Control of Culicoides sonorensis (Diptera: Ceratopogonidae) blood feeding on sheep with long-lasting repellent pesticides.

Culicoides sonorensis is the primary vector of bluetongue and epizootic hemorrhagic disease viruses in North America. Bluetongue disease is one of the most economically important arthropod-borne diseases of sheep in North America, because it causes significant morbidity and mortality and can lead to local quarantines and international trade restrictions. Long-lasting repellent pesticides could be applied to sheep as they are moved down from mountain pastures to protect them from biting midges until the 1st frost. We tested long-lasting pesticides on sheep as repellents against C. sonorensis. Both Python ear tags with 10% zeta-cypermethrin (9.8 g/tag) synergized with 20% piperonyl butoxide (PBO) and a 12-ml low-volume spray application of ready-to-use sheep insecticide (Y-TEX) with 2.5% permethrin and 2.5% PBO in an oil-based formulation were repellent to C. sonorensis for at least 3-5 wk after a single application.

A dynamic model of jaw and hyoid biomechanics during chewing.

Our understanding of human jaw biomechanics has been enhanced by computational modelling, but comparatively few studies have addressed the dynamics of chewing. Consequently, ambiguities remain regarding predicted jaw-gapes and forces on the mandibular condyles. Here, we used a new platform to simulate unilateral chewing. The model, based on a previous study, included curvilinear articular guidance, a mobile hyoid apparatus, and a compressible food bolus. Muscles were represented by Hill-type actuators with drive profiles tuned to produce target jaw and hyoid movements. The cycle duration was 732 ms. At maximum gape, the lower incisor-point was 20.1mm down, 5.8mm posterior, and 2.3mm lateral to its initial, tooth-contact position. Its maximum laterodeviation to the working-side during closing was 6.1mm, at which time the bolus was struck. The hyoid's movement, completed by the end of jaw-opening, was 3.4mm upward and 1.6mm forward. The mandibular condyles moved asymmetrically. Their compressive loads were low during opening, slightly higher on the working-side at bolus-collapse, and highest bilaterally when the teeth contacted. The model's movements and the directions of its condylar forces were consistent with experimental observations, resolving seeming discordances in previous simulations. Its inclusion of hyoid dynamics is a step towards modelling mastication.

Life cycle details of Solenopotes capillatus (Anoplura: Linognathidae).

The duration of immature life stages and the preoviposition period of Solenopotes capillatus Enderlein (Anoplura: Linognathidae) were determined by daily observation in vivo of individual specimens. The duration of the egg and nymphal stages was obtained by daily observation of eggs deposited by females transferred to normal predilection sites of uninfested cattle. The preoviposition period was determined by transferring third instars to uninfested cattle and then recording the period from adult eclosion to first oviposition. The egg stage required 11-13 d. Both first and second instars required 3-4 d, and third instars, based on observations of females, required 5-6 d. The preoviposition period was 2 d. Between 27 and 29 d was required for completion of the cycle (egg to egg). The size (length) of unmounted specimens, in millimeters, was egg 0.70; first instar 0.69; second instar, 0.82; third instar, 1.06; adult female, 1.50; and adult male, 1.08.

Endocoprid activity of Aphodius fossor (Coleoptera: Scarabaeidae) related to bovine dung decomposition in a mixed grass prairie.

