Seroepidemiology of Bovine Herpes Virus-1 Infection in Water Buffaloes from the state of Veracruz, Mexico.

Water buffaloes (Bubalus bubalis) were introduced to Mexico at the end of the last century. In Mexico, buffaloes are commonly pastured together with cattle; however few studies have been done on buffalo herd health in Mexico. We hypothesized that a better knowledge of the epidemiology of infections shared between cattle and buffaloes may improve herd profitability and promote buffalo production in areas unsuitable to cattle farming. This study aimed to determine the prevalence of antibodies against bovine herpes virus - 1 (BoHV1) in water buffaloes raised on six farms from the state of Veracruz, Mexico. Of 368 buffaloes sampled, 217 (59%) were seropositive for BoHV-1. Age was identified as a risk factor for BoHV-1 infection with buffaloes older than 5 years being the most likely to be infected. Animals more than 7 years old had the highest prevalence (86.0%). Females and males had similar seroprevalence rates. Females with history of abortion had higher prevalence of antiBoHV-1 antibodies than those with no record of abortion. Buffaloes and cattle were raised together in only one of the six farms under study. Interaction with cattle was not a risk factor for BoHV-1 seropositivity. This study showed that BoHV-1 is prevalent among buffalo herds in the state of Veracruz, Mexico. Buffaloes appear to play an important role in the epidemiology of BoHV-1 infection in parts of Mexico when there is no apparent risk of interaction with cattle. Animal health programs established to mitigate the burden caused by BoHV-1 must take into consideration buffaloes when this bovid species is part of the agroecosystem shared with cattle.

Efficacy of novaluron as a feed-through for control of immature horn flies, house flies, and stable flies (Diptera: Muscidae) developing in cow manure.

Two rates (0.4 mg/kg body weight/d and 0.6 mg/kg body weight/d) of a daily feed-through formulation of novaluron (Novaluron 0.67% active ingredient Cattle Mix), a newer benzoylphenyl urea insecticide, were evaluated for efficacy in controlling the larval stage of horn flies, Haematobia irritans (L.), house flies, Musca domestica L., and stable flies, Stomoxys calcitrans (L.), developing in cow manure. Both rates of feed-through novaluron, delivered consecutively for 10 d, reduced adult emergence of all three species when compared with the untreated control. The presence of deformed puparia indicated that novaluron had an insect growth regulator effect on the developing fly larvae. Both of the feed-through rates evaluated resulted in 100% reduction of adult stable fly emergence after the second day of feed-through treatment. The level of control efficacy observed against these three fly species make this feed-through formulation a candidate for use in an integrated livestock pest management program, particularly in confined cattle production situations where a feed-through product could be easily administered.

Effects of pyriproxyfen and buprofezin on immature development and reproduction in the stable fly.

The stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), is one of the most significant biting flies that affect cattle. The use of traditional insecticides for stable fly control has only a limited success owing to the insect's unique feeding behaviours and immature development sites. A laboratory study was conducted to evaluate the effects of two insect growth regulator (IGR) products, pyriproxyfen and buprofezin, on the development of the immature stages of the stable fly and the effects of pyriproxyfen on oviposition and egg hatch. Both pyriproxyfen and buprofezin had significant inhibitory effects on immature development. The LC(50) s of pyriproxyfen and buprofezin were 0.002 and 18.92 p.p.m., respectively. Topical treatment of adult females with different doses of pyriproxyfen had significant negative effects on both female oviposition and egg hatching when 1- and 3-day-old females were treated, and the effects were dose dependent. A significant reduction in the mean number of eggs laid was observed only at the highest pyriproxyfen dose (8 µg/fly) and egg hatch was unaffected by pyriproxyfen treatment when 5-day-old females were treated. Results from the present study indicate that pyriproxyfen has the potential to be used as part of an integrated stable fly management programme.

Laboratory evaluation of novaluron as a development site treatment for controlling larval horn flies, house flies, and stable flies (Diptera: Muscidae).

A granular formulation of novaluron (Novaluron 0.2G, 0.2% [AI]), a newer benzoylphenyl urea insecticide, was evaluated for its efficacy in controlling the larval stage of horn flies, Haematobia irritans (L.); house flies, Musca domestica L.; and stable flies, Stomoxys calcitrans (L.), in cow manure. Various rates and insecticide placement locations (top, middle, and bottom of manure) were evaluated in this study and all combinations of these variables reduced adult emergence of all three species when compared with the untreated controls. The presence of deformed pupae indicated that novaluron had an insect growth regulator effect on the developing fly larvae. Top, middle, or bottom application rates of 0.125, 0.195, 0.25, and 0.375 g novaluron onto manure samples, reduced adult horn fly emergence by > 90%. Middle and bottom application rates of 0.195, 0.25, and 0.375 g novaluron reduced adult house fly emergence >93%. All rates and placement combinations resulted in >98% reduction of adult stable fly emergence. The level of control efficacy observed against these three fly species along with the ease of use of a granular formulation, make this product an ideal candidate for use in an integrated livestock pest management program.

