Acari community in association with delayed pig carrion decomposition.

Acari community structure and function associated with delayed pig carrion decomposition has not been examined. In this study, 18 swine carcasses were studied in central Texas, USA, during two consecutive summers (2013 and 2014). Samples of ca. 400 g soil were collected from beneath, aside, and 5 m away from each pig carcass over 180 days. Mites from soil samples were extracted using Berlese funnels and identified to order and family levels and classified according to ecological function. In total 1565 and 1740 mites were identified from the 2013 and 2014 soil samples, respectively. Significant differences were determined for mite community structure at order and family levels temporally on carrion (e.g., day 0 × day 14) regardless of treatments and between soil regions where mites were collected (e.g., soil beneath vs. soil 5 m away from carrion). However, no significant differences were found in mite community structure at the order level between pig carrion with and without delayed Diptera colonization (i.e., treatments). Analysis at the family level determined a significant difference across treatments for both summers. Ecological function of mites did not change significantly following the delayed decomposition of pig carcasses. However, detritivores and fungivores were significant indicator groups during the pig carrion decomposition process. Furthermore, 13 phoretic mite species associated with eight forensically important beetle species were documented. Data from this study indicated that the rate of nutrient flow into the soil impacted associated arthropod communities; however, detecting such shifts depends on the taxonomic resolution being applied.

Blood feeding of Ornithodoros turicata larvae using an artificial membrane system.

An artificial membrane system was adapted to feed Ornithodoros turicata (Ixodida: Argasidae) larvae from a laboratory colony using defibrinated swine blood. Aspects related to larval feeding and moulting to the first nymphal instar were evaluated. A total of 55.6% of all larvae exposed to the artificial membrane in two experimental groups fed to repletion and 98.0% of all fed larvae moulted. Mortality rates of first instar nymphs differed significantly depending on the sorting tools used to handle engorged larvae (χ2 = 35.578, P < 0.0001): engorged larvae handled with featherweight forceps showed significantly higher mortality (odds ratio = 4.441) than those handled with a camel-hair brush. Differences in the physical properties of the forceps and camel-hair brush may affect the viability of fragile soft tick larvae even when care and the same technique are used to sort them during experimental manipulations. The current results represent those of the first study to quantify successful feeding to repletion, moulting and post-moulting mortality rates in O. turicata larvae using an artificial membrane feeding system. Applications of the artificial membrane feeding system to fill gaps in current knowledge of soft tick biology and the study of soft tick-pathogen interactions are discussed.

Association of Myianoetus muscarum (Acari: Histiostomatidae) With Synthesiomyia nudiseta (Wulp) (Diptera: Muscidae) on Human Remains.

Synthesiomyia nudiseta (Wulp) (Diptera: Muscidae) was identified during the course of three indoor medicolegal forensic entomology investigations in the state of Texas, one in 2011 from Hayes County, TX, and two in 2015 from Harris County, TX. In all cases, mites were found in association with the sample and subsequently identified as Myianoetus muscarum (L., 1758) (Acariformes: Histiostomatidae). This report represents the first records of a mite associated with S. nudiseta in the continental United States. In particular, this association is believed to be of potential future value in forensic investigations, as it lends new insight into the community structure of colonizers on human remains in indoor environments.

Simulation of climate-tick-host-landscape interactions: Effects of shifts in the seasonality of host population fluctuations on tick densities.

