Ornithonyssus Sylviarum Research Articles

Contrasted ecological repartition of the Northern Fowl Mite Ornithonyssus sylviarum (Mesostigmata : Macronyssidae) and the Chicken Red Mite Dermanyssus gallinae (Mesostigmata: Dermanyssidae)

The two hematophagous mite species, the Northern Fowl Mite Ornithonyssus sylviarum (Macronyssidae) and the Chicken Red Mite Dermanyssus gallinae (Dermanyssidae), are considered serious pests in fowl farms in the USA and in Europe respectively. However, neither of them seems to be restricted to either of these two continents according to sparse records in the literature. The aim here was to explore the respective ecological repartitions of these two species in France and to compare them with data from the USA. We thus analyzed hematophagous mesostigmatid mites collected in France in natura, in orchards agroecosystems, in pet bird and fowl farms and compared DNA sequences from some North American and French mites in both species. It is remarkable that O. sylviarum has been recurrently encountered in bird nests from France and yet been absent from French layer farms, whereas it is a serious pest in layer farms in the USA. On the other hand, O. sylviarum has been isolated from ornamental bird farms in France (canary, pheasant). This suggests either a strong impact of different farming practices between continents or a colonization in process in Europe. It remains to be explored whether the opposite applies to D. gallinae in the USA. Lastly, mites belonging to the special lineage D. gallinae L1 have been isolated from North American pigeons providing mt and nDNA sequences very close to French L1 isolates. This confirms the specific status of this cryptic entity.

Comparative efficacy of oil solution and wettable powder of lambda-cyhalothrin to naturally occurring Ornithonyssus sylviarum infestation of chickens

The Northern Fowl Mite (NFM), Ornithonyssus sylviarum, is one of the most important and common pests of poultry. Most of available pesticides applied in the NFM control are formulated as wettable powder or emulsifiable concentrate and require to be diluted with water before use. As water has very low affinity to bird feathers, a part of the diluted pesticide will fall on the ground, on the cages, on feed bins or drift in the air upon application, which becomes a source of a potential harm to administrative workers and birds. In contrast to water, an oil solution of pesticide has a higher affinity for feathers and can stay on the feather for a longer time, and maybe provide a high efficacy and be effective for a longer, persistent period against the NFM. In the present study, the efficacy of oil solution and wettable powder of lambda-cyhalothrin to NFM in breeders was compared; the results showed that while spraying lambda-cyhalothrin wettable powder on birds could effectively control NFM, painting lambda-cyhalothrin oil solution on birds gave complete control of NFM for at least 6 weeks. In the application of lambda-cyhalothrin oil solution, no containment of pesticide to cages, feed bin and no pesticide drifting in the air was observed. These results indicated that lambda-cyhalothrin oil solution has a potential to become an effective and safe formulation to control NFM in breeders.

Host inflammatory response governs fitness in an avian ectoparasite, the northern fowl mite ( Ornithonyssus sylviarum)

Vertebrate immune responses to ectoparasites influence pathogen transmission and host fitness costs. Few studies have characterized natural immune responses to ectoparasites and resultant fitness effects on the ectoparasite. These are critical gaps in understanding vertebrate–ectoparasite interaction, disease ecology and host-parasite co-adaptation. This study focused on an ectoparasite of birds—the northern fowl mite (NFM) ( Ornithonyssus sylviarum). Based on prior evidence that chickens develop resistance to NFM, these experiments tested two hypotheses: (i) skin inflammation blocks mite access to blood, impairing development, reproduction and survival; and (ii) host immunogenetic variation influences the inflammatory response and subsequent effects on the ectoparasite. On infested hosts, histology of skin inflammation revealed increased epidermal cell number and size, immigration of leukocytes and deposition of serous exudates on the skin surface. Survival of adult mites and their offspring decreased as the area of skin inflammation increased during an infestation. Inflammation increased the distance to blood vessels beyond the length of mite mouthparts (100–160 μm) and prevented protonymphs and adults from reaching a blood source. Consequently, protonymphs could not complete development, evidenced by a significant inverse relationship between inflammation and protonymph feeding success, as well as an increasing protonymph/adult ratio. Adult females were unable to feed and reproduce, indicated by an inverse relationship between inflammation and egg production, and decreasing female/juvenile ratio. These combined impacts of host inflammation reversed NFM population growth. Intensity of inflammation was influenced by the genotype of the major histocompatibility complex (MHC), supporting previous research that linked these immunological loci with NFM resistance. Overall, these data provide a model for a mechanism of avian resistance to an ectoparasitic arthropod and the fitness costs to the parasite of that host defense.

