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PubMed2003

Acquired resistance of horses to Amblyomma cajennense (Fabricius, 1787) ticks.

Acquired immunity of horses to larvae, nymphs and adults of the Amblyomma cajennense tick was evaluated through three consecutive experimental infestations of tick-bite naïve hosts. Data from these infestations were compared to those from field-sensitized horses and donkeys. It was observed that tick-bite naïve horses developed a low level of resistance after two infestations as shown by a significant decrease in larval yield and a tendency for lower engorged weight of nymphs during third infestation. Ticks fed on field-sensitized horses had a similar biological performance to that observed on the third infestation of tick-bite naïve horses but the mean engorged nymph weight was significantly lower than that of the first infestation from tick-bite naïve horses. Donkeys presented the strongest resistance with significantly lower engorged weights of all instars and of the egg mass compared to the first infestation of tick-bite naïve horses. Donkeys also displayed a significantly higher resistance than field-sensitized horses as demonstrated by significantly lower egg mass weights. Overall these results indicate that donkeys but not horses maintain a strong resistance to A. cajennense ticks. The importance of these findings in relation to vectoring of tick-borne diseases is discussed.

Animals↗
PubMed2001

Differential adhesion of major surface proteins 1a and 1b of the ehrlichial cattle pathogen Anaplasma marginale to bovine erythrocytes and tick cells.

Anaplasma marginale is a tick-borne ehrlichial pathogen of cattle for which six major surface proteins (MSPs) have been described. The MSP1 complex, a heterodimer composed of MSP1a and MSP1b, was shown to induce a protective immune response in cattle and both proteins have been identified as putative adhesins for bovine erythrocytes. In this study the role of MSP1a and MSP1b as adhesins for bovine erythrocytes and tick cells was defined. msp1alpha and msp1beta1 genes from the Oklahoma isolate of A. marginale were cloned and expressed in Escherichia coli K-12 under the control of endogenous and tac promoters for both low and high level protein expression. Expression of the recombinant polypeptides was confirmed and localised on the surface of transformed E. coli. The adhesion properties of MSP1a and MSP1b were determined by allowing recombinant E. coli expressing these surface polypetides to react with bovine erythrocytes, Dermacentor variabilis gut cells and cultured tick cells derived from embryonic Ixodes scapularis. Adhesion of the recombinant E. coli to the three cell types was determined using recovery adhesion and microtiter haemagglutination assays, and by light and electron microscopy. MSP1a was shown by all methods tested to be an adhesin for bovine erythrocytes and both native and cultured tick cells. In contrast, recombinant E. coli expressing MSP1b adhered only to bovine erythrocytes and not to tick cells. When low expression vectors were used, single E. coli expressing MSP1a was seen adhered to individual tick cells while reaction of tick cells with the E. coli/MSP1a/high expression vector resulted in adhesion of multiple bacteria per cell. With electron microscopy, fusion of E. coli cell membranes expressing MSP1a or MSP1b with erythrocyte membranes was observed, as well as fusion of tick cell membranes with E. coli membranes expressing MSP1a. These studies demonstrated differential adhesion for MSP1a and MSP1b for which MSP1a is an A. marginale adhesin for both bovine erythrocytes and tick cells while MSP1b is an adhesin only for bovine erythrocytes. The role of the MSP1 complex, therefore, appears to vary among vertebrate and invertebrate hosts.

Adhesins, Bacterial↗
PubMed2003

Molecular cloning, expression and isolation of ferritins from two tick species--Ornithodoros moubata and Ixodes ricinus.

Genes encoding ferritins were isolated and cloned from cDNA libraries of hard tick Ixodes ricinus and soft tick Ornithodoros moubata. Both tick ferritins are composed of 172 amino-acid residues and their calculated mass is 19,667.2 Da and 19,974.5 Da for I. ricinus and O. moubata, respectively. The sequences of both proteins are closely related to each other as well as to the ferritin from another tick species Dermacentor variabilis (>84% similarity). The proteins contain the conserved motifs for ferroxidase center typical for heavy chains of vertebrate ferritins. The stem-loop structure of a putative iron responsive element was found in the 5' untranslated region of ferritin mRNA of both ticks. Antibodies against fusion ferritin from O. moubata were raised in a rabbit and used to monitor the purification of a small amount of ferritins from both tick species. The authenticity of ferritin purified from O. moubata was confirmed by mass-fingerprinting analysis. In the native state, the tick ferritins are apparently larger (~500 kDa) than horse spleen ferritin (440 kDa). On SDS-PAGE tick ferritins migrate as a single band of about 21 kDa. These results suggest that tick ferritins are homo-oligomers of 24 identical subunits of heavy-chain type. The Northern blot analysis revealed that O. moubata ferritin mRNA level is likely not up-regulated after ingestion of a blood meal.

