Detection of ectoparasites and investigation of infection by Rickettsia spp. and Trypanosoma spp. in bats from Rio Grande do Sul, Brazil.

This study aimed to investigate the presence of ectoparasites and the occurrence of natural infection by Rickettsia spp. and Trypanosoma spp. in bats from Rio Grande do Sul (RS), Brazil. The evaluated animals were obtained from the Instituto de Pesquisas Veterinárias Desidério Finamor, sent by the Centro Estadual de Vigilância Sanitária, to carry out rabies diagnostic tests, during the period from 2016 to 2021. The bats came from 34 municipalities in RS. Of the 109 animals surveyed, 35.8% (39/109) had 385 ectoparasites, with an average of 9.9 parasites per animal. Of these bats, all had insectivorous feeding habits, with 35.9% (14/39) females and 64.1% (25/39) males. The co-parasitism of Chirnyssoides sp., Ewingana inaequalis, and Chiroptonyssus robustipes on Molossus currentium (Mammalia, Chiroptera) was recorded for the first time. All bats surveyed were negative for infection by the protozoan and bacteria. Thus, the expansion of the occurrence of these ectoparasites in insectivorous bats in RS was observed. Furthermore, this study corresponds to the first recorded interspecific associations for the species.

Video evidence that cuckoos farm their hosts by ejecting nestlings.

When host nests are scarce, avian brood parasites would benefit from behaviours that increase the availability of suitable nests. Several studies reported ejection of host nestlings from nests by brood parasites; however, whether brood parasites do so to induce the host to re-nest and thus increase opportunities for future parasitism (i.e. 'farming' behaviour) remains unclear. Here, we report observational evidence of farming behaviour by a common cuckoo Cuculus canorus female in a Daurian redstart Phoenicurus auroreus population: (1) the cuckoo destroyed a host nest by ejecting all nestlings, (2) the host then produced a new nest and (3) the cuckoo successfully parasitized the replacement nest. We suggest that farming behaviour may be more common, but often goes undetected because it requires intense nest monitoring.

The multidimensional spectrum of eco-evolutionary relationships between sharks and remoras.

Remoras are a highly specialised group of fishes known to associate with a range of marine megafauna, including elasmobranchs, cetaceans and marine reptiles. Remoras appear to benefit from these interspecific interactions through consumption of host dermal parasites or reduced cost of transport. Shark-remora associations are widely documented, yet our understanding of the costs and benefits involved in these interactions is poor. Studies frequently make claims about mutualistic, commensalistic or parasitic relationships without providing the necessary quantitative information necessary to make these claims. Here I explain why this approach is problematic, and proceed to examine shark-remora interactions in a rigorous eco-evolutionary framework. These interactions cannot be properly classified without considering net evolutionary fitness and context dependence. In reality, shark-remora interactions are best defined by a multidimensional spectrum of fitness consequences, with net fitness outcomes shifting between mutualism and parasitism (and vice versa) through space and time.

Variations and reduction of plastome are associated with the evolution of parasitism in Convolvulaceae.

Parasitic lifestyle can often relax the constraint on the plastome, leading to gene pseudogenization and loss, and resulting in diverse genomic structures and rampant genome degradation. Although several plastomes of parasitic Cuscuta have  been reported, the evolution of parasitism in the family Convolvulaceae which is linked to structural variations and reduction of plastome has not been well investigated. In this study, we assembled and collected 40 plastid genomes belonging to 23 species representing four subgenera of Cuscuta and ten species of autotrophic Convolvulaceae. Our findings revealed nine types of structural variations and six types of inverted repeat (IR) boundary variations in the plastome of Convolvulaceae spp. These structural variations were associated with the shift of parasitic lifestyle, and IR boundary shift, as well as the abundance of long repeats. Overall, the degradation of Cuscuta plastome proceeded gradually, with one clade exhibiting an accelerated degradation rate. We observed five stages of gene loss in Cuscuta, including NAD(P)H complex → PEP complex → Photosynthesis-related → Ribosomal protein subunits → ATP synthase complex. Based on our results, we speculated that the shift of parasitic lifestyle in early divergent time promoted relaxed selection on plastomes, leading to the accumulation of microvariations, which ultimately resulted in the plastome reduction. This study provides new evidence towards a better understanding of plastomic evolution, variation, and reduction in the genus Cuscuta.

