect the susceptibility of one nest being parasitized and predated, as nest predation rate was similar regardless of the intensity of parasitism. Predation rate during the nestling phase did not vary according to intensity of parasitism, which does not support either the 'mutualism' hypothesis or the 'predation cost of begging' hypothesis. [ABSTRACT FROM AUTHOR]

If the risk of larval competition is high and its consequence on offspring mortality is important, we expect female behavioural strategies favouring the survival of their offspring to be selected for. In parasitoids, hosts can be parasitized several times, in some cases by females of different species (i.e., multiparasitism). In solitary parasitoids, only one offspring can develop per host: supernumerary individuals are eliminated through larval competition. Under these conditions, mothers can lay additional eggs in/on the same host (i.e., self‐superparasitism) to increase the chances of one of their offspring winning the competition. They can also aggressively protect their offspring against competing females to prevent them from multiparasitism and ovicide. Both strategies (self‐superparasitism and host defence) are observed in females of the solitary ectoparasitoid wasp, Dinarmus basalis Rondani (Hymenoptera: Pteromalidae), when facing females of another solitary ectoparasitoid species, Eupelmus vuilleti (Hymenoptera: Eupelmidae), during host exploitation. Here, we aimed to explore whether D. basalis females' behaviours relate to their offspring survival chances during larval competition: we expect mothers to defend their hosts only during the vulnerability period of their offspring and self‐superparasitize to increase the chances of their offspring winning the larval competition. We thus measured the effect of oviposition order (D. basalis females oviposited first or second), delay between ovipositions (30–60 min or 3–4 h) and the occurrence of D. basalis females' self‐superparasitism on D. basalis offspring survival when competing with E. vuilleti juveniles. Our results showed D. basalis offspring constantly had a lower survival probability than E. vuilleti offspring. Only being laid first increased D. basalis offspring survival rate, whereas the time delay between ovipositions and self‐superparasitism did not significantly increase it further. The fact that offspring survival chances under interspecific competition may not be the main driver of maternal host protection and self‐superparasitism is discussed. [ABSTRACT FROM AUTHOR]

Brood parasites are expected to lay only one egg per parasitized nest, as the existence of several parasitic nestlings in a brood increases competition and can lead the starvation of some of them. However, multiparasitism (laying of two or more eggs by one or more parasitic females in a single host nest) is surprisingly frequent. Here, we study multiparasitism by different females or by the same female (repeated parasitism) in the great spotted cuckoo Clamator glandarius, a non‐evictor brood parasite that mainly parasitizes the magpie Pica pica, and whose chicks may be raised together with host nestlings in the same nest. We used a total of 262 magpie nests found during four breeding seasons. Multiparasitism and repeated parasitism are very frequent because this brood parasite is less virulent than other cuckoo species and magpie hosts can successfully raise more than one parasitic nestling per nest. The total number of cuckoo chicks fledged was higher in multiparasitized nests than in single‐ or double‐parasitized magpie nests. Magpie breeding success (i.e. the proportion of eggs that produce young that leave the nest) did not differ between single‐, double‐, and multiparasitized magpie nests. These results suggest that multiparasitism is an adaptation in the great spotted cuckoo. The intensity of parasitism (number of cuckoo eggs per nest), after controlling for the potential effect of year, did not affect nest desertion or nest predation rate, neither during the incubation nor the nestling periods. This implies that nest concealment does not affect the susceptibility of one nest being parasitized and predated, as nest predation rate was similar regardless of the intensity of parasitism. Predation rate during the nestling phase did not vary according to intensity of parasitism, which does not support either the ‘mutualism' hypothesis or the ‘predation cost of begging' hypothesis.

Multiparasite communities inhabiting individual hosts are common and often consist of parasites from multiple taxa. The effects of parasite community composition and complexity on host fitness are critical for understanding how host–parasite coevolution is affected by parasite diversity. To test how naturally occurring parasites affect host fitness of multiple host genotypes, we performed a common-garden experiment where we inoculated four genotypes of host plant Plantago lanceolata with six microbial parasite treatments: three single-parasite treatments, a fungal mixture, a viral mixture, and a cross-kingdom treatment. Seed production was affected by both host genotype and parasite treatment, and their interaction jointly determined the growth of the hosts. Fungal parasites had more consistent negative effects than viruses in both single- and mixed-parasite treatments. These results demonstrate that parasite communities have the potential to affect the evolution and ecology of host populations through their effects on host growth and reproduction. Moreover, the results highlight the importance of accounting for the diversity of parasites as well as host genotypes when aiming to predict the consequences of parasites for epidemics as the effects of multiparasitism are not necessarily additive of single-parasite effects, nor uniform across all host genotypes. [ABSTRACT FROM AUTHOR]

Parasites can exert a substantial influence on the ecology of wildlife populations by altering host condition. Our objectives were to estimate single and multiparasite-condition relationships for fallow deer (Dama dama) and red deer (Cervus elaphus) in Denmark and to assess potential health effects along the parasite burden gradient. Fallow deer hosted on average two endoparasite taxa per individual (min = 0, max = 5) while red deer carried on average five parasite taxa per individual (min = 2, max = 9). Body condition of both deer species was negatively related to presence of Trichuris ssp. eggs while body condition of red deer was positively related to antibodies of the protozoan Toxoplasma gondii. For the remaining parasite taxa (n = 12), we either found weak or no apparent association between infection and deer body condition or low prevalence levels restricted formal testing. Importantly, we detected a strong negative relationship between body condition and the sum of endoparasite taxa carried by individual hosts, a pattern that was evident in both deer species. We did not detect systemic inflammatory reactions, yet serology revealed reduced total protein and iron concentrations with increased parasite load in both deer species, likely due to maldigestion of forage or malabsorption of nutrients. Despite moderate sample sizes, our study highlights the importance of considering multiparasitism when assessing body condition impacts in deer populations. Moreover, we show how serum chemistry assays are a valuable diagnostic tool to detect subtle and sub-clinical health impacts of parasitism, even at low-level infestation. [Display omitted] • Single parasite-condition relationships in deer varied in strength and direction. • Body condition of deer negatively correlated to total sum of endoparasite taxa. • Serum chemistry assays revealed sub-clinical health impacts of multiparasitism. [ABSTRACT FROM AUTHOR]

