Evaluation of the in vitro acaricidal effect of five organic compounds on the cattle fever tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae).

The cattle fever tick, Rhipicephalus (Boophilus) microplus, is the most economically important tick worldwide. Infestations with this tick can lead to direct damage and cattle mortality due to the transmission of potentially deadly pathogens. Management of this tick species has been focused on the use of synthetical acaricides; however, the emergence of acaricide resistance to single or multiple active ingredients has resulted in a need for novel acaricide compounds. Among potential avenues for the discovery of novel acaricides are plant-derived compounds. The efficacy of five organic compounds (nootkatone, Stop the Bites®, BioUD®, lavender oil, and cedarwood oil) was evaluated using larval immersion tests (LITs), repellency assays, and adult immersion tests (AITs). The results from the LITs indicate that three of the organic compounds (NootkaShield™, Stop the Bites, BioUD) led to significant mortalities at low concentrations (0.2, 0.02, and 0.08%, respectively). By comparison, lavender and cedar oil led to around 90% mortality at 10 and 1% concentrations, respectively. Similarly, NootkaShield, Stop the Bites, and BioUD had strong repellent properties with over 90% repellency at the two highest concentrations tested. Using the FAO 2004 guidelines, we evaluated the effectiveness of these organic compounds at reducing the fecundity of R. (B.) microplus and show that Nootkatone, Stop the Bites, and BioUD may significantly decrease tick populations (Drummond's index > 90% at concentrations of 5%), highlighting their potential as alternatives to synthetic acaricides for the control of cattle fever ticks.

Medicated corn feeders to disinfest cattle fever ticks, Boophilus (Boophilus) microplus (Acari: Ixodidae), from a suburban population of white-tailed deer, Odocoileus virginianus (Cervidae).

Following its eradication from the USA, the cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini), a vector of bovine babesiosis, has made episodic incursions into, and sometimes beyond, an established barrier zone separating tick-free from endemic areas. In large part the incursions involve hosting and transport by wild ungulates, particularly deer and antelope. One approach to disinfest ticks from wild hosts is with food baits medicated to stop parasites. The approach has had mixed success due to factors that have been previously identified with supplemental feeding of wildlife especially competition for the bait, social dominance behavior, and the availability of alternative food sources. Given that not all of the target hosts will intake a therapeutic dose of the medication (ivermectin) at all seasons of the year, an open question is whether the approach is efficacious as a stand-alone treatment or even as part of an integrated program. As detailed in the present study an intensive effort was successful in eradicating a local outbreak of fever ticks.

Questing by Tick Larvae (Acari: Ixodidae): A Review of the Influences That Affect Off-Host Survival.

Questing is a host-seeking behavior in which ticks ascend plants, extend their front legs, and wait poised for a chance to attach to a passing host. Hard ticks are ectoparasites of terrestrial vertebrates and because some species vector disease, they are among the most medically important of arthropod pests. All ixodid ticks require blood to survive and reproduce with the number of blood-hosts needed to complete their life cycle varying among species. The vast majority are three-host ticks requiring a different host for each developmental stage: larva, nymph, and adult. A few, including some of the most economically important species, are one-host ticks, that quest only in the larval stage. Questing is a rate-limiting behavior critical to tick survival and disease transmission. For the off-host larval stage, survival is highly dependent on ecological and physiological factors. Yet, off-host larval ecophysiology is often overlooked for the more obvious adult and nymphal tick-host interactions. This review summarizes the literature on ixodid larval questing with emphasis on how specific biotic and abiotic factors affect off-host survival.

Phylogeographic Structure in Anastrepha ludens (Diptera: Tephritidae) Populations Inferred With mtDNA Sequencing.

Anastrepha ludens (Loew) (Diptera: Tephritidae), the Mexican fruit fly, is a major pest of citrus and mango. It has a wide distribution in Mexico and Central America, with infestations occurring in Texas, California, and Florida with origins believed to have been centered in northeastern Mexico. This research evaluates the utility of a sequence-based approach for two mitochondrial (COI and ND6) gene regions. We use these markers to examine genetic diversity, estimate population structure, and identify diagnostic information for A. ludens populations. We analyzed 543 individuals from 67 geographic collections and found one predominant haplotype occurring in the majority of specimens. We observed 68 haplotypes in all and see differences among haplotypes belonging to northern and southern collections. Mexico haplotypes differ by few bases possibly as a result of a recent bottleneck event. In contrast to the hypothesis suggesting northeastern Mexico as the origin of this species, we see that specimens from two southern collections show high genetic variability delineating three mitochondrial groups. These data suggest that Central America is the origin for A. ludens. We show that COI and ND6 are useful for phylogeographic studies of A. ludens.

Comparison of torula yeast and various grape juice products as attractants for Mexican fruit fly (Diptera: Tephritidae).