Response of Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae) parasitized by the nematode Metaparasitylenchus hypothenemi Poinar (Tylenchida: Allantonematidae) to different colors of light.

Metaparasitylenchus hypothenemi is a nematode that naturally parasitizes Hypothenemus hampei in a coffee-producing region in Chiapas, Mexico. This study investigated changes in the attraction of parasitized borers to light. We compared the attraction of adult H. hampei females (parasitized and uninfected) to 14 different light wavelengths (350-670 nm) with a control (570 nm, yellow) under laboratory conditions. The response ranges of non-parasitized and parasitized borers were 370-650 nm and 340-650 nm, respectively. The attraction curve showed a similar shape in both borer groups (parasitized and non-parasitized), but a wide wavelength range (380-590 nm) attracted more parasitized than non-parasitized borers. The maximum response of the uninfected borers occurred at 520 nm (green), while parasitized borers exhibited three response peaks (380 nm, violet; 460 nm, blue; 520 nm, green). Parasitized borers were significantly more attracted to green light (520 nm) than to the control. The altered attraction to light in borers parasitized by M. hypothenemi is discussed from the perspective of possible host manipulation and the natural prevalence of this parasite.

The curious case of the disappearing piRNAs.

Small non-coding RNAs are key regulators of gene expression across eukaryotes. Piwi-interacting small RNAs (piRNAs) are a specific type of small non-coding RNAs, conserved across animals, which are best known as regulators of genome stability through their ability to target transposable elements for silencing. Despite the near ubiquitous presence of piRNAs in animal lineages, there are some examples where the piRNA pathway has been lost completely, most dramatically in nematodes where loss has occurred in at least four independent lineages. In this perspective I will provide an evaluation of the presence of piRNAs across animals, explaining how it is known that piRNAs are missing from certain organisms. I will then consider possible explanations for why the piRNA pathway might have been lost and evaluate the evidence in favor of each possible mechanism. While it is still impossible to provide definitive answers, these theories will prompt further investigations into why such a highly conserved pathway can nevertheless become dispensable in certain lineages. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs RNA Evolution and Genomics > RNA and Ribonucleoprotein Evolution.

Phylogeny, morphology, virulence, ecology, and host range of Ordospora pajunii (Ordosporidae), a microsporidian symbiont of Daphnia spp.

The impacts of microsporidia on host individuals are frequently subtle and can be context dependent. A key example of the latter comes from a recently discovered microsporidian symbiont of Daphnia, the net impact of which was found to shift from negative to positive based on environmental context. Given this, we hypothesized low baseline virulence of the microsporidian; here, we investigated the impact of infection on hosts in controlled conditions and the absence of other stressors. We also investigated its phylogenetic position, ecology, and host range. The genetic data indicate that the symbiont is Ordospora pajunii, a newly described microsporidian parasite of Daphnia. We show that O. pajunii infection damages the gut, causing infected epithelial cells to lose microvilli and then rupture. The prevalence of this microsporidian could be high (up to 100% in the lab and 77% of adults in the field). Its overall virulence was low in most cases, but some genotypes suffered reduced survival and/or reproduction. Susceptibility and virulence were strongly host-genotype dependent. We found that North American O. pajunii were able to infect multiple Daphnia species, including the European species Daphnia longispina, as well as Ceriodaphnia spp. Given the low, often undetectable virulence of this microsporidian and potentially far-reaching consequences of infections for the host when interacting with other pathogens or food, this Daphnia-O. pajunii symbiosis emerges as a valuable system for studying the mechanisms of context-dependent shifts between mutualism and parasitism, as well as for understanding how symbionts might alter host interactions with resources. IMPORTANCE: The net outcome of symbiosis depends on the costs and benefits to each partner. Those can be context dependent, driving the potential for an interaction to change between parasitism and mutualism. Understanding the baseline fitness impact in an interaction can help us understand those shifts; for an organism that is generally parasitic, it should be easier for it to become a mutualist if its baseline virulence is relatively low. Recently, a microsporidian was found to become beneficial to its Daphnia hosts in certain ecological contexts, but little was known about the symbiont (including its species identity). Here, we identify it as the microsporidium Ordospora pajunii. Despite the parasitic nature of microsporidia, we found O. pajunii to be, at most, mildly virulent; this helps explain why it can shift toward mutualism in certain ecological contexts and helps establish O. pajunii is a valuable model for investigating shifts along the mutualism-parasitism continuum.

