Parasites from feral pigeons as a health hazard for humans

Feral pigeons live in almost every large city in the world. The feeding of pigeons by humans, deliberately or accidentally, allows the build‐up of large populations that can cause a variety of problems, primarily the fouling of buildings and monuments by their droppings. Excreta of wild birds are a well‐known source of pathogenic microorganisms that can cause infection in man. The most important ectoparasites of feral pigeons are the red blood mite, Dermanyssus gallinae, and the pigeon tick, Argas reflexus, both of which can migrate into human living space when they lose their natural hosts. The bites of the red blood mite are irritating but harmless, whereas the pigeon tick can cause severe health problems to predisposed persons. After repeated bites from A. reflexus, people can develop IgE‐mediated (type I) allergy, which in extreme situations may lead to life‐threatening symptoms of anaphylactic shock. So far, one fatality due to A. reflexus deriving from feral pigeons has been reported. In the case of parasitic infestations of humans, the source must be removed by excluding pigeons from further breeding and by disinfection of the environment of pigeon‐breeding sites.     

Life cycle and seaonal development of postembryonicArgas reflexus (Acari: Argasidae) at two thermally different locations in Central Europe

Seasonal development was investigated in the pigeon tick,Argas reflexus (F.) over a 5-year period. The ticks were kept in desiccators at two deposition sites with different temperature conditions: a warmer attic and a cooler outdoor aviary. The life cycle ofA. reflexus consists of the egg, larva, a variable number of two to four nymphal instars and the adult stage. In the cooler aviary, the ticks passed, on average, fewer nymphal instars than in the attic. At both locations, ecdysis of the nymphs and adults occurred only during the summer months, with peak numbers of ticks finishing the moult in August. This consistent pattern was evident irrespective of the feeding date of the preceding developmental stage or the year of observation. The results strongly suggest that nymphs II, nymphs I and larvae fed later than in mid-July, August or September, respectively, entered a state of diapause and, thus, overwintered in the engorged state.Argas reflexus nymphs II from a laboratory stock that were deposited inside the attic showed a remarkably different seasonal pattern of development, even more than 1 year after their deposition. This suggests that a circannual rhythm may be involved in the ticks' seasonal timing. Mortality of the engorged ticks (from repletion to ecdysis of the following stage/instar) was below 1.5% in most cases, irrespective of the season and the location. Unfed larvae survived for a maximum of one year inside the attic, whereas the median survival period of unfed nymphs was at least 3 years at the same location. Based on the present results, the generation time from (F₁) egg deposition to oviposition in the F₂ generation might be 3–11 years in Central EuropeanA. reflexus, depending on the course of development (two or three nymphal instars) and the number of gonotrophic cycles (probably up to six) of the F₁. The life span of a single tick might take approximately 7–11 years or even longer.     

Host-odour recognition in two tick species is coded in a blend of vertebrate volatiles

The questing behaviour of ixodid ticks serves for identification and localisation of approaching hosts and is evoked by carbon dioxide, vibrations, visual and odour stimuli. In an olfactometer, we examined the specificity of the questing response of larvae of Boophilus microplus, a one-host tick which develops mainly on cattle, and Ixodes ricinus, a three-host tick with a broader host spectrum. While all mammalian odours tested were equally stimulatory for I. ricinus, B. microplus was clearly more activated by bovine odours. A phenolic fraction of bovine odour stimulated B. microplus only. Attractive components of the host odours were identified by exposing the ticks to single chemicals and mixtures. Single chemicals stimulated questing responses only at levels higher than the levels detected in the bovine odour. However, an artificial odour blend of 37 pure chemicals, diluted to concentrations at which the individual components were inactive, proved to be as effective as natural host odour for both tick species. Further fractionation of the blend revealed that the combinatory effect was achieved by only 7 compounds in both species. Although B. microplus responded to the same synergistic mixture of volatiles as I. ricinus, it showed significant higher sensitivity to the cattle-associated compounds 1-octen-3-ol and 2-nitrophenol and this might contribute to its host-specificity. Accepted: 20 March 1999     

Polyphagy and primary host plants: oviposition preference versus larval performance in the lepidopteran pest Helicoverpa armigera

