Influence of oviposition strategy of Nemorilla pyste and Nilea erecta (Diptera: Tachinidae) on parasitoid fertility and host mortality

AbstractThe recent Californian hot drought (2012–2016) precipitated unprecedented ponderosa pine (Pinus ponderosa) mortality, largely attributable to the western pine beetle (Dendroctonus brevicomis; WPB). Broad-scale climate conditions can directly shape tree mortality patterns, but mortality rates respond non-linearly to climate when local-scale forest characteristics influence the behavior of tree-killing bark beetles (e.g., WPB). To test for these cross-scale interactions, we conduct aerial drone surveys at 32 sites along a gradient of climatic water deficit (CWD) spanning 350 km of latitude and 1000 m of elevation in WPB-impacted Sierra Nevada forests. We map, measure, and classify over 450,000 trees within 9 km2, validating measurements with coincident field plots. We find greater size, proportion, and density of ponderosa pine (the WPB host) increase host mortality rates, as does greater CWD. Critically, we find a CWD/host size interaction such that larger trees amplify host mortality rates in hot/dry sites. Management strategies for climate change adaptation should consider how bark beetle disturbances can depend on cross-scale interactions, which challenge our ability to predict and understand patterns of tree mortality.

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Host mortality and variability in epizootics of Schistocephalus solidus infecting the threespine stickleback, Gasterosteus aculeatus

Parasitology ◽

10.1017/s003118201000048x ◽

2010 ◽

Vol 137 (11) ◽

pp. 1681-1686 ◽

Cited By ~ 21

Author(s):

D. C. HEINS ◽

E. L. BIRDEN ◽

J. A. BAKER

Keyword(s):

Gasterosteus Aculeatus ◽

Infected Fish ◽

Threespine Stickleback ◽

Intensity Of Infection ◽

Host Fish ◽

Schistocephalus Solidus ◽

Second Intermediate Host ◽

Host Mortality ◽

Abiotic And Biotic Factors ◽

Host Behaviour

SUMMARYAn analysis of the metrics of Schistocephalus solidus infection of the threespine stickleback, Gasterosteus aculeatus, in Walby Lake, Alaska, showed that an epizootic ended between 1996 and 1998 and another occurred between 1998 and 2003. The end of the first epizootic was associated with a crash in population size of the stickleback, which serves as the second intermediate host. The likely cause of the end of that epizootic is mass mortality of host fish over winter in 1996–1997. The deleterious impact of the parasite on host reproduction and increased host predation associated with parasitic manipulation of host behaviour and morphology to facilitate transmission might also have played a role, along with unknown environmental factors acting on heavily infected fish or fish in poor condition. The second epizootic was linked to relatively high levels of prevalence and mean intensity of infection, but parasite:host mass ratios were quite low at the peak and there were no apparent mass deaths of the host. A number of abiotic and biotic factors are likely to interact to contribute to the occurrence of epizootics in S. solidus, which appear to be unstable and variable. Epizootics appear to depend on particular and, at times, rare sets of circumstances.

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NOTES ON MATING BEHAVIOR AND OVIPOSITION OF CHRYSOCHARIS LARICINELLAE (HYMENOPTERA: EULOPHIDAE), A PARASITE OF THE LARCH CASEBEARER (COLEOPHORA LARICELLA)

The Canadian Entomologist ◽

10.4039/ent99326-3 ◽

1967 ◽

Vol 99 (3) ◽

pp. 326-331 ◽

Cited By ~ 33

Author(s):

F. W. Quednau

Keyword(s):

Mating Behavior ◽

Fourth Instar ◽

Egg Laying ◽

Feeding Pattern ◽

Host Feeding ◽

Chemical Surface ◽

Coleophora Laricella ◽

Host Mortality

AbstractChrysocharis laricinellae (Ratz.) mated readily in the laboratory when several individuals of both sexes were held together in a vial. The courtship dance performed by the male is described. Parasite females develop mature eggs 3 days after emergence and are apparently capable of resorbing the eggs if hosts are not available, and to produce new ones after host-feeding. Storage of eggs in the ovary for 5 months at 55°F and sterility (phasic castration) of certain individuals is reported. Longevity of egg-laying females at 75°F was about 1 month less than that of parasites that had been denied contact with hosts. Odor apparently plays little or no role in the location of the larch casebearer larvae by C. laricinellae, but chemical surface stimuli seem to exist on the surface of a mine or case of Coleophora laricella (Hbn.). The parasite is also stimulated by vibrations of the host in its case. The oviposition and host-feeding pattern of C. laricinellae is described. Host-feeding on fourth-instar larvae of the larch casebearer contributed little to host mortality.