Amino Acid Sequence↗
PubMed1988

The effect of temperature on the rate of transmission of Theileria parva parva infection to cattle by its tick vector, Rhipicephalus appendiculatus.

A steer was infected with Theileria parva parva Kilae stabilate; nymphal Rhipicephalus appendiculatus ticks were applied to its ears so that they completed repletion when the steer had a high piroplasm parasitaemia. The engorged nymphs were subsequently incubated at 28 degrees C for 26-29 days to complete moulting, when the adult ticks were divided into two groups; one was incubated at 18 degrees C for 20 days and the other at 18 degrees C for 14 days and then at 37 degrees C for 6 days. Groups of ticks incubated at 37 and 18 degrees C were triturated and each resultant supernatant fluid inoculated into a steer. Both steers became infected, but the 37 degrees C supernatant group showed a much shorter pre-patent period to schizonts. Groups of ticks incubated at 37 or 18 degrees C were applied to pairs of cattle for 24, 48 and 72 h and then removed. There was a more rapid transmission of theileriosis to cattle by ticks kept at high ambient temperatures compared to those kept at low ambient temperatures. All cattle on which ticks treated at 37 degrees C were applied developed acute and fatal T. parva infection irrespective of the duration of tick application, while only 1 animal receiving ticks treated at 18 degrees C and fed for 72 h developed infection. The pre-patent period for macroschizonts was very short in all the groups receiving ticks incubated at 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Feeding aggregation of the tick Rhipicephalus appendiculatus (Ixodidae): benefits and costs in the contest with host responses.

Gregariousness can be advantageous in interspecific competition while intraspecific competition may favour solitude. We examined feeding behaviour of the ixodid tick, Rhipicephalus appendiculatus, in the context of interspecific (tick-host) and intraspecific (tick-tick) competition. Such competition is mediated through host rejection responses to tick infestation to which ticks respond by secreting immunodulatory saliva. We observed that group feeding adults increased their blood-feeding rate, reducing the time to mating and repletion, compared with individual feeding of paired adults. The benefits of feeding aggregation indicate direct reciprocity between ticks, most likely resulting from the shared activities of their bioactive saliva. However, fast-feeding ticks appeared to impair blood-feeding success of slow-feeding females during group feeding. This may be explained by the faster feeders exacerbating host responses on detachment that are then directed against the slower feeders. As female fecundity is generally proportional to the size of the bloodmeal, there will be a selection pressure to feed gregariously. Greater understanding of the benefits and costs of feeding aggregation may help to improve tick control strategies.

Animals↗
PubMed2004

Systematics and evolution of ticks with a list of valid genus and species names.

In recent years there has been much progress in our understanding of the phylogeny and evolution of ticks, in particular the hard ticks (Ixodidae). Indeed, a consensus about the phylogeny of the hard ticks has emerged which is quite different to the working hypothesis of 10 years ago. So that the classification reflects our knowledge of ticks, several changes to the nomenclature of ticks are imminent or have been made. One subfamily, the Hyalomminae, should be sunk, while another, the Bothriocrotoninae, has been created (Klompen, Dobson & Barker, 2002). Bothriocrotoninae, and its sole genus Bothriocroton, have been created to house an early-diverging ('basal') lineage of endemic Australian ticks that used to be in the genus Aponomma. The remaining species of the genus Aponomma have been moved to the genus Amblyomma. Thus, the name Aponomma is no longer a valid genus name. The genus Rhipicephalus is paraphyletic with respect to the genus Boophilus. Thus, the genus Boophilus has become a subgenus of the genus Rhipicephalus (Murrell & Barker, 2003). Knowledge of the phylogenetic relationships of ticks has also provided new insights into the evolution of ornateness and of their life cycles, and has allowed the historical zoogeography of ticks to be studied. Finally, we present a list of the 899 valid genus and species names of ticks as of February 2004.