Urban socioeconomic variation influences the ecology and evolution of trophic interactions.

As urbanization expands, it is becoming increasingly important to understand how anthropogenic activity is affecting ecological and evolutionary processes. Few studies have examined how human social patterns within cities can modify eco-evolutionary dynamics. We tested how socioeconomic variation corresponds with changes in trophic interactions and natural selection on prey phenotypes using the classic interaction between goldenrod gall flies (Eurosta solidaginis) and their natural enemies: birds, beetles, and parasitoid wasps. We sampled galls from 84 sites across neighbourhoods with varying socioeconomic levels, and quantified the frequency of predation/parasitism on flies and natural selection by each enemy. We found that bird predation was higher in the highest income neighbourhoods, increasing the strength of selection for smaller galls. Wasp and beetle attack, but not their strength of selection, increased in lower income neighbourhoods. We show that socioeconomic variation in cities can have strong unintended consequences for the ecology and evolution of trophic interactions.

Immune system modulation & virus transmission during parasitism identified by multi-species transcriptomics of a declining insect biocontrol system.

BACKGROUND: The Argentine stem weevil (ASW, Listronotus bonariensis) is a significant pasture pest in Aotearoa New Zealand, primarily controlled by the parasitoid biocontrol agent Microctonus hyperodae. Despite providing effective control of ASW soon after release, M. hyperodae parasitism rates have since declined significantly, with ASW hypothesised to have evolved resistance to its biocontrol agent. While the parasitism arsenal of M. hyperodae has previously been investigated, revealing many venom components and an exogenous novel DNA virus Microctonus hyperodae filamentous virus (MhFV), the effects of said arsenal on gene expression in ASW during parasitism have not been examined. In this study, we performed a multi-species transcriptomic analysis to investigate the biology of ASW parasitism by M. hyperodae, as well as the decline in efficacy of this biocontrol system. RESULTS: The transcriptomic response of ASW to parasitism by M. hyperodae involves modulation of the weevil's innate immune system, flight muscle components, and lipid and glucose metabolism. The multispecies approach also revealed continued expression of venom components in parasitised ASW, as well as the transmission of MhFV to weevils during parasitism and some interrupted parasitism attempts. Transcriptomics did not detect a clear indication of parasitoid avoidance or other mechanisms to explain biocontrol decline. CONCLUSIONS: This study has expanded our understanding of interactions between M. hyperodae and ASW in a biocontrol system of critical importance to Aotearoa-New Zealand's agricultural economy. Transmission of MhFV to ASW during successful and interrupted parasitism attempts may link to a premature mortality phenomenon in ASW, hypothesised to be a result of a toxin-antitoxin system. Further research into MhFV and its potential role in ASW premature mortality is required to explore whether manipulation of this viral infection has the potential to increase biocontrol efficacy in future.

Histone Acetylation Enhancing Host Melanization in Response to Parasitism by an Endoparasitoid Wasp.

Endoparasitoids are insects that develop within other insects, employing unique strategies to enhance their offspring's survival. They inject polydnavirus and/or venom into their hosts along with eggs, effectively suppressing the host's immune system. Polydnavirus from Braconidae and Ichneumonidae wasps can integrate into the host's genome to express viral genes using the host's transcription systems. However, the ability of parasitoids without polydnavirus to manipulate host gene expression remains unclear. Lysine acetylation (LysAc), a post-translational modification critical for gene regulation, is hypothesized to be used by endoparasitoids lacking polydnavirus. We utilized the Chalcidoidea wasp Tetrastichus brontispae, which lacks polydnavirus, as an idiobiont endoparasitoid model to test this hypothesis, with pupae of the nipa palm hispid beetle Octodonta nipae as the host. Parasitism by T. brontispae resulted in the reduced expression of histone deacetylase Rpd3 and elevated levels of LysAc modification at histones H3.3K9 and H3.3K14 through proteomics and LysAc modification omics. The knockdown of Rpd3 increased the expression level of OnPPAF1 and OnPPO involved in the phenoloxidase cascade, leading to melanization in the host body whereby it resembled a mummified parasitized pupa and ultimately causing pupa death. This study enhances our understanding of how endoparasitoids employ histone acetylation to regulate immunity-related genes, offering valuable insights into their survival strategies.