Tick vector systems are comprised of complex climate-tick-host-landscape interactions that are difficult to identify and estimate from empirical observations alone. We developed a spatially-explicit, individual-based model, parameterized to represent ecological conditions typical of the south-central United States, to examine effects of shifts in the seasonal occurrence of fluctuations of host densities on tick densities. Simulated shifts in the seasonal occurrence of periods of high and low host densities affected both the magnitude of unfed tick densities and the seasonality of tick development. When shifting the seasonal densities of all size classes of hosts (small, medium, and large) synchronously, densities of nymphs were affected more by smaller shifts away from the baseline host seasonality than were densities of larval and adult life stages. When shifting the seasonal densities of only a single size-class of hosts while holding other size classes at their baseline levels, densities of larval, nymph, and adult life stages responded differently. Shifting seasonal densities of any single host-class earlier resulted in a greater increase in adult tick density than when seasonal densities of all host classes were shifted earlier simultaneously. The mean densities of tick life stages associated with shifts in host densities resulted from system-level interactions of host availability with tick phenology. For example, shifting the seasonality of all hosts ten weeks earlier resulted in an approximately 30% increase in the relative degree of temporal co-occurrence of actively host-seeking ticks and hosts compared to baseline, whereas shifting the seasonality of all hosts ten weeks later resulted in an approximately 70% decrease compared to baseline. Differences among scenarios in the overall presence of active host-seeking ticks in the system were due primarily to the degree of co-occurrence of periods of high densities of unfed ticks and periods of high densities of hosts.

Plane of nutrition x tick burden interaction in cattle: effect on fecal composition.

Effective tick management on grazing animals is facilitated by accurate noninvasive detection methods. Fecal analysis provides information about animal health and nutrition. Diet affects fecal composition; stress may do likewise. The constituents in feces that may be affected by tick burdens and in turn affect near-infrared spectra have not been reported. Our objective was to examine the interaction between plane of nutrition and tick burden on fecal composition in cattle. Angus cross steers (n = 28; 194 ± 3.0 kg) were assigned to 1 of 4 treatments (n = 7 per group) in a 2 × 2 factorial arrangement: moderate (14.0 ± 1.0% CP and 60 ± 1.5% TDN) vs. low (9.0 ± 1.0% CP and 58 ± 1.5% TDN) plane of nutrition and control (no tick) vs. tick treatment [infestation of 300 pair of adult Lone Star ticks (Amblyomma americanum) per treated animal]. Fecal samples were collected at approximately 0700 h on d -7, 0, 7, 10, 14, 17, and 21 relative to tick infestation. Fecal constituents measured were DM, OM, pH, Lactobacillus spp., Escherchia coli, acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, IgA, and cortisol. Experimental day affected (P < 0.05) all constituents measured. Plane of nutrition affected (P < 0.05) DM, OM, VFA, and IgA. Tick treatment numerically (P = 0.13) reduced cortisol. A multivariate stepwise selection model containing cortisol and E. coli values on d 10 and d 14 accounted for 33% of the variation in daily adult female tick feeding counts across both planes of nutrition (P < 0.07). Within the moderate plane of nutrition, a model containing only cortisol on d 10 and d 14 described 59% of the variation in the number of feeding ticks (P < 0.02). Similarly, a model including cortisol, propionate, isovalerate, and DM at d 10 and d 14 d described 95% of the variation in total feeding ticks in the low plane of nutrition. Of the constituents measured, fecal cortisol offers the best possibility of noninvasively assessing stress by way of a single assay but the presence of ticks would still need to be confirmed visually. Although several constituents measured in this study should exist in sufficient quantity to directly affect near-infrared spectra, none stood out as a clear descriptor of prior observed differences in fecal spectra between tick-treated versus non-tick-treated animals. There were, however, groups of fecal constituents related to daily adult female tick feeding numbers (as a visual estimation of tick stress).

Plane of nutrition by tick-burden interaction in cattle: effect on growth and metabolism.