Animals↗
PubMed1999

Abundance of ticks (Acari: Ixodidae) infesting the western fence lizard, Sceloporus occidentalis, in relation to environmental factors.

We examined the impact of environmental characteristics, such as habitat type, topographic exposure and presence of leaf litter, on the abundance of Ixodes pacificus ticks infesting the western fence lizard (Sceloporus occidentalis) at the University of California Hopland Research and Extension Center (HREC), Mendocino County, California. A total of 383 adult lizards were slip-noosed and examined for tick infestation in April and May 1998. At least 94% of the lizards were infested by ticks and at least 20% of the females and 33% of the males carried > 15 ticks. This intensive utilization of western fence lizards (which do not serve as natural reservoirs for Lyme disease spirochetes) by subadult ticks, is probably the primary reason for the low prevalence of infection with Borrelia burgdorferi in I. pacificus nymphs and adults previously recorded at the HREC. Tick loads were higher on male than female lizards. Also, male lizards were generally more heavily infested in late April than in late May. The prevalence of tick infestation exceeded 88% in all habitat types but males collected in woodland and grass/woodland edges had higher tick loads than those collected in open grassland. Male lizards captured in open, exposed grassland tended to carry heavier tick loads in northern/eastern, as compared to southern/western, exposures, and when leaf litter was present.

Animals↗
PubMed1999

Detecting resistance to organophosphates and carbamates in the cattle tick Boophilus microplus, with a propoxur-based biochemical test.

Rapid and sensitive detection of resistance to insecticides in arthropods is needed. In the cattle tick. Boophilus microplus, resistance to a variety of acaricides is widespread. The most commonly used assay for resistance, the larval packet test, takes at least two, but generally six weeks for a one-host tick like B. microplus to complete and may take up to three months to complete for three-host ticks. Here we describe a test for resistance to organophosphate acaricides that can be used on larvae and adult ticks which takes less than 24 hours. The test measures the difference in acetylcholinesterase (AChE) activity in homogenates of ticks in the presence and absence of propoxur, a carbamate acaricide. We found clear discrimination of organophosphate-susceptible and organophosphate-resistant adults with 100 microM propoxur. AChE from susceptible ticks had almost no activity at this concentration of propoxur whereas AChE from resistant ticks had 67% of its potential activity. AChE from heterozygote ticks could also be distinguished from AChE from homozygous-susceptible and homozygous-resistant ticks. This is the first biochemical test for resistance to an acaricide. Rapid, sensitive tests like ours will allow resistance to organophosphates to be detected soon after it develops in the field, thus, the spread of resistance might be slowed and the useful life of acaricides extended.

Acetylcholinesterase↗
PubMed2002

Evolution of the secondary structure of the rRNA internal transcribed spacer 2 (ITS2) in hard ticks (Ixodidae, Arthropoda).

ITS2 sequences are used extensively in molecular taxonomy and population genetics of arthropods and other animals yet little is known about the molecular evolution of ITS2. We studied the secondary structure of ITS2 in species from each of the six main lineages of hard ticks (family Ixodidae). The ITS2 of these ticks varied in length from 679 bp in Ixodes scapularis to 1547 bp in Aponomma concolor. Nucleotide content varied also: the ITS2 of ticks from the Prostriata lineage (Ixodes spp.) had 46-49% GC whereas ITS2 sequences of ticks from the Metastriata lineage (all other hard ticks) had 61-62% GC. Despite variation in nucleotide sequence, the secondary structure of the ITS2 of all of these ticks apparently has five domains. Stems 1, 3, 4 and 5 of this secondary structure were obvious in all of the species studied. However, stem 2 was not always obvious despite the fact that it is flanked by highly conserved sequence motifs in the adjacent stems, stems 1 and 3. The ITS2 of hard ticks has apparently evolved mostly by increases and decreases in length of the nucleotide sequences, which caused increases, and decreases in the length of stems of the secondary structure. This is most obvious when stems of the secondary structures of the Prostriata (Ixodes spp.) are compared to those of the Metastriata (all other hard ticks). Increases in the size of the ITS2 may have been caused by replication slippage which generated large repeats, like those seen in Haemaphysalis humerosa and species from the Rhipicepalinae lineage, and the small repeats found in species from the other lineages of ticks.