Simple Summary: Maculinea butterflies are endangered social parasites of Myrmica ants. In late summer, caterpillars abandon their foodplants and wait for a Myrmica worker to retrieve and carry them into the nest. Here the caterpillars spend 11 months consuming the ant brood or being fed by workers; then they pupate early in summer, and in one month the adults emerge. Our study aimed to assess the spatial relationship between nests parasitized by Maculinea teleius and those unparasitized and the factors influencing the parasite presence inside host nests. We searched for Ma. teleius caterpillars in ant nests in autumn, during the initial larval development, and in the following late spring. Unsurprisingly, we found a substantial decrease in the proportion of parasitized nests from autumn to late spring. The biggest Myrmica nests adopted a higher number of parasites, but mid-size nests provided the best trade-off between competition and resource availability, leading to high parasite survival observed in spring. The spatial distribution of parasitized nests in autumn was uniform, while the colonies in which Ma. teleius survived until pupation were grouped. Overall, our results suggest that host colonies' features and spatial relationships should be considered when trying to preserve these rare butterflies. The parasitic relationship between Maculinea butterflies and Myrmica ants has been extensively studied but little information is available on the spatial occurrence of Maculinea larvae. We searched for the presence of Maculinea teleius in 211 ant nests at two sites in two crucial phases of its life cycle, i.e., in autumn, during the initial larval development, and in the following late spring, before pupation. We assessed variations in the proportion of infested nests and factors correlated with spatial distributions of parasites in Myrmica colonies. The parasitism rate in autumn was very high (∼50% of infestation rate) but decreased in the following spring. The most important factor explaining parasite occurrence in both seasons was the nest size. Further factors, such as the presence of other parasites, the Myrmica species or the site, concurred to explain the differential survival of Ma. teleius until the final development. Irrespective of the host nest distribution, the parasite distribution changed from even in autumn to clumped in late spring. Our work showed that the survival of Ma. teleius is correlated with colony features but also with the nest spatial distribution, which therefore should be taken into consideration in conservation strategies aiming at preserving these endangered species. [ABSTRACT FROM AUTHOR]

Anamnesis: A polytraumatized wild oncilla (Leopardus tigrinus) was admitted to the Unidad de Rehabilitación y Rescate de Animales Silvestres (URRAS) veterinary clinic of the Universidad Nacional de Colombia. Despite the medical efforts, the animal died six hours later. Clinical and laboratory findings: Necropsy examination revealed multiple white nodules of about 2 mm in diameter distributed on the visceral surface of lung caudal lobes. Histopathology revealed lymphoplasmacytic interstitial pneumonia with multiple coiled larvae of metastrongyloid nematodes in alveoli and bronchioles. First-stage Aelurostrongylus abstrusus nematode was identified in a fecal sample using the Ritchie copromicroscopic technique. Conclusion: This study reports an incidental severe pulmonary parasitism caused by A. abstrusus in a wild Oncilla (L. tigrinus). This is the first report of A. abstrusus infection associated with pathological lesions in a L. tigrinus from Colombia. [ABSTRACT FROM AUTHOR]

The groups of nemathodes who infect fish has been studyied since it has been noticed that these parasites infect a large variety of organisms, being widespread all over the world, in both freshwater and marine species. The aim of this study was to investigate the infections with Eustrongylides sp. in perch, pike, pikeperch, sheat fish, and sun perch, fished into the natural Romanian's lakes, around the Danubian Delta. Our study started on October 2005 and ended on March 2008. The fish have been clinically, pathologically and parasitologically examinated. Following these exams, we have identified the Eustrongylides sp. larvae in muscles, cavity of body and gut in perch, sheat fish and pike; in liver, mesentery and body cavity in pikeperch; into the cavity of body in sun perch. We have also noticed unspecific lesions in these structures, pointing out the presence of circulatory disturbances (congestion and hemorrhage). In perch we have observed the multiparasiting phenomenon, in which Eustrongylides sp. has been found associated with Myxobolus sp., Triaenophorus sp. and Piscicola sp. into the same host.

Anamnesis: A polytraumatized wild oncilla (Leopardus tigrinus) was admitted to the Unidad de Rehabilitación y Rescate de Animales Silvestres (URRAS) veterinary clinic of the Universidad Nacional de Colombia. Despite the medical efforts, the animal died six hours later. Clinical and laboratory findings: Necropsy examination revealed multiple white nodules of about 2 mm in diameter distributed on the visceral surface of lung caudal lobes. Histopathology revealed lymphoplasmacytic interstitial pneumonia with multiple coiled larvae of metastrongyloid nematodes in alveoli and bronchioles. First-stage Aelurostrongylus abstrusus nematode was identified in a fecal sample using the Ritchie copromicroscopic technique. Conclusion: This study reports an incidental severe pulmonary parasitism caused by A. abstrusus in a wild Oncilla (L. tigrinus). This is the first report of A. abstrusus infection associated with pathological lesions in a L. tigrinus from Colombia.

Abstract Understanding competition between scelionid parasitoids that exploit the same host may provide insight into strategies that allow coexistence on a shared resource. Competition studies typically focus on interactions between native and exotic parasitoids that do not share an evolutionary history; however, coevolved parasitoids may be more likely to demonstrate strategies to avoid or exploit a shared resource. We examined intrinsic and extrinsic competition between Asian Trissolcus japonicus (Ashmead) and T. cultratus (Mayr) (Hymenoptera: Scelionidae) associated with Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) that share an evolutionary history. Interspecific interactions were assessed by providing parasitized egg masses to each species at various intervals post‐parasitism, and measuring host acceptance, developmental suitability, and guarding behaviour. Trissolcus japonicus showed high acceptance of parasitized hosts up to 72 h following oviposition by T. cultratus, despite a very poor developmental outcome. In contrast, T. cultratus generally avoided ovipositing in H. halys eggs containing T. japonicus early‐instar larvae but did not avoid parasitizing H. halys that contained eggs and third instar larvae. The adaptive value of this behaviour was supported by developmental outcome: T. cultratus outcompeted T. japonicus eggs but not early‐instar larvae, and a trophic shift occurred wherein T. cultratus developed as a facultative hyperparasitoid on third instar T. japonicus larvae. Trissolcus japonicus guarded egg masses 8–12× longer and displayed more aggressive interactions than T. cultratus, suggesting T. japonicus is the superior extrinsic competitor. Development as a facultative hyperparasitoid provided a competitive niche for Asian T. cultratus and confirms its instrinsic competitive superiority. This also occurs in a biologically distinct European population of T. cultratus, suggesting that facultative hyperparasitism as a competitive strategy is retained in geographically separated populations that have not coevolved with H. halys or T. japonicus.