The Parasitism and Tumors Carcinogenesis: A Review Subject.

BACKGROUND: Multi-factorial reasons are an induction to cause cancer. Different infections and infestations with viruses, bacteria, and parasites have been detected for many years to be related to human carcinogenesis. PURPOSE: The study aimed to review all ideas of tumor carcinogenesis and its associations with parasitic infections and infestations. METHODS: We reviewed several articles (published and imprinted) by selecting, extracting, and synthesizing data about the relationship between cancers and parasites. RESULTS: Several helminths infections as schistosomiasis, are highly carcinogenic agents for bladder cancer, whereas trypanosomiasis has a bi-model role in cancer development. Leishmaniasis may be a cause of hepatocarcinoma, skin cancer, and lymphomas. In addition, malaria appears to be causative in the carcinogenesis of some cancers; as Burkitt lymphoma. Also, data from previous studies suggested that Strongyloides stercoralis may be a relevant co-factor in lymphomas. CONCLUSION: There are different mechanisms of parasitic infection to be enhancing in carcinogenesis of cancer in human.

Response of the symbiotic microbial community of Dioscorea opposita Thunb. cv. Tiegun to root-knot nematode infection.

Yam is an important medicinal and edible dual-purpose plant with high economic value. However, nematode damage severely affects its yield and quality. One of the major effects of nematode infestations is the secondary infection of pathogenic bacteria or fungi through entry wounds made by the nematodes. Understanding the response of the symbiotic microbial community of yam plants to nematodes is crucial for controlling such a disease. In this study, we investigated the rhizosphere and endophytic microbiomes shift after nematode infection during the tuber expansion stage in the Dioscorea opposita Thunb. cv. Tiegun yam. Our results revealed that soil depth affected the abundance of nematodes, and the relative number of Meloidogyne incognita was higher in the diseased soil at a depth of 16-40 cm than those at a depth of 0-15 cm and 41-70 cm. The abundance of and interactions among soil microbiota members were significantly correlated with root-knot nematode (RKN) parasitism at various soil depths. However, the comparison of the microbial alpha diversity and composition between healthy and diseased rhizosphere soil showed no difference. Compared with healthy soils, the co-occurrence networks of M. incognita-infested soils included a higher ratio of positive correlations linked to plant health. In addition, we detected a higher abundance of certain taxonomic groups belonging to Chitinophagaceae and Xanthobacteraceae in the rhizosphere of RKN-infested plants. The nematodes, besides causing direct damage to plants, also possess the ability to act synergistically with other pathogens, especially Ramicandelaber and Fusarium, leading to the development of disease complexes. In contrast to soil samples, RKN parasitism specifically had a significant effect on the composition and assembly of the root endophytic microbiota. The RKN colonization impacted a wide variety of endophytic microbiomes, including Pseudomonas, Sphingomonas, Rhizobium, Neocosmospora, and Fusarium. This study revealed the relationship between RKN disease and changes in the rhizosphere and endophytic microbial community, which may provide novel insights that help improve biological management of yam RKNs.

Phylogenomic analysis of Stylops reveals the evolutionary history of a Holarctic Strepsiptera radiation parasitizing wild bees.

