Metabolic theory of ecology successfully predicts distinct scaling of ectoparasite load on hosts

The impacts of parasites on hosts and the role that parasites play in ecosystems must be underlain by the load of parasites in individual hosts. To help explain and predict parasite load across a broad range of species, quantitative theory has been developed based on fundamental relationships between organism size, temperature and metabolic rate. Here, we elaborate on an aspect of that ‘scaling theory for parasitism’, and test a previously unexplored prediction, using new data for total ectoparasite load from 263 wild birds of 42 species. We reveal that, despite the expected substantial variation in parasite load among individual hosts, (i) the theory successfully predicts the distinct increase of ectoparasite load with host body size, indicating the importance of geometric scaling constraints on access to host resources, (ii) ectoparasite load appears ultimately limited by access—not to host space—but to host energy, and (iii) there is a currency-dependent shift in taxonomic dominance of parasite load on larger birds. Hence, these results reveal a seemingly new macroecological pattern, underscore the utility of energy flux as a currency for parasitism and highlight the promise of using scaling theory to provide baseline expectations for parasite load for a diversity of host species.

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Body size, not age, predicts parasite load in Clark’s Spiny Lizards (Sceloporus clarkii)

Canadian Journal of Zoology ◽

10.1139/cjz-2017-0328 ◽

2019 ◽

Vol 97 (3) ◽

pp. 220-224 ◽

Cited By ~ 3

Author(s):

H.V. Watkins ◽

G. Blouin-Demers

Keyword(s):

Body Size ◽

Surface Area ◽

Intraspecific Variation ◽

Wild Population ◽

Parasite Load ◽

Older Individuals ◽

Fundamental Goal ◽

Males And Females ◽

Ectoparasite Load

Determining the factors that influence parasite load is a fundamental goal of parasitology. Body size often influences parasite load in reptiles, but it is unclear whether higher levels of parasitism are a result of greater surface area of individuals (a function of size) or of longer periods of exposure to parasites (a function of age). Using skeletochronology in a wild population of Clark’s Spiny Lizards (Sceloporus clarkii Baird and Girard, 1852), we tested the hypotheses that (i) larger individuals have higher parasite loads due to increased surface area available for colonization by parasites and their vectors and that (ii) older individuals have higher parasite loads because they have had longer exposure to parasites and their vectors. Males harboured more ectoparasites than females. Males and females differed in how body size influenced chigger (Acari: Trombiculidae) load; larger males harboured more chiggers than smaller males, but this was not the case in females. Age did not affect ectoparasite load in either sex. These results emphasize the importance of disentangling the effects of size and age in models of parasitism to gain a clearer understanding of intraspecific variation in parasite load.

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Host allometry influences the evolution of parasite host-generalism: theory and meta-analysis

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2016.0089 ◽

2017 ◽

Vol 372 (1719) ◽

pp. 20160089 ◽

Cited By ~ 6

Author(s):

Josephine G. Walker ◽

Amy Hurford ◽

Jo Cable ◽

Amy R. Ellison ◽

Stephen J. Price ◽

...

Keyword(s):

Body Size ◽

Host Species ◽

Meta Analysis ◽

Transmission Risk ◽

New Host ◽

Host Body ◽

Biological Interest ◽

Single Host ◽

Future Work ◽

Host Body Size

Parasites vary widely in the diversity of hosts they infect: some parasite species are specialists—infecting just a single host species, while others are generalists, capable of infecting many. Understanding the factors that drive parasite host-generalism is of basic biological interest, but also directly relevant to predicting disease emergence in new host species, identifying parasites that are likely to have unidentified additional hosts, and assessing transmission risk. Here, we use mathematical models to investigate how variation in host body size and environmental temperature affect the evolution of parasite host-generalism. We predict that parasites are more likely to evolve a generalist strategy when hosts are large-bodied, when variation in host body size is large, and in cooler environments. We then explore these predictions using a newly updated database of over 20 000 fish–macroparasite associations. Within the database we see some evidence supporting these predictions, but also highlight mismatches between theory and data. By combining these two approaches, we establish a theoretical basis for interpreting empirical data on parasites' host specificity and identify key areas for future work that will help untangle the drivers of parasite host-generalism. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.