Animals↗
PubMed2001

Identification and characterization of a homologue of the pro-inflammatory cytokine Macrophage Migration Inhibitory Factor in the tick, Amblyomma americanum.

Studying tick feeding and digestion, we discovered in a cDNA library from partially fed Amblyomma americanum ticks the first known arthropod homologue of a human cytokine, the pro-inflammatory Macrophage Migration Inhibitory Factor (MIF). The tick origin of the MIF cDNA clone was confirmed by sequencing a genomic fragment that contained the full-length tick MIF gene with two introns. Antiserum to a tick MIF-specific peptide as well as antiserum to complete tick MIF revealed the expression of tick MIF in the salivary gland and midgut tissues of A. americanum ticks. In an in vitro functional assay, recombinant tick MIF inhibited the migration of human macrophages to the same extent that recombinant human MIF did.

Amino Acid Sequence↗
PubMed2001

Prophylaxis with single-dose doxycycline for the prevention of Lyme disease after an Ixodes scapularis tick bite.

BACKGROUND: It is unclear whether antimicrobial treatment after an Ixodes scapularis tick bite will prevent Lyme disease. METHODS: In an area of New York where Lyme disease is hyperendemic we conducted a randomized, double-blind, placebo-controlled trial of treatment with a single 200-mg dose of doxycycline in 482 subjects who had removed attached I. scapularis ticks from their bodies within the previous 72 hours. At base line, three weeks, and six weeks, subjects were interviewed and examined, and serum antibody tests were performed, along with blood cultures for Borrelia burgdorferi. Entomologists confirmed the species of the ticks and classified them according to sex, stage, and degree of engorgement. RESULTS: Erythema migrans developed at the site of the tick bite in a significantly smaller proportion of the subjects in the doxycycline group than of those in the placebo group (1 of 235 subjects [0.4 percent] vs. 8 of 247 subjects [3.2 percent], P<0.04). The efficacy of treatment was 87 percent (95 percent confidence interval, 25 to 98 percent). Objective extracutaneous signs of Lyme disease did not develop in any subject, and there were no asymptomatic seroconversions. Treatment with doxycycline was associated with more frequent adverse effects (in 30.1 percent of subjects, as compared with 11.1 percent of those assigned to placebo; P<0.001), primarily nausea (15.4 percent vs. 2.6 percent) and vomiting (5.8 percent vs. 1.3 percent). Erythema migrans developed more frequently after untreated bites from nymphal ticks than after bites from adult female ticks (8 of 142 bites [5.6 percent] vs. 0 of 97 bites [0 percent], P=0.02) and particularly after bites from nymphal ticks that were at least partially engorged with blood (8 of 81 bites [9.9 percent], as compared with 0 of 59 bites from unfed, or flat, nymphal ticks [0 percent]; P=0.02). CONCLUSIONS: A single 200-mg dose of doxycycline given within 72 hours after an I. scapularis tick bite can prevent the development of Lyme disease.

Adolescent↗
PubMed2006

Postexposure treatment with doxycycline for the prevention of tick-borne relapsing fever.

BACKGROUND: Tick-borne relapsing fever (TBRF) is an acute febrile illness. In Israel, TBRF is caused by Borrelia persica and is transmitted by Ornithodoros tholozani ticks. We examined the safety and efficacy of postexposure treatment to prevent TBRF. METHODS: In a double-blind, placebo-controlled trial, 93 healthy subjects with suspected tick exposure (52 with signs of tick bites and 41 close contacts--those without signs but with a similar risk of contact with ticks) were randomly assigned to receive either doxycycline (Dexxon, in a dose of 200 mg the first day and then 100 mg per day for four days) or placebo after presumed exposure to TBRF. Cases of TBRF were defined by fever and a positive blood smear. Serologic analysis for cross-reactivity to Borrelia burgdorferi and polymerase chain reaction (PCR) for the borrelia glpQ gene were also performed. RESULTS: After randomization, 47 subjects (26 with signs of tick bites and 21 close contacts) received doxycycline. Forty-six other subjects (26 with signs of tick bites and 20 close contacts) received placebo. All 10 cases of TBRF identified by a positive blood smear were in the placebo group of subjects with signs of a tick bite (P<0.001). These findings suggested a 100 percent efficacy of preemptive treatment (95 percent confidence interval, 46 to 100 percent). PCR for the borrelia glpQ gene was negative at baseline for all subjects and subsequently positive in all subjects with fever and a positive blood smear. Seroconversion was detected in eight of nine cases of TBRF. PCR and serum samples were negative for all of the other subjects tested. No major treatment-associated adverse effects were identified. CONCLUSIONS: Treatment with doxycycline is safe and efficacious in preventing TBRF after suspected exposure to ticks in a high-risk environment. (ClinicalTrials.gov number, NCT00237016 [ClinicalTrials.gov].).