Holarctic Stylops is the largest genus of the enigmatic insect order Strepsiptera, twisted winged parasites. Members of Stylops are obligate endoparasites of Andrena mining bees and exhibit extreme sexual dimorphism typical of Strepsiptera. So far, molecular studies on Stylops have focused on questions on species delimitation. Here, we utilize the power of whole genome sequencing to infer the phylogeny of this morphologically challenging genus from thousands of loci. We use a species tree method, concatenated maximum likelihood analysis and Bayesian analysis with a relaxed clock model to reconstruct the phylogeny of 46 Stylops species, estimate divergence times, evaluate topological consistency across methods and infer the root position. Furthermore, the biogeographical history and coevolutionary patterns with host species are assessed. All methods recovered a well resolved topology with close to all nodes maximally supported and only a handful of minor topological variations. Based on the result, we find that included species can be divided into 12 species groups, seven of them including only Palaearctic species, three Nearctic and two were geographically mixed. We find a strongly supported root position between a clade formed by the spreta, thwaitesi and gwynanae species groups and the remaining species and that the sister group of Stylops is Eurystylops or Eurystylops + Kinzelbachus. Our results indicate that Stylops originated in the Western Palaearctic or Western Palaearctic and Nearctic in the early Neogene or late Paleogene, with four independent dispersal events to the Nearctic. Cophylogenetic analyses indicate that the diversification of Stylops has been shaped by both significant coevolution with the mining bee hosts and host-shifting. The well resolved and strongly supported phylogeny will provide a valuable phylogenetic basis for further studies into the fascinating world of Strepsipterans.

Co-inoculation with novel nodule-inhabiting bacteria reduces the benefits of legume-rhizobium symbiosis.

The ecologically and economically vital symbiosis between nitrogen-fixing rhizobia and leguminous plants is often thought of as a bi-partite interaction, yet studies increasingly show the prevalence of non-rhizobial endophytes (NREs) that occupy nodules alongside rhizobia. Yet, what impact these NREs have on plant or rhizobium fitness remains unclear. Here, we investigated four NRE strains found to naturally co-occupy nodules of the legume Medicago truncatula alongside Sinorhizobium meliloti in native soils. Our objectives were to (1) examine the direct and indirect effects of NREs on M. truncatula and S. meliloti fitness, and (2) determine whether NREs can re-colonize root and nodule tissues upon reinoculation. We identified one NRE strain (522) as a novel Paenibacillus species, another strain (717A) as a novel Bacillus species, and the other two (702A and 733B) as novel Pseudomonas species. Additionally, we found that two NREs (Bacillus 717A and Pseudomonas 733B) reduced the fitness benefits obtained from symbiosis for both partners, while the other two (522, 702A) had little effect. Lastly, we found that NREs were able to co-infect host tissues alongside S. meliloti. This study demonstrates that variation of NREs present in natural populations must be considered to better understand legume-rhizobium dynamics in soil communities.

Host size matters for reproduction: Evolution of spawning preference and female reproductive phenotypes in mussel-symbiotic freshwater bitterling fishes.

Bitterling fishes evolve an idiosyncratic symbiosis with freshwater mussels, in which they are obligated to spawn in the gills of mussels for reproduction. In recent years, freshwater mussel populations have been drastically diminishing, due to accelerating anthropogenic impacts, which can be large threats to the risk of bitterling's extinction cascade (i.e. 'coextinction'). The host mussel size may be an important factor driving the adaptation and evolution of bitterling's reproductive phenotypes. Here we examined the host size preference and morphological adaptation of female bitterling to the host size from 17 localities at the Han River in Korea. Using our developed molecular-based species identification for bitterling's eggs/larvae inside the mussels, we further determined the spawning patterns of seven bitterling species. Mean length of spawned mussels (N = 453) was significantly larger than that of unspawned mussels (N = 1814), suggesting that bitterling prefers to use larger hosts as a spawning ground. Spawning probability was clearly greater as mussel size increases. Results of our reciprocal transplant experiments do provide some evidence supporting the 'bitterling's larger host preference' hypothesis. Interspecific competition appeared to be intense as two fish species often spawned eggs in the same mussel individuals simultaneously. Longer ovipositor and more elongated egg may evolve in females of Tanakia signifer in response to larger host environments. The observed bitterling's spawning preference for large-sized mussels may evolve perhaps because of the fitness advantage in relation to the offspring survival. Our findings further inform on the development of effective conservation and management strategy for the endangered bitterling fishes.