Temporal changes in distribution, prevalence and intensity of northern fowl mite ( Ornithonyssus sylviarum) parasitism in commercial caged laying hens, with a comprehensive economic analysis of parasite impact

Establishment and spread of Ornithonyssus sylviarum were documented through time on sentinel hens (50 per house of 28,000–30,000 hens) in the first egg production cycle of three large commercial flocks (12 houses) of white leghorn hens. Mites were controlled using acaricide, and the impacts of treatment on mite populations and economic performance were documented. Mite prevalence and intensity increased rapidly and in tandem for 4–8 weeks after infestation. Intensity declined due to immune system involvement, but prevalence remained high, and this would affect mite sampling plan use and development. Early treatment was more effective at controlling mites; 85% of light infestations were eliminated by a pesticide spray (Ravap), versus 24% of heavy infestations. Hens infested later developed lower peak mite intensities, and those mite populations declined more quickly than on hens infested earlier in life. Raw spatial association by distance indices (SADIE), incorporating both the intensity and distribution of mites within a house, were high from week-to-week within a hen house. Once adjusted spatially to reflect variable hen cohorts becoming infested asynchronously, this analysis showed the association index tended to rebound at intervals of 5–6 weeks after the hen immune system first suppressed them. Large, consistent mite differences in one flock (high vs. low infestation levels) showed the economic damage of mite parasitism (assessed by flock indexing) was very high in the initial stages of mite expansion. Unmitigated infestations overall reduced egg production (2.1–4.0%), individual egg weights (0.5–2.2%), and feed conversion efficiency (5.7%), causing a profit reduction of $0.07–0.10 per hen for a 10-week period. Asynchronous infestation patterns among pesticide-treated hens may have contributed to a lack of apparent flock-level economic effects later in the production cycle. Individual egg weights differed with mite loads periodically, but could be either higher or lower, depending on circumstances and interactions with hen weight. Individual hen weight gains were depressed by high/moderate mite loads, but the heavier hens in a flock harbored more mites. This led to compensatory weight gains after mites declined. Tradeoffs between resource allocation to body growth or production versus immune system function appeared to be operating during the early and most damaging mite infestation period, when high egg production was beginning and the hens were gaining weight. The results were related to other studies of mite impact on domestic hens and to wild bird–ectoparasite studies. Much of the mite economic damage probably is due to engaging and maintaining the immune response.

Temperature and Humidity Effects on Off-Host Survival of the Northern Fowl Mite (Acari: Macronyssidae) and the Chicken Body Louse (Phthiraptera: Menoponidae)