Roseau cane (Phragmites australis (Cav). Trin. ex Steud.) is the dominant plant species of the Mississippi River Delta in Louisiana, USA, and protects the coastline from erosion and storm‐related impacts, maintaining shipping channels and oil infrastructure. Widespread dieback and thinning of P. australis were noted in the Mississippi River Delta in the fall of 2016. Invasive populations of the roseau cane scale (Nipponaclerda biwakoensis Kuwana), which is native to Asia, were found at outbreak levels in the stands. Subsequent research implicated N. biwakoensis in the diebacks. As a safe, cost‐effective and long‐term approach for managing this invasive scale, classical (importation) biological control methods are being considered. As the first step to developing biological control, research evaluating the natural enemies of the N. biwakoensis in the native range is necessary. This study investigated the population dynamics of N. biwakoensis and its associated parasitoids on P. australis in Taiwan from July to November 2019 at five study sites. Scale densities across sites increased over the growing season, peaking in September at 85.77 ± 6.36 scales/stem, which is half as dense as found in Louisiana. Mean parasitism of adult female scales across sites and season was 14.00%, while parasitism on immature scales was lower (3.00%). Four parasitoid wasp species were reared from the scale—Asytymachus lasallei Noyes and Higashiura, Boucekiella depressa Hoffer, Neastymachus japonicus Tachikawa and Aprostocetus sp. Westwood. Neastymachus japonicus was the dominant species parasitizing adult female scales, while A. lasallei was the dominant wasp species parasitizing immature scales. Astymachus lasallei and B. depressa were frequently reared from the same individual host, suggesting multiparasitism or hyperparasitism. Overall, this study provides important information on the identity and role of parasitoids of N. biwakoensis in its native range, which will aid in developing a classical biological control programme for the invasive N. biwakoensis. [ABSTRACT FROM AUTHOR]

Amidst global shifts in the distribution and abundance of wildlife and livestock, we have only a rudimentary understanding of ungulate parasite communities and parasite-sharing patterns. We used qPCR and DNA metabarcoding of fecal samples to characterize gastrointestinal nematode (Strongylida) community composition and sharing among 17 sympatric species of wild and domestic large mammalian herbivore in central Kenya. We tested a suite of hypothesis-driven predictions about the role of host traits and phylogenetic relatedness in describing parasite infections. Host species identity explained 27–53% of individual variation in parasite prevalence, richness, community composition and phylogenetic diversity. Host and parasite phylogenies were congruent, host gut morphology predicted parasite community composition and prevalence, and hosts with low evolutionary distinctiveness were centrally positioned in the parasite-sharing network. We found no evidence that host body size, social-group size or feeding height were correlated with parasite composition. Our results highlight the interwoven evolutionary and ecological histories of large herbivores and their gastrointestinal nematodes and suggest that host identity, phylogeny and gut architecture—a phylogenetically conserved trait related to parasite habitat—are the overriding influences on parasite communities. These findings have implications for wildlife management and conservation as wild herbivores are increasingly replaced by livestock. [ABSTRACT FROM AUTHOR]

Habitat disturbance can have negative impacts on biodiversity, such as reducing species richness. The effects of habitat disturbances on parasite infections of host species, potentially altering their survival rate and thus abundance, are less well known. We examined the influence of forest logging in combination with seasonality, host abundance, host body condition, and host sex, on the community composition of gastrointestinal parasites infecting Edward's swamp rat, Malacomys edwardsi. Community composition of parasites did not differ between logged and undisturbed sites, but the abundance of some nematodes (i.e. Ascaris and hookworm) was higher in undisturbed than logged sites. The higher abundance of these nematode species implies a changed host-parasite relationship, thus potentially influencing host persistence. [ABSTRACT FROM AUTHOR]

Knowledge on reproductive strategies and host use in insect parasitoids is fundamental for biological control purposes. Superparasitism and multiparasitism, oviposition in a previously parasitized host by a female of the same or different species, respectively, may impact pest management decisions. Our objective was to determine the occurrence of superparasitism and multiparasitism in three species of native larval−pupal solitary endoparasitoids that attack Anastrepha Shiner species (Diptera: Tephritidae) in the Neotropical region, and the possible effect on offspring fitness parameters. Doryctobracon crawfordi (Viereck), Utetes anastrephae (Viereck), and Opius hirtus (Fischer) occur in sympatry in Mexico, and are currently under consideration for use as biocontrol agents. Experiments were conducted under laboratory conditions with females acting alone (self-superparasitism), females in groups of the same species (conspecific superparasitism), and females in mixed groups (multiparasitism). Our results showed that self-superparasitism is an uncommon strategy in the three native species and is rare under conditions of intraspecific competition. In the case of multiparasitism, a higher number of immature stages of U. anastrephae was observed, compared to those of D. crawfordi and O. hirtus. However, it is not clear yet if this was due to some adult female trait or to the competitive ability of the larvae. We conclude that most females of the native species studied appeared to avoid superparasitism, specifically when acting alone, suggesting a high discrimination ability, which is probably a result of a close relationship and evolutionary history with Anastrepha hosts. [ABSTRACT FROM AUTHOR]