Oviposition preference and several measures of offspring performance of Helicoverpa armigera (Hübner) were investigated on a subset of its host plants that were selected for their reputed importance in the field in Australia. They included cotton, pigeon pea, sweet corn, mungbean, bean and common sowthistle. Plants were at their flowering stage when presented to gravid female moths. Flowering pigeon pea evoked far more oviposition than did the other plant species and was the most preferred plant for neonate larval feeding. It also supported development of the most robust larvae and pupae, and these produced the most fecund moths. Common sowthistle and cotton were equally suitable to pigeon pea for larval development, but these two species received far fewer H. armigera eggs than did pigeon pea. Mungbean also received relatively few eggs, but it did support intermediate measures of larval growth and survival. Fewest eggs were laid on bean and it was also the least beneficial in terms of larval growth. Among the host plant species tested, only flowering pigeon pea supported a good relationship between oviposition preference of H. armigera and its subsequent offspring performance. Australian H. armigera moths are thus consistent with Indian H. armigera moths in their ovipositional behaviour and larval performance relative to pigeon pea. The results suggest that the host recognition and acceptance behaviour of this species is fixed across its geographical distribution and they support the theory that pigeon pea might be one of the primary host plants of this insect. These insights, together with published results on the sensory responses of the females to volatiles derived from the different host plant species tested here, help to explain why some plant species are primary targets for the ovipositing moths whereas others are only secondary targets of this polyphagous pest, which has a notoriously broad host range. Handling Editor: Joseph Dickens     

Host location by larvae of the reptile tick Amblyomma vikirri (Acari: Ixodidae)

The newly described tick Amblyomma vikirri has a narrow host range, being found mainly on the Australian lizard, Egernia stokesii and rarely on another lizard, Tiliqua rugosa. Both hosts are in the family Scincidae. Larvae of A. vikirri were as successful in locating E. stokesii as T. rugosa from a range of release distances between 20 and 120 mm from the host. Over this range the proportion of ticks which successfully located hosts declined and the time taken by successful ticks to locate hosts increased with increasing release distance. From 60 mm, larvae of A. vikirri located four other lizard species from the families Scincidae and Agamidae and two non-living targets as successfully as they did E. stokesii. The only evidence that there was any host specificity in the searching behaviour of larvae of A. vikirri was that A. vikirri larvae spent less time paused and questing when they were searching for E. stokesii than when they were searching for T. rugosa. Aponomma hydrosauri, a tick which commonly infests T. rugosa but not E. stokesii, spent less time paused and questing when it was searching for T. rugosa than when it was searching for E. stokesii. However, the results overall suggest that the narrow host range of A. vikirri cannot be explained by any ability of the larvae of that species to discriminate between their natural host and other reptile species.     

Comparative response of Metarhizium brunneum to the cuticles of susceptible and resistant hosts

Earlier studies demonstrated that Metarhizium brunneum, usually a broad-host pathogen of arthropods, is unable to complete its pathogenic life cycle when inoculated on the fungus-resistant tick, Hyalomma excavatum engorged females. While the fungus penetrates the cuticle of fungus-susceptible tick, Rhipicephalus annulatus females, it is unable to penetrate the cuticle of fungus-resistant tick, and even perishes on its surface. This is probably due to high concentration of antifungal fatty acids and probably also due to a hypersensitive-like response of the tick. To understand the metabolic pathways occurring in the fungal hyphae upon encountering the cuticles, we compared the response of the fungus to cuticle from susceptible and resistant tick cuticles by 2D-gels. The intracellular proteomes of M. brunneum Mb7 exposed to cuticle of the fungus-susceptible tick, R. annulatus, and to the fungus-resistant tick, H. excavatum engorged females were compared after exposure to either cuticles. By means of liquid chromatography-mass spectrometry/mass spectrometry we identified in both proteomes common proteins involved in biological processes as well as unique proteins identified only in the proteome of fungus exposed to fungus-resistant tick cuticle. These proteins were identified in high probability as heat shock proteins, four key enzymes of the glyoxylate cycle, and proteins associated with hypoxia, and exposure to antifungal drugs. These findings are discussed within the M. brunneum-tick pathosystem in relation to tick resistance and host resistance in general.     

Host specificity and host recognition in a chemically-defended herbivore, the tenthredinid sawfly Rhadinoceraea nodicornis

The sawfly Rhadinoceraea nodicornis Konow (Hymenoptera: Tenthredinidae) is a member of a closely related group of species, the tribe Phymatocerini, which feed on the Liliales and Ranunculales. It is known to sequester steroid alkaloids from its host plants, species in the genus Veratrum (Liliales: Melanthiaceae), and to use them as a defence against predators. There are known chemical relationships between the hosts of R. nodicornis and hosts of related sawfly species. We tested whether the R. nodicornis larvae would accept hosts of closely- and more distantly-related sawflies, but found that they accepted only plant species in the genus Veratrum. This specificity was apparently innate, as it was independent of early larval experience. A feeding bioassay showed that the steroid alkaloids from Veratrum nigrum were phagostimulatory for R. nodicornis larvae, suggesting that they may be involved in host recognition. We discuss the possibility that the evolution of recognition of specific compounds may represent the mechanism of host radiation within the Phymatocerini.     