Aphodius fossor (L.) (Coleoptera: Scarabaeidae), a common endocoprid dung beetle in southeastern Wyoming, may have a survival strategy to maintain dung pad integrity and moisture crucial to larval survival in an arid climate (annual precipitation <30 cm). Typically, A. fossor seems to contribute little to dung pad decomposition, because inhabited dung pads seem to be intact and weigh approximately the same as uninhabited pads, even after 1 yr on pasture. To assess the role of A. fossor in dung pad decomposition and nutrient recycling, artificially formed bovine dung pads were inoculated with five pairs of adult A. fossor. After 40 d, A. fossor activity had no measurable effect on external surface area or moisture retention within the dung pad cores. Pads inhabited by A. fossor weighed significantly more than did control pads on most weigh dates of the experiment, possibly because of incorporation of soil particles at the dung/soil interface. Externally, A. fossor-inhabited dung pads seemed intact; however extensive tunneling was evident throughout the core of the pad leaving an intact, protective crust. A. fossor activity increased microbial biomass carbon in the soil beneath the dung pad. Levels of total nitrogen (N) and carbon (C) decreased in the pads but increased in soil beneath the pads. Dung in the core and in the crust of pads with A. fossor had significantly less total N than pads with no beetles and total C was significantly lower in the crust.

Persistent activity of moxidectin long-acting injectable formulations against natural and experimentally enhanced populations of lice infesting cattle.

A study was conducted under a common protocol in Wisconsin and Wyoming, USA, to evaluate therapeutic and persistent efficacy of two long-acting injectable formulations of moxidectin against lice populations infesting cattle. At each site, 30 beef calves were blocked into groups of three based on naturally acquired Linognathus vituli populations, then randomly assigned to treatments within blocks. Treatments, injected subcutaneously into the proximal third of the ear on Day 0, included saline, a long-acting oil-based formulation containing 10% moxidectin given at the rate of 1 mg moxidectin/kg body weight (M10/1.0), or a long-acting oil-based formulation containing 15% moxidectin given at the rate of 0.75 mg moxidectin/kg b.w. (M15/0.75). Species of sucking and chewing lice were quantified on nine predilection sites before treatment, then 28, 63, 98, 133 and 168 days after treatment. During intervals between lice counts after Day 28, study animals from the three treatment groups were commingled for 32 days with two lice-free sentinels plus four to six seeder calves with infestations of both sucking and chewing lice. Following each 32-day commingling interval, seeder and sentinel animals were removed, and principal animals were sorted into pens by treatment. Lice were quantified on sentinel animals on the day of removal, and lice were quantified on principal study animals 3 days after removal of sentinel and seeders. Moxidectin was generally not efficacious against Bovicola bovis in the injectable formulations tested, whereas Haematopinus eurysternus infestations were inadequate to judge product effectiveness. Based on geometric means, both M15/0.75 and M10/1.0 provided statistically significant therapeutic efficacy against existing infestations of L. vituli and Solenopotes capillatus (100% efficacy on Day 28), and provided persistent protection against reinfestation with L. vituli and S. capillatus (efficacy >97%) for at least 133 days following treatment.

Suppression of bloodfeeding by Ochlerotatus dorsalis and Ochlerotatus melanimon on cattle treated with python ear tags.

Adult mosquitoes were collected by drop traps to compare bloodfeeding rates between cattle treated with 2 Python ear tags (10% zeta-cypermethrin and 20% piperonyl butoxide) per animal and animals that were untreated. Mosquitoes were collected both 2 and 4 wk after application of the ear tags. Bloodfeeding by Ochlerotatus dorsalis was reduced by 79 and 77%, respectively, and bloodfeeding by Ochlerotatus melanimon was reduced by 84 and 81%, respectively, at 2 and 4 wk. Based on chi-square analysis, differences in bloodfeeding rates due to treatment were significant. The effect of the treatment appeared to be repellency, because no mosquito mortality was observed at the time of collection and no mortality was observed among bloodfed mosquitoes that were collected and held for 24 h.

Suppression of mosquito (Diptera: Culicidae) and black fly (Diptera: Simuliidae) blood feeding from Hereford cattle and ponies treated with permethrin.