Understanding competition between scelionid parasitoids that exploit the same host may provide insight into strategies that allow coexistence on a shared resource. Competition studies typically focus on interactions between native and exotic parasitoids that do not share an evolutionary history; however, coevolved parasitoids may be more likely to demonstrate strategies to avoid or exploit a shared resource. We examined intrinsic and extrinsic competition between Asian Trissolcus japonicus (Ashmead) and T. cultratus (Mayr) (Hymenoptera: Scelionidae) associated with Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) that share an evolutionary history. Interspecific interactions were assessed by providing parasitized egg masses to each species at various intervals post‐parasitism, and measuring host acceptance, developmental suitability, and guarding behaviour. Trissolcus japonicus showed high acceptance of parasitized hosts up to 72 h following oviposition by T. cultratus, despite a very poor developmental outcome. In contrast, T. cultratus generally avoided ovipositing in H. halys eggs containing T. japonicus early‐instar larvae but did not avoid parasitizing H. halys that contained eggs and third instar larvae. The adaptive value of this behaviour was supported by developmental outcome: T. cultratus outcompeted T. japonicus eggs but not early‐instar larvae, and a trophic shift occurred wherein T. cultratus developed as a facultative hyperparasitoid on third instar T. japonicus larvae. Trissolcus japonicus guarded egg masses 8–12× longer and displayed more aggressive interactions than T. cultratus, suggesting T. japonicus is the superior extrinsic competitor. Development as a facultative hyperparasitoid provided a competitive niche for Asian T. cultratus and confirms its instrinsic competitive superiority. This also occurs in a biologically distinct European population of T. cultratus, suggesting that facultative hyperparasitism as a competitive strategy is retained in geographically separated populations that have not coevolved with H. halys or T. japonicus. [ABSTRACT FROM AUTHOR]

The parasitic relationship between Maculinea butterflies and Myrmica ants has been extensively studied but little information is available on the spatial occurrence of Maculinea larvae. We searched for the presence of Maculinea teleius in 211 ant nests at two sites in two crucial phases of its life cycle, i.e., in autumn, during the initial larval development, and in the following late spring, before pupation. We assessed variations in the proportion of infested nests and factors correlated with spatial distributions of parasites in Myrmica colonies. The parasitism rate in autumn was very high (∼50% of infestation rate) but decreased in the following spring. The most important factor explaining parasite occurrence in both seasons was the nest size. Further factors, such as the presence of other parasites, the Myrmica species or the site, concurred to explain the differential survival of Ma. teleius until the final development. Irrespective of the host nest distribution, the parasite distribution changed from even in autumn to clumped in late spring. Our work showed that the survival of Ma. teleius is correlated with colony features but also with the nest spatial distribution, which therefore should be taken into consideration in conservation strategies aiming at preserving these endangered species.

The Enemy Release Hypothesis (ERH) has been a factor influencing the establishment of some exotic species worldwide. We tested if the ERH could be influencing populations of the exotic predator Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in Brazil. During two years, three local predatory coccinellid species and Harmonia axyridis were sampled in Brassica oleracea in six organic farms in the midwest of the country. Parasitoids were detected by rearing (emerged) and qPCR Melting Curve Analysis (unemerged). Host density-dependence and spillovers were used to evaluate coccinellid population effects of parasitism. Six parasitoid species were found, including two new records for Brazil. Although Harmonia axyridis harbored fewer parasitoid species, parasitism was not lower and parasitoid density-dependence was not weaker on it compared to the local species. Spillovers among hosts occurred both onto Harmonia axyridis and from it. The ERH was rejected for these parasitoids and, therefore, it did not contribute to the invasiveness of Harmonia axyridis in Brazil. [ABSTRACT FROM AUTHOR]

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 instar larvae and pupae. Ooencyrtus telenomicida offspring emergence from multiparasitized eggs was significantly lower than that from rearing controls, independent of the order of parasitization. Anastatus bifasciatus offspring emergence was not influenced by the presence of O. telenomicida when it parasitized as the first species, but emergence was decreased after oviposition in eggs containing O. telenomicida larvae and pupae. There was no indication that O. telenomicida can act as a facultative hyperparasitoid of A. bifasciatus. These results suggest that A. bifasciatus is the superior intrinsic competitor and no or minor negative implications for A. bifasciatus are expected if released in combination with O. telenomicida. [ABSTRACT FROM AUTHOR]

An adult free-ranged female maned wolf was rescued from a periurban area subject to anthropogenic disturbances in the Minas Gerais, Brazil. The animal presented poor body condition and anemia. The clinical condition rapidly deteriorated culminating in dead and a necropsy was performed. The main gross lesions were marked anemia and blood content in the intestines accompanied by many types of parasites. The protozoa Rangelia vitalii was identified by histopathological analysis predominantly within the cytoplasm of endothelial cells of capillaries of the small intestine. The lymph nodes, spleen, bone marrow, dermis, lungs and kidney had similar protozoal forms but with mild or moderate intensity. Rangelia vitalii was confirmed by molecular assays. Hepatozoon sp., Leishmania sp., and Entamoeba spp., apparently not related to the clinical signs were also detected. The myriad parasites found in the intestines included nematodes (Ancylostoma caninum, A. braziliensis,, Molineus sp., Pterygodermatites sp., and Trichuris sp.), cestodes (Spirometra sp.) and (acanthocephalans. To our knowledge, R. vitalii was identified in C. brachyurus for the first time. These findings emphasize the fragility of Brazilian ecosystems, especially in disturbed areas, reinforcing the necessity of efforts to preserve these areas and wild carnivores, some of which are threatened with extinction, such as the maned wolf.

The effect of intrinsic competition between the exotic parasitoid Diachasmimorpha longicaudata (Ashmead) and the native species Doryctobracon crawfordi (Viereck), Utetes anastrephae (Viereck) and Opius hirtus (Fischer) (all Braconidae: Opiinae) was studied under laboratory conditions. Each native species and D. longicaudata acted as both a resident and an invader, and all species were introduced to the host simultaneously. Diachasmimorpha longicaudata was found to be the most competitive species because it achieved the highest parasitism percentage under all the experimental conditions, but it was also negatively affected by the presence and parasitic activity of the native parasitoids. Utetes anastrephae was the only species that maintained its parasitic rate when all species attacked the available hosts simultaneously. The emergence probability of a female D. longicaudata was positively associated with the increase in the number of scars on the cuticle of the host pupa, but this association was not observed for the native species. It was concluded that D. longicaudata is an intrinsic competitor that is superior to D. crawfordi, U. anastrephae and O. hirtus, whether acting as a resident or an invader, producing a female-biased sex ratio in all the evaluation conditions. Utetes anastrephae was the native species that was least affected by the competitive presence of D. longicaudata, which suggests that it could be used as a complementary biological control agent for Anastrepha fruit flies. [ABSTRACT FROM AUTHOR]