Host location and discrimination mediated through olfactory stimuli in two species of Encyrtidae

The role of olfactory stimuli in host detection and evaluation was studied in two encyrtid Hymenoptera. The first, Epidinocarsis lopezi De Santis, is a monophagous parasitoid of the cassava mealybug Phenacoccus manihoti Matile-Ferrero, itself feeding exclusively on cassava, Manihot esculenta Crantz. The second, Leptomastix dactylopii Howard, is a monophagous parasitoid of the Citrus mealybug, Planococcus citri Risso, but this latter is highly polyphagous. The behaviour of females of both parasitoids (attaction and locomotion) was compared in a tubular olfactometer for the odours of their respective hosts on cassava and poinsettia. Tests were made using: 1) healthy host-plant alone; 2) host-plant infested with unparasitized mealybugs; 3) unparasitized mealybugs only; 4) host-plant infested with parasitized mealybugs and 5) parasitized mealybugs only. Only E. lopezi was attracted by the odour of the host-plant alone, but both species were attracted by the odour of an infested host-plant and that of unparasitized mealybugs. The odour of parasitized mealybugs, alone or on host-plant, induced an undirected activity. The attraction of E. lopezi to the odour of the host-plant alone could be linked to the monophagous diet of its host, whereas the attraction of the two species of parasitoids to the odours of infested host-plants and unparasitized mealybugs could be due to the fact that both parasitoids are specialists. The behavioural response of both species to the odour of parasitized mealybugs revealed a new aspect in host discrimination: the identification of parasitized hosts could be partly mediated through olfactory stimuli, and not only through gustatory stimuli.     

Host specificity of a generalist parasite: genetic evidence of sympatric host races in the seabird tick Ixodes uriae

Due to the close association between parasites and their hosts, many ‘generalist’ parasites have a high potential to become specialized on different host species. We investigated this hypothesis for a common ectoparasite of seabirds, the tick Ixodes uriae that is often found in mixed host sites. We examined patterns of neutral genetic variation between ticks collected from Black‐legged kittiwakes (Rissa tridactyla) and Atlantic puffins (Fratercula arctica) in sympatry. To control for a potential distance effect, values were compared to differences among ticks from the same host in nearby monospecific sites. As predicted, there was higher genetic differentiation between ticks from different sympatric host species than between ticks from nearby allopatric populations of the same host species. Patterns suggesting isolation by distance were found among tick populations of each host group, but no such patterns existed between tick populations of different hosts. Overall, results suggest that host‐related selection pressures have led to the specialization of I. uriae and that host race formation may be an important diversifying mechanism in parasites.     

Behavioral responses of the parasitoid Melittobia digitata to volatiles emitted by its natural and laboratory hosts

Responses of macropterous females of the ectoparasitoid Melittobia digitata Dahms (Hymenoptera: Eulophidae) to direct and indirect cues emitted by its natural hosts as well as laboratory hosts were investigated using a Y‐tube olfactometer. To locate the nest of mud dauber wasps, Trypoxylon politum Say (Hymenoptera: Crabronidae), and one of their inquilines, Anthrax spec., parasitoids exploit volatiles from the freshly built nest mud and the empty cocoon constructed by the wasps, as well as their meconium. However, the parasitoids did not respond to odors emitted by older nest mud or by the host stages that are attacked (T. politum prepupae and Anthrax spec. larvae). Melittobia digitata was not attracted to direct volatiles released by the dipteran hosts Anastrepha ludens Loew (Diptera: Tephritidae) (a natural host) and Sarcophaga bullata (Parker) (Diptera: Sarcophagidae) (a laboratory host). Based on our results, we suggest that M. digitata adopts a ‘sit and wait’ strategy to locate mud dauber wasps, relying mainly on indirect host‐related cues: females search for nests that are under construction and once found, they wait inside the cell until the host completes its cocoon and releases meconium, an indicator that is associated with host suitability. No attraction was found to dipteran hosts, suggesting that parasitization of these hosts may be incidental, due to the broad host plasticity of Melittobia wasps.     