Efficacy of amitraz-impregnated collars on white-tailed deer (Artiodactyla: Cervidae) in reducing free-living populations of lone star ticks (Acari: Ixodidae).

Over a 7 yr period, we monitored the effect of a commercially available, amitraz impregnated anti-tick collar in controlling free-living populations of lone star ticks, Amblyomma americanum (L.) when manually fitted around necks of white-tailed deer, Odocoileus virginianus (Zimmermann). Study animals in treatment and control groups were confined in 38.8 ha game-fenced and densely vegetated treatment plots in South Texas. Tick densities during years 1 and 7 served as untreated pre- and posttreatment comparisons and treatments occurred during years 2 through 5. Reductions in tick densities in the treatment plot were compared against tick densities in a control plot having similar vegetation and numbers of untreated deer. During years of treatment, indices of control pressure ranged from 18.2 to 82.6 for nymphs and 16.9-78.7 for adults, and efficacy, expressed as percentage control during the final year of treatment, was 77.2 and 85.0%, respectively, for nymphal and adult ticks. These data show that acaricidal collar treatments provide efficacies very similar to those achieved with the existing ivermectin-medicated bait and '4-Poster' topical treatment technologies to control ticks feeding on wild white-tailed deer.

Distribution of Rhipicephalus (Boophilus) microplus and Rhipicephalus (Boophilus) annulatus (Acari: Ixodidae) infestations detected in the United States along the Texas/Mexico border.

Species identification and global positioning system coordinates of infestations of cattle fever ticks, Rhipicephalus (Boophilus) annulatus (Say) and Rhipicephalus (Boophilus) microplus (Canestrini), were determined for 790 specimens submitted to the National Veterinary Services Laboratory between 1 October 1999 and 30 September 2010. Cattle fever tick specimens obtained by personnel of the United States Department of Agriculture-Animal and Plant Health Inspection Service-Cattle Fever Tick Eradication Program from infested cattle and wildlife along the Texas/ Mexico border were submitted for identification, as required by the program. A geographic information system database was developed that incorporates location, collection, and infestation records. Submitted ticks came from 11 Texas counties and were comprised of 19.5% R. (B.) annulatus and 80.5% R. (B.) microplus. Maps produced from this study locate and define the parapatric boundary between R. (B.) annulatus and R. (B.) microplus.

Formulations of deet, picaridin, and IR3535 applied to skin repel nymphs of the lone star tick (Acari: Ixodidae) for 12 hours.

The efficacies of a 20% 1-methyl-propyl-2- (hydroxyethyl)-1-piperidinecarboxylate (picaridin) spray, 20% 3-(N-acetyl-N-butyl)aminopropionic acid ethyl ester (IR3535) spray, 20% picaridin lotion, 10% IR3535 lotion, and 33% N,N-diethyl-3-methylbenzamide (deet) cream in repelling nymphal lone star ticks, Amblyomma americanum (L.), were determined at 2-h intervals over 12 h using human subjects. A repellent formulation was applied in a 5-cm-wide band encircling a volunteer's lower leg. For each challenge, 70 host-seeking nymphs were released on each volunteer's ankle, and tick locations were recorded 10 min after the ticks were released. Ticks that crawled entirely across the repellent band were considered not repelled. For all formulations and time points, significantly fewer (all P < 0.0001) A. americanum nymphs crossed the treatment bands on the volunteers' ankles than crossed the corresponding area on the untreated control legs. Formulations containing > or = 20% active ingredient were highly effective, with <10% of the ticks crossing through the treatment bands for any challenge during the 12 h. At least 40% of ticks exposed to any formulation for any challenge fell or crawled off the volunteers. There was no difference in effectiveness between the 20% spray and 20% lotion formulations of picaridin. The 10% IR3535 lotion was significantly less effective than the formulations with higher concentrations of repellent. In the formulations tested, deet, picaridin, and IR3535 provided lasting protection against A. americanum.

Evidence for role of white-tailed deer (Artiodactyla: Cervidae) in epizootiology of cattle ticks and southern cattle ticks (Acari: Ixodidae) in reinfestations along the Texas/Mexico border in south Texas: a review and update.