Adult↗
PubMed2005

Detecting ticks on light versus dark clothing.

It is a common belief that ticks are more visible and easier to detect on light clothing in comparison with dark clothing. We studied which of the clothing, light or dark, had the least attractive effect on Ixodes ricinus, thus minimizing exposure and thereby in theory helping to prevent tick-borne diseases in humans. 10 participants, exposed by walking in tick endemic areas, wore alternately light and dark clothing before every new exposure. Nymphal and adult ticks on the clothing were collected and counted. In total, 886 nymphal ticks were collected. The overall mean in found ticks between both groups differed significantly, with 20.8 more ticks per person on light clothing. All participants had more ticks on light clothing in all periods of exposure. Dark clothing seems to attract fewer ticks.

Adolescent↗
PubMed1999

A serological study of cohorts of young dogs, naturally exposed to Ixodes ricinus ticks, indicates seasonal reinfection by Borrelia burgdorferi sensu lato.

Thirty-three family dogs were monitored for antibodies to Borrelia burgdorferi sensu lato over a 3-year period. Serum samples were collected before and during the season of high tick activity. Antibody levels were measured with an ELISA based on whole-cell antigens and an ELISA with a purified recombinant flagellin (r410). Antibody levels measured with the whole-cell ELISA increased after the first exposure to ticks. Following the first seasonal period of tick quiescence, antibody levels decreased, and subsequently increased again in the second tick season. Thereafter whole-cell ELISA titres persisted at moderate levels and did not decrease between tick seasons. The recombinant flagellin ELISA did not show a strong response in the first tick season, but did in the second tick season and levels of antibodies continued to fluctuate thereafter. We conclude that most dogs in this study developed an antibody response against Borrelia burgdorferi sensu lato after their first tick infestation and were thereafter repeatedly immunologically stimulated, probably reinfected, during the consecutive tick seasons.

Animals↗
PubMed1989

Control of lone star ticks (Acari: Ixodidae) on Spanish goats and white-tailed deer with orally administered ivermectin.

Ivermectin administered orally to Spanish goats, Capra hircus (L.), or to white-tailed deer, Odocoileus virginianus (Zimmerman), was highly effective against lone star ticks, Amblyomma americanum (L.). For Spanish goats, daily oral doses of 20 micrograms/kg resulted in greater than or equal to 2 ppb ivermectin in the blood. This level was sufficient to cause greater than 95% reduction of estimated larvae from feeding ticks. A bioassay with horn flies, Haematobia irritans (L.), was developed to estimate oral intake of ivermectin. Probit analysis of dose-mortality data indicated that a 50% reduction in adult horn fly emergence can be expected when the manure from goats treated orally with ivermectin at 10, 20, 35, and 50 micrograms/kg/d was mixed with untreated cow manure at a rate of 0.345, 0.110, 0.100, and 0.092%, respectively. In studies with white-tailed deer, daily oral doses of 35 and 50 micrograms/kg/d provided 100% control of adult and about 90% control of nymphs that were placed on treated fawns. A single oral dose of 50 micrograms/kg gave greater than 90% control of adult and nymphal ticks attached to treated fawns at the time of drug administration and 70% control of ticks placed on treated deer three days thereafter. When ticks were placed on fawns treated with a single dose of ivermectin (50 micrograms/kg) the engorgement period was longer, ticks were lighter in weight, and females laid fewer eggs than ticks detaching from control fawns. A single oral dose of ivermectin at 20 micrograms/kg prevented about 60% of the adult and nymphal ticks attached at the time of drug administration from engorging, but did not affect other ticks placed on the animals after treatment.