An interspecific foraging association with polar bears increases foraging opportunities for avian predators in a declining Arctic seabird colony.

Interspecific foraging associations (IFAs) are biological interactions where two or more species forage in association with each other. Climate-induced reductions in Arctic sea ice have increased polar bear (Ursus maritimus) foraging in seabird colonies, which creates foraging opportunities for avian predators. We used drone video of bears foraging within a common eider (Somateria mollissima) colony on East Bay Island (Nunavut, Canada) in 2017 to investigate herring gull (Larus argentatus) foraging in association with bears. We recorded nest visitation by gulls following n = 193 eider flushing events from nests during incubation. The probability of gulls visiting eider nests increased with higher number of gulls present (ß = 0.14 ± 0.03 [SE], p < .001) and for nests previously visited by a bear (ß = 1.14 ± 0.49 [SE], p < .02). In our model examining the probability of gulls consuming eggs from nests, we failed to detect statistically significant effects for the number of gulls present (ß = 0.09 ± 0.05 [SE], p < .07) or for nests previously visited by a bear (ß = -0.92 ± 0.71 [SE], p < .19). Gulls preferred to visit nests behind bears (χ2 = 18, df = 1, p < .0001), indicating gulls are risk averse in the presence of polar bears. Our study provides novel insights on an Arctic IFA, and we present evidence that gulls capitalize on nests made available due to disturbance associated with foraging bears, as eiders disturbed off their nest allow gulls easier access to eggs. We suggest the IFA between gulls and polar bears is parasitic, as gulls are consuming terrestrial resources which would have eventually been consumed by bears. This finding has implications for estimating the energetic contribution of bird eggs to polar bear summer diets in that the total number of available clutches to consume may be reduced due to avian predators.

Changes in capture availability due to infection can lead to detectable biases in population-level infectious disease parameters.

Correctly identifying the strength of selection that parasites impose on hosts is key to predicting epidemiological and evolutionary outcomes of host-parasite interactions. However, behavioral changes due to infection can alter the capture probability of infected hosts and thereby make selection difficult to estimate by standard sampling techniques. Mark-recapture approaches, which allow researchers to determine if some groups in a population are less likely to be captured than others, can be used to identify infection-driven capture biases. If a metric of interest directly compares infected and uninfected populations, calculated detection probabilities for both groups may be useful in identifying bias. Here, we use an individual-based simulation to test whether changes in capture rate due to infection can alter estimates of three key metrics: 1) reduction in the reproductive success of infected parents relative to uninfected parents, 2) the relative risk of infection for susceptible genotypes compared to resistant genotypes, and 3) changes in allele frequencies between generations. We explore the direction and underlying causes of the biases that emerge from these simulations. Finally, we argue that short series of mark-recapture sampling bouts, potentially implemented in under a week, can yield key data on detection bias due to infection while not adding a significantly higher burden to disease ecology studies.

Habitat shift of adult Caligus undulatus (Copepoda: Siphonostomatoida: Caligidae) from host fish to plankton in response to host behavior.

Before 2019, adults of the sea louse Caligus undulatus were reported exclusively in plankton from ocean samples worldwide and were not known to parasitize fish hosts. In 2019, the first instance of this caligid parasitizing a fish host, Japanese sardinella Sardinella zunasi, was reported in the Seto Inland Sea, Japan. The presently reported study aimed to investigate the biology and ecology of adult C. undulatus in plankton communities in the Seto Inland Sea and surrounding waters from March 2020 to November 2021. The occurrence of sea lice in plankton communities was restricted to the period of August-January, mainly between October and December with maximum plankton abundance (10.5 ind. per 1000 m3) recorded on 30 November 2020. All post-naupliar stages of C. undulatus were found on the host fish, and they represented a typical life cycle pattern known for Caligus species. The sex ratios in both planktonic and parasitic adults were not significantly different. The frequency of occurrence of planktonic and parasitic adult females with egg strings was 68 and 46%, respectively. The number of eggs per string was significantly higher in parasitic adult females (mean ± SD: 16.9 ± 8.6) than in planktonic females (10.4 ± 10.8). These data suggest that adult females were detached from their hosts and continued to produce eggs without feeding. Seasonal migration of S. zunasi to brackish water for spawning may result in the detachment of mature caligids from the host and may be effective in protecting the offspring, which are less tolerant of less brackish water.