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Potential host ranges of three Asian larval parasitoids of Drosophila suzukii

Journal of Pest Science ◽

10.1007/s10340-021-01368-1 ◽

2021 ◽

Author(s):

Kent M. Daane ◽

Xingeng Wang ◽

Brian N. Hogg ◽

Antonio Biondi

Keyword(s):

Body Size ◽

Host Species ◽

Classical Biological Control ◽

Developmental Time ◽

The Body ◽

Phylogenetic Position ◽

Egg Load ◽

Drosophila Suzukii ◽

Larval Parasitoids ◽

Female Body Size

AbstractAsobara japonica (Hymenoptera: Braconidae), Ganaspis brasiliensis and Leptopilina japonica (Hymenoptera: Figitidae) are Asian larval parasitoids of spotted wing drosophila, Drosophila suzukii (Diptera: Drosophilidae). This study evaluated these parasitoids’ capacity to attack and develop from 24 non-target drosophilid species. Results showed that all three parasitoids were able to parasitize host larvae of multiple non-target species in artificial diet; A. japonica developed from 19 tested host species, regardless of the phylogenetic position of the host species, L. japonica developed from 11 tested species; and G. brasiliensis developed from only four of the exposed species. Success rate of parasitism (i.e., the probability that an adult wasp successfully emerged from a parasitized host) by the two figitid parasitoids was low in hosts other than the three species in the melanogaster group (D. melanogaster, D. simulans, and D. suzukii). The failure of the figitids to develop in most of the tested host species appears to correspond with more frequent encapsulation of the parasitoids by the hosts. The results indicate that G. brasiliensis is the most host specific to D. suzukii, L. japonica attacks mainly species in the melanogaster group and A. japonica is a generalist, at least physiologically. Overall, the developmental time of the parasitoids increased with the host’s developmental time. The body size of female A. japonica (as a model species) was positively related to host size, and mature egg load of female wasps increased with female body size. We discuss the use of these parasitoids for classical biological control of D. suzukii.

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Explaining variability in parasite aggregation levels among host samples

Parasitology ◽

10.1017/s0031182012002053 ◽

2013 ◽

Vol 140 (4) ◽

pp. 541-546 ◽

Cited By ~ 85

Author(s):

ROBERT POULIN

Keyword(s):

Body Size ◽

Strong Relationship ◽

Host Susceptibility ◽

Helminth Parasites ◽

Susceptibility To Infection ◽

Host Body ◽

Parasite Aggregation ◽

Using Data ◽

Species Specific ◽

Host Body Size

SUMMARYAggregated distributions among individual hosts are a defining feature of metazoan parasite populations. Heterogeneity among host individuals in exposure to parasites or in susceptibility to infection is thought to be the main factor generating aggregation, with properties of parasites themselves explaining some of the variability in aggregation levels observed among species. Here, using data from 410 samples of helminth parasites on fish hosts, I tested the contribution of (i) within-sample variation in host body size, taken as a proxy for variability in host susceptibility, and (ii) parasite taxon and developmental stage, to the aggregated distribution of parasites. Log-transformed variance in numbers of parasites per host was regressed against log mean number across all samples; the strong relationship (r2 = 0·88) indicated that aggregation levels are tightly constrained by mean infection levels, and that only a small proportion of the observed variability in parasite aggregation levels remains to be accounted for by other factors. Using the residuals of this regression as measures of ‘unexplained’ aggregation, a mixed effects model revealed no significant effect of within-sample variation in host body size or of parasite taxon or stage (i.e. juvenile versus adult) on parasite aggregation level within a sample. However, much of the remaining variability in parasite aggregation levels among samples was accounted for by the number of individual hosts examined per sample, and species-specific and study-specific effects reflecting idiosyncrasies of particular systems. This suggests that with most differences in aggregation among samples already explained, there may be little point in seeking universal causes for the remaining variation.

