Population‐level impact of native arthropod predators on the poultry red mite Dermanyssus gallinae

Abstract

Stimulating the regulation of pests by their natural enemies is a way to improve the sustainability of agriculture and respect for the environment. However, the presence of natural enemies does not guarantee the existence of a pest control service. To what extent are predatory mites commonly found in henhouses actually able to regulate a major egg industry pest mite, Dermanyssus gallinae?To answer this question, we have experimentally recreated portions of a poultry house ecosystem allowing the development of the pest over several generations in the presence of a chick and detritivorous mites (Astigmata) that are ubiquitous and abundant in layer farms. In these conditions, we compared the growth of D. gallinae populations in the presence and absence of native predatory arthropods. No effect of native predators on the growth of the D. gallinae population could be detected despite high initial predator-to-prey ratios and satisfactory growth of predator populations. Prey switching to the alternative prey Astigmata likely dilutes the effect of predation on the target prey. Further exploration is needed to see whether action could be taken to enhance the effect of top-down regulation.

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

“…This is consistent with our previous results which showed a lethal effect of D. gallinae infestation in our mesocosms, with chicks tending to die past 35 days experiment starting from an inoculum of 400 adult females. 18 Adjusting the size of the inoculum (200 adult females) and the duration of the experiment to avoid chick mortality did not suppress it in the last interval. The r showed considerable variation at T + 7 days (range: −0.044-0.175, mean 0.063 ± 0.075) and was stabilized thereafter with fairly high values (range: 0.125-0.184, mean 0.161 ± 0.017) (Fig.…”

“…All experiments were conducted in compliance with relevant guidelines and regulations on animal experimentation. The mites were sampled a few days before the start of the experiments in a laying hen barn located at Pierrelattes (France), from the same farm as for the experiments conducted by Zriki et al 18,26 . (Farm DIN).…”

“…Yet we have uncovered a dramatic underestimation of this pest's population growth rate by the model built by Huber et al. 17,18 This dramatic underestimation is likely due to imperfect estimates of reproductive and longevity variables collected in the literature for model parameterization. 18 The model of Huber et al 17 describes by stochastic delayed differential equations for cohort individuals the demographic dynamics of D. gallinae and allows to simulate the population dynamics from a given number of mites at each life stage.…”

“…Our experimental systems consisted of closed mesocosms equipped with or without electronic trackers where the number of mites and their direction are automatically and continuously recorded and where a chick was accessible either from everywhere or via a constrained path for exhaustive tracking of foraging mites. Experiment A was motivated by the results and postdictions discussed earlier by Zriki et al 18 . and Dotson 19 .…”

“…24 Our experimental systems consisted of closed mesocosms equipped with or without electronic trackers where the number of mites and their direction are automatically and continuously recorded and where a chick was accessible either from everywhere or via a constrained path for exhaustive tracking of foraging mites. Experiment A was motivated by the results and postdictions discussed earlier by Zriki et al 18 and Dotson. 19 It was purely descriptive, with the objective to characterize the temporal population dynamics to evaluate how far observed population growth differs from population growth predicted by the Huber model.…”