The blood feeding of mosquitoes and black flies from Hereford cattle and ponies treated with commercial formulations of permethrin was evaluated using an animal enclosure trap sample system that allowed comparison of insect blood-feeding levels between treated and nontreated animals. Blood feeding of both Aedes dorsalis Meigen and A. melanimon Dyar from heifers treated with pour-on concentrate and whole body spray treatments was reduced significantly by 79-88% at 4 d posttreatment, with apparent but not significant reductions of 61-68% at 11 d posttreatment. Simulium bivittatum Malloch and S. griseum Coquillett blood feeding was reduced significantly by 96% to >99% at 4 d posttreatment, but apparent reductions of 30-87% at 11 d posttreatment were not significant. Blood feeding of S. bivittatum from ponies treated with a permethrin fly wipe was reduced significantly by 98 and 87% at 1 and 7 d posttreatment, respectively. No evidence of treatment-induced mortality was observed for recently blood-fed female mosquitoes or black flies captured from treated animals and held for 24 h. The potential benefit of using permethrin to protect livestock from insect-transmitted pathogens was estimated with a model based on level of host attack, pathogen infection rate in the vector, and suppression of blood feeding. Suppression of blood feeding by 90% is predicted to prevent the exposure of a host to a pathogen for up tolO d at 1,000 insect feedings per d when the vector population infection rate is one insect per 1,000. If insect feedings are lower (100/d) and the insect infection rate remains at one per 1,000, protection is predicted for 100 d. In contrast, a 90% suppression of blood feeding is predicted to provide protection for less than 1 d at 1,000 feeding per day and a vector infection rate of one insect per 100.

Persistent efficacy of doramectin topical solution against induced infestations of Bovicola bovis and Solenopotes capillatus.

A study was conducted in two locations, Wyoming and Wisconsin, USA, to evaluate the persistent efficacy of doramectin topical solution at a dose rate of 500 microg/kg body weight against artificially induced infestations of Bovicola bovis and Solenopotes capillatus on cattle. At each location, lice-free beef calves were individually housed and randomly allocated to treatment. Both B. bovis and S. capillatus were transferred from untreated donor animals to doramectin-treated cattle at the end of 35, 63, 91 or 126 day post-treatment periods. Cattle treated with a saline pour-on served as the control. Based on the geometric means of lice counts 2 weeks following transfer, the persistent efficacy of a single treatment with doramectin topical solution against induced infestations of B. bovis was 100.0, 100.0, 99.5, and 100.0% at post-treatment days of 35, 63, 91, and 126, respectively. Persistent efficacy against induced infestations of S. capillatus, for the same intervals, were 100.0, 94.9, 86.3, and 74.9%.

Simulated predictions of insect phenological events made by using mean and median functional lower developmental thresholds.

A computer-simulated study was conducted to determine whether mean or median functional lower developmental thresholds and required degree-days were superior for predicting the dates on which insect phenological events occurred. In addition, these simulations allowed us to determine if the type of year (weatherwise) influenced those predictions. Results indicated that when median functional lower developmental thresholds and required degree-days were used their predictions were closer to the dates on which the phenological events occurred than were predictions that were made using mean thresholds and required degree-days. Also, the predictions of phenological events made when using median functional lower developmental thresholds and required degree-days were not strongly influenced by the type of year. However, the influence of type of year was quite strong when predictions were made when using mean thresholds and required degree-days. The variability in predictions that were made when using median functional lower developmental thresholds and required degree-days was greater than the variability in predictions that were made when using mean thresholds and required degree days. However, the increased variability was caused by many predictions being closer to, rather than farther from, the actual dates on which the phenological events occurred. Based on these findings, we suggest that median functional lower developmental thresholds, along with median required degree-days, be considered for use when predicting insect phenological events in the field.

Seasonal distribution and relationship to temperature and precipitation of the most abundant species of Culicoides in five provinces of Andalusia, Spain.