Trichogramma parasitoids are important biological control agents for insect pest management. However, efficient means for mass production of Trichogramma parasitoids are needed, particularly for T. ostriniae, which often fail to form emergence holes on host eggs of Chinese oak silkworm, Antheraea pernyi, because of the hard chorion. In the present study, we evaluated the possibilities to enhance adult emergence of T. ostriniae by utilizing emergence holes made by T. dendrolimi during multiparasitism on host eggs of A. pernyi and other biological parameters such as pre-emergence time, parasitism rate, and emergence rate of the two parasitoids, which were also evaluated between the two parasitism regimes of multi- and monoparasitism. Our data showed that multiparasitism on host eggs of A. pernyi significantly facilitated the emergence of adult T. ostriniae. Generally, both Trichogramma species favored parasitizing A. pernyi eggs, with multiple parasitoid adults emerged per host egg. The overall performance of T. dendrolimi was similar between the two parasitism regimes, although a significantly higher number of unemerged adults were found in the multiparasitized eggs than in the monoparasitized. For T. ostriniae, significantly more adults emerged, and a higher emergence rate was recorded on host eggs multiparasitized with T. dendrolimi than that on monoparasitized. Furthermore, significantly fewer unemerged adults were found in multi- than monoparasitized host eggs. The results of this study provided useful information on the feasibility of mass production of T. ostriniae via multiparasitism with T. dendrolimi on large eggs of A. pernyi. [ABSTRACT FROM AUTHOR]

Abstract Most parasites co-occur with other parasites, although the importance of such multiparasitism has only recently been recognised. Co-infections may result when hosts are independently infected by different parasites at the same time or when interactions among parasite species facilitate co-occurrence. Such interactions can have important repercussions on human or animal health because they can alter host susceptibility, infection duration, transmission risks, and clinical symptoms. These interactions may be synergistic or antagonistic and thus produce diverse effects in infected humans and animals. Interactions among parasites strongly influence parasite dynamics and therefore play a major role in structuring parasite populations (both within and among hosts) as well as host populations. However, several methodological challenges remain when it comes to detecting parasite interactions. The goal of this review is to summarise current knowledge on the causes and consequences of multiparasitism and to discuss the different methods and tools that researchers have developed to study the factors that lead to multiparasitism. It also identifies new research directions to pursue.

Abstract Background Pyrenean chamois (Rupicapra pyrenaica pyrenaica) is a nearly monomorphic mountain ungulate with an unbiased sex-specific overwinter adult survival. Few differences in gastrointestinal parasitism have been reported by coprology as yet. This study aims to assess diversity, prevalence, intensity of infection and aggregation of gastrointestinal nematodes in male and female adult chamois. We expect no differences in the parasite infection rates between sexes. Findings Gastrointestinal tracts of 28 harvested Pyrenean chamois in the Catalan Pyrenees (autumn 2012 and 2013) were necropsied and sexual differences in the diversity and structure of parasite community, prevalence, intensity of infection, and richness were investigated. We found 25 helminth species belonging to 13 different genera. Conclusions Contrary to our expectations, male chamois showed different parasite communities, higher prevalence, intensity of infection and richness than females. Such sexual differences were clear irrespective of age of individuals. Hence, male chamois must cope with a more diverse and abundant parasite community than females, without apparent biological cost. Further research will be required to confirm this hypothesis.

Both the ectoparasitoid Tamarixia lyciumi Yang (Hymenoptera: Eulophidae) and the endoparasitoid Psyllaephagus arenarius (Hymenoptera: Encyrtidae) are solitary nymphal parasitoids of Paratrioza sinica (Hemiptera: Psyllidae), a pest of goji berry, Lycium barbarum . Moreover, T. lyciumi is frequently attacked by a hyperparasitoid Marietta picta Andre (Hymenoptera: Aphelinidae) in the field. To analyze competitive interactions between T. lyciumi and P. arenarius mediated by M. picta , we evaluated interspecific host discrimination and larval competition between T. lyciumi and P. arenarius , and the effect of M. picta on their competitive interactions, under laboratory conditions. The results showed that T. lyciumi could discriminate hosts pre-parasitized by P. arenarius , but not vice versa. However, P. arenarius was a superior intrinsic competitor in multiparasitized hosts regardless the order of parasitism. Although multiparasitized hosts produced more P. arenarius and fewer T. lyciumi after exposure to M. picta , the total number of emerging T. lyciumi and P. arenarius did not decline significantly, and sex ratios did not change. Thus, larval superiority would appear to favor the establishment of newly introduced P. arenarius in the Ningxia region, while the inferior competitor T. lyciumi is able to utilize interspecific host discrimination to avoid larval competition. Competitive interactions between T. lyciumi and P. arenarius are mediated by M. picta , and the observed host–parasitoid–hyperparasitoid interactions potentially facilitate their collective coexistence in biological control of P. sinica . [ABSTRACT FROM AUTHOR]

Interspecific competition among different species of insect parasitoids may affect the establishment or efficacy of species used for biological control of a target pests. Peristenus spretus Chen & van Achterberg and Peristenus relictus Loan (syn. P. stygicus ) (Hymenoptera: Braconidae) are two dominant solitary parasitoids of mirid bugs in China. In this study, interspecific competition between larvae of P. spretus and P. relictus for the nutrients inside their common host, the green plant bug ( Apolygus lucorum Meyer-Dürin), as well as their extrinsic competition for host resources were investigated in the laboratory. We examined the effect of four different time intervals between oviposition by the two species (10 min, 24 h, 48 h, and 72 h) and two parasitoid sequences (i.e., P. spretus before P. relictus [ Ps - Pr ] and P. relictus before P. spretus ( Pr - Ps )] in no-choice tests to measure nutrient competition between the two species. In choice tests, three densities of A. lucorum nymphs (40, 80, and 120) were presented to various combinations of P. spretus and P. relictus (1,1; 2,2; or 3,3 pairs). In addition, the developmental times of the immature stage (from egg to late instar larva) of P. spretus and P. relictus were determined. We found that neither the time interval between oviposition by the two competing species, nor the order the parasitoids attacked ( Ps - Pr or Pr - Ps ) had any influence on the percentage of parasitoid offspring that belonged a particular parasitoid species. Peristenus spretus dominated, accounting for 89.2–97.9% of parasitoid offspring in the no-choice nutrient competition experiment. Parasitoid sequence did, however, affect sex ratio in the dominant parasitoid’s offspring, with 48.2% of P. spretus offspring being female in the Pr-Ps sequence, while only 29.2% were female in the Ps-Pr sequence. Overall, in the host resource competition experiment, 64.7–82.2% of all emerged adult parasitoids of the offspring generation, for all host density treatments, were P. spretus . The percentage of emerged parasitoids that were a given species was significantly affected by host density, but neither by the number of pairs of P. spretus or P. relictus nor by the parasitoid density × host density interaction. The developmental time of the immature stage of P. spretus was 2.2 days shorter than that of P. relictus , an important factor in making P. spretus a superior competitor over P. relictus in all the competition trials. Based on these results, we conclude P. spretus will have an important advantage when competing with P. relictus, a factor that should be considered in any biological control program using these two parasitoids in China. [ABSTRACT FROM AUTHOR]

