Spillover of an alien parasite reduces expression of costly behaviour in native host species

The dilution effect was originally proposed to describe the negative effect of increased host diversity on parasite abundance; with greater host diversity, parasite levels per host are predicted to be lower due to a higher probability of dispersing parasites encountering non-competent hosts. Dilution effects could also occur in many mutualisms if dispersing symbionts encounter hosts that vary in their competency. The introduction of non-native hosts can change community competency of a local group of host species. Crayfish introductions are occurring world-wide and these introductions are likely disrupting native crayfish-symbiont systems. Branchiobdellidan symbionts declined on native Cambarus crayfish occurring in the presence and absence of non-native Faxonius crayfish in the New River, USA. We performed an experiment investigating the effect of host density (1 vs 2 native hosts) and host diversity (1 native host and 1 introduced host) on branchiobdellidan abundance. The introduced F. cristavarius is a non-competent host for these worms. Six C. ingens were stocked on a C. chasmodactylus in each treatment and worm numbers were followed over 34 days. Worm numbers decreased over time on C. chasmodactylus alone and in the treatment in which a C. chasmodactylus was paired with an F. cristavarius. Worm numbers remained highest in the 2 C. chasmodactylus treatment . There was no significant effect of host diversity on worm reproduction. Crayfish invasions may have negative effects on mutualistic symbionts depending on the competence of introduced hosts. Loss of native symbionts is one of the potential hidden, negative effects of invasions on native freshwater diversity.

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Interactions of Helicoverpa punctigera (Lepidoptera: Noctuidae) Larvae and Adults With Four Native Host Plants Relative to Field Use Patterns

Environmental Entomology ◽

10.1093/ee/nvaa160 ◽

2020 ◽

Author(s):

Lachlan C Jones ◽

Michelle A Rafter ◽

Gimme H Walter

Keyword(s):

Host Species ◽

Host Plants ◽

Survival Rates ◽

Larval Survival ◽

Relative Distribution ◽

Long Distance ◽

Primary Host ◽

Relative Attractiveness ◽

Native Host ◽

Lepidoptera Noctuidae

Abstract Generalist insect herbivores may be recorded from a great variety of host plants. Under natural conditions, however, they are almost invariably associated with a few primary host species on which most of the juveniles develop. We experimentally investigated the interaction of the generalist moth Helicoverpa punctigera Wallengren (Lepidoptera: Noctuidae) with four of its native host plants, two designated primary hosts and two secondary hosts (based on field observations). We tested whether primary host plants support higher survival rates of larvae and whether they are more attractive to ovipositing moths and feeding larvae. We also evaluated whether relative attractiveness of host plants for oviposition matches larval survival rates on them—the preference-performance hypothesis. Moths laid significantly more eggs on two of the four host plant species, one of them a primary host, the other a secondary host. Larvae developed best when reared on the attractive secondary host, developed at intermediate levels on the two primary hosts, and performed worst on the less attractive secondary host. Relative attractiveness of the four host plants to caterpillars differed from that of the moths. Neither adult nor larval attraction to host plants fully supported the preference-performance hypothesis, but oviposition was better correlated with larval survival rates than was larval attraction. Our results suggest the relative frequency at which particular host species are used in the field may depend on factors not yet considered including the long-distance attractants used by moths and the relative distribution of host species.

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Biology, Management, and Conservation of Lampreys in North America

Biology, Management, and Conservation of Lampreys in North America ◽

10.47886/9781934874134.ch9 ◽

2009 ◽

Keyword(s):

Host Species ◽

Lake Trout ◽

Human Impacts ◽

Handling Time ◽

Dry Mass ◽

Wisconsin River ◽

Ash Weight ◽

The Common ◽

Native Host ◽

Management And Conservation

Abstract.—Silver lamprey Ichthyomyzon unicuspis has been most strongly associated with native host species that are relatively large and have naked skin or relatively small scales, including paddlefish Polyodon spathula, lake sturgeon Acipenser fulvescens, lake trout Salvelinus namaycush, ictalurid catfishes, and esocids. In many regions, however, and especially in the southern part of the silver lamprey’s geographic range, these host species have declined in abundance through a combination of human impacts, and the most abundant large fish species is now the common carp Cyprinus carpio, an exotic species with large scales. Silver lampreys removed from paddlefish in the Wisconsin River and allowed to feed on carp in the laboratory displayed very little growth relative to lampreys in the river. Although paddlefish lack scales, skin densities of carp and paddlefish, measured as dry mass per unit area, were similar. However, dried samples of paddlefish skin displayed a substantial lipid residue, and skin density of paddlefish expressed as ash weight was less than that of carp. It is likely that increased handling time contributes to reduced growth by silver lampreys on carp. The importance of paddlefish skin lipids to silver lamprey feeding ecology should be investigated.