Distinguishing cophylogenetic signal from phylogenetic congruence clarifies the interplay between evolutionary history and species interactions.

Interspecific interactions, including host-symbiont associations, can profoundly affect the evolution of the interacting species. Given the phylogenies of host and symbiont clades and knowledge of which host species interact with which symbiont, two questions are often asked: "Do closely related hosts interact with closely related symbionts?" and "Do host and symbiont phylogenies mirror one another?". These questions are intertwined and can even collapse under specific situations, such that they are often confused one with the other. However, in most situations, a positive answer to the first question, hereafter referred to as "cophylogenetic signal", does not imply a close match between the host and symbiont phylogenies. It suggests only that past evolutionary history has contributed to shaping present-day interactions, which can arise, for example, through present-day trait matching, or from a single ancient vicariance event that increases the probability that closely related species overlap geographically. A positive answer to the second, referred to as "phylogenetic congruence", is more restrictive as it suggests a close match between the two phylogenies, which may happen, for example, if symbiont diversification tracks host diversification or if the diversifications of the two clades were subject to the same succession of vicariance events. Here we apply a set of methods (ParaFit, PACo, and eMPRess), which significance is often interpreted as evidence for phylogenetic congruence, to simulations under three biologically realistic scenarios of trait matching, a single ancient vicariance event, and phylogenetic tracking with frequent cospeciation events. The latter is the only scenario that generates phylogenetic congruence, whereas the first two generate a cophylogenetic signal in the absence of phylogenetic congruence. We find that tests of global-fit methods (ParaFit and PACo) are significant under the three scenarios, whereas tests of event-based methods (eMPRess) are only significant under the scenario of phylogenetic tracking. Therefore, significant results from global-fit methods should be interpreted in terms of cophylogenetic signal and not phylogenetic congruence; such significant results can arise under scenarios when hosts and symbionts had independent evolutionary histories. Conversely, significant results from event-based methods suggest a strong form of dependency between hosts and symbionts evolutionary histories. Clarifying the patterns detected by different cophylogenetic methods is key to understanding how interspecific interactions shape and are shaped by evolution.

Floral resources enhance fitness of the parasitoid Hadronotus pennsylvanicus (Hymenoptera: Scelionidae) but not biological control of its host Leptoglossus zonatus (Heteroptera: Coreidae).

The diet of adult parasitoid wasps is vital for their survival and reproduction. However, the availability of food resources, such as plant nectar, can vary widely in cropping systems, potentially affecting parasitoid fitness and thereby biological control of pests. The egg parasitoid Hadronotus pennsylvanicus (Ashmead) (Hymenoptera: Scelionidae) is a potential biological control agent of the pistachio pest Leptoglossus zonatus (Dallas) (Heteroptera: Coreidae). While H. pennsylvanicus is known to attack L. zonatus eggs in California, USA, parasitism rates in orchards are highly variable. Floral resource provisioning has the potential to enhance parasitoid longevity and thus improve parasitism rates, leading to reduced pest densities. Here, a combination of field and laboratory studies was used to assess the influence of flowering groundcovers on the reproductive fitness of H. pennsylvanicus and the abundance of L. zonatus. Evaluated groundcovers included oat (Avena sativa L.), cowpea (Vigna unguiculata L.), white mustard (Sinapis alba L.), and buckwheat (Fagopyrum esculentum Moench). Under laboratory conditions, buckwheat and mustard provided the greatest benefit to female H. pennsylvanicus longevity. However, females provided a buckwheat diet produced the greatest number of offspring over the course of their lifetime. In field trials, flowering groundcovers did not influence the abundance of H. pennsylvanicus nor parasitism rates on L. zonatus. While the availability of floral resources can improve the reproductive fitness of H. pennsylvanicus, the use of groundcovers in pistachio did not enhance biological control of L. zonatus.