Ticks (Acari: Ixodoidea: Argasidae, Ixodidae) of Chile

The tick species recorded from Chile can be listed under the following headings: (1) endemic or established: Argas keiransi Estrada-Peña, Venzal and Gonzalez-Acuña, A. neghmei Kohls and Hoogstraal; Ornithodoros amblus Chamberlin; Otobius megnini (Dugès); Amblyomma parvitarsum Neumann; A. tigrinum Koch; Ixodes auritulus Neumann; I. chilensis Kohls; I. cornuae Arthur, I. sigelos Keirans, Clifford and Corwin; I. stilesi Neumann; I. uriae White; Rhipicephalus sanguineus Koch. (2) Probably established or endemic: Argas miniatus Koch; Ornithodoros spheniscus Hoogstraal, Wassef, Hays and Keirans; Ixodes abrocomae Lahille; I. neuquenensis Ringuelet; I. pararicinus Keirans and Clifford. (3) Doubtfully established: Argas reflexus Fabricius; Ornithodoros talaje (Guérin-Méneville). (4) Exotic: Amblyomma argentinae Neumann; A. latum Koch, Rhipicephalus (=Boophilus) microplus (Canestrini). (5) Erroneously identified as present in Chile: Amblyomma americanum (Linnaeus); A. maculatum Koch; A. varium Koch; Ixodes conepati Cooley and Kohls; I. frontalis (Panzer); I. ricinus (Linnaeus); Margaropus winthemi Karsch. (6) Nomina nuda: Argas reticulatus Gervais; Amblyomma inflatum Neumann; Ixodes lagotis Gervais. Hosts and localities (including new records) are presented. Argas neghmei, O. amblus, O. megnini, I. uriae and R. sanguineus may cause severe injury to their hosts, including humans. The Chilean Ixodes fauna is unique to the Neotropical Zoogeographic Region, and additional research is needed in order to understand the biological importance of these species.This revised version was published online in May 2005 with a corrected cover date.     

Does mother really know best? Oviposition preference reduces reproductive performance in the generalist parasitoid Aphidius ervi

The reproductive success of female parasitoids is dependent on their ability to accurately assess the suitability of a host for larval development. For generalist parasitoids, which utilize a broad range of species and instars as hosts, a set of assessment criteria determines whether a host is accepted or rejected. The suitability of a host, however, can only be imperfectly assessed by the female parasitoid, which can result in the selection of lesser quality hosts for oviposition. In this study we explored the disparity between host quality and host preference using the generalist koinobiotic parasitoid Aphidius ervi Haliday (Hymenoptera: Aphidiidae) and the host Aulacorthum solani (Harris) (Homoptera: Aphididae), the foxglove aphid. The second instar hosts produced the highest level of reproductive success, while third and fourth instars resulted in a substantially reduced reproductive performance. When given a choice of host instars, parasitoids preferred the older hosts for oviposition disregarding their reduced suitability for larval development. Results are discussed in context of mechanisms involved in A. ervi host selection and biases in the criteria used to assess hosts that may arise when parasitoids transfer host species between generations.     

The influence of physiological age of Argas reflexus larvae (Acari: Argasidae) and of temperature and photoperiod on induction and duration of diapause

The occurrence of diapause and quiescence was investigated in Argas reflexus engorged larvae, nymphs I and nymphs II. For diapause experiments, larvae were maintained at five different locations: at constant 20°C long day (LD; 17 h light:7 h dark) or short day (SD; 10 h light:14 h dark), at two locations with natural photoperiod and temperature and at one location with natural photoperiod but constant 15°C. At 20°C, diapause incidence was low in physiologically young larvae, increased with larval age, and then decreased to zero in specimens of increased physiological age. This pattern, observed both at constant LD and SD, suggests that the propensity to diapause changes with the physiological age of the unfed larva. The duration of diapause decreased with increasing larval physiological age at all locations, resulting in a seasonally synchronized moulting pattern. The results suggest that A. reflexus larvae are photoperiodically sensitive both before and after feeding and that decreasing daylengths may be particularly strong inductive stimuli. The developmental zero and thermal constant of the larvae were determined as 13.24°C and 220 degree-days, respectively. Degree-day measurements revealed that larval A. reflexus may enter a diapause of different length when fed between August and December and kept at natural daylength. Development of engorged nymphs I and nymphs II, but not of larvae, was ultimatively restricted at a temperature of 37.5°C, but immediately resumed at 25°C, demonstrating the occurrence of quiescence at high temperatures. Similarly, at a low temperature of 15°C, many nymphs I and II did not develop within 58 months, but did so successfully after transfer to 25°C, without additional food intake. Received: 20 May 1997 / Accepted: 4 August 1997     

Aversion of the invasive Asian longhorned tick to the white-footed mouse,the dominant reservoir of tick-borne pathogens in the U.S.A.