Extensive rearing of monarch larvae (Danaus plexippus L.) through the citizen science Monarch Larva Monitoring Project (MLMP) revealed that monarchs' primary parasitoids are flies in the family Tachinidae and that these parasitoids result in appreciable larval mortality. We document the tachinid community that attacks monarchs in the United States, evaluate their relative frequency, and examine variation in their specificity, oviposition strategy, and use of host stages. Based on results of rearing >20,000 monarchs by MLMP volunteers, overall parasitism by tachinids across life stages was 9.8% (17% for monarchs collected as fifth instars). We identified the flies that emerged from 466 monarch hosts, and found seven Tachinidae species. In decreasing order of frequency, these included Lespesia archippivora (Riley), Hyphantrophaga virilis (Aldrich & Webber), Compsilura concinnata (Meigen), Leschenaultia n. sp., Madremyia saundersii (Williston), Lespesia sp., and Nilea erecta (Coquillett). Lespesia sp., Leschenaultia n. sp., and N. erecta had not been previously reported as monarch parasitoids, and Leschenaultia n. sp. is apparently undescribed. We include new state records (Texas and Iowa) for C. concinnata. Lespesia archippivora and C. concinnata were overrepresented as parasitoids of later instars and were absent from monarchs collected as eggs, but H. virilis and Leschenaultia sp., which lay their eggs on foliage, were reared from caterpillars collected as eggs. To our knowledge, we include the first report of multiparasitism of monarchs, in which more than one parasitoid species emerged from a host. The biology of the tachinid parasitoids we identified and their relationship with monarchs is examined. [ABSTRACT FROM AUTHOR]

In solitary parasitoids, a host can only support the complete development of a single parasitoid. For this reason, intraspecific or interspecific competition takes place whenever two or more individuals of the same or different species parasitize the same host. The exotic Diadegma semiclausum ( Hellen) ( Hymenoptera: Ichneumonidae) was introduced into Kenya in 2002 for the control of the diamondback moth, Plutella xylostella L. ( Lepidoptera: Plutellidae), and led to the competitive displacement of its indigenous congeneric species Diadegma mollipla ( Holmgren) in some areas but not in others. In an attempt to understand this process, superparasitism in D. mollipla and multiparasitism involving both species were investigated in the laboratory through exposure of non-parasitized and parasitized host larvae to D. mollipla. Hosts were exposed to the two congeners both simultaneously and sequentially. The study revealed that D. mollipla minimizes parasitism and superparasitism in the presence of hosts containing a larva of a conspecific female. When the two parasitoid species competed for non-parasitized hosts simultaneously, there were no significant differences in the total progeny produced under intraspecific vs. interspecific competition. Under simultaneous interspecific competition, D. semiclausum produced 74% of total progeny. Under sequential exposure, the species that attacked first always dominated with 85-96% of the resultant progeny, irrespective of the exposure interval. Offspring sex ratio was significantly more female-biased when the larvae were exposed to D. mollipla first. Overall, our results indicate that D. semiclausum dominates under simultaneous competition and D. mollipla dominates in terms of female progeny, but under delayed exposure to the other species, the first attacker is always the winner. On the basis of our results, D. semiclausum may not completely displace D. mollipla from diamondback moth in the field. [ABSTRACT FROM AUTHOR]

Aphelinus asychis Walker ( Hymenoptera: Aphelinidae) and Aphidius gifuensis Ashmead ( Hymenoptera: Braconidae: Aphidiinae) are solitary kionobiont endoparasitoids, which can parasitize the green peach aphid, Myzus persicae ( Sulzer) ( Hemiptera: Aphididae). We determined the influence of oviposition sequence and various time intervals (0, 24, 48, and 72 h) between two ovipositions on self- and conspecific discrimination and interspecific intrinsic competition between A. asychis and A. gifuensis. When offered unparasitized M. persicae and those parasitized by the other parasitoid species, the two parasitoid species oviposited more often in unparasitized hosts. Aphelinus asychis and A. gifuensis could, however, not avoid to multiparasitize hosts parasitized by the other species. Both parasitoid species had a limited interspecific discrimination ability through ovipositor insertion to detect internal cues. Aphidius gifuensis most often out-competed A. asychis. The outcome of this interspecific competition was not influenced by oviposition sequence or time intervals between two ovipositions. Aphidius gifuensis eliminated competitors by physical combat at the first instar and probably by physiological suppression in later stages; A. asychis possibly used physiological suppression in all larval stages. [ABSTRACT FROM AUTHOR]

An adult free-ranged female maned wolf was rescued from a periurban area subject to anthropogenic disturbances in the Minas Gerais, Brazil. The animal presented poor body condition and anemia. The clinical condition rapidly deteriorated culminating in dead and a necropsy was performed. The main gross lesions were marked anemia and blood content in the intestines accompanied by many types of parasites. The protozoa Rangelia vitalii was identified by histopathological analysis predominantly within the cytoplasm of endothelial cells of capillaries of the small intestine. The lymph nodes, spleen, bone marrow, dermis, lungs and kidney had similar protozoal forms but with mild or moderate intensity. Rangelia vitalii was confirmed by molecular assays. Hepatozoon sp., Leishmania sp., and Entamoeba spp., apparently not related to the clinical signs were also detected. The myriad parasites found in the intestines included nematodes ( Ancylostoma caninum , A . braziliensis ,, Molineus sp., Pterygodermatites sp., and Trichuris sp.), cestodes ( Spirometra sp.) and (acanthocephalans. To our knowledge, R . vitalii was identified in C . brachyurus for the first time. These findings emphasize the fragility of Brazilian ecosystems, especially in disturbed areas, reinforcing the necessity of efforts to preserve these areas and wild carnivores, some of which are threatened with extinction, such as the maned wolf. [ABSTRACT FROM AUTHOR]

