Darkness increases the population growth rate of the poultry red mite Dermanyssus gallinae

Abstract

Background The 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 . Methods The 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. Results The 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. Conclusions Our 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.

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

“…outside the visible spectrum of the chicken and still far from the thermal infrared range) and physical access to the host (unconstrained versus spatially restricted and unnatural). Experiment B showed that reducing temporal access to the host only slightly impacted population growth, and that this impact was not comparable to the difference between STD and TR mesocosms in experiment A. Darkness was shown to increase population growth in D. gallinae instead of slowering it 37 . Although we cannot completely eliminate a possible effect of the LEDs on the mite's behavior, the infrared light emitted around the Plexiglas plate does not constitute a barrier in any way.…”

Parasitic Mite Fauna in Asian Poultry Farming Systems

“…Experimental studies and field trials suggested the possibility of using light regimen and gas for managing mite infestation. The population growth rate of PRM in rearing system under prolonged darkness (1: 23 h L:D) was three-fold higher than that with conventional lighting regimen (12: 12 h L:D) (74). Application of carbon dioxide could induce asphyxiation and thus reduce mite population by 85% within 24 h and 100% by 120 h (75).…”

Possibilities for IPM Strategies in European Laying Hen Farms for Improved Control of the Poultry Red Mite (Dermanyssus gallinae): Details and State of Affairs

“…Studies have shown that mite populations can be affected by disrupting light-dark cycles. Host-searching activity of D. gallinae starts during the dark period, with the highest activity 5–11 h after darkness, so when this dark period is interrupted, their host-seeking activity will decrease and their natural feeding cycle will be disrupted ( 114 , 115 ). Indeed, the reduction of numbers of D. gallinae by short-cycle intermittent light/dark periods has been illustrated by Zoons ( 116 ) and Stafford et al ( 117 ), and prolonged darkness compared to standard light regimes resulted in increased number of mites ( 115 ).…”

“…Host-searching activity of D. gallinae starts during the dark period, with the highest activity 5–11 h after darkness, so when this dark period is interrupted, their host-seeking activity will decrease and their natural feeding cycle will be disrupted ( 114 , 115 ). Indeed, the reduction of numbers of D. gallinae by short-cycle intermittent light/dark periods has been illustrated by Zoons ( 116 ) and Stafford et al ( 117 ), and prolonged darkness compared to standard light regimes resulted in increased number of mites ( 115 ). However, disturbing the dark-light rhythm will also largely affect hens, and EU legislation requires a statutory dark period of 8 h (1999/74/EC), so this technique cannot be applied as such in Europe.…”