Thermal ecology of western tent caterpillars <i>Malacosoma californicum pluviale</i> and infection by nucleopolyhedrovirus

Frid, Leonardo; Myers, Judith H.

doi:10.1046/j.1365-2311.2002.00460.x

Cited by 33 publications

(40 citation statements)

References 32 publications

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“…A number of previous studies have found that insects with a higher body temperature are more likely to survive viral, fungal, bacterial, microsporidial and even macroparasitic infections (Blanford, Thomas & Langewald 2000; Carruthers et al. 1992; Kobayashi, Inagaki & Kawase 1981; Mohamed, Coppel & Podgwaite 1985; Adamo 1998; Olsen & Hoy 2002; Frid & Myers 2002; Thomas & Blanford 2003) and that they even behaviourally induce ‘fever’ when they are infected (Karban 1988; McClain, Magnuson & Warner 1988; Watson, Mullens & Petersen 1993; Adamo 1998; Blanford, Thomas & Langewald 1998). Direct effects of temperature on haemocyte counts have also been reported: a gradual increase in temperature from 10 to 20 °C caused a significant increase in haemocyte number in the crab Carcinus maenus (Truscott & White 1990), and total haemocyte number was found to be significantly higher in the two crayfish species Pacifastacus leniusculus and Astacus astacus when kept at 18 °C rather than at 4 °C (Jiravanichpaisal, Söderhäll & Söderhäll 2004).…”

Section: Discussionmentioning

confidence: 99%

Interactions between environmental variables determine immunity in the Indian meal moth Plodia interpunctella

Triggs

Knell²

2011

Journal of Animal Ecology

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1. Animals raised in good environmental conditions are expected to have more resources to invest in immunity than those raised in poor conditions. Variation in immune activity and parasite resistance in response to changes in environmental temperature, population density and food quality have been shown in many invertebrate species. 2. Almost all studies to date have examined the effects of individual variables in isolation. The aim of this study was to address whether environmental factors interact to produce synergistic effects on phenoloxidase (PO) activity and haemocyte count, both indicators of immune system activity. Temperature, food quality and density were varied in a fully factorial design for a total of eight treatment combinations. 3. Strong interactions between the three environmental variables led to the magnitude and in some cases the direction of the effect of most variables changing as the other environmental factors were altered. Overall, food quality had the most important and consistent influence, larvae raised on a good-quality diet having substantially higher PO activity in every case and substantially higher haemocyte counts in all treatments except unheated/low density. 4. When food quality was good, the larvae showed 'density-dependent prophylaxis': raising their investment in immunity when population density is high. When food quality was poor and the temperature low, however, those larvae raised at high densities invested less in immunity. 5. Increased temperature is often thought to lead to increased immune reactivity in ectotherms, but we found that the effect of temperature was strongly dependent on the values of other environmental variables. PO activity increased with temperature when larvae were raised on good food or when density was high, but when food was poor and density low, a higher temperature led to reduced PO activity. A higher temperature led to higher haemocyte counts when density was high and food quality was poor, but in all other cases, the effect of increased temperature was either close to zero or somewhat negative. 6. Although PO activity and haemocyte count were weakly correlated across the whole data set, there were a number of treatments where the two measures responded in different ways to environmental change. Overall, effect sizes for PO activity were substantially higher than those for haemocyte count, indicating that the different components of the immune system vary in their sensitivity to environmental change. 7. Predictions of the effect of environmental or population change on immunity and disease dynamics based on laboratory experiments that only investigate the effects of single variable are likely to be inaccurate or even entirely wrong.

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Section: Discussionmentioning

confidence: 99%

Interactions between environmental variables determine immunity in the Indian meal moth Plodia interpunctella

Triggs

Knell²

2011

Journal of Animal Ecology

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“…1981; Johnson et al. 1982; Frid & Myers 2002). Because in our study a north‐south gradient of temperature (lower temperature to the north) correlated with the cline in virus frequency, we tested whether variations in temperature may impair virus transmission across generations, possibly explaining the pattern.…”

Section: Discussionmentioning

confidence: 99%

Prevalence of a virus inducing behavioural manipulation near species range border