A total of 177,344 Culicoides specimens were collected from 3,109 light trap collections made weekly from August 1990 to October 1991 at 62 sites in the provinces of Cádiz, Córdoba, Huelva, Seville, and Málaga, Spain. Reported for the 1st time are Culicoides agathensis, Culicoides bahrainensis, Culicoides marcleti, and Culicoides odiatus in the Iberian Peninsula, and Culicoides scoticus in Andalusia, Spain. As a group, Culicoides were active throughout the year. The 3 most common species were Culicoides imicola (56,254), Culicoides newsteadi (24,359), and Culicoides circumscriptus (16,720). Numbers of C. imicola peaked in October, C. newsteadi peaked in May, and C. circumscriptus peaked in June. Based on regression analyses, the optimal minimum and maximum air temperatures, respectively, for adult insect activity were approximately > or = 18 degrees C and > or = 38 degrees C for C. imicola, 12 degrees C for C. newsteadi, 14 degrees C for C. circumscriptus (minimum temperature only), 16 degrees C and > or = 38 degrees C for "other" Culicoides, and 14 degrees C and 32 degrees C for total Culicoides. Optimal minimum and maximum temperatures could not be determined for Culicoides pulicaris, Culicoides punctatus, subgenus Monoculicoides, and the Culicoides obsoletus group. During August and September, the months when African horse sickness outbreaks occurred, C. imicola was the predominant species in the coastal Mediterranean zone. If the "other" Culicoides spp. group was not considered, the predominant species were C. imicola in the Guadalquivir River valley zone, C. newsteadi in the Subbética mountainous range zone, and subgenus Monoculicoides in the coastal Atlantic zone.

Efficacy of eprinomectin against Hypoderma spp in cattle.

OBJECTIVE: To determine the efficacy of a topical formulation of eprinomectin against natural infestations of first (L1)-stage, and second and third (L2/L3)-stage larvae of Hypoderma spp. ANIMALS: 140 approximately 6- to 18-month-old cattle of various breeds. PROCEDURE: Cattle, selected from herds with high prevalence of Hypoderma infestation, were treated in 4 experiments: within each replicate, 1 animal received eprinomectin at a dosage of 500 micrograms/kg of body weight against first-stage larvae (L1). The second animal received the same treatment against second or third-stage larvae (L2/L3). The third animal served as an untreated control. In a fifth experiment, visible warbles were treated on half of the cattle. Remaining cattle served as vehicle-treated controls. In 1 experiment, warbles were examined from time of treatment until all lesions were resolved. In 4 experiments, emerging Hypoderma larvae were recovered, speciated, and enumerated, and viability was determined. RESULTS: Eprinomectin (500 micrograms/kg) efficacy was complete against L1. Hypoderma L2/L3 eradication approached 100% efficacy (1 live larva was recorded). Warbles in treated cattle resolved in a significantly shorter time than did those in controls. Adverse reactions related to treatment were not observed in any of the trials. CONCLUSIONS: Eprinomectin (500 micrograms/kg) applied topically was safe and highly efficacious for treatment of all larval stages of Hypoderma spp in these trials. CLINICAL RELEVANCE: Attributes of eprinomectin besides antiparasite efficacy allow treatment of all classes of cattle with no need for meat or milk withdrawal.

Density and distribution of cattle lice (Phthiraptera:Haematopinidae, Linognathidae, Trichodectidae) on six steers.

The density and distribution of four species of cattle louse, Bovicola bovis (L.). Haematopinus eurysternus (Nitzsch), Linognathus vituli (L.), and Solenopotes capillatus (Enderlein), were elucidated from the hides of six slaughtered steers. Adult and nymphal lice were first removed from one hide by hand and the location of each specimen mapped. The remaining lice were removed by a detergent wash, and KOH dissolution of hide and hair. Lice from the remaining five hides were removed using KOH dissolution of cattle hair and subsequent filtration of the effluent. Bovicola bovis was most abundant, followed by H. eurysternus, L. vituli and S. capillatus. Significant variation was observed in B. bovis, H. eurysternus and L. vituli population densities. Solenopotes capillatus population densities did not differ significantly. All species were contagiously distributed, i.e. 'clumped', suggesting species dependent predilection sites. Predilection sites were ranked according to louse density to facilitate the development of field sampling strategies. Additional biological data were gathered on sex and life stage ratios for each species.

