1
|
Wang LQ, Liu ZT, Wang JJ, Fang YH, Zhu H, Shi K, Zhang FS, Shuai LY. Complex effects of testosterone level on ectoparasite load in a ground squirrel: an experimental test for the immunocompetence handicap hypothesis. Parasit Vectors 2024; 17:164. [PMID: 38555448 PMCID: PMC10981293 DOI: 10.1186/s13071-024-06261-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 03/23/2024] [Indexed: 04/02/2024] Open
Abstract
BACKGROUND The immunocompetence handicap hypothesis suggests that males with a higher testosterone level should be better at developing male secondary traits, but at a cost of suppressed immune performance. As a result, we should expect that males with an increased testosterone level also possess a higher parasite load. However, previous empirical studies aimed to test this prediction have generated mixed results. Meanwhile, the effect of testosterone level on parasite load in female hosts remains poorly known. METHODS In this study, we tested this prediction by manipulating testosterone level in Daurian ground squirrels (Spermophilus dauricus), a medium-sized rodent widely distributed in northeast Asia. S. dauricus is an important host of ticks and fleas and often viewed as a considerable reservoir of plague. Live-trapped S. dauricus were injected with either tea oil (control group) or testosterone (treatment group) and then released. A total of 10 days later, the rodents were recaptured and checked for ectoparasites. Fecal samples were also collected to measure testosterone level of each individual. RESULTS We found that testosterone manipulation and sex of hosts interacted to affect tick load. At the end of the experiment, male squirrels subjected to testosterone implantation had an averagely higher tick load than males from the control group. However, this pattern was not found in females. Moreover, testosterone manipulation did not significantly affect flea load in S. dauricus. CONCLUSIONS Our results only lent limited support for the immunocompetence handicap hypothesis, suggesting that the role of testosterone on regulating parasite load is relatively complex, and may largely depend on parasite type and gender of hosts.
Collapse
Affiliation(s)
- Li-Qing Wang
- Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
| | - Zhi-Tao Liu
- College of Life Sciences, Harbin Normal University, Harbin, China
| | - Jian-Jun Wang
- Inner Mongolia Autonomous Region Comprehensive Center for Disease Control and Prevention, Hohhot, China
| | - Yu-Han Fang
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Hao Zhu
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Ke Shi
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Fu-Shun Zhang
- Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
| | - Ling-Ying Shuai
- College of Life Sciences, Huaibei Normal University, Huaibei, China.
| |
Collapse
|
2
|
Shuai LY, Wang LQ, Wang JJ, Xia Y, Zhai BY, Xu WJ, Chen XM, Yang XY, Zhang FS. Ecological correlates of ectoparasite load in a rodent: Complex roles of seasonality. Int J Parasitol Parasites Wildl 2022; 18:244-248. [PMID: 35800108 PMCID: PMC9253529 DOI: 10.1016/j.ijppaw.2022.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/19/2022] [Accepted: 06/20/2022] [Indexed: 11/19/2022]
Abstract
Understanding the mechanisms driving parasite distributions is not only important for understanding ecosystem functioning, but also crucial for disease control. Previous studies have documented the important roles of host sex, host body size, host behavioral trait (such as boldness and trappability), and seasonality in shaping parasite load. However, few studies have simultaneously assessed the roles of these factors, as well as their interactions. In spring and summer of 2021, we conducted live trapping in Hohhot, China, to collect ectoparasites on Daurian ground squirrel (Spermophilus dauricus), a small rodent widely distributed in East Asian grassland. We then used generalized linear models to explore the effects of several biological factors (sex, body weight, trappability, and reproductive status) and seasonality on the abundance of ticks and fleas in S. dauricus. Significant but inconsistent seasonal effects were observed: tick load was significantly greater in summer than in spring, while flea load was greater in spring than in summer. Seasons also significantly interacted with host trappability and body weight to affect tick abundance. Our results highlight the importance of considering seasonal changes in parasitism, as well as interactions between season and host biological traits in shaping parasite distributions. Both fleas and ticks show seasonal changes in abundance but in different directions. Relationship between host body weight and tick load changes between seasons. Effect of trappability on tick abundance depends on season.
Collapse
Affiliation(s)
- Ling-Ying Shuai
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Li-Qing Wang
- Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
- Corresponding author.