Administration, Oral↗
PubMed1995

Physiological responses of beef cattle to Gulf Coast tick (Acari: Ixodidae) infestations.

Nine yearling crossbred beef steers, Bos taurus L., were used to examine physiological responses to Gulf Coast tick, Amblyomma maculatum Koch, infestation. Steers were stanchioned indoors in individual environmentally controlled rooms. On day 0, each animal received 0, 25, or 75 pairs of ticks. Physiological variables measured daily were feed intake, heart rates, rectal temperatures, and respiration rates. Blood samples were collected from each animal on days 7, 21, and 42 for serum constituent analysis. To monitor metabolic hormone status, intensive blood samples were collected hourly for 6 h on days 21 and 42. Throughout the treatment period, feed intake values were similar among treatments resulting in comparable body weight at the end of the trial. Heart rates and rectal temperatures were unaffected, however, respiration rates of steers infested with 25 pairs of ticks were higher than the other treatment groups. Treatment effects were detected in uric acid concentrations on day 7 in steers infested with 75 pairs of ticks. Treatment effects were detected in total, direct and indirect bilirubin, gamma-glutamyl transpeptidase, and aspartate amino transferase concentrations. Likewise, creatine kinase concentrations were higher in the tick-infested steers on day 7. Elevated white blood cell counts were observed in tick-infested steers. All other serum components were similar and were within their normal ranges. Serum insulin, prolactin, growth hormone, and cortisol concentrations were unaffected by tick infestations. Gulf coast tick infestation resulted in altered blood composition indicative of infection caused by tick feeding habits.

Animals↗
PubMed1991

Effect of ivermectin on the volume of blood ingested by two species of ticks (Acari: Ixodidae) feeding on cattle.

Females of the lone star tick, Amblyomma americanum (L.), and the American dog tick, Dermacentor variabilis (Say), were fed on ivermectin (Ivomec)-treated and untreated bovines to determine the effect of the acaricide on volume of blood ingested and to compare the weight differences between the treatment and control groups at various time intervals after attachment. Adult females from each genus were collected from Bos tarus hosts and subjected to hematin assays on three collection dates to estimate the volume of blood ingested. Before feeding, lone star ticks contained an average of 2.0 microliters of blood and had an average weight of 5.2 mg. Unengorged American dog tick females had an average blood volume of 3.3 microliters and a mean weight of 5.8 mg. Ticks of both species reacted to ivermectin by expressing lower mean weights, and they consumed smaller quantities of blood. Lone star tick females were significantly affected in terms of amount of blood consumed and body weight changes when compared with control ticks. After feeding on treated cattle, lone star tick females contained smaller quantities of blood than pretreatment females, but there were no significant differences observed until day 12 between the control and the treated groups. American dog tick females on treated hosts had measurable quantities of blood that were significantly different among the experimental groups.

Animals↗
PubMed1999

Novel Ehrlichia organism (Rickettsiales: Ehrlichieae) in white-tailed deer associated with lone star tick (Acari: Ixodidae) parasitism.

Polymerase chain reaction (PCR) evidence of a novel Ehrlichia organism was found recently in wild white-tailed deer, Odocoileus virginianus Zimmermann, and lone star ticks, Amblyomma americanum L., from the southeastern United States. To evaluate whether lone star tick parasitism was associated with the presence of this novel Ehrlichia organism in deer, 2 retrospective studies were conducted using specific nested PCR to test archived deer serum samples. The 1st study of 150 serum samples collected from a single deer population over a 15-yr period examined the temporal association between the presence of the Ehrlichia organism in deer and parasitism by lone star ticks. The deer Ehrlichia was not detected in serum samples collected before 1986, when lone star ticks were absent or rare, but was detected in samples collected in 1986 and every year thereafter, when lone star ticks became increasingly abundant. In the 2nd study, serum samples from 120 deer from 24 sites in 14 southeastern states were tested to evaluate if a site-specific, spatial association existed between the presence of the deer Ehrlichia and lone star ticks. All 60 serum samples from the 12 deer populations without evidence of lone star tick infestation were negative for the deer Ehrlichia, whereas 83% of the 12 populations infested by lone star ticks had PCR evidence of infection. These data suggest that lone star ticks may be a vector of the deer Ehrlichia; however, they do not preclude the involvement of other arthropods in maintaining infection with this organism in deer populations.

Animals↗