Parasites constitute essential elements of biodiversity, playing fundamental roles for the functioning and configuration of any ecosystem. The continuous and accelerated human expansion into previously pristine territories is changing landscape structure and climatic regimes that could alter host – parasite dynamics. We explore the influence of landscape structure and habitat quality on gastrointestinal parasites in several species of mammals inhabiting remnants of tall evergreen forest within a matrix of anthropic vegetation. Here, we record 32 taxa of gastrointestinal parasites with nematodes as the most diverse group. Landscape variables such as forest edge density, river density and percentage of conserved habitat were among the best predictors of gastrointestinal parasites. Parasite species richness increased with a higher proportion of conserved habitat, but hosts living in disturbed areas show higher intensity of infection. The results presented here indicate that parasites are susceptible to habitat perturbation. It is pertinent to keep monitoring wildlife health in human dominated landscapes to understand disease dynamics, zoonotic risk, and ecosystem health. [Display omitted] [ABSTRACT FROM AUTHOR]

The most common infections in human beings are caused by intestinal parasites. They can lead to a number of harmful effects, which could include, among others, intestinal obstruction, malnutrition, iron deficiency anemia, diarrhea, and poor absorption. In Brazil, enteroparasites are one of the main public health issues. The present study aims at analyzing the distribution and frequency of enteroparasite occurrence in 635 children from seven community schools in the city of Guarapuava, Paraná (PR). In addition, we used similarity and diversity indices to analyze the parasite community. We found 475 samples with at least one parasite showing that 75.27% of children had enteroparasites. A smaller fraction (26.73%) of children harbored several parasites (multiparasitism), especially Giardia duodenalis (56%), and Ascaris lumbricoides (18%). Statistical analysis showed that three (out of seven) children communities had higher similarity in frequency and amount of parasites. Our results suggest that the children studied were highly infected by enteroparasites. These levels of infestation could be related to several factors, such as climate, social and economic conditions and characteristics of the parasites.As infecções mais freqüentemente encontradas em seres humanos são ocasionadas por parasitos intestinais, os quais podem causar danos aos hospedeiros, que incluem, entre outros agravos, a obstrução intestinal, desnutrição, anemia por deficiência de ferro, quadros de diarréia e de má absorção. No Brasil, as enteroparasitoses estão entre os principais problemas de saúde pública. Este trabalho teve como objetivo avaliar a distribuição e freqüência de enteroparasitos em 635 crianças pertencentes a sete comunidades escolares do município de Guarapuava - PR. Além disso, verificar índices de similaridade e diversidade de parasitas nas comunidades. Nos resultados, foram encontradas 475 amostras positivas para pelo menos um parasito, cuja prevalência de enteroparasitoses nesta população foi de 75,27 % e a ocorrência de casos de poliparasitismo de 26,73 %, dos quais foram registrados maiores índices de infecções por Giardia duodenalis (56 %) e Ascaris lumbricoides (18 %). A análise estatística mostrou que três das sete comunidades avaliadas apresentaram maior índice de similaridade quanto à freqüência e carga parasitária. Nossos resultados sugerem que as crianças avaliadas apresentavam altos índices de infecção por enteroparasitas e que fatores como clima, condições sociais e econômicas da população estudada e características próprias do parasito podem estar facilitando o acometimento destes indivíduos.

Asaphes suspensus (Nees) and Dendrocerus carpenteri (Curtis) are common aphid hyperparasitoids that attack aphidiine primary parasitoids in mummified aphids. In this study, we investigated the self- and interspecific host discrimination and interspecific ovicidal behavior of A. suspensus and D. carpenteri. In choice tests, females of both species laid significantly more eggs on unparasitized hosts than on hosts parasitized by themselves. Interspecific host discrimination was observed in D. carpenteri, which avoided oviposition on hosts previously parasitized by A. suspensus. Asaphes suspensus, however, did not avoid oviposition on hosts parasitized by D. carpenteri. Dissection of mummies after experimental trials of interspecific discrimination revealed that damaged D. carpenteri eggs with a concave puncture site were found only when A. suspensus laid eggs on hosts parasitized by D. carpenteri. Additional observations indicated that most D. carpenteri eggs on parasitized hosts exposed to A. suspensus oviposition behavior were killed (~85 %). The apparent lack of interspecific host discrimination by A. suspensus suggests that the ovicidal ability of this species diminishes its fitness loss by multiparasitism. [ABSTRACT FROM AUTHOR]

The seasonal pattern of parasitism by a parasitoid can be influenced by many factors, such as interspecific competition and host instar preference. We conducted field and laboratory experiments to describe the seasonal pattern of parasitism of spruce budworm Choristoneura fumiferana (Clemens) larvae by Tranosema rostrale (Brischke), and to investigate whether this pattern can be explained by interaction with other parasitoid species, or by host instar preference. Larval survival, developmental time, sex ratio, and adult size of T. rostrale developing in different host instars were also measured to further assess the potential importance of host instar on parasitoid life history. Parasitism by T. rostrale increased over the season, reaching the highest rate during the fourth-instar larva, and then decreased again until the sixth-instar. At the same time, parasitism by another parasitoid, Elachertus cacoeciae (Howard), increased over the season, and multiparasitism with T. rostrale suggests potential competition between these two parasitoids. Tranosema rostrale showed no host instar preference when third- to sixth-instar larvae were exposed simultaneously in a manipulative field experiment. The proportion of females emerging from spruce budworm larvae increased over the season; however, no difference in sex ratio was observed in the manipulative field experiment. Only male pupal development time and adult size were marginally increased in fifth-instar spruce budworm larvae. We conclude that T. rostrale's seasonal phenology or competition with E. cacoeciae, but not host instar preference, were possibly responsible for the observed seasonal pattern of parasitism. [ABSTRACT FROM AUTHOR]

