Effect of Host Density on Parasitism

1935 ◽  
Vol 28 (6) ◽  
pp. 898-900 ◽  
Author(s):  
S. E. Flander
Keyword(s):  
Host Density

Natural parasitism of eggs of yellow stem borer, Scirpophaga incertulas Walker (Lepidoptera: Crambidae) in rice ecosystem at Tiruchirappalli, Tamil Nadu

ENTOMON ◽  
2020 ◽  
Vol 45 (3) ◽  
pp. 181-188
Author(s):  
T. Sharmitha ◽  
C. Gailce Leo Justin ◽  
S. Sheeba Joyce Roseleen ◽  
P. Yasodha
Keyword(s):  
Field Study ◽  
Tamil Nadu ◽  
Host Density ◽  
Stem Borer ◽  
Scirpophaga Incertulas ◽  
Egg Masses ◽  
Yellow Stem Borer ◽  
Rice Ecosystem ◽  
Natural Parasitism

Three species of parasitoids viz., Telenomus dignus Gahan, Trichogramma japonicum, Ishii and Tetrastichus schoenobii Ferriere were recorded from the egg masses of rice yellow stem borer, Scirpophaga incertulas (Walker) in a field study. The extent of parasitism was high during Rabi (43.33 – 93.33 %) and low during Kharif (0 - 40.00 %). Parasitism by T. dignus was maximum in October (50.00 %), T. japonicum, in November (23.08 %) and T. schoenobii in February (55.55 %). dignus and T. schoenobii in combination parasitized maximum number of egg masses (41.82 %). Multiple parasitism by the three species was high in December (8.33 %) and January (7.14%). Parasitic potential was maximum, when T. schoenobii alone parasitised the egg masses followed by T. dignus and T. schoenobii in combination. Host density in the field influenced the extent of parasitism.

Quantifying 25 years of disease‐caused declines in Tasmanian devil populations: host density drives spatial pathogen spread

2021 ◽  
Vol 24 (5) ◽  
pp. 958-969
Author(s):  
Calum X. Cunningham ◽  
Sebastien Comte ◽  
Hamish McCallum ◽  
David G. Hamilton ◽  
Rodrigo Hamede ◽  
...  
Keyword(s):  
Host Density ◽  
Tasmanian Devil

scholarly journals Host density predicts the probability of parasitism by avian brood parasites

2019 ◽  
Vol 374 (1769) ◽  
pp. 20180204 ◽  
Author(s):  
Iliana Medina ◽  
Naomi E. Langmore
Keyword(s):  
Spatial Distribution ◽  
Reproductive Success ◽  
Host Species ◽  
Field Data ◽  
Host Density ◽  
Brood Parasites ◽  
Parasitism Rates ◽  
Analyse Data ◽  
First Time ◽  
Determining Factor

The spatial distribution of hosts can be a determining factor in the reproductive success of parasites. Highly aggregated hosts may offer more opportunities for reproduction but can have better defences than isolated hosts. Here we connect macro- and micro-evolutionary processes to understand the link between host density and parasitism, using avian brood parasites as a model system. We analyse data across more than 200 host species using phylogenetic comparative analyses and quantify parasitism rate and host reproductive success in relation to spatial distribution using field data collected on one host species over 6 years. Our comparative analysis reveals that hosts occurring at intermediate densities are more likely to be parasitized than colonial or widely dispersed hosts. Correspondingly, our intraspecific field data show that individuals living at moderate densities experience higher parasitism rates than individuals at either low or high densities. Moreover, we show for the first time that the effect of host density on host reproductive success varies according to the intensity of parasitism; hosts have greater reproductive success when living at high densities if parasitism rates are high, but fare better at low densities when parasitism rates are low. We provide the first evidence of the trade-off between host density and parasitism at both macro- and micro-evolutionary scales in brood parasites. This article is part of the theme issue ‘The coevolutionary biology of brood parasitism: from mechanism to pattern’.