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Peer Review #1 of "Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size (v0.2)"

10.7287/peerj.3675v0.2/reviews/1 ◽

2017 ◽

Author(s):

B Lester

Keyword(s):

Body Size ◽

Intermediate Host ◽

Peer Review ◽

Spatiotemporal Variability ◽

Host Body ◽

Host Parasite ◽

Host Body Size

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Peer Review #2 of "Mesoscale spatiotemporal variability in a complex host-parasite system influenced by intermediate host body size (v0.1)"

10.7287/peerj.3675v0.1/reviews/2 ◽

2017 ◽

Keyword(s):

Body Size ◽

Intermediate Host ◽

Peer Review ◽

Spatiotemporal Variability ◽

Host Body ◽

Host Parasite ◽

Host Body Size

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Infection patterns of helminths in Norops brasiliensis (Squamata, Dactyloidae) from a humid forest, Northeastern Brazil and their relation with body mass, sex, host size, and season

Helminthologia ◽

10.2478/helm-2019-0011 ◽

2019 ◽

Vol 56 (2) ◽

pp. 168-174 ◽

Cited By ~ 1

Author(s):

D. M. Amorim ◽

R. W. Ávila

Keyword(s):

Body Size ◽

Ecological Factors ◽

Parasite Load ◽

Helminth Fauna ◽

Northeastern Brazil ◽

Rainfall Regime ◽

New Host ◽

Humid Forest ◽

Host Sex ◽

New Host Records

SummaryClimatic and ecological factors can influence the parasite load of a host. Variation in rainfall, body size, and sex of the hosts may be related to the abundance of parasites. This study investigated the helminth fauna associated with a population of Norops brasiliensis, together with the effect of host biology (sex, body size, and mass) and variation in rainfall regime on the abundance of helminths. Species of three groups of endoparasites were found (Nematoda, Cestoda, and Trematoda), with nematodes as the most representative taxa with eight species, prevalence of 63.2 %, mean intensity of 4.0 ± 0.58 (1 – 25), and mean abundance of 2.66 ± 0.44 (0 – 25). Nine helminth species are new host records for N. brasiliensis. The nematode Rhabdias sp. had the highest prevalence (53.3 %). There was no significant relationship between abundance of the trematode Mesocoelium monas and host sex or season, although the abundance of this parasite increased significantly with host body size and mass, while abundance of nematodes was related to season and host mass. This study increases the knowledge about the diversity of helminth fauna associated with N. brasiliensis, revealing infection levels of hosts from northeastern Brazil.

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Host Body Size, Prevalence, and Breeding Season of the Microparasitic Snail Pelseneeria castanea on the Sea Urchin Strongylocentrotus nudus in Coastal Waters of the Sea of Japan off Western Hokkaido, Japan

Japanese journal of benthology ◽

10.5179/benthos.61.16 ◽

2006 ◽

Vol 61 ◽

pp. 16-20 ◽

Cited By ~ 1

Author(s):

Tadashi KAWAI ◽

Kazuya NAGASAWA

Keyword(s):

Body Size ◽

Breeding Season ◽

Sea Urchin ◽

Sea Of Japan ◽

Coastal Waters ◽

The Sea Of Japan ◽

Host Body ◽

Strongylocentrotus Nudus ◽

Host Body Size

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Variation in ectoparasite load in the Mehely’s horseshoe bat, Rhinolophus mehelyi (Chiroptera: Rhinolophidae) in a nursery colony in western Iran

Acta Parasitologica ◽

10.2478/s11686-013-0122-1 ◽

2013 ◽

Vol 58 (2) ◽

Cited By ~ 2

Author(s):

Mozafar Sharifi ◽

Najmeh Taghinezhad ◽

Fatema Mozafari ◽

Somaye Vaissi

Keyword(s):

Parasite Species ◽

Parasite Load ◽

Early Summer ◽

Western Iran ◽

Pregnant Females ◽

Solitary Males ◽

Horseshoe Bat ◽

Free Ranging ◽

Forearm Length ◽

Ectoparasite Load

AbstractWe studied variation of ectoparasite load in a free ranging populations of Mehely’s horseshoe bat (Rhinolophus mehelyi) on five successive occasions in a nursery roost in western Iran. In total, 87 Rhinolophus mehelyi were captured. The patterns of abundance differed greatly among parasite species but total parasite load was markedly higher in pregnant females in spring and early summer and lower in solitary males. On average, 90% of bats were infested by Eyndhovenia sp. with a mean intensity of 13.79 individuals per bat. Penicillidia sp. and one species from Streblidae were found in 66.7% and 11.49% of bats with parasite load of 2.31 and 1.8 parasite per bat, respectively. Using ratio of forearm length to body mass as an indication of bat health the correlation coefficient between parasite load and the health indicator was 0.002 for males and 0.06 for females indicating that parasite load has no apparent impact on bat’s health.

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