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Host mortality and parasitoid impact

Pattern and Process in Host-Parasitoid Interactions ◽

10.1017/cbo9780511721885.006 ◽

1994 ◽

pp. 111-131 ◽

Cited By ~ 1

Keyword(s):

Host Mortality

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Seasonal growth and duration of the parasitic life stage of the landlocked sea lamprey (Petromyzon marinus)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f95-122 ◽

1995 ◽

Vol 52 (6) ◽

pp. 1257-1264 ◽

Cited By ~ 40

Author(s):

Roger A. Bergstedt ◽

William D. Swink

Keyword(s):

Seasonal Pattern ◽

Life Stage ◽

Petromyzon Marinus ◽

Biomass Accumulation ◽

Sea Lamprey ◽

Gonadal Development ◽

Adult Size ◽

Sea Lampreys ◽

Mean Size ◽

Host Mortality

We used lengths and weights of 2367 live parasitic-phase sea lampreys (Petromyzon marinus) collected from Lake Huron, 1984–1990, to calculate their mean size at half-month intervals. Growth in weight was linear during June through September; increments averaged 11.1 g per half month. Growth increased sharply in October to several times the summer rate. We speculate that the increase in growth in October is explained partly by water temperature and partly by an increase in appetite related to the onset of gonadal development. The greater compression of biomass accumulation in autumn than has been previously demonstrated better explains the autumn pulse of sea lamprey induced host mortality. Based on the seasonal pattern of growth and on recaptures of marked sea lampreys, we conclude that landlocked individuals grow to adult size and mature in one parasitic growth year. Regressions of weight (grams) on total length (millimetres) differed significantly among months, and the season of collection must be considered in predicting weight from length.

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The population dynamics of metacercariae of Apatemon gracilis (Trematoda: Digenea) in three species of lake-dwelling leeches

Parasitology ◽

10.1017/s0031182000081221 ◽

1986 ◽

Vol 93 (3) ◽

pp. 517-530 ◽

Cited By ~ 8

Author(s):

S. M. Spelling ◽

J. O. Young

Keyword(s):

Population Dynamics ◽

Relative Density ◽

Sexual Maturity ◽

Egg Production ◽

Seasonal Pattern ◽

Distinct Pattern ◽

The Other ◽

Mean Intensity ◽

Density Values ◽

Host Mortality

SUMMARYMonthly samples of the leeches Erpobdella octoculata, Glossiphonia complanata and Helobdella stagnalis were taken over a two-year period from an eutrophic, English lake to detect metacercariae of the trematode, Apatemon gracilis. In each cohort of each of the three leeches, prevalence was low in young individuals, rose to a peak in autumn/winter, and then declined until the cohort had almost died out; in E. octoculata and H. stagnalis a final brief increase occurred. Mean intensity and relative density values followed a similar seasonal pattern of change to that of prevalence in these last two species, but in G. complanata values fluctuated irregularly with no distinct pattern. The frequency distribution of the parasite in G. complanata was highly over-dispersed, but less so in the other two species. Infected E. octoculata reached sexual maturity. The parasite reduced egg production in G. complanata and H. stagnalis, but only by maximum values of 2·5 and 9% respectively. This reduction in fecundity is low compared to the subsequent high mortality, at 95% or more, of newly recruited young from as yet unidentified causes. Parasite-related host mortality was difficult to assess in young leeches, but there was some evidence for its occurrence in older leeches of E. octoculata and H. stagnalis. However, this is unlikely to play a prominent role in the control and regulation of lacustrine leech populations.