Off-host survival of the northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago) (Acari: Macronyssidae), and the chicken body louse, Menacanthus stramineus (Nitzsch) (Phthiraptera: Menoponidae), was studied at 12 combinations of temperature (15, 21, 27, and 33 degrees C) and humidity (31, 65, and 85% RH). Mite protonymphs and louse third instars survived longer on average than the respective adult stages. Higher temperatures significantly reduced survival of adult and immature stages of both ectoparasites, whereas relative humidity had significant effects on O. sylviarum (especially protonymphs) but not M. stramineus. The LT50 values for adult northern fowl mites ranged from 1.9 (at 33 degrees C, 31%RH) to 8.3 d (at 15 degrees C, 85%RH), LT50 values for mite protonymphs ranged from 2.0 (at 33 degrees C, 31%RH) to 18.1 d (at 15 degrees C, 85%RH), LT50 values for adult lice ranged from 0.5 (at 33 degrees C, 31%RH) to 1.7 d (at 15 degrees C, 65%RH), and LT50 values for nymphal lice ranged from 1.2 (at 33 degrees C, 65%RH) to 3.3 d (at 21 degrees C, 31%RH). Maximum survival of the northern fowl mite was up to 35 d for adults and 29 d for protonymphs. Maximum survival for the chicken body louse was 3.3 d for adults and 5.8 d for nymphs. The data provide minimum guidelines for leaving poultry houses vacant long enough to allow ectoparasites to die before introduction of subsequent new flocks.

Arthropods (Pseudoscorpionidea, Acarina, Coleoptera, Siphonaptera) in nests of the bearded tit (Panurus biarmicus)

AbstractIn the period 1993–2006, during investigation of reproduction biology of the bearded tit, 106 deserted nests of the species were collected in Slovakia, Austria and Italy and their arthropod fauna was analyzed. Occasionally introduced individuals of the pseudoscorpion Lamprochernes nodosus, a frequent species in Central Europe, were recorded in the nests. Altogether 984 individuals and 33 species of mesostigmatic mites (Acari) were found in 46.2% of the nests examined. The ectoparasite Ornithonyssus sylviarum was most abundant and frequent; it represented almost 68.3% of all individuals. Due to it, the parasitic mites predominated (69.4% of individuals). Other ecological groups were less represented: edaphic detriticols − 11.6%, coprophils − 10.7%, species of vegetation stratum − 8.2%, and nidicols − 0.2%. Beetles (40 species, 246 individuals) were present in 57 nests. Most of the beetles were strongly hygrophilous species inhabiting soil surface in the reed stands or other types of wetlands and the shore vegetation. Predators represented 59% of all individuals. They might find food in the nests, but none of the species had a close relationship to bird nests and represented 35% of species. All beetle species penetrated the nests occasionally, when ascending on the vegetation or searching cover during periods of increased water level. Occasionally, larvae and nymphs of the Dermacentor marginatus tick were found. They were most probably introduced by insectivores of the genus Neomys. Only one species of fleas, Ceratophyllus garei — a parasite of birds nesting in humid environment, was recorded in the nests.

Host Records for <I>Ornithonyssus sylviarum</I> (Mesostigmata: Macronyssidae) from Birds of North America (Canada, United States, and Mexico)

The northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago, 1877) (Mesostigmata: Macronyssidae) is a broadly distributed blood-feeding parasite that has been collected from many birds of temperate regions. Previously, the most complete host list was published in 1938, and it included 15 North American (Canada, United States, and Mexico) host species. In the process of a general survey of bird-associated mites in Alberta, Canada, we recovered many O. sylviarum specimens. Herein, we update the previous host list with these observations and records published since 1938. We collected mites by washing the bodies of salvaged birds and examining the filtrate. Northern fowl mites were collected from 26 host species, with 16 of these species being the first host records for North America. Including results from the current study, O. sylviarum has been reported from 72 species of North American birds from 26 families. This updated host list will be useful to anyone interested in the role of O. sylviarum in transmission of avian disease.

