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Eastern larch beetle Dendroctonus simplex LeConte has been outbreaking for the past two decades in the Great Lakes region of North America, impacting approximately 400,000 hectares of eastern larch Larix laricina (tamarack) forest in Minnesota, United States, alone. Range expansions of some Dendroctonus species driven by climate change have occurred across North America as rising temperatures increase climatically suitable habitats across latitudes and elevations. The range of eastern larch beetle is currently sympatric to that of its host, eastern larch, but the insect could, in theory, eventually access ranges of other species of Larix native to North America. We compared host suitability of two potential novel hosts, western larch (Larix occidentalis Nutt.) and subalpine larch (Larix lyalli Parl.) against the beetle's native host, eastern larch, using a reproductive success experiment conducted in cut bolts of all three species. We measured fertility, maternal gallery length, and offspring size and lipid content as metrics of reproductive success. We found beetles could reproduce in both novel Larix species, with subalpine larch having high levels of success compared to the beetle's native host, eastern larch. These findings suggest that subalpine larch may be at risk should a range expansion of eastern larch beetle occur. [ABSTRACT FROM AUTHOR]

Eastern larch beetle Dendroctonus simplex LeConte has been outbreaking for the past two decades in the Great Lakes region of North America, impacting approximately 400,000 hectares of eastern larch Larix laricina (tamarack) forest in Minnesota, United States, alone. Range expansions of some Dendroctonus species driven by climate change have occurred across North America as rising temperatures increase climatically suitable habitats across latitudes and elevations. The range of eastern larch beetle is currently sympatric to that of its host, eastern larch, but the insect could, in theory, eventually access ranges of other species of Larix native to North America. We compared host suitability of two potential novel hosts, western larch (Larix occidentalis Nutt.) and subalpine larch (Larix lyalli Parl.) against the beetle’s native host, eastern larch, using a reproductive success experiment conducted in cut bolts of all three species. We measured fertility, maternal gallery length, and offspring size and lipid content as metrics of reproductive success. We found beetles could reproduce in both novel Larix species, with subalpine larch having high levels of success compared to the beetle’s native host, eastern larch. These findings suggest that subalpine larch may be at risk should a range expansion of eastern larch beetle occur.

Host plant expansion is an important survival strategy for tephritids as they expand their range. Successful host expansion requires tephritids to adapt to the chemical and nonchemical properties of a novel host fruit, such as fruit color, phenology, and phytochemicals. These plant properties trigger a series of processes in tephritids, with each process having its own genetic basis, which means that various genes are involved in regulating host plant expansion by tephritids. This review summarizes current knowledge on the categories and roles of genes involved in host plant expansion in several important tephritid species, including genes related to chemoreception (olfactory and gustation), vision, digestion, detoxification, development, ribosomal and energy metabolism. Chemoreception- and detoxification- and digestion-related genes are stimulated by volatile chemicals and secondary chemicals of different hosts, respectively, which are involved in the regulation of nervous signal transduction that triggers behavioral, physical, and chemical responses to the novel host fruit. Vision-, nerve-, and development-related genes and metabolism-associated genes are activated in response to nonchemical stimuli from different hosts, such as color and phenology, to regulate a comprehensive adaptation of the extending host for tephritids. The chemical and nonchemical signals of hosts activate ribosomal and energy-related genes that result in the basic regulation of many processes of host expansion, including detoxification and development. These genes do not regulate novel host use individually, but multiple genes regulate multilevel adaptation to novel host fruits via multiple mechanisms. These genes may also be potential target genes for RNAi-based control of tephritid pests.

Bean common mosaic virus from the genus Potyvirus has a wide range of hosts and a very negative impact on cultivated crops from the genus Phaseolus. The risk of viral infection of economically important crops increases even if the carriers of the virus are related plant species growing on agroecological interfaces. Such plant species have emerged as new hosts for BCMV, usually harboring novel genetic variants of the virus. A novel genetic variant of BCMV was isolated from a symptomatic crownvetch plant, where the presence of this virus was confirmed via Western blot analysis and via amino acid identities in peptide fragments of CI, HC-pro, and CP proteins using the nanoLC-ESI-Q-TOF. The novel BCMV SVK isolate differed from the most genetically similar one in 0.91% of nucleotides and 1.55% of amino acids. The highest number of amino acid substitutions (8.8% of amino acids) was in the P1 protein, followed by CP (2.44% of amino acids). Minor substitutions were in Hc-pro, CI, and Nib proteins. The symptomatic crownvetch plant was confirmed as a new host and carrier of the novel BCMV isolate. [ABSTRACT FROM AUTHOR]

The mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), recently underwent a notable range-expansion event in western Canada, resulting in access to the novel host jack pine, Pinus banksiana Lamb. We assessed the suitability of jack pine for mountain pine beetle, as well as the historic host lodgepole pine, Pinus contorta Dougl. var. latifolia Engelm., and the non-Pinus host white spruce, Picea glauca (Moench) Voss, to help inform an assessment of the risk of future spread into Canada's boreal forest and to further our understanding of host use in bark beetles. Several performance traits we measured were similar between lodgepole pine and jack pine, but gallery length and productivity indicated that lodgepole pine was the more suitable host. Development appeared to be faster in jack pine; however, in contrast to previous studies, we attribute it to oviposition arresting earlier in the novel host compared to the other hosts and not a difference in development rate. Initial productivity was surprisingly high in spruce, but we found evidence of a delayed negative effect that manifested as reduced cold tolerance, delayed development, and high mortality of late-instar larvae. Although jack pine is a suitable host for the mountain pine beetle, our results indicate that the beetle's eruptive potential could be lower in jack pine compared to lodgepole pine, given all other factors are equal. Other factors that may also affect mountain pine beetle population dynamics require additional research and include the composition and structure of jack pine forests, environmental conditions, and biotic interactions. [ABSTRACT FROM AUTHOR]

The first representative of a seemingly novel virus family has been found during the metagenomic examination of a diseased and dead horse in the USA [Li et al. in J Gen Virol 96:2721–2733, 2015]. These authors have suggested the need for the establishment of a new family with the tentative name Kirkoviridae; however, the suggested name is not official yet. Soon after the discovery, similar, relatively large CRESS-DNA viruses have been detected in various animals in China and elsewhere. Besides the two main genes (rep and cap), characteristic for members of the family Circoviridae, the tentative kirkoviruses have considerably larger genomes of approximately 4000 nucleotides. Accordingly, these viruses possess three four additional ORFs coding for proteins of unknown function. This has been described previously. In the present manuscript, the authors report the sequence of kirkovirus-like viruses, detected by PCR in donkey excretes in China. From 73 samples, 8 were found positive. From three of these newly detected viruses, the full genomic sequence was determined, whereas from the other five only one gene, namely the replication-associated (Rep) protein was sequenced. [ABSTRACT FROM AUTHOR]

North American forests have been heavily impacted from the loss of ash trees (Fraxinus spp.) due to emerald ash borer (EAB, Agrilus planipennis) invasion. Recently, white fringetree (Chionanthus virginicus), an ash relative, has been found to support the development of EAB in ornamental plantings, but interactions between EAB and this plant have never been examined in wild populations. We monitored two wild white fringetree populations in Ohio throughout the invasion wave of EAB to examine its impacts and factors that increased the likelihood of attack. Within 2 years of study initiation, the majority of white ash (F. americana) were attacked by EAB in these areas, in contrast to a few individual fringetrees. By the end of 5 years, however, EAB attacked up to 30% of white fringetrees and caused branch mortality in several individual plants. The percentage of white fringetrees attacked was significantly lower than in white ash trees, the majority of ash died due to EAB. Those fringetrees that were attacked displayed signs of stress, including epicormic branching and canopy thinning, both symptoms of larval damage by EAB. Our results provide the first reported findings of the dynamics and impact of EAB on wild white fringetree populations. [ABSTRACT FROM AUTHOR]

Disruptive effects of climate change include range shifts, phenological mismatches among consumers and producers, and population declines. While these biological alterations have been widely documented, studies identifying specific mechanisms linking climate change to population declines are scarce. Extreme events, such as heatwaves can have devastating effects on living organisms and are increasing in frequency as Earth warms. Hence, understanding the effects of heatwaves on insects is necessary to inform conservation efforts and to develop predictions of population dynamics under future climate scenarios. Here, we experimentally evaluated the effects of heatwaves on the survival and phenology of the Baltimore Checkerspot (Euphydryas phaeton phaeton), a wetland butterfly with imperiled populations that has incorporated a novel host. We performed laboratory manipulations (implementing realistic temperature regimes) to assess the effect of heatwaves during summer and winter on the survival and phenology of E. p. phaeton. In addition, we analyzed historical temperature records to quantify the incidence of heatwaves within E. p. phaeton's range to assess their potential role in the decline of southeastern populations. We found that winter heatwaves with maximum temperatures of 20°C can have more devastating effects on survival than summer heatwaves (up to 41°C). Eggs endured acute heat stress during summer with no significant effects on phenology and survival; similarly, pre-overwintering larvae were robust to heatwave exposure, as only the most intense heatwave treatment reduced their survival (37% reduction compared to control conditions). By contrast, dormant larvae were the most vulnerable stage, as they lost from 2 to 6% of their body mass after a three-day summer heatwave. Furthermore, their exposure to winter heatwaves resulted in 75 to 100% mortality. Feeding on the native host provided higher resilience under thermal stress than feeding on the invasive, recently acquired host. Finally, both heatwave incidence and severity have increased in the southern range of E. p. phaeton in the period from 1894 to 2011. We show that warm winter days induced severe mortality, providing a mechanistic explanation of how climate change can trigger population declines in E. p. phaeton and other insects.