The Asian longhorned tick (Haemaphysalis longicornis) was reported for the first time in the U.S.A. in 2017 and has now spread across 12 states. The potential of this invasive tick vector to transmit pathogens will be determined through its association to hosts, such as the white-footed mouse (Peromyscus leucopus), which is the primary reservoir for the causative agent of Lyme disease (Borrelia burgdorferi) and other zoonotic pathogens. Larval H. longicornis were placed on P. leucopus; 65% of the larvae (n = 40) moved off the host within a short period of time, and none engorged. By contrast, larval blacklegged ticks (Ixodes scapularis) did not move from where they were placed in the ear of the mouse. A laboratory behavioural assay was then conducted to assess the interaction of H. longicornis with the hair of potential mammalian host species in the U.S.A. H. longicornis larvae were significantly less likely to enter the hair zone of P. leucopus and humans compared to the hair of domestic cats, domestic dogs and white-tailed deer. This study identifies a tick–host interaction behaviour, which can be quantified in a laboratory assay to predict tick–host associations and provides insights into how ticks select a host.     

PATTERNS IN HOST RANGE FOR TWO STRAINS OF AMOEBOPHRYA (DINOPHYTA) INFECTING THECATE DINOFLAGELLATES: AMOEBOPHYRA SPP. EX ALEXANDRIUM AFFINE AND EX GONYAULAX POLYGRAMMA1

The endoparasitic dinoflagellate Amoebophrya ceratii (Koeppen) Cachon uses a number of its free‐living relatives as hosts and may represent a species complex composed of several host‐specific parasites. Two thecate host–parasite systems [Amoebophrya spp. ex Alexandrium affine (Inoue and Fukuyo) Balech and ex Gonyaulax polygramma Stein], were used to test the hypothesis that two strains of Amoebophrya have a high degree of host specificity. To test this hypothesis, a series of cross‐infection experiments were conducted, with 10 thecate and three athecate dinoflagellate species as potential hosts. Surprisingly, the two strains of Amoebophrya lacked host specificity and had wider host ranges than previously recognized. Among the host species tested, Amoebophrya sp. ex Alexandrium affine was capable of infecting only species of genus Alexandrium (Alexandrium affine, Alexandrium catenella, and Alexandrium tamarense), while the parasite from Gonyaulax polygramma infected species covering five genera (Alexandrium, Gonyaulax, Prorocentrum, Heterocapsa, and Scripsiella). In the context of previous reports, these results suggest that host specificity of Amoebophrya strains varies from extremely species‐specific to rather unspecific, with specificity being stronger for strains isolated from athecate hosts. Information on host specificity of Amoebophrya strains provided here will be helpful in assessing the possibility of using these parasites as biological control agents for harmful algal blooms, as well as in defining species of Amoebophrya in the future.     

Volatile cues used by the parasitoid, Aphytis melinus, for host location: California red scale revisited

Aphytis melinus DeBach (Hymenoptera: Aphelinidae) is a biological control agent of diaspidid scale insects. The parasitoid has a narrow host range but its hosts are polyphagous. We determined the source of volatile cues the wasp uses to locate its few host species when those hosts occur on more than one host plant species. We addressed four questions in regard to the use of volatile cues in host location of California red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae): (1) Does A. melinus use volatile cues to assist in host location? (2) Are these cues innately recognized or learned? (3) Are cues produced by female California red scale, or from other sources? (4) Are the cues specific to the host or host plant? These questions were tested through the use of a Y-tube olfactometer. Female A. melinus used volatile cues to orient toward both infested and uninfested host plant material. Wasps learned these cues by associating odors from the host plant with host presence. They had no innate preferences for scale insect or host plant volatile stimuli. Contrary to previous studies, we found no evidence of orientation toward the female-produced sex pheromone of California red scale, nor to volatile cues from the attacked host stage. Wasps given experience with scale insects growing on lemon fruit subsequently oriented toward lemon and orange fruit and leaves. The scale species with which the wasp was given experience did not affect this preference. Wasps given experience with California red scale growing on squash did not orient toward infested lemon fruit. The host ranges of the parasitoid and its hosts are used to explain the adaptive value for the evolution of learned rather than fixed responses to cues used in foraging behavior.     