Northern Fowl Mite

The northern fowl mite (Figure 1) is the most important external parasite of poultry in Florida and is widely distributed throughout the state. This mite is found throughout many of the temperate regions of the world parasitizing domestic fowl and wild birds. It has been shown to cause economic damage on poultry farms by causing anemia, lower egg production and even death to birds. Also of considerable importance, the mites will bite man (egg handlers) causing itching and irritation to the skin. This document is ENY-286 (IG141), one of a series of the Department of Entomology and Nematology, UF/IFAS Extension. Originally published as Livestock Protection Pointer Number 3, August 1978. Revised March 2006. ENY-286/IG141: Northern Fowl Mite (ufl.edu)

Effectiveness of Various Acaricides in the Treatment of Naturally Occurring Ornithonyssus sylviarum (Northern Fowl Mite) Infestations of Chickens

Northern fowl mite infestation of caged layers, and to a lesser degree breeding birds, remains a frequent occurrence in poultry production. Successful control of these infestations requires accurate monitoring of mite presence, adequate methods of mite exclusion and removal, and effective as well as timely acaricide application. In the present study, parasiticides currently available for treatment of birds with northern fowl mite infestations were evaluated for effectiveness by index scoring and feather digests; data needed on a regional and periodic basis given the tendency for mite populations to develop and retain resistance. Tetrachlorvinphos with dichlorvos was the most effective product. Malathion dust and an application of 10% garlic oil each resulted in significantly reduced mite populations. Permethrin treatment failed to result in significant reductions of index scores or feather digest mite counts.

Northern fowl mite orientation in a thermal gradient and evidence for idiothetic course control

Abstract. The northern fowl mite, Ornithonyssus sylviarum, is an ectoparasite of birds and a poultry pest. The ability of northern fowl mites to orientate to a heat source is investigated with individual mites video‐recorded in two‐dimensional arenas and exposed to spatial or temporal heat gradients. Recorded tracks are digitally analysed for variation in linear velocity, mean direction of movement, and patterns in angular displacement. Mean direction of movement in a spatial gradient is significantly associated with the position of the heat source for 24/29 mites tested (P < 0.05), whereas most control (no heat) mean bearings are randomly distributed (16/25; P > 0.1). Angular displacement that orientates a mite towards the heat source is positively correlated with the preceding deviation from that direction (P < 0.01). Angular displacement away from the heat source is random. The temporal heat gradient is such that no spatial reference to the heat source exists within the plane of the arena. Mites in an ambient (27 °C) to heated (30 °C) transition have angular displacement distributions similar to control mites (ambient to ambient transition). However, mites in a heated to ambient transition execute angular displacements approximately 25° greater than mites in the other treatments (P < 0.03). Mites compare the shift in temperature over time and alter their direction of movement by a programmed (idiothetic) response to a decrease in temperature, rather than through detection of the spatial position of the gradient (allothetic).

A SURVEY OF SELECTED PARASITIC AND VIRAL PATHOGENS IN FOUR SPECIES OF MEXICAN PARROTS, AMAZONA AUTUMNALIS, AMAZONA ORATRIX, AMAZONA VIRIDIGENALIS, AND RHYNCHOPSITTA PACHYRHYNCHA

Isolated populations of four species of Mexican parrots were sampled for evidence of selected pathogens of concern in birds originating in Latin America. Data were collected between June and September 1997, and ectoparasite collection was repeated with Rhynchopsitta pachyrhyncha in September 2000. Serum samples from nine Amazona oratrix, 10 Amazona viridigenalis, 6 Amazona autumnalis, and 25 R. pachyrhyncha chicks were screened for neutralizing antibodies to psittacid herpesvirus and avian influenza and for antibodies to paramyxovirus serotypes 1 and 3. Chicks were also examined visually for fecal parasites and ectoparasites. All serologic and fecal parasite tests were negative. Ectoparasites included ticks, Ixodidae; mites, Ornithonyssus sylviarum; fleas, Psyttopsylla mexicana; lice, Paragoniocotes mexicanus, Heteromenopon sp., and Psittacobrosus sp.; and bugs, Ornithocoris sp. This study provides baseline information to guide future health studies.