| | - Jian-Jun Wang
- Inner Mongolia Autonomous Region Comprehensive Center for Disease Control and Prevention, Hohhot, China
| | - Yang Xia
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Bin-Yan Zhai
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Wen-Jie Xu
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Xing-Ming Chen
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Xiao-Yu Yang
- College of Life Sciences, Huaibei Normal University, Huaibei, China
| | - Fu-Shun Zhang
- Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot, China
| |
Collapse
|
3
|
Le Coeur C, Pisanu B, Chapuis JL, Robert A. Within- and between-year variations of reproductive strategy and cost in a population of Siberian chipmunks. Oecologia 2018; 188:765-776. [PMID: 30219947 DOI: 10.1007/s00442-018-4259-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 09/10/2018] [Indexed: 10/28/2022]
Abstract
Reproduction costs depend on the general life-history strategies employed by organisms for resource acquisition, the decision rules on resource allocation, and the resource availability. Although the predictability of resource availability is expected to influence the breeding strategy, the relationship between predictability and strategy has rarely been investigated at the population level. One reason is that, while the resource availability is commonly variable in space and time, their predictability is generally assumed constant. Here, we addressed the temporal variation of the breeding strategy and its associated survival cost in a hibernating population of Tamias sibiricus, in which food resources vary in their availability between years and in their predictability within years. Based on 11 years of mark-recapture data, we used multi-event modelling to investigate seasonal variations in reproduction costs of female chipmunks that breed twice a year (spring and summer). In summer, during which a large variety and quantity of resources is available (income breeding strategy), the proportion of breeding females was consistent across years and reproduction yielded no mortality cost. In contrast, in spring, the proportion of breeding females was positively correlated with the amount of resources available for hibernation (partial capital breeding strategy). Spring reproduction yielded no immediate cost, but induced a delayed mortality cost over the next winter if future unknown conditions were unfavorable. Our findings highlight complex temporal reproductive patterns in a short-lived species: not only does the modality of resource acquisition vary among seasons, but also the decision rule to breed and its associated cost.
Collapse
Affiliation(s)
- Christie Le Coeur
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne-Université, 61 rue Buffon, 75005, Paris, France.
| | - Benoît Pisanu
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne-Université, 61 rue Buffon, 75005, Paris, France
| | - Jean-Louis Chapuis
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne-Université, 61 rue Buffon, 75005, Paris, France
| | - Alexandre Robert
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne-Université, 61 rue Buffon, 75005, Paris, France
| |
Collapse
|
4
|
Mazzamuto MV, Pisanu B, Romeo C, Ferrari N, Preatoni D, Wauters LA, Chapuis JL, Martinoli A. Poor Parasite Community of an Invasive Alien Species: Macroparasites of Pallas's Squirrel in Italy. ANN ZOOL FENN 2016. [DOI: 10.5735/086.053.0209] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
5
|
Inter-annual and inter-individual variations in survival exhibit strong seasonality in a hibernating rodent. Oecologia 2016; 181:795-807. [PMID: 26969470 DOI: 10.1007/s00442-016-3597-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/24/2016] [Indexed: 12/13/2022]
Abstract
Most research on the demography of wild animal populations has focused on characterizing the variation in the mortality of organisms as a function of intrinsic and environmental characteristics. However, such variation in mortality is difficult to relate to functional life history components (e.g. reproduction, dispersal, hibernation) due to the difficulty in monitoring biological processes at a sufficiently fine timescale. In this study, we used a 10-year individual-based data set with an infra-annual timescale to investigate both intra- and inter-annual survival patterns according to intrinsic and environmental covariates in an introduced population of a small hibernating rodent, the Siberian chipmunk. We compared three distinct periods related to particular life history events: spring reproduction, summer reproduction and hibernation. Our results revealed strong interactions between intrinsic and temporal effects. First, survival of male chipmunks strongly decreases during the reproduction periods, while survival is high and equal between sexes during hibernation. Second, the season of birth affects the survival of juveniles during their first hibernation, which does not have long-lasting consequences at the adult stage. Third, at an inter-annual scale, we found that high food resource availability before hibernation and low chipmunk densities specifically favour subsequent winter survival. Overall, our results confirm that the well-known patterns of yearly and inter-individual variation of mortality observed in animals are themselves strongly variable within a given year, suggesting that they are associated with various functional components of the animals' life history.
Collapse
|
6
|
Differences in the ectoparasite fauna between micromammals captured in natural and adjacent residential areas are better explained by sex and season than by type of habitat. Parasitol Res 2016; 115:2203-11. [PMID: 26946133 DOI: 10.1007/s00436-016-4962-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 02/17/2016] [Indexed: 02/01/2023]
Abstract
We compared the ectoparasite fauna in 608 micromammals (chiefly 472 wood mice Apodemus sylvaticus, 63 Algerian mice Mus spretus, and 51 greater white-toothed shrews Crocidura russula) captured in natural and adjacent residential areas in spring and autumn during three consecutive years in four areas in periurban Barcelona (NE Spain). We found little support for an association of urbanization with differences in infestation by ectoparasites. Prevalence of Rhipicephalus sp. tick in wood mice and shrews was significantly higher in residential than in natural habitats, and the opposite was found for the flea Ctenophtalmus andorrensis catalanensis in shrews. Marked differences in the prevalence of the flea Leptopsylla taschenbergi amitina in wood mice between seasons were observed in natural but not in residential habitats, probably due to enhanced flea survival probabilities in the latter. However, as a rule, males were more frequently and heavily infested than females, and the prevalence was higher in autumn than in spring. Our results suggest that the ectoparasite fauna of periurban micromammals is shaped more by other factors than by habitat modification. People living in residential areas are at risk of contact with the arthropods borne by non-commensal micromammals and the pathogens transmitted by them.