Patot¹,

Martinez²,

Allemand³

et al. 2010

Molecular Ecology

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The densities of conspecific individuals may vary through space, especially at the edge of species range. This variation in density is predicted to influence the diffusion of species-specific horizontally transmitted symbionts. However, to date there is very little data on how parasite prevalence varies around the border of a host species. Using a molecular epidemiology approach, we studied the prevalence of a vertically and horizontally transmitted virus at the edge of the geographic range of its insect host, the Drosophila parasitoid wasp Leptopilina boulardi. L. boulardi is a Mediterranean parasitoid species showing a recent range expansion to the north (in France). The LbFV virus manipulates the behaviour of females, increasing their tendency to lay additional eggs in already parasitized Drosophila larvae (superparasitism). This is beneficial for the virus because it allows the virus to be horizontally transferred during superparasitism. We show that LbFV prevalence is very high in central populations, intermediate in marginal populations and almost absent from newly established peripheral populations of L. boulardi. We failed to detect any influence of temperature and diapause on viral transmission efficiency but we observed a clear relationship between prevalence and parasitoid density, and between parasitoid density and the occurrence of superparasitism, as predicted by our epidemiological model. Viral strains were all efficient at inducing the behavioural manipulation and viral gene sequencing revealed very low sequence variation. We conclude that the prevalence reached by the virus critically depends on density-dependent factors, i.e. superparasitism, underlying the selective pressures acting on the virus to manipulate the behaviour of the parasitoid.

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“…In neither case were the Hin dIII restriction fragment patterns identical to those shown here, and that of Keddie and Erlandson (1995) has considerably fewer bands than the isolate shown here, which has an estimated size of 129.4 kb. There are few comparable bioassay data for either species; Ebling and Kaupp (1997) cited an LD 50 value of 20 000 occlusion bodies for fourth‐instar M. disstria infected with MadiNPV, and Frid and Myers (2002) measured the LD 50 of third‐instar M. c. pluviale at ≈1000 occlusion bodies. In the current study, an LD 50 of 1629 occlusion bodies was estimated for third‐instar M. disstria larvae infected with MadiNPV and mortality in fourth‐ and fifth‐instar M. disstria was consistently above 50% in the bioassays, even with doses as low as ≈1000 occlusion bodies.…”

Section: Discussionmentioning

confidence: 99%

Nucleopolyhedroviruses of forest and western tent caterpillars: cross‐infectivity and evidence for activation of latent virus in high‐density field populations

Cooper

Cory

Theilmann

et al. 2003

Ecological Entomology

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Abstract. 1. Cyclic population dynamics of forest caterpillars are often associated with epizootics of nucleopolyhedrovirus, but it is not known how these viruses persist between generations or through the fluctuations in host population density.2. To explore the question of virus persistence at different phases of the population cycle, the nucleopolyhedroviruses of two species of tent caterpillar that co-occur in British Columbia, Canada, Malacosoma californicum pluviale (western tent caterpillar) and Malacosoma disstria (forest tent caterpillar), were characterised. The cross-infectivity of the viruses in these two host species was investigated to determine whether there might be a route for virus persistence via the alternative host species. Any virus produced in the cross-infections was characterised to confirm true cross-infection or to ascertain whether cross-inoculation triggered latent virus persisting within the population.3. The virus associated with forest tent caterpillars (MadiNPV) did not infect western tent caterpillars from low-density populations, nor did it trigger a latent virus infection; however, inoculation of forest tent caterpillars from high-density populations with virus from western tent caterpillars (McplNPV) resulted in viral infection, but without a dose±response relationship.4. Analysis of DNA profiles of virus resulting from cross-infection of the forest tent caterpillar with McplNPV, revealed that 88% of these infections were caused by MadiNPV rather than McplNPV; however the virus from all 44 infected individuals was identical and differed in DNA profile from the stock MadiNPV used for cross-infection. This suggests strongly that forest tent caterpillars from high-density field populations harbour a latent, persistent, or sublethal form of MadiNPV that was triggered by exposure to nucleopolyhedrovirus from the western tent caterpillar.5. Virus was not activated in western tent caterpillars collected over 2 years of late population decline and the first year of population increase.

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Thermal ecology of western tent caterpillars Malacosoma californicum pluviale and infection by nucleopolyhedrovirus

Cited by 33 publications

References 32 publications

Interactions between environmental variables determine immunity in the Indian meal moth Plodia interpunctella

Interactions between environmental variables determine immunity in the Indian meal moth Plodia interpunctella

Prevalence of a virus inducing behavioural manipulation near species range border

Nucleopolyhedroviruses of forest and western tent caterpillars: cross‐infectivity and evidence for activation of latent virus in high‐density field populations

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