Early research investigating attractants for the Mexican fruit fly, Anastrepha ludens Loew, during the 1930s indicated that fermentation products were effective attractants for Mexican fruit flies and other tropical Tephritidae, but that attraction to fruit components was only of academic interest. Tests reported here were carried out on populations of Mexican fruit flies from 2004 to 2011. Trapping experiments carried out at sites in the states Nuevo Leon and San Luis Potosi compared grape juice, reconstituted grape concentrate and powdered grape mixes, and torula yeast extract in orchards at each site. The Nuevo Leon orchard was mixed with alternate rows of pears and surrounded by alternate hosts. The San Luis Potosi site was surrounded by other orange orchards or nonhosts. Each test was run for at least 10 mo and included highest and lowest trapping periods. Results showed that grape juice captured the most total flies and had the fewest samples with zero flies. However, in the series of experiments, each product had the most captures in at least one experiment. Hydrolyzed torula was superior in one of the six experiments. In five of the tests, polyethylene glycol was tested as an additive to the grape products but never improved capture rate compared with the product without the additive. These results indicate that grape juice is superior to grape concentrate or powder and grape juice is at least equal to torula yeast hydrolysate for trapping pest populations of Mexican fruit flies in commercial citrus orchards.

Tripius gyraloura n. sp. (Aphelenchoidea: Sphaerulariidae) parasitic in the gall midge Lasioptera donacis Coutin (Diptera: Cecidomyiidae).

A new nematode, Tripius gyraloura n. sp., is described from the arundo gall midge, Lasioptera donacis Coutin (Diptera: Cecidomyiidae). This gall midge is being considered as a biological control agent for use in North America against the introduced giant reed Arundo donax (L.) (Poaceae: Cyperales). Thus the present study was initiated to investigate a nematode parasite that was unknown at the time studies with L. donacis were initiated. The new species has a rapid development in the fly host and the mature parasitic female nematodes evert their uterine cells in the hosts' hemolymph. Because large numbers of nematodes sterilise the host, eradication of the parasite from laboratory colonies of the midge may be necessary before populations of the fly are released.

Degree-days and off-host longevity of cattle fever ticks, Boophilus spp. (Acari: Ixodidae) in south Texas pastures.

Cattle fever ticks, Boophilus microplus (Canestrini) and Boophilus annulatus (Say), are native to Eurasia and have invaded the New World as vectors of bovine Babesiosis. Due to severe losses in livestock production, an eradication program by the USDA was established. Premises infested with Boophilus ticks are subject to regulatory oversight that includes acaricide treatment and quarantine. The quarantine duration varies between summer through winter and is based on the available information on the persistence of the off-host stages in pastures far from south Texas. The objective of this study was to assess the specific effect of thermal stress measured in degree-days on the longevity of B. annulatus and B. microplus off-host stages in south Texas pastures. Our results demonstrate that the longest off-host persistence for B. annulatus was 142 days under canopied habitat in the winter and 130 days in the summer. On the other hand, B. microplus off-host persistence was 113 days under canopy and 103 days in exposed habitat, both in winter. The results indicate that temperature was a key variable that prolonged the survival of B. annulatus but not B. microplus. In areas such as south Texas at the northernmost extent of B. microplus range, where mild winters prevail, we found a maximum persistence of less than 4 months (113 days), very close to the previous published record of 116 days. A reduction in the Texas pasture quarantine period from 9 months to 6 months would be justified for this species.

Phylogeography of Anastrepha obliqua inferred with mtDNA sequencing.

Anastrepha obliqua (Macquart) (Diptera: Tephritidae), the West Indian fruit fly, is a frugivorous pest that occasionally finds its way to commercial growing areas outside its native distribution. It inhabits areas in Mexico, Central and South America, and the Caribbean with occasional infestations having occurred in the southern tier states (California, Florida, and Texas) of the United States. This fly is associated with many plant species and is a major pest of mango and plum. We examine the genetic diversity of the West Indian fruit fly based on mitochondrial COI and ND6 DNA sequences. Our analysis of 349 individuals from 54 geographic collections from Mexico, Central America, the Caribbean, and South America detected 61 haplotypes that are structured into three phylogenetic clades. The distribution of these clades among populations is associated with geography. Six populations are identified in this analysis: Mesoamerica, Central America, Caribbean, western Mexico, Andean South America, and eastern Brazil. In addition, substantial differences exist among these genetic types that warrants further taxonomic review.

Bovine fecal chemistry changes with progression of Southern Cattle Tick, Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) infestation.