Influenza A virus (IAV) is known to circulate among human and animal reservoirs, yet there are few studies that address the potential for urban rodents to carry and shed IAV. Rodents are often used as influenza models in the lab, but the few field studies that have looked for evidence of IAV in rodents have done so primarily in rural areas following outbreaks of IAV in poultry. This study sought to assess the prevalence of IAV recovered from wild Norway rats in a dense urban location (Boston). To do this, we sampled the oronasal cavity, paws, and lungs of Norway rats trapped by the City of Boston's Inspectional Services from December 2016 to September 2018. All samples were screened by real-time, reverse transcriptase PCR targeting the conserved IAV matrix segment. A total of 163 rats were trapped, 18 of which (11.04%) were RT-PCR positive for IAV in either oronasal swabs (9), paw swabs (9), both (2), or lung homogenates (2). A generalized linear model indicated that month and geographic location were correlated with IAV-positive PCR status of rats. A seasonal trend in IAV-PCR status was observed with the highest prevalence occurring in the winter months (December–January) followed by a decline over the course of the year, reaching its lowest prevalence in September. Sex and weight of rats were not significantly associated with IAV-PCR status, suggesting that rodent demography is not a primary driver of infection. This pilot study provides evidence of the need to further investigate the role that wild rats may play as reservoirs or mechanical vectors for IAV circulation in urban environments across seasons.

In order to study the relationships between mistletoes and their host species, comprehensive collections of both mistletoes and hosts are needed. The effect of sampling effort on the estimation of mistletoe host range was demonstrated in a comparison of an inventory of host mistletoe interactions published by Downey in 1998 and a 2019 inventory presented here, which is based on data from collections in the Australian Virtual Herbarium and information in the literature. New hosts were recorded for 93% of the 90 Australian mistletoes. There were 338 previously known hosts recorded to be parasitised by additional mistletoe species, and 317 new host species that were not previously known as mistletoe hosts (25 being alien species). These were from 78 new host genera and 13 new host families. The total number of host species was 1186 within 327 genera from 92 host families. A total of 63% of all Australian mistletoes parasitise species of either Eucalyptus or Acacia or both these genera. The large rise in host species recorded in less than two decades between inventories suggests that current knowledge of hosts is still incomplete, such that further new hosts will be discovered in future. Some mistletoe species show a strong preference to one host family or genus but due to insufficient collecting it is premature to conclude that any of the three species known from a single host are host specific. A national survey of the hosts of Australian mistletoes revealed a 30% increase in host species since the previous inventory in 1998. A total of 63% of Australian mistletoes parasitise species of Acacia , or Eucalyptus or species from both of these genera. We recorded 317 species not previously known as hosts including 25 alien species. The increase in host numbers over 19 years suggests that information on hosts is still incomplete. These new data allow future analyses of host–parasite relationships to be made with greater accuracy. [ABSTRACT FROM AUTHOR]

Understanding the potential outcomes of interactions between native insects and invasive plants is important for predicting the magnitude of effects caused by an invader in its new environment. Here, we investigate the ability of the native western leaf beetle, Chrysochus cobaltinus, and a hybrid of North American Chrysochus species, (hybrid of eastern C. auratus and western C. cobaltinus) to initiate a novel association with introduced pale swallow-wort (Vincetoxicum rossicum) (Apocynaceae). This European vine is invasive in eastern North America but has not yet been encountered by C. cobaltinus in the field. Lab tests demonstrate that C. cobaltinus can feed on introduced V. rossicum foliage, and that they are not locally-specialized to hosts from which they were collected. Thus, adult C. cobaltinus may use V. rossicum as a transient host when encountered in the field. Chrysochus hybrids were unable to feed on introduced V. rossicum (similar to their C. auratus parents) but did feed on native North American Asclepias spp. (similar to their C. cobaltinus parents). Hybridization and subsequent gene introgression may explain both decreased feeding by western C. cobaltinus and increased feeding by eastern C. auratus on native Asclepias spp. in this region, but does not appear to affect feeding on V. rossicum. We predict the potential novel association between native C. cobaltinus and invasive V. rossicum will have a positive or neutral outcome for the beetles, but is unlikely to slow the spread of the vine in North America unless further adaptation occurs. [ABSTRACT FROM AUTHOR]