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First Report of Powdery Mildew Caused by Leveillula taurica on Giant Blazing Star (Mentzelia laevicaulis)

Plant Disease ◽

10.1094/pdis-94-1-0132a ◽

2010 ◽

Vol 94 (1) ◽

pp. 132-132 ◽

Cited By ~ 2

Author(s):

R. K. Sampangi ◽

D. A. Glawe ◽

T. Barlow ◽

S. K. Mohan

Keyword(s):

Powdery Mildew ◽

Pacific Northwest ◽

Host Species ◽

The United States ◽

Similar Species ◽

Voucher Specimen ◽

First Report ◽

Leveillula Taurica ◽

The Pacific ◽

Native Host

Mentzelia laevicaulis (Dougl. ex Hook.) Torr. & Gray (Loasaceae; common names are giant blazing star and smoothstem blazing star) is widely distributed throughout western North America in sites ranging from lowland deserts to mountainous areas in Canada and the United States. During a plant disease survey in June 2007 in the Owyhee Mountains, Canyon County, Idaho, leaves of M. laevicaulis displaying whitish, mycelial growth were collected from plants growing on stream banks and gravelly road embankments. Diseased leaves exhibited localized, chlorotic discolorations associated with signs of a powdery mildew. Of approximately 20 plants at the site, 50% were infected. White mycelia and conidia were more abundant on the adaxial leaf surfaces than on the abaxial surfaces. Severely diseased leaves were buckled and slightly twisted. By August and through September, sporulation was greatest on mature plants, and lowermost leaves were completely covered with flocculose, dense, white mycelia. Dimorphic conidia were lanceolate or cylindrical and measured (44-) 46 to 67 (-71) × (14-) 14.5 to 20 (-21) μm. DNA was extracted and PCR was used to amplify the internal transcribed spacer (ITS) region as described previously (2), except that primers ITS 5 and P3 (4) were used. The resulting 633-bp sequence (GenBank Accession No. GQ860947) included a 616-bp region identical to a sequence reported previously for Leveillula taurica (Lév.) Arnaud from eastern Washington (GenBank No. AY912077), as well as ITS regions from L. taurica previously reported from Iran (GenBank No. AB048350) (2) and Australia (GenBank No. AF 073351) (2). Based on the ITS sequence, the present fungus grouped within Khodaparast et al. (3) Clade 1 that included L. taurica strains they distinguished from other, superficially similar species of Leveillula. On the basis of morphological and sequence data, the fungus was determined to be L. taurica (1,3). A voucher specimen was deposited in the Mycology Herbarium (WSP) at Washington State University. To our knowledge, this is the first report of a named powdery mildew species from a member of the Loasaceae. The only previous report of a powdery mildew on a loasaceous host was an undetermined Oidium sp. on a species of Mentzelia (1). The discovery of L. taurica on a previously unknown native host species is further evidence that this introduced pathogen is becoming endemic to the Pacific Northwest. Native host species, such as M. laevicaulis, may play a role in the epidemiology of powdery mildew diseases caused by L. taurica on crop and ornamental species in the Pacific Northwest. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) D. A. Glawe et al. Mycol. Prog. 4:291, 2005. (3) S. A. Khodaparast et al. Mycol. Res. 105:909, 2001. (4) S. Takamatsu and Y. Kano. Mycoscience 42:135, 2001.

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Defence responses of native and invasive plants to the native generalist vine parasite Cassytha pubescens – anatomical and functional studies

Australian Journal of Botany ◽

10.1071/bt19136 ◽

2020 ◽

Vol 68 (4) ◽

pp. 300

Author(s):

Evelina Facelli ◽

Noriko Wynn ◽

Hong T. Tsang ◽

Jennifer R. Watling ◽

José M. Facelli

Keyword(s):