Influence of Heat and Vibration on the Movement of the Northern Fowl Mite (Acari: Macronyssidae)

Heat and vibration are common host-generated cues that ectoparasites use to orient to hosts. Three experiments evaluated effects of heat and vibration on the movement of northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago). Individual arrested mites in an isolation chamber always initiated movement (walking) after substrate vibration (7.8-min walking duration), but only initiated movement 50% of the time (2.8-min walking duration) upon exposure to a 3 degrees C heat fluctuation. Heat fluctuation in combination with vibration extended the period of activity by approximately 50% (11.6-min walking duration) compared with activity initiated by vibration alone. Mites with longer time off-host moved for shorter durations. In a choice test, individual mites consistently moved closer to a 35 degrees C heat source 1 or 6 mm away, but not to a heat source 11 mm away. In a circular arena, mites were able to orient accurately to a 35 degrees C heat source and reached the arena edge almost 4 times faster (11.2 s) than mites without a heat source (41.2 s). These results suggest that northern fowl mite is capable of directed thermo-orientation, as well as modulation of activity depending on the type of sensory information perceived. The adaptive significance of this orientation for a "permanent" ectoparasite is discussed.

Acaricide Resistance in Northern Fowl Mite (Ornithonyssus sylviarum) Populations on Caged Layer Operations in Southern California

Southern California caged layer operations were visited over 3 yr. Northern fowl mites from 26 field populations were tested for acaricide resistance using a capillary pipette and glass dish bioassay. One was a susceptible field population with no pesticide exposure for over 30 yr (reference site for resistance ratio calculation). Technical and commercial formulations of malathion, carbaryl (Sevin), permethrin, and a commercial formulation of tetrachlorvinphos/dichlorvos (Ravap) were tested. Malathion did not have high activity for mites relative to other materials, but resistance to both technical and commercial formulations was low (< 5×). Resistance to other materials was moderate to extreme. Frequency of carbaryl resistance (> 10×) was higher with the commercial (88%) than the technical material (41%); 19% of the populations had resistance > 100x to commercial carbaryl. Frequency of Ravap resistance (> 10×) was 68%; 8% of populations had resistance > 100x. Frequency of permethrin resistance (> 10×) was 72% for the technical material and 88% for the commercial formulation. Extreme permethrin resistance (> 1,000×) was observed in 56 and 50% of mite populations assayed using the technical and commercial formulations, respectively. Among sites, resistance to permethrin was uncorrelated with resistance to other chemicals, suggesting a different resistance mechanism. Resistance to carbaryl and Ravap was highly correlated [r = 0.76 at the LC50 level (concentrations estimated to be lethal to 50% of the test population) and r = 0.99 at the LC95 level], suggesting a common resistance mechanism. Producers currently depend completely on pesticides to control mite infestations. Mite resistance to registered materials emphasizes the need for integrated control measures.

Macronyssidae in wild bird nests in Mexico, including new synonymies, and the genus Pellonyssus in the worl (Acari: Mesostigmata)

Pellonyssus nidicolus Baker, Delfinado, and Abbatiello, 1976 es un nuevo sinónimo de Pellonyssus reedi (Zumpt y Patterson, 1952). La sinonimia de Pellonyssus passeri Clark y Yunker, 1956 con P. reedi se mantiene. Los ejemplares de Pellonyssus reportados por Estébanes-González (1997) son identificados aquí como pertenecientes en parte a P. reedi y en parte a P. marui Yunker y Radovsky, 1966, es el primer reporte de estas especies en México. La tercera especie identificada de Pellonyssus conocida en el Nuevo Mundo es un parásito de colibrís Pellonyssus gorgasi Yunker y Radovsky, 1966, previamente reportado de México. Las claves para identificación de hembras, machos y protoninfas de estas 3 especies se incluyen. Un carácter común se da para comparar rasgos distintivos de las hembras de 9 especies validas de Pellonysssus en el mundo. La subespecie Ornithonyssus sylviarum utrechtensis Micherdzinski, 1980 es sinonimizada con la subespecie nominal O. s. sylviarum (Canestrini y Fanzago, 1877).