Collapse
|
7
|
Mysterud A, Byrkjeland R, Qviller L, Viljugrein H. The generalist tick Ixodes ricinus and the specialist tick Ixodes trianguliceps on shrews and rodents in a northern forest ecosystem--a role of body size even among small hosts. Parasit Vectors 2015; 8:639. [PMID: 26671686 PMCID: PMC4681159 DOI: 10.1186/s13071-015-1258-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/11/2015] [Indexed: 11/20/2022] Open
Abstract
Background Understanding aggregation of ticks on hosts and attachment of life stages to different host species, are central components for understanding tick-borne disease epidemiology. The generalist tick, Ixodes ricinus, is a well-known vector of Lyme borrelioses, while the specialist tick, Ixodes trianguliceps, feeding only on small mammals, may play a role in maintaining infection levels in hosts. In a northern forest in Norway, we aimed to quantify the role of different small mammal species in feeding ticks, to determine the extent to which body mass, even among small mammals, plays a role for tick load, and to determine the seasonal pattern of the two tick species. Methods Small mammals were captured along transects in two nearby areas along the west coast of Norway. All life stages of ticks were counted. Tick load, including both prevalence and intensity, was analysed with negative binomial models. Results A total of 359 rodents and shrews were captured with a total of 1106 I. ricinus (60.0 %) and 737 I. trianguliceps (40.4 %), consisting of 98.2 % larvae and 1.8 % nymphs of I. ricinus and 91.2 % larvae, 8.7 % nymphs and 0.1 % adult females of I. trianguliceps. Due to high abundance, Sorex araneus fed most of the larvae of both tick species (I. ricinus 61.9 %, I. trianguliceps 64.9 %) with Apodemus sylvaticus (I. ricinus 20.4 %, I. trianguliceps 10.0 %) and Myodes glareolus (I. ricinus 10.9 %, I. trianguliceps 9.5 %) as the next most important hosts. Individual A. sylvaticus and M. glareolus had higher infestation intensity than S. araneus, while Sorex minutus had markedly lower infestation intensity. The load of I. ricinus larvae and nymphs was related to body mass mainly up to ~10 g, while the load of I. trianguliceps was less dependent of body mass. The load of I. trianguliceps was higher in spring than in fall, while the seasonal pattern was reversed for I. ricinus with higher loads in fall. Conclusions Body mass was important for explaining load of I. ricinus mainly up to a body mass of ~10 g across a range of smaller mammalian hosts. Consistent with earlier work elsewhere in Europe, we found the highest tick infestation intensity on the wood mouse A. sylvaticus. However, this rodent species fed only 20.4 % of all I. ricinus larvae, while the much more abundant S. araneus fed 61.9 %. Our study emphasizes an important quantitative role of the common shrew S. araneus as a main host to I. ricinus larvae and to both I. trianguliceps larvae and nymphs. The partly seasonal distinct attachment pattern of I. ricinus and I. trianguliceps is evidence for niche separation.
Collapse
Affiliation(s)
- Atle Mysterud
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066 Blindern, NO-0316, Oslo, Norway.
| | - Ragna Byrkjeland
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066 Blindern, NO-0316, Oslo, Norway.
| | - Lars Qviller
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066 Blindern, NO-0316, Oslo, Norway. .,Norwegian Veterinary Institute, P.O. Box 750 Sentrum, NO-0106, Oslo, Norway.
| | - Hildegunn Viljugrein
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066 Blindern, NO-0316, Oslo, Norway. .,Norwegian Veterinary Institute, P.O. Box 750 Sentrum, NO-0106, Oslo, Norway.
| |
Collapse
|
8
|
Ectoparasite load in the crested porcupine Hystrix cristata Linnaeus, 1758 in Central Italy. Parasitol Res 2015; 114:2223-9. [PMID: 25773184 DOI: 10.1007/s00436-015-4413-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 03/03/2015] [Indexed: 10/23/2022]
Abstract
The crested porcupine Hystrix cristata is a large body-sized rodent, occurring in Europe only in the Italian Peninsula, where it may have been introduced in early Medieval times. Its parasite fauna is currently poorly known and limited to few anecdotal observations. We have analyzed the ectoparasite load of 165 crested porcupines from Tuscany and Latium (Central Italy). Both captured and road-killed individuals were checked for fleas and ticks. Overall, only 39 porcupines were infested by four species of ticks and five of fleas. Abundance of ectoparasites was higher in areas with higher habitat richness, with respect to densely wooded areas. The most frequent species was the flea Pulex irritans (25%), whose prevalence peaked in winter probably because of optimal abiotic conditions in the porcupine's den. The remaining species of both hard ticks (Rhipicephalus bursa, Pholeoixodes hexagonus, and Ixodes ventalloi) and fleas (Paraceras melis, Ctenocephalides canis, Dasypsyllus gallinulae, and Hystrichopsylla talpae), all with prevalence lower than 5%, could be due to den sharing with other vertebrates, mainly carnivores such as, e.g., red foxes and badgers. The second most prevalent species was the generalist tick Ixodes ricinus (21%). An adult male-biased parasitism for ticks has been detected, suggesting a possible role of testosterone related immune-depressive effect. The low richness in dominant ectoparasite species, built up by locally acquired generalist taxa, provides support to the allochthonous origin of this rodent in Italy.
Collapse
|