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Influence of Water Temperature on the Growth Rate of the Landlocked Sea Lamprey (Petromyzon marinus) and the Associated Rate of Host Mortality

Journal of the Fisheries Research Board of Canada ◽

10.1139/f77-197 ◽

1977 ◽

Vol 34 (9) ◽

pp. 1373-1378 ◽

Cited By ~ 24

Author(s):

G. J. Farmer ◽

F. W. H. Beamish ◽

P. F. Lett

Keyword(s):

Growth Rate ◽

Great Lakes ◽

Water Temperature ◽

Growth Rates ◽

Petromyzon Marinus ◽

Sea Lamprey ◽

Instantaneous Growth ◽

Exponential Decline ◽

Influence Of Water ◽

Host Mortality

Groups of sea lampreys (Petromyzon marinus) of 10–90 g initial weight were held at temperatures of 1–20 °C for 30 days and allowed to feed ad lib. on white suckers (Catostomus commersoni). Increases in water temperature and in lamprey size caused the rate of host mortality to increase in agreement with observations that mortality in the Great Lakes is seasonal. Instantaneous growth rates were maximal at 20 °C for lampreys of 10–30 g, the optimal temperature for growth shifting to 15 °C for larger lampreys of 30–90 g. Growth rates were intermediate at 10 °C and lowest at 4 °C for lampreys of all size. Accordingly, host mortality increased with temperature over the 4–20 °C range. At all experimental temperatures, increases in lamprey weight were accompanied by an exponential decline in instantaneous growth rates, a phenomenon also observed for teleosts. Laboratory growth rates at temperatures of 5–15 °C were comparable to rates observed for lampreys in Lake Huron between April and November and agree with the observation that lampreys feed in deeper waters between April and June before moving to warmer, shallower waters during the summer when growth rate increases. Key words: sea lamprey, white sucker, host, temperature, growth, Great Lakes, mortality

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Detection, not mortality, constrains the evolution of virulence

10.1101/2021.11.14.468516 ◽

2021 ◽

Author(s):

David A Kennedy

Keyword(s):

Mathematical Model ◽

Disease Severity ◽

Behavioral Change ◽

Scientific Literature ◽

Empirical Support ◽

Infectious Period ◽

Trade Off ◽

Evolution Of Virulence ◽

Host Mortality

Why would a pathogen evolve to kill its hosts when killing a host ends a pathogen's own opportunity for transmission? A vast body of scientific literature has attempted to answer this question using "trade-off theory," which posits that host mortality persists due to its cost being balanced by benefits of other traits that correlate with host mortality. The most commonly invoked trade-off is the mortality-transmission trade-off, where increasingly harmful pathogens are assumed to transmit at higher rates from hosts while the hosts are alive, but the pathogens truncate their infectious period by killing their hosts. Here I show that costs of mortality are too small to plausibly constrain the evolution of disease severity except in systems where survival is rare. I alternatively propose that disease severity can be much more readily constrained by a cost of behavioral change due to the detection of infection, whereby increasingly harmful pathogens have increasing likelihood of detection and behavioral change following detection, thereby limiting opportunities for transmission. Using a mathematical model, I show the conditions under which detection can limit disease severity. Ultimately, this argument may explain why empirical support for trade-off theory has been limited and mixed.

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Thermal effects on the seasonal dynamics of Paradiplozoon homoion (Bychowsky & Nagibina, 1959) parasitizing roach, Rutilus rutilus (L.)

Journal of Helminthology ◽

10.1017/s0022149x0000883x ◽

1989 ◽

Vol 63 (2) ◽

pp. 93-101 ◽

Cited By ~ 10

Author(s):

Johan Höglund ◽

Jan Thulin

Keyword(s):

Relative Density ◽

Nuclear Power ◽

Rutilus Rutilus ◽

Artificial Lake ◽

Roach Rutilus Rutilus ◽

Temporal Shift ◽

Total Prevalence ◽

Heated Area ◽

Host Mortality ◽

One Year

ABSTRACTThe prevalence and relative density of the monogenean Paradiplozoon homoion, were monitored over one year in populations of roach, Rutilus rutilus, captured in a thermally raised artificial lake located outside a nuclear power station and in a nearby reference locality. Recruitment of P. homoion started earlier in the warmer lake. A temporal shift of the life-cycle was thus observed but there were no differences between the total prevalence or the total relative density of the parasite in the two areas. Since there is no evidence of parasite-induced host mortality, or for the development of protective immunity, the main regulatory process in the heated area are most likely an increased mortality due to reduced thermal tolerance of the adult parasite.

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