Background: The host represents a heterogeneous ecosystem where multiple parasite species co-occur and interact with each other for space and resources. Although these interactions may rule the features of an infracommunity and may shape the infracommunity response to external perturbations, the resilience of ectoparasite communities to new infestations remains poorly explored. Methods: We analysed the composition of the ectoparasite communities found on 214 individual Iberian ibexes (Capra pyrenaica) inhabiting the Sierra Nevada Natural Space, southern Spain. Using classification and regression trees, we explored how the presence of Sarcoptes scabiei (a highly contagious mite), the off-host environment and the host sex govern the prevalence and abundance of lice and ticks. Null model analysis was applied to assess the impact of S. scabiei on the structure of the ectoparasite communities. Results: Our results suggest that S. scabiei infestation acts in tandem with off-host environment and host sex to define the prevalence and abundance of lice and ticks. We also provided evidence for differences in species co-occurrence only at the early stages of S. scabiei infestation. Regarding species diversity, we recorded that ectoparasite communities in scabietic ibexes reached a high richness faster than those in healthy individuals. Conclusions: Even though we show that ectoparasite burden is correlated with S. scabiei infestation, off-host environment and host sex, the species response to S. scabiei infestation and climate seem to be highly variable and influenced by ectoparasite life-history traits. Ectoparasite communities also appear resilient to perturbations which is in agreement with what was previously reported for endoparasites. Future refinement of sample collection and the incorporation of ecological and epidemiological-related variables may allow us to establish causal effects and deepen the knowledge about the mechanisms and consequences of ectoparasite interactions. [ABSTRACT FROM AUTHOR]

Anastrepha fraterculus (Wiedemann) is a serious pest of commercial fruit production in Argentina. Consequently, biological control is being taken into consideration as a key component of ongoing area-wide fruit fly management strategies. Two parasitoid species are currently considered for mass production and augmentative releases against pest species in the genus Anastrepha in the Americas: the braconid Diachasmimorpha longicaudata (Ashmead), a larval-prepupal koinobiont endoparasitoid, and the diapriid Coptera haywardi (Ogloblin), a native idiobiont pupal endoparasitoid. The prediction that the combined use of D. longicaudata and C. haywardi would be more efficient at suppressing A. fraterculus populations than using them individually was tested under natural environmental conditions. Particularly, the efficacy of both parasitoid species to kill their host, the proportion of superparasitism and the effect of intrinsic competition on effectiveness of host control were determined. Females of both parasitoids were singly and sequentially released inside a field cage. Peaches artificially inoculated with A. fraterculus larvae were exposed to D. longicaudata , whereas A. fraterculus pupae inside Petri dishes were exposed to C. haywardi . While used separately, effectiveness rates of D. longicaudata and C. haywardi were around 75% and 56%, respectively. However, the total efficacy increased to 93% when they were used sequentially. Coptera haywardi was able to attack hosts that had escaped to D. longicaudata parasitism, contributing by around 19% of the total parasitism in A. fraterculus . Both parasitoid species would induce host mortality through superparasitism. The simultaneous use of both parasitoids in fruit-growing regions for the biological control of A. fraterculus in Argentina is recommended. [ABSTRACT FROM AUTHOR]

Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae) is a polyphagous parasitoid known to have an extremely wide host range, attacking larvae from at least 11 lepidopteran families. It was first detected in New Zealand in 1996 and spread rapidly, raising concerns that it may disrupt an integrated pest management program for Helicoverpa armigera (Hübner) that relied on two introduced larval parasitoids: Cotesia kazak and Microplitis croceipes. A series of laboratory experiments was undertaken to assess larval competition among these three parasitoid species. H. armigera larvae were exposed to the three parasitoid species in pairwise combinations and the subsequent formation of parasitoid cocoons and emergence of adults were recorded. Separate assays were run with 0, 24 and 48 h time intervals between ovipositions by each wasp species. The results showed that C. kazak prevailed over M. pulchricornis and M. croceipes in all experimental combinations and time intervals, accounting for 79–100% of parasitoid cocoons, and that M. pulchricornis was similarly dominant over M. croceipes . The observed dominance of C. kazak in processing tomato crops in New Zealand may be partly explained by the competitive advantage of its larvae, combined with a reportedly faster development rate. However, the nature of the competitive relationship between these species may well be modified by extrinsic factors in the field. In particular, M. pulchricornis may gain an advantage in more diverse cropping systems where it may exploit alternative hosts that are not suitable for the other species. [ABSTRACT FROM AUTHOR]

Multiparasitism (females of multiple species parasitizing the same host) is a ubiquitous phenomenon in parasitoids, yet the role of within-host competition has been mostly ignored in multiparasitoid-host models. Here we study the effect of varying the degree of competition at different life stages: competition over oviposition sites (between-adult competition) and larval competition over resources within the host (within-host competition). We adapt a Nicholson-Bailey model to allow for varying levels of between-adult competition (varying the overlap in species distributions) and withinhost competition (varying the number of offspring that can successfully emerge from a host). Surprisingly, while stronger between-adult competition reduces coexistence, stronger within-host competition promotes it. Asymmetric between-adult competition (a fecundity difference between the two species) reduces coexistence when compared to symmetric competition; this can be counteracted by asymmetric within-host competition (within-host competitive advantage of the lower-fecundity species), but only when within-host competition is strong and the correlation between the parasitoids' distributions is intermediate. We discuss our results in the context of the interaction between two parasitoid species, Nasonia vitripennis and Nasonia giraulti, which have strongly correlated distributions and high levels of multiparasitism in the field. We conclude that either low or asymmetric within-host competition is unlikely to explain their coexistence. [ABSTRACT FROM AUTHOR]

On the basis of a twenty-year investigation, the life-cycle of Torymus cyanimus Boheman (Hymenoptera: Torymidae), a hyperparasitoid of a gall-forming fly in the Volga-Kama region is described. This parasitoid is the top-consumer in a food chain on Cirsium setosum (Willdenow) Iljin, in which the herbivore is Urophora cardui L. (Diptera: Tephritidae) and the primary parasitoids belong to the genus Eurytoma (Hymenoptera: Eurytomidae). Mating and oviposition behaviour were studied, and the superparasitism and larval cannibalism investigated in the second parasitoid generation. The superparasitism in T. cyanimus evolved in connection with the ovipositor elongation, leading to eggs being laid later when the fly host has already been completely consumed by larvae of Eurytoma serratulae F. Hyperparasitism and larval cannibalism in the second generation of T. cyanimus might account for the evolution of hyperparasitism in this species.