Seasonal and geographical distribution of Culicoides imicola Kieffer (Diptera: Ceratopogonidae) in southwestern Spain.

Culicoides imicola Kieffer adults were collected in light traps weekly between August 1990 and October 1991. The species was collected at all 62 sites located in 5 provinces of the Autonomous Region of Andalucía (Spain). Culicoides imicola represented 31.7% of the total collection of Culicoides. The highest numbers of C. imicola were collected from September through November 1990 and September and October 1991. The lowest numbers were collected from December 1990 through April 1991. The presence or absence of C. imicola was related to the mean monthly minimum and maximum air temperature. Greatest numbers of C. imicola were collected at daily minimum and maximum temperatures of 18 degrees C and 38 degrees C, respectively. The relevance of this information to previous outbreaks of African horse sickness is discussed.

Eprinomectin: a novel avermectin for control of lice in all classes of cattle.

Eight trials were conducted in the United States to determine the efficacy of eprinomectin applied topically against four common species of lice in cattle. In two dose titration trials, eprinomectin dosages of 125 to 750 mcg/kg body weight applied topically were compared to untreated controls. In dose confirmation studies, animals treated topically with eprinomectin applied at the rate of 500 mcg/kg were compared to vehicle-treated controls. Four species of lice were present in these trials: Linognathus vituli, Haematopinus eurysternus, Solenopotes capillatus, all sucking lice, and Damalinia (Bovicola) bovis, the cattle biting louse. Louse counts were made on six to nine predilection sites (the same number of sites in all animals in the same trial) prior to treatment. The same sites were counted again seven days after treatment and weekly thereafter until trial termination eight weeks after treatment. When no lice were found in the predilection sites, a modified whole body search was conducted. Each species of lice was present on at least six animals in each treatment group on at least one counting date in two or more trials. No lice were found on any animal treated topically with eprinomectin at a dosage of > or = 500 mcg/kg after 14 days posttreatment until termination of the trials eight weeks after treatment.

Salivary creatinine assays as a potential screen for renal disease.

Salivary creatinine concentrations are 10-15% of serum creatinine concentrations in healthy populations but have not previously been measured in patients with renal disease. The Cobas Mira automated Jaffé method was adapted to measure salivary creatinine concentration. The method was linear to 1200 mumol/L, had a mean recovery of 78% and a detection limit of 6 mumol/L. Intra-assay variability was 13.5, 5.5 and 1.4% at 10.6, 17.8 and 128.4 mumol/L, respectively. Inter-assay variability was 35.0 and 4.8% at 6.2 and 130.4 mumol/L, respectively. The median salivary creatinine concentrations was 8.5 mumol/L (range 6-18 mumol/L) in healthy subjects (n = 23), and 84 mumol/L (range 18-591 mumol/L) in patients with renal disease (n = 25). Salivary and serum creatinine concentrations were not related in healthy subjects, however, a significant relationship was found in the patients (r = 0.784, P < 0.001). Using salivary creatinine concentration of 16.8 mumol/L as a cut off value, all patients would have been detected with one false positive result (sensitivity 100%, specificity 95.7%, efficiency 97.7%). Thus, salivary creatinine estimations may be used to identify subjects with serum creatinine concentrations above 120 mumol/L.

Doramectin systemic activity against cattle grubs, Hypoderma lineatum and H. bovis (Diptera: Oestridae), and cattle lice, bovicola bovis (Mallophaga: Trichodectidae), Linognathus vituli and Solenopotes capillatus (Anoplura: Linognathidae), and Haematopinus eurysternus (Anoplura: Haematopinidae), in Wyoming.

