Abstract
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.
Highlights
The poultry red mite (PRM), Dermanyssus gallinae, is one of the most economically deleterious ectoparasites affecting egg-laying hens worldwide
We evaluated the effect of two photoperiods: conventional light regime of 12 h light followed by 12 h darkness (12:12 h L:D) and a prolonged darkness photoperiod receiving only 1 h light followed by 23 h darkness (1:23 h L:D) on the population growth rate of D. gallinae
We found that the mean survival rates for 1:23 h L:D fluctuated within a narrow range of 98.07 ± 0.10% to 98.93 ± 0.19% over the 4-week period, which were slightly higher than that under the 12:12 h L:D photoperiod, with the mean survival rates ranging from 95.88 ± 0.94% to 98.28 ± 0.33% at 7–28 dpc
Summary
The poultry red mite (PRM), Dermanyssus gallinae, is one of the most economically deleterious ectoparasites affecting egg-laying hens worldwide. The poultry red mite (PRM), Dermanyssus gallinae, is the most significant parasitic threat to egg-laying hens, worldwide [1]. This species is reported from layers in many parts of the world, including the USA, Europe, Japan and China [2,3,4]. This blood-sucking ectoparasite causes widespread problems in egg production and challenges animal health, the animal welfare and raises an increased public health concern due to its capacity of being a vector of various animal and zoonotic pathogens [1]. It has been acknowledged that D. gallinae can affect the health and wellbeing of persons working with poultry, reportedly causing avian mite dermatitis/ gamasoidosis; manifested as itching, allergic reactions, and by inflammation of the skin [8]
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