From 1907 when the fever tick eradication campaign began until 1933, the tick eradication methods of dipping cattle in an acaricide or "pasture vacation" were enormously successful in eradicating southern cattle ticks [Rhipicephalus (Boophilus) microplus (Canestrini)], until failures began to occur in some areas of Florida. Regarding the failures in Florida, the consensus was that populations of white-tailed deer [Odocoileus virginianus (Zimmermann)] infested with southern cattle ticks were responsible. After numerous deer in several counties were killed, eradication was achieved in Florida. As in Florida, in Texas increasing numbers of failures of the pasture vacation approach to tick eradication from the 1970s to the present are known to be related to the abundance of white-tailed deer and perhaps other wild ungulate species. A sizable body of evidence confirms the hypothesis that white-tailed deer support the dispersal and maintenance of both cattle ticks [Rhipicephalus (Boophilus) annulatus (Say)] and southern cattle ticks (cattle fever ticks) within the permanent quarantine or buffer zone in South Texas along the Rio Grande, as well as in the so-called free ("cattle fever tick-free") area north and east of the buffer zone and extending to the east coast of the United States. As of August 2009, in addition to the permanent quarantine zone of approximately 2233 km2, three temporary preventative or blanket quarantines were established. Currently, only two methodologies exist to control ticks feeding on white-tailed deer: (1) a systemic treatment method involving dispersal of ivermectin-medicated corn, Zea mays L.; and (2) two topical treatment methods, '4-poster' deer treatment bait stations and '2-poster' deer treatment feeder adapters, both of which passively apply topically active acaricide to deer for the eradication of populations of cattle fever tick associated with white-tailed deer. This study presents and summarizes confirmational support for the role of white-tailed deer derived from historical accounts, circumstantial evidence from review of recent infestations, and cattle fever tick infestations on white-tailed deer that were live-captured and examined specifically for cattle fever ticks.

Effects of photoperiod on reproduction, nymphal developmental timing, and diapause in Amblyomma maculatum (Acari: Ixodidae).

Female engorgement weight, oviposition, and molting times of larvae and nymphs of Amblyomma maculatum Koch (Acari: Ixodidae) were studied at various photoperiods under constant humidity and temperature in the laboratory. Ticks were held at photoperiods of 0:24, 10:14, 12:12, or 14:10 (L:D) h from egg through unfed nymphal stage and then at either the same or a different regime from fed nymphs to adults. No significant effects were observed on oviposition, female engorgement weights, survival, or molting time to unfed nymphs. Nymphal molting times were significantly shorter at the short-day regime (10:14) during the larval stage and 12:12 during the nymphal stage compared with those held at either 14:10 during both life periods or at 0:24 during both life periods. Longer molting times also were observed in ticks held at 12:12 during the larval phase and either 10:14, 12:12, or 0:24 during the nymphal phase compared with 14:10 during both life periods or 0:24 during both life periods. Ticks held at 10:14 during the larval phase and at 0:24 or 10:14 had longer molting times compared with those at 14:10 or 0:24 during both life periods. No differences in survival to either nymphal or adult stages were observed at any regime, and at day 25 no individuals were observed to be in developmental diapause. This study demonstrates that developmental diapause does not seem to be photoperiodically induced in fed nymphal A. maculatum in the laboratory.

Efficacy of eprinomectin and doramectin against Amblyomma americanum (Acari: Ixodidae) on cattle.

Steers were treated with doramectin or eprinomectin by daily oral capsule for 28 consecutive days. The level of doramectin in the serum of steers treated at 200 microg/kg/d reached a maximum of 104.0 +/- 22.1 ppb at day 21 and declined from 93.3 +/- 20.5 ppb on the final day of treatment to below detectable by day 56. Steers treated at 50 microg/kg/d reached a maximum level of doramectin in the serum of 24.7 +/- 1.2 ppb on day 21 and declined from 24.7 +/- 0.6 ppb on the final day of treatment to less than detectable on day 42. Both doramectin dosages provided 100% control of estimated larvae (EL) of Amblyomma americanum (L.) (Acari: Ixodidae) throughout the 28-d treatment period. Daily oral treatment with eprinomectin at a dosage of 200 microg/kg for 28 consecutive days produced a maximum concentration in the serum of 41.6 +/- 11.0 ppb at day 14. On the final day of eprinomectin treatment, the serum concentration was 38.3 +/- 5.9 ppb. Seven days later at day 35, eprinomectin was not detectable in the serum. For steers treated at 50 microg/kg/d for 28 consecutive days, the serum level of eprinomectin reached a maximum of 10.0 +/- 3.0 ppb on day 28 and was undetectable on day 35. Both eprinomectin dosages provided complete control of EL of A. americanum during the 28-d treatment period. Because eprinomectin is efficacious against A. americanum at lower serum levels in cattle and is eliminated from the serum at a more rapid rate than either doramectin or ivermectin, it provides advantages for use in applications such as the medicated bait for control of ticks on white-tailed deer and could have potential for use in the Cattle Fever Tick Eradication Program.