Behavioural responses of Ixodes ricinus nymphs to carbon dioxide and rodent odour

Many haematophagous ectoparasites use carbon dioxide (CO₂) and host odour to detect and locate their hosts. The tick Ixodes ricinus (Linnaeus) (Ixodida: Ixodidae) walks only small distances and quests in vegetation until it encounters a host. The differential effects of CO₂ and host odour on the host‐finding behaviour of I. ricinus have, however, never been clarified and hence represent the subject of this study. The effects of CO₂ and odour from bank voles on the activation and attraction of I. ricinus nymphs were analysed in a Y‐tube olfactometer. Carbon dioxide evoked a response in the absence and presence of host odour, but did not attract nymphs. Host odour, however, did not evoke a response but did attract nymphs in the absence and presence of CO₂. The current results show that CO₂ is an activator, but not an attractant, and that host odour is an attractant, but not an activator, of I. ricinus nymphs, and provide ecological insights into the host‐finding behaviour of I. ricinus.     

An experimental test of potential host range in the ant parasitoid Apocephalus paraponerae

1. The work reported here tested experimentally whether specialisation in Apocephalus paraponerae was due to physiological interactions that limit the parasitoid to the host ant Paraponera clavata. The suitability of other ant species as hosts was tested, and behavioural traits that may promote a high degree of specificity within this host–parasitoid system are discussed. 2. Data for development time, number of puparia, and adult eclosion success for A. paraponerae ovipositing in the regular host P. clavata are provided. A new method for testing host suitability in parasitoids of ants is described. Eggs of A. paraponerae were transferred directly into potential ant hosts. The development time, number of puparia, and adults eclosed for the eggs transferred into other ant host species are compared with comparable data from P. clavata. 3. Seven ant species within the Ponerinae are suitable for the development of A. paraponerae. The potential host range is greater than the actual host range of A. paraponerae. Flies are not limited solely by host suitability of related ant species for the development of larvae. Host location and acceptance behaviours are proposed as the primary reasons for host specialisation. The large size of the primary host P. clavata, and the ability of multiple females to raise many offspring successfully from those hosts may influence the specialisation of A. paraponerae on P. clavata.     

Being a parasitoid of parasites: host finding in the tick wasp Ixodiphagus hookeri by odours from mammals

The parasitic wasp Ixodiphagus hookeri Howard (Hymenoptera: Encyrtidae) parasitizes larvae and nymphs of a number of tick species worldwide. Ticks themselves are parasitic on vertebrate hosts. To study the specificity and reliability of vertebrate odours used by I. hookeri for host location, we conducted bioassays in a four‐chamber olfactometer. Wasps were arrested by carbon dioxide and by odours from roe deer faeces and odours from hair of roe deer and wild boar. Odours from faeces of cattle, rabbit, and field mouse as well as odours from hair of cattle and field mouse had no effect. Odours from faeces of the host tick species Ixodes ricinus L. (Acari: Ixodidae) were attractive only up to a distance of 1 cm. Thus, I. hookeri reacts to general (carbon dioxide) and specific vertebrate odours from wild boar and deer. Examination of freshly shot specimens demonstrates that deer and wild boars are infested with a sufficient number of tick nymphs to tap the full reproductive potential of an I. hookeri female, which makes cues from these mammal species reliable. These results indicate that I. hookeri locates its hosts using specific and reliable mammal odours and that ticks are parasitized on their vertebrate hosts. The implications of this host‐finding strategy and its benefits for the parasitoid are discussed.     

Distribution and 16S rDNA sequences of <Emphasis Type="Italic">Argas monachus</Emphasis> (Acari: Argasidae), a soft tick parasite of <Emphasis Type="Italic">Myiopsitta monachus</Emphasis> (Aves: Psittacidae)

Specimens of Argas monachus Keirans et al. were collected from Myiopsitta monachus nests in 42 localities in Argentina and Paraguay from 2006 to 2010. A list of localities where this tick has been found is presented. 16S rDNA sequences of specimens of A. monachus from different localities were compared to confirm whether they belong to the same specific taxon. Argas monachus is present in the phytogeographic provinces of Chaco, Espinal, and Monte, but not in the Pampa (all from de Chaco Domain) where the host is well distributed. No differences were found among 16S rDNA sequences of geographically distant specimens.