Herbivorous insects can defend themselves against pathogens via an immune response, which is influenced by the nutritional quality and phytochemistry of the host plant. However, it is unclear how these aspects of diet interact to influence the insect immune response and what role is played by ingested foliar microbes. We examined dietary protein, phytochemistry, and the caterpillar microbiome to understand variation in immune response of the Melissa blue butterfly, Lycaeides melissa. We also asked if these factors have host plant-specific effects by measuring L. melissa immune response when reared on a recently colonized exotic host plant (Medicago sativa) as compared to the immune response on an ancestral, native host (Astragalus canadensis). L. melissa did not experience immunological benefits directly related to consumption of the novel plant M. sativa. However, we did find negative, direct effects of phytochemical diversity and negative, direct effects of diet-derived microbial diversity on constitutive immune response for caterpillars fed M. sativa, as measured by phenoloxidase activity. Foliar protein did not directly influence the immune response, but did do so indirectly by increasing weight gain. Our results highlight the important effects of host diet on caterpillar physiology and raise the possibility that foliar microbiota, despite being rapidly passed through the gut, can affect the caterpillar immune response. [ABSTRACT FROM AUTHOR]

We illustrate an evolutionary host shift driven by increased fitness on a novel host, despite maladaptation to it in six separate host‐adaptive traits. Here, local adaptation is defined as possession of traits that provide advantage in specific environmental contexts; thus individuals can have higher fitness in benign environments to which they are maladapted than in demanding environments to which they are well adapted. A population of the butterfly Euphydryas editha adapted to a long‐lived, chemically well‐defended host, Pedicularis, had traditionally been under natural selection to avoid the ephemeral, less‐defended Collinsia. The lifespan of Collinsia was so short that it senesced before larvae entered diapause. After logging killed Pedicularis in clear‐cut patches and controlled burning simultaneously extended Collinsia lifespan, insect fitness on Collinsia in clearings suddenly became higher than on Pedicularis in adjacent unlogged patches. Collinsia was rapidly colonized and preference for it evolved, but insects feeding on it retained adaptations to Pedicularis in alighting bias, two aspects of postalighting oviposition preference, dispersal bias, geotaxis, and clutch size, all acting as maladaptations to Collinsia. Nonetheless, populations boomed on Collinsia in clearings, creating sources that fed pseudosinks in unlogged patches where Pedicularis was still used. After c. 20 years, butterfly populations in clearings disappeared and the metapopulation reverted to Pedicularis‐feeding. Here we show, via experimental manipulation of oviposition by local Pedicularis‐adapted and imported Collinsia‐adapted butterflies, that the highest survival at that time would have been from eggs laid in clearings by butterflies adapted to Collinsia. Second highest were locals on Pedicularis. In third place would have been locals on Collinsia in clearings, because local females maladaptively preferred senescent plants. Collinsia had been colonized despite maladaptation and, after successional changes, abandoned because of it. However, the abandoned Collinsia could still have provided the highest fitness, given appropriate adaptation. The butterflies had tumbled down an adaptive peak. [ABSTRACT FROM AUTHOR]

Abstract: The North American lodgepole pine Pinus contorta has been planted on 660 000 ha in Sweden. We compared the performance of Ips typographus and Pityogenes chalcographus in storm‐felled and standing pheromone‐baited trees of the historical host species Norway spruce (Picea abies) and lodgepole pine. In the first summer after a storm, I. typographus colonized 0.2% and P. chalcographus colonized 2.4% of the storm‐felled lodgepole pines compared with 31% and 25%, respectively, of the storm‐felled Norway spruces. In the second summer 1.6% and 41.5% of the lodgepole pines were colonized by I. typographus and P. chalcographus, respectively. The reproductive success of I. typographus was five‐fold higher in Norway spruce than in lodgepole pine. Other species colonizing lodgepole pine were Ips duplicatus, Orthotomicus proximus, Orthotomicus laricis, Monochamus sutor and Pissodes pini. The male attack densities of both bark beetle species required to overcome defences of standing pheromone‐baited trees were much higher in lodgepole pine than in Norway spruce. The reproductive success of I. typographus and P. chalcographus was approximately five‐ and 14‐fold higher, respectively, in Norway spruce than in lodgepole pine. Larvae of the most important groups of bark beetle enemies were present in both storm‐felled and standing pheromone‐baited lodgepole pines colonized by I. typographus and P. chalcographus. In the standing trees, the densities of enemy larvae were lower in lodgepole pine than in Norway spruce, whereas the opposite was true for storm‐felled trees. [ABSTRACT FROM AUTHOR]

