Topic
Infestation
About: Infestation is a research topic. Over the lifetime, 8308 publications have been published within this topic receiving 82305 citations.
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TL;DR: The results suggest that the effect of host age on host–parasite dynamics may not explicitly be determined by age-dependent differences in ectoparasite recruitment or mortality processes but may also be affected by other host-related and parasite-related traits.
Abstract: Host age is one of the key factors in host-parasite relationships as it possibly affects infestation levels, parasite-induced mortality of a host, and parasite distribution among host individuals. We tested two alternative hypotheses about infestation pattern and survival under parasitism in relation to host age. The first hypothesis assumes that parasites are recruited faster than they die and, thus, suggests that adult hosts will show higher infestation levels than juveniles because the former have more time to accumulate parasites. The second hypothesis assumes that parasites die faster than they are recruited and, thus, suggests that adults will show lower infestation levels because of acquired immune response and/or the mortality of heavily infested juveniles and, thus, selection for less infested adults. As the negative effects of parasites on host are often intensity-dependent, we expected that the age-related differences in infestation may be translated to lower or higher survival under parasitism of adults, in the cases of the first and the second hypotheses, respectively. We manipulated ectoparasite numbers using insecticide and assessed the infestation pattern in adult and juvenile gerbils (Gerbillus andersoni) in the Negev Desert. We found only a partial support for age-dependent parasitism. No age-related differences in infestation and distribution among host individuals were found after adjusting the ectoparasite numbers to the host's surface area. However, age-related differences in survival under parasitism were revealed. The survival probability of parasitized juveniles decreased in about 48% compared to unparasitized hosts while the survival probability of adults was not affected by ectoparasites. Our results suggest that the effect of host age on host-parasite dynamics may not explicitly be determined by age-dependent differences in ectoparasite recruitment or mortality processes but may also be affected by other host-related and parasite-related traits.
81 citations
TL;DR: Individual palm attributes appear as key drivers of infestation, suggesting that CD surveillance must incorporate local-scale knowledge and that peridomestic palm tree management might help lower transmission risk.
Abstract: Background: Failure to detect a disease agent or vector where it actually occurs constitutes a serious drawback in
epidemiology. In the pervasive situation where no sampling technique is perfect, the explicit analytical treatment of
detection failure becomes a key step in the estimation of epidemiological parameters. We illustrate this approach with a
study of Attalea palm tree infestation by Rhodnius spp. (Triatominae), the most important vectors of Chagas disease (CD) in
northern South America.
Methodology/Principal Findings: The probability of detecting triatomines in infested palms is estimated by repeatedly
sampling each palm. This knowledge is used to derive an unbiased estimate of the biologically relevant probability of palm
infestation. We combine maximum-likelihood analysis and information-theoretic model selection to test the relationships
between environmental covariates and infestation of 298 Amazonian palm trees over three spatial scales: region within
Amazonia, landscape, and individual palm. Palm infestation estimates are high (40–60%) across regions, and well above the
observed infestation rate (24%). Detection probability is higher (,0.55 on average) in the richest-soil region than elsewhere
(,0.08). Infestation estimates are similar in forest and rural areas, but lower in urban landscapes. Finally, individual palm
covariates (accumulated organic matter and stem height) explain most of infestation rate variation.
Conclusions/Significance: Individual palm attributes appear as key drivers of infestation, suggesting that CD surveillance
must incorporate local-scale knowledge and that peridomestic palm tree management might help lower transmission risk.
Vector populations are probably denser in rich-soil sub-regions, where CD prevalence tends to be higher; this suggests a
target for research on broad-scale risk mapping. Landscape-scale effects indicate that palm triatomine populations can
endure deforestation in rural areas, but become rarer in heavily disturbed urban settings. Our methodological approach has
wide application in infectious disease research; by improving eco-epidemiological parameter estimation, it can also
significantly strengthen vector surveillance-control strategies.
81 citations
TL;DR: Crosses show that between-strains variation is inherited by the matrocline route, and the hypothesis of cytoplasmic-symbiotic microorganisms accounting for the higher infestation efficiency in the H strain is supported by microscopic observations.
Abstract: InTrichogramma bourarachae (Hymenoptera: Trichogrammatidae), the infestation efficiency presents important variation among strains: 60 eggs/5 days/female in the High (H) strain and 25 eggs/5 days/female in the Low (L) strain. Crosses show that between-strains variation is inherited by the matrocline route. Antibiotic and heat treatments reduce infestation efficiency in the H strain and have no effect on the L strain. The hypothesis of cytoplasmic-symbiotic microorganisms accounting for the higher infestation efficiency in the H strain is supported by microscopic observations. The origin and the significance of this between-strains variation are discussed.
81 citations
TL;DR: Resistant cultivars showed greater constitutive POD activity in the tillering, stem elongation, and flag leaf stages, while aphid infestation induced P OD activity in all cultivars, especially in susceptible ones.
Abstract: Phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD) are considered important biochemical markers in host plant resistance against pest insects. Constitutive activity of these enzymes was analyzed in resistant and susceptible wheat cultivars against cereal aphid Sitobion avenae (F.) at various developmental stages, i.e., tillering, stem elongation, flag leaf, and ear. Following aphid infestation, the activity of these enzymes was determined at the flag leaf and ear stages. Resistant cultivars exhibited greater constitutive PAL activity than susceptible ones at the tillering, stem elongation, and flag leaf stages. Aphid infestation enhanced levels of PAL activity in the flag leaf and ear stages in both resistant and susceptible cultivars. Constitutive PPO activity was higher in the resistant cultivars at all developmental stages. Aphid infestation induced increases in PPO activity in the flag leaf and ear stages of one susceptible cultivar, whereas induction in resistant cultivars was weaker. Resistant cultivars showed greater constitutive POD activity in the tillering, stem elongation, and flag leaf stages, while aphid infestation induced POD activity in all cultivars, especially in susceptible ones. The potential role of PAL, PPO, and POD in wheat defense against aphid infestation is discussed.
80 citations
TL;DR: This study provides the first evidence for parasite-mediated host natal dispersal and local recruitment in relation to sex and shows that flea infestation led to a higher proportion of male fledglings recruiting in the local population in one year.
Abstract: Dispersal patterns of organisms are a fundamental aspect of their ecology, modifying the genetic and social structure of local populations. Parasites reduce the reproductive success and survival of hosts and thereby exert selection pressure on host life-history traits, possibly affecting host dispersal. Here we test experimentally whether infestation by hen fleas, Ceratophyllus gallinae, affects sex-related recruitment of great tit, Parus major, fledglings. Using sex-specific DNA markers, we show that flea infestation led to a higher proportion of male fledglings recruiting in the local population in one year. In infested broods, the proportion of male recruits increased with brood size over a three year period, whereas the proportion of male recruits from uninfested broods decreased with brood size. Natal dispersal distances of recruits from infested nests were shorter than those from uninfested nests. To our knowledge, this study provides the first evidence for parasite-mediated host natal dispersal and local recruitment in relation to sex. Current theory needs to consider parasites as potentially important factors shaping life-history traits associated with host dispersal.
80 citations