Host Species ◽

Vascular System ◽

The Other ◽

Defence Mechanisms ◽

Functional Studies ◽

Defence Responses ◽

Native Parasite ◽

Effective Transfer ◽

Native Host ◽

Potential Use

We investigated the responses of two invasive and two native host species to the parasitic vine Cassytha pubescens R.Br. using glasshouse experiments. We assessed growth of the parasite and its hosts, and anatomy and functionality of haustoria. Target hosts were infected using C. pubescens already established on a donor host. This enabled measurement of growth in target hosts that were detached (parasite connection severed) or not from the donor host. Haustorial connections to hosts were investigated using histological methods. We tested the functionality of haustoria in one invasive and one native host using radiolabelled phosphorus (32P). After it was severed from the donor host, C. pubescens grew poorly on the native host, Acacia myrtifolia (Sm.)Willd. This was likely due to a lack of effective functional haustorial development because although haustoria were firmly attached and morphologically alike those formed on the other hosts, their anatomy was different: their connections with the vascular system were not developed and there was no transfer of 32P from A. myrtifolia to the parasite. In contrast, the other three host species supported the growth of the parasite and had fully developed haustoria. Effective transfer of 32P from the invasive host to the parasite confirmed this. Our results suggest a range of defence mechanisms in C. pubescens hosts and are consistent with reports of strong detrimental effects on invasive hosts. Further, they amount to evidence for the potential use of a native parasite as biological control for invasive species.

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Light conditions affect the performance of Yponomeuta evonymellus on its native host Prunus padus and the alien Prunus serotina

Bulletin of Entomological Research ◽

10.1017/s0007485316000791 ◽

2016 ◽

Vol 107 (2) ◽

pp. 208-216 ◽

Cited By ~ 6

Author(s):

A. Łukowski ◽

M.J. Giertych ◽

U. Walczak ◽

E. Baraniak ◽

P. Karolewski

Keyword(s):

Host Species ◽

Insect Pest ◽

Light Condition ◽

Larval Feeding ◽

Light Conditions ◽

Plant Host ◽

Low Light ◽

Potential Fecundity ◽

Prunus Padus ◽

Native Host

AbstractThe bird cherry ermine moth, Yponomeuta evonymellus L., is considered an obligatory monophagous insect pest that feeds only on native European Prunus padus L. In recent years, however, increased larval feeding on alien P. serotina Ehrh. has been observed. In both species, general defoliation is extensive for shade grown trees, whereas it is high in P. padus, but very low in P. serotina, when trees are grown in full light conditions. The aim of the present study was to identify how the plant host species and light conditions affect the performance of Y. evonymellus. The influence of host species and light condition on their growth and development, characterized by the parameters of pupation, adult eclosion, body mass, potential fecundity, and wing size, was measured in a 2 × 2 experimental design (two light treatments, two hosts). In comparison with high light (HL) conditions, a greater percentage of pupation and a longer period and less dynamic adult emerge was observed under low light (LL) conditions. The effect of host species on these parameters was not significant. In contrast, mass, fecundity and all of the studied wing parameters were higher in larvae that grazed on P. padus than on P. serotina. Similarly the same parameters were also higher on shrubs in HL as compared with those grown under LL conditions. In general, light conditions, rather than plant species, were more often and to a greater extent, responsible for differences in the observed parameters of insect development and potential fecundity.

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Endangered Butterflies and their Non-Native Host Plants: Examining Shifting Values of Belonging in Restoration

Case Studies in the Environment ◽

10.1525/cse.2019.002147 ◽

2019 ◽

Vol 3 (1) ◽

pp. 1-9

Author(s):

Robert M. Anderson ◽

Amy M. Lambert

Keyword(s):

Ecological Restoration ◽

Native Species ◽

Puget Sound ◽

A Value ◽

The Social ◽

Remote Island ◽

Scientific Truth ◽

Native Host

The island marble butterfly (Euchloe ausonides insulanus), thought to be extinct throughout the 20th century until re-discovered on a single remote island in Puget Sound in 1998, has become the focus of a concerted protection effort to prevent its extinction. However, efforts to “restore” island marble habitat conflict with efforts to “restore” the prairie ecosystem where it lives, because of the butterfly’s use of a non-native “weedy” host plant. Through a case study of the island marble project, we examine the practice of ecological restoration as the enactment of particular norms that define which species are understood to belong in the place being restored. We contextualize this case study within ongoing debates over the value of “native” species, indicative of deep-seated uncertainties and anxieties about the role of human intervention to alter or manage landscapes and ecosystems, in the time commonly described as the “Anthropocene.” We interpret the question of “what plants and animals belong in a particular place?” as not a question of scientific truth, but a value-laden construct of environmental management in practice, and we argue for deeper reflexivity on the part of environmental scientists and managers about the social values that inform ecological restoration.

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