The sugarbeet root maggot, Tetanops myopaeformis Röder (Diptera: Ulidiidae), is native to North America. However, its primary crop host, sugarbeet, Beta vulgaris L. was introduced to the continent from Europe in the late 19th century. This field and greenhouse research was conducted to compare the relative attractiveness of eight cultivated and wild plant species for oviposition by T. myopaeformis , and the suitability of these potential host plants for larval development to elucidate the potential native and current host range of this pest. Results indicated that females preferred ovipositing in soil immediately adjacent to or on the following plant species: sugarbeet; spinach, Spinacia olerocea L.; common lambsquarters, Chenopodium album L.; redroot pigweed, Amaranthus retroflexus L.; Palmer amaranth, Amaranthus palmeri S. Wats.; and to a lesser extent, spear saltbush, Atriplex patula L. Larval survival was greatest on spinach, sugarbeet, and spear saltbush, which all belong to the family Chenopodiaceae. Larval survival on these plants suggests that T. myopaeformis could have exploited wild chenopodiaceous plants or others within the order Caryophyllales before sugarbeet was introduced to North America. Low larval survival on common lambsquarters, redroot pigweed, and Palmer amaranth suggests that these species are suboptimal hosts, despite demonstrated attractiveness for oviposition. A general lack of oviposition preference by T. myopaeformis females was observed for sunflower, Helianthus annuus L. and common ragweed, Ambrosia artemisiifolia L. These results provide insights regarding the successful and somewhat rapid host preference shift by this insect to sugarbeet after cultivation of the crop began in the continent. [ABSTRACT FROM AUTHOR]

Abstract: Some subcortical insects have devastating effects on native tree communities in new ranges, despite benign interactions with their historical hosts. Examples of how insects, aggressive in their native habitat might respond in novel host environs are less common. One aggressive tree‐killing insect undergoing a dramatic range shift is the mountain pine beetle (Dendroctonus ponderosae Hopkins). Ongoing eastward expansion by the mountain pine beetle through the previously climatically unsuitable Canadian boreal forest may have large‐scale impacts on north eastern North American pine forests. No systematic studies have been conducted on potential reproduction of mountain pine beetle on pines common to north eastern North America. We report reproduction of mountain pine beetle in logs of novel pine species (jack, Pinus banksiana Lamb; red, Pinus resinosa Ait.; eastern white, Pinus strobus L.; and Scots Pinus sylvestris L.) compared to the two most common pine hosts in its historical range (ponderosa, Pinus ponderosa Dougl. ex. Laws. var. scopulorum Engelm. and lodgepole Pinus contorta Dougl. var. latifolia Engelm.) in a two year study. Successful reproduction of mountain pine beetle occurred in all novel hosts, demonstrating that constitutive defences pose no barrier to further range expansion. Despite the number of progeny in novel hosts on par with that of historical hosts, a greater number of adult brood in novel hosts died prior to emergence. Brood mortality was correlated with the number of brood that developed to adulthood prior to winter, particularly in red pine. Brood developed more rapidly in novel vs. historical pine hosts and, the summer after a warm fall, exhibited less synchronized emergence in novel hosts. Synthesis and applications. Outbreaks by an aggressive bark beetle may be possible outside its historical host range, but constrained by an interaction between host and seasonality. Our results suggest that pines common to north eastern North America are suitable hosts for mountain pine beetle and highlight the value of monitoring efforts and response preparations as the insect moves eastward. [ABSTRACT FROM AUTHOR]

A description of a new species of horsehair worm, Acutogordius taiwanensis sp. n., a redescription of Chordodes formosanus, and novel host records for the latter are provided. Acutogordius taiwanensis sp. n. is morphologically similar to A. protectus with moderately flat areoles on its tail tips, but is distinguishable by small mid-body ornamentations. Despite the distinct differences in the post-cloacal crescents between 14 male samples, their conspecific status, along with that of nine female samples, was upheld by a phylogenetic comparison of partial cytochrome oxidase subunit I (COI) sequences. Chordodes formosanus is another common horsehair worm species in Taiwan, which was previously believed to specifically parasitize Hierodula mantids. However, in this study, five C. formosanus were observed emerging from an Acromantis mantid, and two long-horned grasshopper hosts (Leptoteratura sp. and Holochlora japonica). These five worms showed high degrees of similarity in COI sequences and morphology, but one of these individuals bore abnormal crowned areoles, which has never been observed in C. formosanus, and may be attributed to the incomplete development of this particular individual. [ABSTRACT FROM AUTHOR]