Dispersal of Northern Fowl Mites, Ornithonyssus sylviarum, Among Hens in an Experimental Poultry House

Northern fowl mites were introduced in the center of each of four rows of cages in a poultry house containing uninfested White Leghorn hens. Individually housed hens (seven per row) were separated by empty cages. The vent regions of all hens were examined every 2 to 4 days for 11 weeks. Light infestations were noted in all four rows within the first 14 days, but mites apparently disappeared from two of the four rows (Rows 1 and 2) in the first 4 weeks. Infestations in the remaining two rows (Rows 3 and 4) increased first on the nearest hens and were detected on more distant hens only after mites had increased to moderate-to-high populations on closer hens. Within 8 to 9 weeks, infestations were heavy for all hens in Rows 3 and 4. By 8 weeks, mites again were evident in Rows 1 and 2; all hens in the house were infested by Week 11. Results demonstrate rapid spread of mites achieved by mite movement across open cage areas rather than direct hen contact. The repeated pattern of mite spread (appearance on a hen after mites on an adjacent hen reached moderate-to-high levels) suggests that movement within a row was probably due to mites walking on cage wires rather than dispersal on rodents or wild birds.

Topical application of garlic reduces northern fowl mite infestation in laying hens

Northern fowl mites (NFM) are external parasites that can lower egg production and cause anemia and even death in laying hens. An experiment was conducted with New Hampshire Red and Single Comb White Leghorn laying hens. Hens were individually caged and provided a complete laying diet and water ad libitum. Hens were assigned to groups in a way that assured that treatments, within each breed, would be applied to comparable numbers of birds with light and heavy mite infestations. Each hen was sprayed around the vent with either water or 10% garlic juice in water. Spraying continued each week for 3 wk. During the fourth week, each bird was scored for the presence of NFM on its skin and feathers. A small snippet of feathers was removed from below the vent of each hen and placed in a labeled petri dish with a round, white filter paper insert. The NFM content of each dish was scored by two individuals approximately 1 h after sampling. There was no significant difference in the NFM scores for hens based on breed or future treatment. After the birds were treated for 3 wk, there was no significant difference in external NFM scores based on breed. There were significantly fewer NFM on the birds treated with garlic juice compared with controls, based on external and petri dish scoring (P < 0.002 and P < 0.04, respectively). The reduction in external NFM score was also significant (P < 0.004), with controls declining approximately 0.2 units, whereas garlic-treated hens had a 1.8-unit decrease in external NFM score. Topical application of garlic juice may be an effective way to decrease NFM in laying hens.

Monitoring northern fowl mites (Acari: Macronyssidae) in caged laying hens: feasibility of an egg-based sampling system.

Northern fowl mites were monitored on a caged-layer operation in southern California for 22 mo. Three experienced observers underestimated actual numbers of mites in the vent region approximately 80% of the time. Errors were higher for heavy infestations. Observer estimates were highly correlated with each other (r > 0.89, P < 0.01) and with mite numbers estimated by vent feather removal (r > 0.82, P < 0.01). Mites on hens varied between houses and over time. Molting consistently reduced mite numbers, but did not eliminate then in a flock. Long-term monitoring of individual sentinel hens demonstrated that some hens would support high numbers of mites for several months or more. Use of a new sequential hen sampling plan required approximately 1 min per hen, if mite numbers were estimated. At this site, treatment decisions often could be reached in < 20 min per house. Mite scores (index of estimated mites per hen) were well correlated with percentage of hens infested in both test houses. In a chronically infested house, prevalence of mites on eggs averaged 8.5%, with a range of 0-55%. Applications of tetrachlorvinphos-dichlorvos by the producer appeared to be based on mites on > about 20% of eggs. The chemical was marginal for controlling mites on hens (25% reduction in percentage of hens infested), but effectively reduced mites on eggs (95% fewer mites on eggs at 1 wk and 90% at 2 wk). When data were grouped by mite index score on hens, there was a strong relationship (r2 = 0.83, P < 0.01) between mite prevalence on eggs and the scores of the hens which laid them. Sampling 100 eggs evenly spaced in a house required < 7 min, and adult mites were easily seen. Sampling mites on eggs appears to be useful to localize at least high-level infestations, and egg-based sampling for mites merits further investigation.