Ticks are external parasites, which pose a significant economic burden to domestic animal agriculture. The effects of ticks on grazing animals may be exacerbated during periods of low nutrition, such as those encountered during drought. It is not completely understood how plane of nutrition and tick burden interact to affect metabolism in cattle. The objective of the current research was to examine the plane of nutrition by tick-burden interaction in cattle and determine the effects of this interaction on physiological indicators of growth and metabolism. Eight-month-old Angus cross steers (n = 28, 194 ± 3.0 kg) were stratified by pretrial BW and DMI into 1 of 4 groups (n = 7/group) in a 2 × 2 factorial arrangement. Categories were: moderate (14.0 ± 1.0% CP, 60 ± 1.5% TDN) vs. low (9.0 ± 1.0% CP, 58 ± 1.5% TDN) plane of nutrition and control (no tick) vs. tick treatment (300 pair of adult Amblyomma americanum per treated animal). Steers were individually fed their respective experimental diets ad libitum and feed intake was monitored for 35 d before and 21 d after the start of tick infestation (d 0). Blood samples were harvested via coccygeal venipuncture on d -7, 0, 7, 8, 9, 10, 11, 13, 17, and 21. Plasma cortisol and IGF-I were determined by RIA. Metabolic indicators were determined by colorimetric assay. Steers weighed 195 ± 6 kg on d -35, but on d -7 and d 21, the moderate steers weighed more than the low steers (244.1 ± 8.7 vs. 227.7 ± 8.4 kg, P < 0.07; and 283.4 ± 8.0 vs. 244.0 ± 7.9 kg, P < 0.001, respectively). Cortisol was affected by plane of nutrition and treatment (P < 0.08). Insulin-like growth factor-I was greater (P < 0.01) in moderate than in low and control animals (P < 0.02), compared with tick-treated animals. Tick treatment had no effect (P > 0.05) on any of the metabolites measured in this study. Plane of nutrition affected (P < 0.02) albumin, blood urea nitrogen, and glucose in that values from the moderate group animals were greater than those from the low group. Although cortisol was related to both tick treatment and nutritional status in the current study, with respect to the combination of parasitism and suboptimal nutrition, IGF-I was the most highly indicative constituent measured. Tick burden affected various characteristics of growth and metabolism in these growing cattle and the effects were exacerbated by a low plane of nutrition.

The Gulf Coast tick: a review of the life history, ecology, distribution, and emergence as an arthropod of medical and veterinary importance.

The Gulf Coast tick, Amblyomma maculatum Koch (Acari: Ixodidae), is a unique univoltine ectoparasite of seven vertebrate host classes in the Western Hemisphere that is increasingly recognized as a pest of livestock and wildlife, a vector of pathogens to humans and canines, and a putative vector of Ehrlichia ruminantium, the causal agent of heartwater, a fatal foreign animal disease of ruminants resident in the Caribbean. This review assembles current and historical literature encompassing the biology, ecology, and zoogeography of this tick and provides new assessments of changes in cyclical population distribution, habitat associations, host utilization, seasonal phenology, and life history. These assessments are pertinent to the emergence of A. maculatum as a vector of veterinary and medical importance, and its pest management on livestock and other animals.

Host selection by questing female Amblyomma maculatum Koch, to cattle with feeding male ticks in southern Texas.

The feeding associations among male and female Gulf Coast ticks, Amblyomma maculatum Koch, were examined using archived data obtained from untreated free-ranging cattle pastured on native rangeland. There was significant evidence of a relationship between male and female tick presence on hosts (p-value <0.0001), suggesting that A. maculatum females will more frequently be attracted and attach to grazing cattle with feeding males than those without. Seasonal data were tested to develop prediction models that estimate the number of female (F) ticks parasitizing cows relative to the number of male (M) ticks present for both early (F=0.090+0.162 M) and late season (F=2.098+0.337 M). These equations could be used to optimize the scheduling of surveillance and control efforts for Gulf Coast tick adults and may establish baseline dosage for pheromone applications.

Effects of a lone star tick (Amblyomma americanum) burden on performance and metabolic indicators in growing beef steers.