Hesperomyces virescens is an ectoparasite of some Coccinellidae, which until the mid-1990s was relatively rarely only reported from warm regions in various parts of the world. Analysis of the host and distribution data of H. virescens recorded in the Western Palaearctic and North America reveals several trends in the occurrence and abundance of H. virescens: (1) it has recently been much more frequently recorded, (2) most of the recent records are for more northerly (colder) localities than the early records and (3) the recent records are mostly of a novel host, the invasive harlequin ladybird (Harmonia axyridis). While in North America H. virescens is almost exclusively found on H. axyridis, all European records of this association are very recent and still less numerous than records of Adalia bipunctata as a host. However, based on a relatively few published cases of the H. axyridis-H. virescens association in Europe and the case described in this paper, it is clear that the harlequin ladybird is currently the main host of this parasite. These changes in the abundance and geographical distribution of H. virescens are probably linked to some features of H. axyridis, such as its abundance, multivoltinism with overlapping generations, high level of promiscuity and overwintering in mass aggregations. The occurrence of these features in one species may make it especially suitable for H. virescens and other parasites that require close contact of host individuals for efficient transmission. Indeed, some of the data indicate that parasites other than H. virescens, like the podapolipid mite Coccipolipus hippodamiae and allantonematid nematodes of the genus Parasitylenchus may also heavily parasitize H. axyridis. We hypothesize that the acquisition of H. axyridis as a host by H. virescens, C. hippodamiae and Parasitylenchus spp. may have further consequences for the abundance and distribution of these parasites, including the expansion of their ranges to other continents colonized by invasive populations of this ladybird and areas in Asia where H. axyridis is native.

Population sizes and range of the native butterfly Pieris oleracea declined after habitat loss and parasitism by an exotic braconid wasp ( Cotesia glomerata) introduced to control the exotic invasive butterfly Pieris rapae. Further declines are attributed to the invasive exotic weed garlic mustard ( Alliaria petiolata), an oviposition sensory trap on which P. oleracea larval survival and growth are very poor. But a population of P. oleracea has adapted to garlic mustard over the past several decades, coincident with the introduction of a second parasitoid, C. rubecula, a specialist on P. rapae that is competitively dominant to C. glomerata. We used stochastic simulation models to assess the plausibility of a hypothesis that reduced parasitoid pressure over this time period enabled P. oleracea to adapt to A. petiolata. We simulated scenarios of trait proliferation via spontaneous mutation or immigration of the trait, and residual variation in the trait following the butterfly's isolation in North America. Results indicate that the most likely scenario for the population that has adapted to garlic mustard includes (1) a change in selection following garlic mustard invasion to favor previously neutral residual variation in the population, (2) release from parasitism, and (3) evolution of improved larval survival on garlic mustard, which allowed an increased host range, and potentially, population size. [ABSTRACT FROM AUTHOR]

Although several expression systems are currently available for the production of recombinant proteins, they still have some inherent disadvantages, thereby resulting in the desire to explore a novel expression system for producing recombinant proteins. Dunaliella salina ( D. salina) has been exploited as a novel expression system for the field of genetic engineering because of its distinct advantages, including low production cost, fast growth, easy culture, ease of transgenic manipulation, and modified abilities of transcription and translation. Thus far, studies on D. salina host have made great development and significant progress. This paper presents a comprehensive summary of the achievements of D. salina host from the following aspects: the advantages of D. salina cells, transformation methods, cloning of D. salina genes, and expression of exogenous genes into D. salina. Furthermore, the authors identified the current main obstacles and future application prospects for the recombinant proteins produced by D. salina, which could be used as a basis for the future maturation of D. salina expression system. [ABSTRACT FROM AUTHOR]

Highlights: [•] We examine cane toads from the southern invasion front for parasites and pathogens. [•] We compare the parasitism of native Australian frogs sympatric with cane toads. [•] Invading cane toads do alter the parasites or pathogens of native Australian frogs. [Copyright &y& Elsevier]