BIOLOGY OF TACHINAEPHAGUS ZEALANDICUS (HYMENOPTERA: ENCYRTIDAE), PARASITOID OF SYNANTHROPIC DIPTERA

1974 ◽  
Vol 106 (8) ◽  
pp. 785-800 ◽  
Author(s):  
G. S. Olton ◽  
E. F. Legner
Keyword(s):  
Life History ◽  
Developmental Stages ◽  
Average Length ◽  
Host Density ◽  
Adult Emergence ◽  
Reproductive Period ◽  
Laboratory Studies ◽  
Pupal Parasitoid ◽  
History Of ◽  
Parasitoid Development

AbstractThe synonymy, distribution, host range, and life history of the gregarious larval–pupal parasitoid Tachinaephagus zealandicus Ashmead, is discussed. Laboratory studies of its biology were conducted at 25° ± 2 °C using Musca domestica L. as host. Its developmental stages are described. Under laboratory conditions its life cycle lasted 23–27 days. Parasitoid development accelerated with higher average densities per host. Single standardized hosts produced 3–18 adult parasitoids. Mated females provided with hosts lived 50.4–67.2 h. The average length of the reproductive period and number of hosts parasitized were independent of host density; however, the average number of eggs deposited per host increased at lower host densities. Adult emergence displayed circadian rhythmicity independent of photoperiod over 3+ days.

Parasite infection and host dynamics in a naturally fluctuating rodent population

2012 ◽  
Vol 90 (9) ◽  
pp. 1149-1160 ◽  
Author(s):  
J.C. Winternitz ◽  
M.J. Yabsley ◽  
S.M. Altizer
Keyword(s):  
Population Density ◽  
Experimental Studies ◽  
Host Density ◽  
Positive Association ◽  
Population Cycles ◽  
Host Population ◽  
Reproductive Status ◽  
Vole Cycles ◽  
Host Infection ◽  
The Impact

Parasites can both influence and be affected by host population dynamics, and a growing number of case studies support a role for parasites in causing or amplifying host population cycles. In this study, we examined individual and population predictors of gastrointestinal parasitism on wild cyclic montane voles ( Microtus montanus (Peale, 1848)) to determine if evidence was consistent with theory implicating parasites in population cycles. We sampled three sites in central Colorado for the duration of a multiannual cycle and recorded the prevalence and intensity of directly transmitted Eimeria Schneider, 1875 and indirectly transmitted cestodes from a total of 267 voles. We found significant associations between host infection status, individual traits (sex, age, and reproductive status) and population variables (site, trapping period, and population density), including a positive association between host density and cestode prevalence, and a negative association between host density and Eimeria prevalence. Both cestode and Eimeria intensity correlated positively with host age, reproductive status, and population density, but neither parasite was associated with poorer host condition. Our findings suggest that parasites are common in this natural host, but determining their potential to influence montane vole cycles requires future experimental studies and long-term monitoring to determine the fitness consequences of infection and the impact of parasite removal on host dynamics.

Risk factors associated with Enteromyxum scophthalmi (Myxozoa) infection in cultured turbot, Scophthalmus maximus (L.)

Parasitology ◽  
2006 ◽  
Vol 133 (4) ◽  
pp. 433-442 ◽  
Author(s):  
M. I. QUIROGA ◽  
M. J. REDONDO ◽  
A. SITJÀ-BOBADILLA ◽  
O. PALENZUELA ◽  
A. RIAZA ◽  
...  
Keyword(s):  
Risk Factors ◽  
Distribution Pattern ◽  
Control Strategies ◽  
Host Density ◽  
Scophthalmus Maximus ◽  
Fish Distribution ◽  
Fish Mortality ◽  
Infection Prevalence ◽  
Western Spain ◽  
Turbot Scophthalmus Maximus