We examined the response of selected animal performance, endocrine, immune, and metabolic factors from 13 steers (254+/-6.1 kg) with and without a lone star (Amblyomma americanum) tick burden during progressive days of the tick feeding cycle. Steers were randomly assigned to either non-treated controls or treated with 300 adult pair of A. americanum per animal. Animals were weighed and blood sampled on days -7, 0, 10, 14, 21, 28, and 35 relative to tick treatment. Tick treatment did not affect (P<0.1) animal performance. Experimental day did (P<0.05) affect body weight gain and dry matter intake. Tick treatment did not affect (P<0.1) metabolic indicators. Experimental day affected (P<0.05) IGF1 and lactate, tended to affect cortisol (P<0.07), but did not affect (P<0.1) glucose concentrations. Tick treatment did not significantly (P<0.1) affect growth hormone receptor (GHR) mRNA in liver, but liver tissue from treated animals had numerically lower GHR mRNA than did tissue from control animals. Day had a significant (P<0.05) effect on liver GHR mRNA. There was a significant treatment by day interaction (P<0.05) for liver IGF1 gene expression, as IGF1 mRNA was reduced in tick-treated cattle versus control cattle on day 35. Overall, liver IGF1 gene expression was lower (P<0.05) in tick than in control animals while there was no effect (P>0.1) due to day. Within the tick-treated group, correlations were found between quantitative female tick feeding characteristics and host metabolic indicators. Feeding by adult female lone star ticks did cause acute stress in growing beef steers on a moderate plane of nutrition as indicated by some physiologic indicators. In particular there may be longer term effects on the somatotrophic axis in the liver which could affect subsequent (i.e. feedlot) performance. It is not known how these observed effects would be manifest under a lower plane of nutrition, as is common and may become more so within the current native range of A. americanum. Other acute effects due to tick feeding may have been masked by the effects of handling and invasive sampling. Non-invasive experimental procedures are called for in order to study the effects of a stressor such as arthropod infestation on grazing animals. Future research efforts will be aimed at non-invasively elucidating the effects of tick stress on grazing animals under various nutritional environments.

Genetic variation in 12S and 16S mitochondrial rDNA genes of four geographically isolated populations of Gulf Coast ticks (Acari: Ixodidae).

Single-strand conformation polymorphism (SSCP) analysis was examined in a 303-bp region of the 16S and 12S mitochondrial rDNA genes to study haplotype frequencies among populations of Gulf Coast ticks collected from Refugio Co., TX, Payne Co., OK, and two sites in Osage Co., KS. Seven haplotypes were identified from the 16S rDNA gene fragment, whereas only two haplotypes were detected from the 12S fragment. Only the results from the 16S rDNA fragment are discussed. Haplotype diversity was greatest in Kansas (site 1), where three of the four haplotypes detected were unique to this site. All Gulf Coast tick populations shared the fourth haplotype. Two haplotypes were determined for Texas and Oklahoma populations, one of which appeared only in Texas, whereas the other was shared. Nei's haplotype diversity (h) indicated that the Texas population was relatively homogeneous (15%), whereas the remaining populations were heterogeneous (42-59%), although the Bonferroni confidence interval found no significant differences (P < 0.05). Nucleotide sequencing of the seven haplotypes and subsequent phylogenetic analysis using neighbor joining showed a monophyletic relationship among these haplotypes. One haplotype, shared by both Oklahoma and Kansas (site 2), was basal to the remaining haplotypes and formed a distinct clade. Two haplotypes, both from Kansas (site 1), formed a unique clade, whereas the remaining four haplotypes were unresolved polytomies.

Fecal NIRS: detection of tick infestations in cattle and horses.

Anti-tick treatments are often applied concurrent to routine livestock management practices with little regard to actual infestation levels. Prescription treatments against ticks on grazing cattle would be facilitated by non-invasive detection methods. One such method is fecal near infrared spectroscopy (NIRS). Four studies utilizing cattle (Bos spp.) and one with horses (Equus caballus) fed varying diets and infested with either Amblyomma americanum, A. maculatum, A. cajennense or Dermacentor albipictus were conducted to determine the ability of fecal NIRS to identify samples from animals with (High stress) and without (Low stress) a tick burden. Discriminant analysis of each individual trial resulted in R(2)>0.80. Similar analyses utilizing all combinations of four studies, predicting group membership in the remaining study, yielded R(2)>0.80, but correct determinations for Low and High tick stress samples of only 53.4 and 60.1%, respectively. All five trials were combined and a random 10 or 25% of the samples were removed from the calibration. As in the previous calibrations, a high degree of discrimination was achieved (R(2)>0.89). The validation samples were correctly identified at 91.7% for Low stress and 96.3% for High stress, respectively. Difficulties in detecting differences in fecal samples due to confounding effects of trial were overcome by combining calibration sets. Overall, differences in fecal NIR spectra apparently due to tick stress were accurately detected across diet, host species, and tick species.