During host-breadth expansion, phytophagous insects incur risk from potentially deleterious novel host environments at the same time as potentially securing a potential escape in space or time from competing species., Bark beetles reproduce under the bark of stems and branches of mature, stressed or moribund trees, and may suffer high mortality from plant defences and inter- and intraspecific competition., An epidemic of mountain pine beetle ( Dendroctonus ponderosae Hopkins) in western Canada has extended to over 18.1 million hectares of lodgepole pine ( Pinus contorta Douglas ex. Loudon) forests., In some areas, mountain pine beetles have been found to reproduce within interior hybrid spruces [ Picea glauca ( Moench) Voss × engelmannii Parry ex. Engelmann], a normally rare occurrence., Using mountain pine beetles reared from naturally-infested interior hybrid spruce and lodgepole pine hosts, we examined the effect of female natal species and colonized host species on the ability to attract mates and reproduce within spruce and pine logs deployed as a choice assay in a field setting. Additionally, we examined whether the arrival and reproduction of competitors such as pine engravers ( Ips spp.) was associated with reduced brood production., Females reared from pine and spruce exhibited similar reproductive potentials. Recruitment and establishment of ovipositional galleries, larval galleries and pupal chambers were similar in the typical and novel hosts., Reproduction by mountain pine beetles in spruce, although successful, was significantly lower than in pine. This reduction occurred despite spruce logs being almost entirely free of competing secondary beetles. [ABSTRACT FROM AUTHOR]

Several cases of speciation by hybridization have been reported in fungi, mostly involving recent hybridizationl between closely related species. In the basidiomycete genus Microbotryum by contrast some species were suspected to have arisen by hybridization between moderately distant species. In particular two species, M. lagerheimii and M. silenes-acaulis, had different placements in phylogenetic trees depending on the genes considered. Microbotryum species exhibit bipolar heterothallism, and here we analyzed sequences of the two alternate pheromone receptors to obtain further insights on the occurrence of hybridizationl Indeed because mating-type loci are always heterozygous homoploid hybrid speciation should leave type locus by a permanent footprint at the mating-retaining the alternate alleles from their respective parental species. The trees obtained with each of the two pheromone receptors were well resolved, and the species relationships were in agreement with published phytogenies. Fungal pheromone receptor genes of basidiomycetes thus appear useful for phylogenetic studies, although it may not be true for die homobasidiomycetes where duplications of these genes have occurred. Furthermore an incongruence between the phylogenies of the two pheromone receptors was found for one species, M. lagerheimii, as previously observed between other nuclear genes. However additional species analyzed here revealed that the incongruence involved the whole clade including both M. lagerheimii and the Microbotryum species parasitizing Lychnis flos-cucucli. The ancestor of these species thus possibly arose via hybridization between distant ancestral lineages, although further studies should address alternative hypotheses, such as chance events during lineage sorting. [ABSTRACT FROM AUTHOR]

Abstract: Pseudocoremia suavis is a New Zealand endemic geometrid present in commercial pine plantations where it has occasionally reached pest levels. It is parasitized by a self-introduced, generalist, solitary, braconid endoparasitoid, Meteorus pulchricornis. Tritrophic impacts on M. pulchricornis of transgenic pine, Pinus radiata, expressing Bacillus thuringiensis (Bt) Cry1Ac toxin, were examined using a laboratory-based system with P. suavis as the host. Unparasitized P. suavis fed with Bt-expressing pine foliage had significantly higher mortality than those fed with control pine and surviving larvae had reduced growth rates and delayed pupation. Parasitoid survival from Bt pine-fed hosts was reduced significantly when pre- and post-emergence survival was combined. Observed pre-emergence host mortality in parasitized Bt pine-fed P. suavis was consistent with the level of host mortality expected if parasitism, which itself caused significant pre-emergence host death, and the Bt toxin were acting independently as larval mortality factors. Parasitized hosts fed on Bt pine had significantly reduced growth rates and parasitoids took longer to emerge. The degree of developmental delay caused by Bt appeared to be greater for unparasitized hosts than for parasitoids. There was no effect of Bt on the parasitoid pupal duration, weight of pupa in cocoon, or number of eggs in F 1 adults’ ovaries. Across both treatments, the number of days to parasitoid emergence was negatively correlated with host weight on parasitism day, and the number of eggs in F 1 adults’ ovaries was positively correlated with cocoon weight. [Copyright &y& Elsevier]

Herbivorous insects are characterized by a great diversity of host plant associations, yet, the processes driving host range evolution are not fully understood. When herbivores encounter a novel host, local selection pressures are expected to shape traits that mediate plant–insect interactions. I show that a leafmining fly, Amauromyza flavifrons (Meigen) (Diptera: Agromyzidae), suffers a profound fitness cost by ovipositing on a novel host, Beta vulgaris L. (sugar beet) (Chenopodiaceae). Leafminers from a sugar beet-free population readily oviposit on B. vulgaris leaves, whereas those collected from a population near sugar beet farms discriminate against B. vulgaris. This finding suggests that oviposition specificity in A. flavifrons populations may have evolved in response to the presence of the novel host, and represents the first evidence of host-avoidance evolution in the wild. Because this study compared only one pair of populations and thus lacks replication, future studies will test whether parallel evolution has occurred at B. vulgaris farm locales across North America. [ABSTRACT FROM AUTHOR]

