Dataset Information

Population dynamics of a poultry hematophagous mite: characterization of the population growth and identification of factors of its slowdown using closed mesocosms.

ABSTRACT:

Background

A thorough knowledge of the population dynamics of pests and of the main factors affecting population growth is an important prerequisite for the development of effective control strategies. Failures of various treatments aimed at regulating populations of Dermanyssus gallinae are regularly reported in poultry farms and pullulations occur very quickly after first detection. To finely characterize population dynamics of D. gallinae, and to identify the factors modulating population growth, we conducted two successive multi-generation experiments using closed mesocosms equipped with or without automatic counters and housing a host full- or part-time (three nights per week).

Results

Population growth was very rapid and the adult to juvenile ratio very different from the prediction by a mathematical model. A male-biased sex ratio was observed in some mesocosms from 21 days and in most mesocosms from 35 days of population growth originating from an inoculum of adult females. A dramatic slowdown in growth was measured in mesocosms equipped with trackers, where the mites' path to the host was constrained. The slowdown in population growth induced by the intermittent presence of the host compared to its full-time presence was much less marked.

Conclusion

These findings suggest avenues of research for new management methods. They question the relevance of a critical threshold based on traditional trap monitoring to manage D. gallinae. Our results highlight a unique characteristic of D. gallinae that makes it a recalcitrant case to threshold-based practices recommended for integrated pest management (IPM) against other arthropod pests. The dramatic effect of a physical constraint for the mite to access the host (unnatural constrained path) confirms an observation made in 1917 and is a reason to design perches that are less conducive to parasite traffic. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

SUBMITTER: Dupray S

PROVIDER: S-EPMC9546284 | biostudies-literature | 2022 Oct

REPOSITORIES: biostudies-literature

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Publications

Population dynamics of a poultry hematophagous mite: characterization of the population growth and identification of factors of its slowdown using closed mesocosms.

Dupray Sébastien S Blatrix Rumsais R Roy Laurent J M LJM Soulié Anne-Sophie AS Dadu Liza L Degueldre David D Sleeckx Nathalie N Bicout Dominique J DJ Roy Lise L

Pest management science 20220628 10

<h4>Background</h4>A thorough knowledge of the population dynamics of pests and of the main factors affecting population growth is an important prerequisite for the development of effective control strategies. Failures of various treatments aimed at regulating populations of Dermanyssus gallinae are regularly reported in poultry farms and pullulations occur very quickly after first detection. To finely characterize population dynamics of D. gallinae, and to identify the factors modulating popula ...[more]

PMID: 35674477

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Project description:BackgroundThe poultry red mite (PRM), Dermanyssus gallinae, is one of the most economically deleterious ectoparasites affecting egg-laying hens worldwide. It may be possible to control D. gallinae populations by manipulating lighting regimes within poultry units. However, no studies have clearly shown the effects of darkness on the population growth rate of D. gallinae.MethodsThe effect of darkness on the population growth rate of D. gallinae was investigated, together with the first description of the molecular identity of the mite from China. Mite variables under two lighting regimens (1:23 h L:D and 12:12 h L:D) were compared, including number of mites and eggs, survival and feeding rates, engorgement, oviposition, hatchability and the life-cycle of D. gallinae.ResultsThe results showed that the number of mites (13,763 ± 956) and eggs (5424 ± 317) in the rearing system with prolonged darkness of 1:23 h L:D at 4th week were 2.4- and 3.6-fold higher than those under a conventional lighting regimen of 12:12 h L:D, respectively. The feeding rates of mites under prolonged darkness ranged from 36.7 ± 1.1% to 52.0 ± 7.0%, which were significantly higher than those under conventional lighting regimen (ranging from 22.6 ± 1.9% to 37.3 ± 1.6%). The mean weight of engorged females (0.26 ± 0.01 mg) and the mean number of eggs per female (on average 5.87 ± 0.36) under prolonged darkness were significantly higher than those under conventional lighting regimen (0.22 ± 0.01 mg and 3.62 ± 0.31, respectively). However, the survival rate ranging from 98.07 ± 0.10% to 98.93 ± 0.19%, hatchability of 97.93 ± 0.01% and the life-cycle of D. gallinae (9 days) was not affected by the lighting period.ConclusionsOur findings demonstrated that prolonged darkness significantly promoted the proliferation levels of D. gallinae, resulting in increased number of mites and eggs in the rearing system. The promoted population growth of D. gallinae was found to be related to the increased feeding rate, engorgement level and oviposition level of mites under prolonged darkness. The egg hatchability, the survival rates and the duration of life-cycle of D. gallinae were not affected by the light regimes.

Project description:ImportanceAfter decades of rapid increase, Medicare per-beneficiary spending growth was historically low in the period leading up to the passage of the Affordable Care Act. In the years immediately following the legislation, Medicare expenditure growth slowed even further.ObjectiveTo evaluate factors contributing to the slowdown in Medicare per-beneficiary spending growth.Design, setting, and participantsIn this cross-sectional study, expected spending growth for 2012 to 2015 and 2016 to 2018 was predicted holding payment rates and population characteristics constant. By contrasting predicted and actual spending growth during these periods, the contribution of population vs payment factors to the Medicare spending slowdown was determined. Analyses included all Medicare fee-for-service beneficiaries aged 65 years and older, ranging from 30 to 35 million beneficiaries annually between 2007 and 2018. Data analyses were conducted from January 2018 to August 2018 and updated with new data in June 2021.Main outcomes and measuresThe main outcome included annual growth in total per-beneficiary spending. The roles of payment rate changes and differences in the Medicare population over time were considered, including demographic characteristics and numbers of chronic conditions.ResultsBetween 2008 to 2011 and 2012 to 2015, the adjusted annual Medicare Parts A and B per-beneficiary spending growth rate declined from 3.3% to -0.1%. From 2016 to 2018, the mean annual Medicare spending growth rate rose relative to the previous period but remained lower than in the baseline period at 1.7% per year. This slowdown extended across all sectors within Parts A and B, except for physician-administered drugs offered under Part B. Changes in payment rates (including sequestration measures) and beneficiary characteristics explained 44% of the difference in overall per-beneficiary spending growth between 2007 to 2011 and 2012 to 2015, and 63% between 2007 to 2011 and 2016 to 2018.Conclusions and relevanceIn this cross-sectional study of trends in spending growth per Medicare beneficiary aged 65 years or older, results suggested that Medicare payment policy, including sector-specific payment rate changes and sequestration, will be a critical determinant of whether the Medicare spending growth slowdown persists.

Dataset Information

Population dynamics of a poultry hematophagous mite: characterization of the population growth and identification of factors of its slowdown using closed mesocosms.

Background

Results

Conclusion

Publications

Population dynamics of a poultry hematophagous mite: characterization of the population growth and identification of factors of its slowdown using closed mesocosms.

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