Mating success of two geographically distinct populations of Gulf Coast ticks, Amblyomma maculatum Koch.

Gulf Coast ticks collected from Refugio Co., TX and Osage Co., KS are reproductively compatible despite differences in genetic haplotypes, geographic separation and seasonal phenologies. Two heifers per mating combination (TX males x TX females, KS males x KS females, TX males x KS females, KS males x TX females) were each infested with 360 pairs of Gulf Coast ticks. Only mean pre-oviposition and mean egg conversion efficiency index for the Texas male-Kansas female mating were significantly different (p<0.05) from other mating treatments. These females began oviposition 1-day later and used 4% less body mass toward egg production when compared to site-specific matings. However, the overall trend in reproductive performance of reciprocal tick matings was slightly lower than that of site-specific matings. There appear to be no pre-zygotic barriers to mating among Gulf Coast ticks from these Texas and Kansas populations.

Feeding predilection of Gulf Coast tick, Amblyomma maculatum Koch, nymphs on cattle.

Gulf Coast tick nymphs successfully attached and fed on cattle after being freely released. Six Hereford heifers were each infested with approximately 2000 Gulf Coast tick nymphs, three with a strain originating from Refugio Co., TX, and three with ticks from Osage Co., KS by free release on the head and legs to simulate field acquisition of questing nymphs. Two re-infestations were conducted, the first at 7 days and the second at 28 days. Nymph dispersal was estimated by daily inspection of 22 body areas and removal of engorging ticks from the third to the fifth days post-infestation. Total recovery of engorging Texas nymphs was 3.0, 10.2, and 0% and Kansas nymphs was 21.5, 3.3, and 0% for infestations one, two and three, respectively. Immunological resistance to tick infestation expressed as cellular hypersensitivity was evident against Kansas nymphs in the second infestation and against both tick strains in the third infestation. Ticks removed from the withers, midline, and tail-head areas accounted for 68% of the total nymphs recovered in the first two infestations. Within these areas, nymphs were observed to aggregate in small spots where the hair was less dense or naturally parted and the remainder were found scattered in dense hair.

Influence of acaricide resistance on cattle-fever tick (Boophilus spp.) infestations in semi-arid thornshrublands: a simulation approach.

Cattle-fever tick (Boophilus microplus and B. annulatus) populations that develop acaricide resistance become more difficult to control or eradicate. We used a simulation model to assess the direct and indirect effects of interactions among season, habitat type, grazing strategy, and acaricide resistance on the ability to eradicate Boophilus infestations in semi-arid thornshrublands of Texas, USA. Season of infestation appeared to have the strongest effect, with infestations begun on 27 September (autumn) tending to die out sooner than those begun on 1 March (spring) and to remain undetected. Habitat type had the next strongest effect, with infestations surviving much longer as canopy cover increased from uncanopied buffelgrass (Cenchrus ciliaris) habitats to mesquite (Prosopis glandulosa)-canopied grass habitats. Acaricide resistance had a moderate effect; as expected, highly resistant tick populations survived longer than those with no acaricide resistance. The importance of grazing strategy varied with changes in habitat type: as canopy cover increased, infestation duration increased faster under continuous grazing than under rotational grazing strategies. Importance of grazing strategy also varied with acaricide resistance: detected tick populations with no and slight acaricide resistance subjected to acaricide treatments tended to survive longer under rotational grazing than continuous grazing, due to reduced contact with a treated host. Populations with moderate and high resistance behaved more like untreated populations, tending to survive longer under continuous, rather than rotational, grazing, because they experienced less mortality on a treated host. Assuming acaricide treatments at 2-week intervals and maintenance of cattle in infested pastures, results indicate that, for each habitat type, infesting ticks have a threshold of acaricide resistance below which one can eradicate them faster with continuous grazing than with rotational grazing. As canopy cover increases, this threshold appears to shift from high resistance (in grass) to slight resistance (in mesquite).