Presence-absence sequential sampling plan for northern fowl mite, Ornithonyssus sylviarum (Acari: Macronyssidae), on caged-layer hens.

Caged-layer hens were scored as infested or uninfested by visual examination of the vent region, and the number of northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago), per hen was estimated. The proportion infested and average number of mites per hen were shown to have a highly significant, positive relationship (r = 0.936). Sampling among houses within a flock, and rows and sections within houses were analyzed to determine the reliability of sampling a representative portion of a flock. Low- and moderate-tolerance treatment thresholds, based on percentage of hens infested with mites, were developed from sampling 1 wk before and 1 wk after acaricide treatments determined necessary by the producer. These thresholds were used to compare a fixed (single) sampling plan, a curtailed procedure of the fixed sampling plan, and a sequential sampling plan based on a sequential probability ratio test, by sampling 174 hens (the maximum number needed for the single sampling plan). The sequential sampling plan required fewer hen examinations on average to reach a treatment decision than did the other plans, depending on the infestation tolerance limits. Using a low tolerance approach in which infestations below 15% are considered noneconomic (safe threshold) and infestations above 25% are considered economically important (action threshold), as few as 5 hens required examination to reach a treatment decision. Sequential sampling plan graphs are presented for 2 tolerance threshold scenarios (a 15% safe-threshold paired with a 25% action threshold and a 35% safe-threshold paired with a 45% action threshold). These sequential sampling plans using presence absence assessments should greatly facilitate monitoring and treatment decisions for this important pest.

California Caged Layer Pest Management Evaluation

California caged-layer poultry producers were surveyed regarding current pest management practices for insects, mites, weeds, pathogens, rodents, and other vertebrate pests. In order of perceived importance, producers identified house flies, Fannia flies (little house flies), northern fowl mites, and mice as the most significant pests. Less serious pests included ground squirrels, rats, wild birds, darkling beetles, weeds, and pathogens; typically these pests were not present in high numbers or were considered easy to control. While biological, mechanical, and cultural controls are regularly employed in most pest suppression systems, pesticides are still considered an important component of virtually all poultry pest management programs.

Changes in infestation rate and age structure of Dermanyssus hirundinis and Ornithonyssus sylviarum (Acarina) during nidification and breeding period of penduline tit.

Populations of 2 parasitic mites, Dermanyssus hirundinis (Hermann) (63,169 collected individuals) and Ornithonyssus sylviarum (Canestrini et Fanzago) (3,425 collected individuals), in 305 penduline tit, Remiz pendulinus L., nests were studied in 1993 and 1994. The nests were divided into 4 groups: nests without eggs, nests with eggs, nests with nestlings, and nests just after fledging. The average percentage of infested nests increased from the nests without eggs to the nests after fledging (at 20% in both years of investigation), and the increase of mite abundance was exponential. Presence of nestlings in the nests stimulated intensive reproduction of parasitic mites. An increasing infestation intensity in nests was observed during the host breeding period. The 2 mite species exhibited similar age structure patterns in the nests of all the groups and during the entire penduline tit breeding period as well. A decrease in the proportion of adult mites (mainly females) and an increase of nymphs (above all of protonymphs) occurred at the time of fledging and at the end of host breeding period. The percentage of the ovigerous females increased in the individual nests, but decreased during the breeding period of penduline tit. The quantitative parameters of D. hirundinis populations in the highly infested nests depended on the individual nidification and nidobiology of the host, whereas the qualitative parameters (age structure) of these populations depended more on abiotic factors and life strategy of the ectoparasite.