Seven individual trials were conducted in Wyoming to evaluate the therapeutic efficacy of doramectin administered subcutaneously at a dosage of 200 micrograms kg-1 against multiple, natural infestations of cattle grubs or cattle lice. Insect species present and the number of trials that included each species were: Hypoderma lineatum, 2; Hypoderma bovis. 1; Bovicola bovis, 5; Haematopinus eurysternus, 1; Linognathus vituli, 5; and Solenopotes capillatus, 3. Examinations for lice were performed prior to treatment and either weekly or bi-weekly thereafter for 28 days. Examinations for cattle warbles were performed either weekly or every 4 to 5 weeks from time of first appearance through last appearance in the backs of the cattle. No H. lineatum, H. bovis, H. eurysternus, L. vituli, or S. capillatus were found on doramectin-treated animals at any time following treatment. By 28 days following treatment, the number of B. bovis was reduced between 58 and 98%. Treatments applied later in the season, i.e. in March, were more efficacious against B. bovis than those applied in January or February.

Elevational distribution of mosquitoes in a mountainous area of southeastern Wyoming.

During the summer of 1984, mosquito sampling with CDC miniature light traps and standard mosquito dippers was used to investigate the elevational distribution of different species of mosquitoes. Of 27 species found in significant numbers in the study area in southeastern Wyoming, 8 were found primarily in the lower elevations (2,134 and 2,591 m). Nine additional species were found in both the middle and lower elevations (2,134-3,048 m), whereas 8 occurred only in the middle areas (2,592-3,048 m). A single species (Aedes punctor) was found in both the middle and upper elevations (2,439-3,292 m), and yet another species (Aedes impiger) was found primarily in the upper (alpine) area, from 3,049, to 3,292 m. There is some evidence to indicate that restriction in elevational distribution is a result of habitat specificity.

Sexual dimorphism and developmental change of the salivary glands in adult Culicoides variipennis (Diptera: Ceratopogonidae).

Salivary glands of adult male and female Culicoides variipennis (Coquillett) were sexually dimorphic when examined by phase contrast light microscopy. Female salivary glands were larger and more complex than those in males. Each female gland consisted of a main gland, which was subdivided into a proximal neck and a distal body with reference to the salivary duct, and four accessory glands. Each male salivary gland consisted of a pear-shaped body with a constriction, or neck, that divided it into a proximal and a distal portion, with reference to the salivary duct. Salivary glands of both sexes increased in length from emergence to day 3, followed by a sex-specific pattern of decrease. Based on these morphological observations, we suggest that the salivary glands of female C. variipennis are specialized in the production of secretory materials for blood-feeding.

A potent new class of kappa-receptor agonist: 4-substituted 1-(arylacetyl)-2-[(dialkylamino)methyl]piperazines.

The synthesis of 4-substituted 1-(arylacetyl)-2-[(alkylamino)methyl]piperazines (10-22, 26, 27, and 30-33) and their activities as kappa-opioid receptor agonists are described. This includes a range of 4-acyl and 4-carboalkoxy derivatives with the latter series showing the greatest kappa-agonist activity. In particular, methyl 4-[(3,4-dichlorophenyl)acetyl]-3-[(1-pyrrolidinyl) methyl]-1-piperazinecarboxylate (18) displays exceptional potency and selectivity. It showed the following activities in functional in vitro assays: rabbit vas deferens (kappa-specific tissue) IC50 = 0.041 nM, rat vas deferens (mu-specific tissue) IC50 > 10,000 nM, and hamster vas deferens (delta-specific tissue) IC50 > 10,000 nM. Compound 18 is also a highly potent antinociceptive agent, as determined in the mouse acetylcholine-induced abdominal constriction test: ED50 = 0.000 52 mg/kg, sc. The activity of 18 resides solely in its 3(R)-enantiomer. The kappa-agonist activity in both the 4-acyl and the 4-carbamate series is sensitive to the size of the 4-substituent. In addition, it would appear that an appreciable negative electrostatic potential in this region of the molecule is an important requirement for optimal potency.