Effects of pyriproxyfen on off-host water-balance and survival of adult lone star ticks (Acari: Ixodidae).

Newly engorged nymphs of the lone star tick, Amblyoma americanum (L.), were continuously exposed to 4 microg/cm2 of pyriproxyfen residues in glass vials. Treatment of engorged nymphs (n = 285) resulted in significant molting inhibition, with more than one-fourth (26.7%, n = 76) of nymphs dying before or during ecdysis. Treatment effects were evident among ticks that molted to the adult stage, with 26.7% (n = 76) of females, and 17.9% (n = 51) of males exhibiting moribund physical characteristics (i.e., lethargy; dull, discolored and desiccated cuticles; lacking full locomotor competency). A few molted adult ticks (10 males, four females) were dead upon inspection. Only 11.2% of pyriproxyfen treated, emergent females (n = 32), and 11.5% of treated emergent males (n = 25) from 285 ticks treated as engorged nymphs, exhibited normal physical appearance and possessed a full range of locomotor activity. Treated adult ticks maintained within a desiccating environmental chamber at 0% RH and 23 degrees C, had significantly accelerated whole-body water loss rates in comparison to untreated males and females maintained under the same environmental conditions. Additionally, treated adult ticks maintained under optimal environmental conditions (23 degrees C and >95% RH) sustained 100% mortality within 32 d following assignment to these conditions (or 79 d posttreatment as engorged nymphs), whereas untreated ticks had 0% mortality for the same duration of time. Results demonstrate that continuous exposure of nymphs to pyriproxyfen disrupted molting, and accelerated both whole-body water loss and subsequent mortality among emergent adult ticks.

Simulation of rotational grazing to evaluate integrated pest management strategies for Boophilus microplus (Acari: ixodidae) in Venezuela.

Ranchers in Venezuela historically have controlled the cattle-fever tick, Boophilus microplus (Canestrini), with acaricide treatments of cattle but no technical planning. We developed a simulation model to evaluate cattle-tick population dynamics in systematic pasture rotation systems and Integrated Pest Management (IPM) approaches to managing ticks in the tropical dry-forest ecological zone of Venezuela. Model output showed five generations of cattle-ticks produced each year throughout the dry and rainy seasons that occur in this zone. Sensitivity analyses showed disproportionately large changes in on-host B. microplus populations in response to small changes in larval mortality rates, such as those resulting from differences in the innate resistance of cattle to tick parasitism. Simulation results with 1-6 pasture systems suggest that adjusting the graze:rest sequence with systematic rotation among 4-6 pastures could suppress, but not eradicate, tick populations.

Detection of a spotted fever group rickettsia in Amblyomma cajennense (Acari: Ixodidae) in south Texas.

Thai tick typhus rickettsia (strain TT-118), a spotted fever group rickettsia of indeterminant pathogenicity, was isolated from a mixed pool of larval Ixodes and Rhipicephalus ticks collected from Thailand in 1962. Here we report the surprising finding of a spotted fever group rickettsia with closest sequence homology to the Thai tick typhus rickettsia in Amblyomma cajennense (F.) ticks from south Texas. Sequence analysis was performed on segments of 3 genes that differentiate rickettsial species; all 3 genes sequenced, the 17-kDa, glta, and rompA, when compared with those of other rickettsiae, showed the highest degree of similarity to the Thai tick typhus rickettsia with 99.5, 99.5, and 100% homology, respectively. This is the 1st finding of a rickettsial species in A. cajennense ticks in Texas and the United States. If this rickettsia is pathogenic, exposure to infected A. cajennense ticks may pose a previously unrecognized health risk to people who have been fed upon by these ticks.

Population dynamics of immature Amblyomma maculatum (Acari: Ixodidae) and other ectoparasites on meadowlarks and northern bobwhite quail resident to the coastal prairie of Texas.