A sustained release gel formulation of doramectin for control of lone star ticks (Acari: Ixodidae) and horn flies (Diptera: Muscidae) on cattle.

A gel formulation formed by incorporating technical doramectin into a 10% hydroxypropyl methylcellulose aqueous solution was used to subcutaneously inject steers at varying dosages. Doramectin serum concentration of steers receiving 600 microg (AI)/kg body weight declined from 21.9 ppb at 0.5 wk to below detectable at 8 wk postinjection. The 1,200 microg (AI)/kg injection resulted in serum concentrations of 29.1 ppb at 0.5 wk and declined to 0.5 ppb at 8 wk postinjection. Both the 600 and 1,200 microg (AI)/kg injections provided 100% inhibition of index of fecundity (IF) in adult lone star ticks, Amblyomma americanum L. (Acari: Ixodidae) through week 8, after which inhibition declined to 79.4 and 45.3%, respectively, during the 12th week posttreatment. For steers treated at 600 microg (AI)/kg, mortality of adult horn flies, Hematobia irritans L. (Diptera: Muscidae), declined from 16.9% during week 2 to 3.1% during week 7 postinjection. The blood from steers treated at 1,200 microg (AI)/kg resulted in a similar decline in mortality of blood fed adult horn flies from 29.4% during week 1 to 4.0% during week 7. The 600 microg (AI)/kg treatment provided complete control of larval horn flies in the manure for 9 wk, whereas the 1,200 microg (AI)/kg injection gave complete control for 14 wk posttreatment. The doramectin gel formulation provided long-lasting delivery of doramectin to cattle and extended control of lone star ticks and larval horn flies. Such a simple and inexpensive formulation could be useful in tick eradication programs by reducing the frequency of gathering cattle.

Pathogenicity of three formulations of entomopathogenic fungi for control of adult Haematobia irritans (Diptera: Muscidae).

Powder formulations of three species of entomopathogenic fungi were evaluated for their pathogenic effect upon adult horn flies, Hematobia irritans (L.) (Diptera: Muscidae). Flies were treated with conidia and blastospores of the entomopathogenic fungi Beauveria bassiana (Bals.) Vuill. (strain GHA), Metarhizium anisopliae (Metschnikoff) Sorokin (strain ESCI), and Paecilomyces fimosoroseus (Wize) Brown & Smith (strain ARSEF 3581) in the laboratory. At 4 d postexposure, flies treated with B. bassiana had an average of 98.4% mortality versus 43.5% from treatment with M. anisopliae and 13.0% from treatment with P. fiimosoroseus. At 7 d postexposure, flies treated with B. bassiana had an average of 100.0% mortality compared with 73.0% from treatment with M. anisopliae and 33.3% from treatment with P.fumosoroseus. Mean lethal time (LT50) was 2.70, 4.98, and 7.97 d for B. bassiana, M. anisopliae, and P. fiumosoroseus, respectively. Entomopathogenic fungi such as B. bassiana and M. anisopliae may have the potential for controlling populations of horn flies. These studies indicate that B. bassiana and M. anisopliae were not only pathogenic to adult horn flies, but they caused mortality in a short time.

Precision application of aldicarb to enhance efficiency of thrips (Thysanoptera: Thripidae) management in cotton.

Field studies were conducted during 1999-2001 in two climatic/edaphic areas of Georgia (Southern Piedmont and East Gulf Coastal Plain) to test the hypothesis that precision placement of aldicarb with cotton seed in hill planting at spatially specific intervals could decrease insecticide use for management of tobacco thrips, Frankliniella fusca (Hinds). Precision-placed aldicarb controlled thrips during cotton seedling stages using per ha amounts of one-half or less than standard in-furrow application rates with no significant differences in yield. Residual analysis of cotton plants showed that plants in precision placement plots had as much or more aldicarb and aldicarb metabolites present as compared with cotton treated with conventional in-furrow treatments. Higher rates of precision-placed aldicarb did cause phytotoxic burning early in the growing season, but no significant impact on yield was observed.