An epidemiological cohort study of Enteromyxum scophthalmi in cultured turbot was performed on a farm in North Western Spain. Four different ongrowing stocks (A, B, C, D) were monitored monthly until market size. Fish from stocks C and D were divided into 2 subgroups, receiving filtered (CF and DF) or unfiltered (CUF and DUF) water. The lack of water filtration was positively associated with infection prevalence, as all fish kept in filtered water remained uninfected. Parasite abundance varied seasonally (P<0·05) in stock B and subgroup CUF. Infection was also associated (P<0·05) with host weight, and the highest prevalences and intensities were detected in 101–200 g and 201–300 g fish. Distribution pattern of E. scophthalmi in subgroups CUF and DUF had a variance higher than the mean, indicating overdispersion. The minimum period necessary for the first detection of the parasite and for the appearance of disease symptoms and mortality, varied depending on the stock and introduction date, although a long pre-patent period was always observed. Several factors, such as host density, parasite recruitment and parasite-induced fish mortality can contribute to the observed distribution pattern. Risk factors found to be associated with E. scophthalmi infection, including water quality and accumulation of infective stages in the culture tanks, should be considered when designing control strategies to prevent the introduction and spread of infective stages in the facilities.

Sublethal effects of organophosphorus insecticide phoxim on patch time allocation and oviposition behavior in a parasitoid wasp Meteorus pulchricornis

2021 ◽  
pp. 1-10
Author(s):  
Sheng Sheng ◽  
Yan Song ◽  
Sheraz Ahmad ◽  
Jiao Wang ◽  
Ying Shao ◽  
...  
Keyword(s):  
Time Allocation ◽  
Sublethal Effects ◽  
Insect Pests ◽  
Oviposition Behavior ◽  
Host Density ◽  
Parasitoid Wasp ◽  
Patch Time Allocation ◽  
Meteorus Pulchricornis ◽  
Allocation Decisions ◽  
Patch Residence Time

Abstract Parasitoid wasps are key agents for controlling insect pests in integrated pest management programs. Although many studies have revealed that the behavior of parasitic wasps can be influenced by insecticides, the strategies of patch time allocation and oviposition have received less attention. In the present study, we forced the endoparasitoid Meteorus pulchricornis to phoxim exposure at the LC30 and tested the foraging behavior within patches with different densities of the host, the larvae of the tobacco cutworm Spodoptera litura. The results showed that phoxim treatment can significantly increase the patch-leaving tendency of female wasps, while host density had no impact. The number of oviposition and the number of previous patch visits also significantly influenced the patch time allocation decisions. The occurrence of oviposition behavior was negatively affected by phoxim exposure; however, progeny production was similar among patches with different host densities. Phoxim exposure shaped the offspring fitness correlates, including longer durations from cocoon to adult wasps, smaller body size, and shorter longevity. The findings of the present study highlight the sublethal effects that reduce the patch residence time and the fitness of parasitoid offspring, suggesting that the application of phoxim in association with M. pulchricornis should be carefully schemed in agroecosystems.

Social-ecological factors determine spatial variation in human incidence of tick-borne ehrlichiosis

2013 ◽  
Vol 142 (9) ◽  
pp. 1911-1924 ◽  
Author(s):  
B. R. BAYLES ◽  
B. F. ALLAN
Keyword(s):  
Socioeconomic Factors ◽  
Ecological Factors ◽  
Host Density ◽  
Positive Association ◽  
Local Variation ◽  
Reservoir Host ◽  
Local Regression ◽  
Targeted Interventions ◽  
Public Health Authorities ◽  
The Usa

SUMMARYThe spatial distribution of human cases of tick-borne diseases is probably determined by a combination of biological and socioeconomic factors. A zoonotic tick-borne pathogen, Ehrlichia chaffeensis, is increasing in human incidence in the USA. In this study, the spatial patterns of probable and confirmed E. chaffeensis-associated cases of ehrlichiosis from 2000 to 2011 were investigated at the zip-code level in Missouri. We applied spatial statistics, including global and local regression models, to investigate the biological and socioeconomic factors associated with human incidence. Our analysis confirms that the distribution of ehrlichiosis in Missouri is non-random, with numerous clusters of high incidence. Furthermore, we identified significant, but spatially variable, associations between incidence and both biological and socioeconomic factors, including a positive association with reservoir host density and a negative association with human population density. Improved understanding of local variation in these spatial factors may facilitate targeted interventions by public health authorities.

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