A survey of ectoparasites from 219 meadowlarks conducted during 2 consecutive fall-winter periods in a coastal prairie found immature Amblyomma maculatum Koch to be the most abundant parasite. Peak larval infestations occurred in December with 80-100% of collected birds infested and with a monthly mean of up to 34 larvae per bird. Peak nymphal infestations occurred in February or March with 95-100% of birds infested and with a monthly mean of up to 11 nymphs per bird. Seasonal dynamics of these stages offered possible insight into the persistence of A. maculatum in an area long infested with the red imported fire ant, Solenopsis invicta Buren. Four other species of ticks also were collected but in substantially lower numbers; Amblyomma cajennense (F.), Amblyomma inornatum (Banks), Haemaphysalis chordeilus (Packard), and Haemaphysalis leporispalustris (Packard). This appears to be the 1st host record of A. cajennense from meadowlarks. A collection of 17 northern bobwhite quail indicated that most of these birds were infested with A. maculatum but at a lower level than meadowlarks. The collections of 2 species of Mallophaga from meadowlarks and 4 species from the northern bobwhite quail are discussed.

Pyriproxyfen effects on newly engorged larvae and nymphs of the lone star tick (Acari:Ixodidae).

Newly engorged larvae and nymphs of the lone star tick, Amblyomma americanum (L.), were exposed to 9 treatments of pyriproxyfen in glass vials consisting of dosages of 4, 8, and 16 micrograms/cm2 for 7 d, 14 d, and continuous exposure periods at each concentration. Treatment of newly engorged larvae resulted in decreased molting, altered postmolt defecation, and nymphal survival with results being dose and exposure dependent. Molting inhibition ranged from 35.9 to 68.4%. Successfully molted nymphs were lethargic, exhibited altered defecation patterns, and were short-lived compared with untreated adults. By 65 d after treatment, cumulative inhibition of molting and hastened mortality of molted adults resulted in 82.6-100% control, depending on dosage and exposure. Treatment of newly engorged nymphs showed minimal to no effect on molting; however, adults were lethargic and displayed altered postmolt defecation patterns. Subsequent adult longevity was most dramatically affected with 87.9-100% control achieved by 82-84 d after treatment. Fecal patterns and survivorship were dose and exposure dependent. Estimates of subsequent feeding success of adults treated as engorged nymphs, show reduced capacities of attachment, engorgement and reproduction.

Perceptions of veterinary clinics and pest control companies regarding tick-related problems in dogs residing in Texas cities.

OBJECTIVE: To determine the extent and source of tick-related problems encountered by veterinary clinics and pest control company (PCC) clientele experiencing residential tick infestations in urban/suburban environments and to determine which tick-related diseases in dogs were diagnosed and treated at veterinary clinics. DESIGN: Cross-sectional survey. SAMPLE POPULATION: Veterinary clinics and PCC in Dallas/Fort Worth and Austin/San Antonio, Tex. PROCEDURE: Surveys were made into professionally printed booklets and mailed to participants. RESULTS: Dallas/Fort Worth and Austin/San Antonio clinics indicated that tick-related problems comprised 21 and 15%, respectively, of their canine-based business. The most frequently observed species was the brown dog tick. Tick infestations were most common during May through August. Immature tick populations were seen by the greatest number of clinics in May and June, and engorged female ticks were encountered most often in June and July. Ticks were most commonly found around homes and adjacent yards or lots. Greenbelts were perceived by all 4 study groups to be the principal place in the community where ticks were acquired by clients' dogs. Canine ehrlichiosis was the most common tick-related disease diagnosed and treated at clinics, followed by anemia caused by tick infestation. CLINICAL IMPLICATIONS: Identification of ticks is important, because different tick species transmit different disease agents and different ecologic factors may be associated with exposure and subsequent treatment. Knowledge of temporal activity patterns of ticks, where they are acquired and where populations become established, combined with improved cooperative efforts between veterinary clinics and PCC, would aid in more effective control and management of ticks.