The American swallow bug (Oeciacus vicarius) is an important ectoparasite of cliff swallows (Petrochelidon pyrrhonota) and is known to harbor several types of arbovirus. A recent study in northeast Texas suggested that O. vicarius might occur in barn swallows (Hirundo rustica) at rates much higher than previously thought. The purpose of this study was to determine the extent to which barn swallows in northeast Texas are parasitized by O. vicarius and how well this parasite is adapting to this novel host. A sample of 498 nests at 54 colonies was inspected for O. vicarius. Forty colonies (74.1%) were infected, while 310 nests (62.2%) were infected. Large colonies were more likely to be infected than small colonies. Colonies that also contained cliff swallows were more likely to be infected than colonies without cliff swallows. Infection levels in barn swallow nests were comparable to those reported for cliff swallows, though age and sex class ratios differed. Demographic changes among swallow species, including range expansions, increased colony sizes, and more frequent interspecific nesting associations have likely facilitated the movement of O. vicarius from the cliff swallow into a novel host, the barn swallow. [ABSTRACT FROM AUTHOR]

Invasive plants are generally thought to have negative impacts on native communities. Rarely, however, are the impacts of invasive plants on native insects examined, limiting our understanding of the broader effects of invasive plants on native habitats. In this study, I document the use of purple loosestrife, Lythrum salicaria L. (Lythraceae), an aggressive wetland invasive, by Hemileuca sp. (Saturniidae), a native silkmoth. This buckmoth is a unique ecological variant of the more widespread buck moth, Hemileuca maia (Drury), and is of conservation concern in some areas. Hemileuca sp. was regularly observed feeding on L. salicaria in 2003 and 2004 at two sites in southern Wisconsin. Densities of late instars were as high as 12 individuals/m² and caused significant defoliation of L. salicaria with an average 34% loss of foliage relative to undamaged plants. Experimental manipulations of Hemileuca sp. caterpillars showed that herbivory could decrease seed production as much as 66%. In a laboratory assay, Hemileuca sp. feeding on L. salicaria had significantly lower pupal mass and lower survivorship to pupation (24%) relative to larvae feeding on Salix foliage (90%). Moreover, in two-choice preference assays, larvae preferred Salix over Lythrum foliage. Populations of Hemileuca sp. were subject to intense parasitism (up to 93%) by a tachinid parasitoid, Leschenaultia flavipes (Bigot). This combination of factors suggests there may be significant negative selection on Hemileuca sp. feeding on L. salicaria and that invaded habitats may be ecological sinks for the native herbivores. [ABSTRACT FROM AUTHOR]

Parasitism of the coffee berry borer, Hypothenemus hampei (Ferrari) by Trichogramma pretiosum Riley resulted in high mortality of developing parasitoids and a low prevalence of adult emergence. A laboratory colony of T. pretiosum reproducing in H. hampei failed after three generations. Adult female T. pretiosum that developed in H. hampei were smaller and produced fewer eggs than conspecifics that developed in a standard lepidopteran host, Sitotroga cerealella (Olivier). Parasitoids that emerged from H. hampei preferentially parasitized S. cerealella over H. hampei. We conclude that T. pretiosum has little potential for biocontrol of the coffee berry borer. [ABSTRACT FROM AUTHOR]

The Sudden Oak Death (SOD) Blitzes consist of yearly surveys led by citizen scientists designed to map the distribution of Phytophthora ramorum , cause of the forest disease called SOD, across northern California. During the 2017 Santa Cruz County SOD Blitz, six rare or endangered Arctostaphylos (manzanita) species were found to be possibly symptomatic for the first time. Symptoms included branch cankers and associated canopy mortality, and affected multiple individuals per species. Isolates of P. ramorum were obtained from each of the six species and, through a 30-day-long inoculation experiment on live plants, Koch's postulates were completed for each one of them, conclusively determining that they all are hosts of this pathogen. Two additional manzanita species were later found to be apparently symptomatic in Marin County. Inoculations on detached branches using an isolate of P. ramorum obtained from one of the six rare species from Santa Cruz County were successful, suggesting that these two species may also be hosts of P. ramorum . Detached leaves of all eight species were also successfully inoculated at the University of California-Berkeley in fall 2018 and then again in spring 2019. In these cases, the same isolate was used for all inoculations, in order to obtain information on the comparative susceptibility of the eight species in question. Both branch and leaf inoculations identified significant interspecific differences in susceptibility. The production of sporangia was low on all species but it was not zero, suggesting that sporulation may cause within-plant and limited across-plant contagion, especially in rainy years.