Surveillance for cattle fever ticks is an essential activity in the U.S. Cattle Fever Tick Eradication Program which prevents reestablishment of these tick vectors of the pathogens causing bovine babesiosis. Other methods of detecting tick infested cattle could augment current physical inspection of restrained cattle by program inspectors. The objective of this study was to determine whether a single infestation of ∼5000 Rhipicephalus (Boophilus) microplus larvae induced changes in fecal chemistry that were detectable using near-infrared reflectance spectroscopy (NIRS). Fecal samples were collected daily from 6 tick-infested and 6 non-infested Bos taurus yearling heifers. Each infested animal received ticks from one of 6 different strains of laboratory colonies of R. microplus. Date of drop and daily sum of engorged female ticks were tabulated to characterize each infestation. Cluster, common factor, principal component and MANOVA analyses were used to define and assess fecal spectra changes associated with experimental stages of infestation. Cluster analyses found no significant differences in fecal samples from each of the 6 infested heifers. Two shifts in fecal chemistry of infested animals were identified by three clusters of NIRS fecal spectra. The first cluster was comprised of samples from pre-infestation to 9 days after infestation, a period inclusive of larval tick attachment and feeding. The second cluster was comprised of samples from day 10-22 corresponding to the period of nymphal feeding, adult feeding, and early drop of engorged females. A third cluster was comprised of samples from days 23-46 corresponding to the period of engorged female drop and declining tick numbers. A Tukey-Kramer multiple comparison procedure identified significant differences in fecal spectra between five experimental stages of R. microplus infestation for principal component 1 including pre-infestation to nymphal feeding, pre-infestation to adult feeding, larval feeding to adult feeding, nymphal feeding to adult feeding and nymphal feeding to engorged female drop; for principal component 2 including pre-infestation to nymphal feeding, pre-infestation to adult feeding, and pre-infestation to engorged female drop; and for principal component 3 including pre-infestation to drop, and adult feeding to drop. These significant pair-wise comparisons reflect developmental phases of tick attachment and blood-feeding that define periods of increasing, peak and declining stress identified in two fecal chemistry shifts defined by three fecal spectra clusters. Among non-infested animals, two shifts in fecal chemistry were also detected by three fecal-spectra clusters that occurred in synchrony with those of their tick-infested counterparts. There were no significant differences in principal components or MANOVA analyses between infested and non-infested animals and the pattern of significant pair-wise Tukey-Kramer multiple comparisons for non-infested animals were similar to those of infested animals. This unintended confounding effect is attributed to the manner in which all 12 animals were preconditioned as a group, then isolated in randomly assigned blind stalls in a common barn facility for the study, creating the basis for physiological stress resonance among non-infested animals.

Evaluation of the efficacy of the methyl bromide fumigation schedule against Mexican fruit fly (Diptera: Tephritidae) in citrus fruit.

Methyl bromide fumigation is widely used as a phytosanitary treatment. Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae), is a quarantine pest of several fruit, including citrus (Citrus spp.), exported from Texas, Mexico, and Central America. Recently, live larvae have been found with supposedly correctly fumigated citrus fruit. This research investigates the efficacy of the previously approved U.S. Department of Agriculture-Animal and Plant Health Inspection Service treatment schedule: 40 g/m3 methyl bromide at 21-29.4 degrees C for 2 h. Tolerance ofA. ludens to methyl bromide in descending order when fumigated in grapefruit (Citrus X paradisi Macfad.) is third instar > second instar > first instar > egg. Two infestation techniques were compared: insertion into fruit of third instars reared in diet and oviposition by adult A. ludens into fruit and development to the third instar. Inserted larvae were statistically more likely to survive fumigation than oviposited larvae. When fruit were held at ambient temperature, 0.23 +/- 0.12% of larvae were still observed to be moving 4 d postfumigation. Temperatures between 21.9 and 27.2 degrees C were positively related to efficacy measured as larvae moving 24 h after fumigation, pupariation, and adult emergence. Coating grapefruit with Pearl Lustr 2-3 h before fumigation did not significantly affect the proportion of third instars moving 24 h after fumigation, pupariating, or emerging as adults. In conclusion, fumigation with 40 g/m3 methyl bromide for 2 h at fruit temperatures >26.7 degrees C is not found to be inefficacious for A. ludens. Although a few larvae may be found moving >24 h postfumigation, they do not pupariate.

Host status of grapefruit and Valencia oranges for Anastrepha serpentina and Anastrepha ludens (Diptera: Tephritidae).

Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) is sporadically captured in the Rio Grande Valley of Texas. Although its preferred hosts are in the Sapotaceae family, several varieties of Citrus, including grapefruit and oranges are listed as alternate hosts. Although Mexican fruit fly, Anastrepha ludens (Loew), is known to be a major pest of Citrus, doubt exists as to the status of Citrus as a breeding host for A. serpentina. To evaluate the host status of commercial Citrus for A. serpentina we compared oviposition and development with that of A. ludens under laboratory conditions with 'Rio Red' grapefruit (Citrus paradisi MacFayden) and 'Valencia' oranges [Citrus sinensis (L.) Osbeck] in different stages of maturity. Both fly species oviposited in early season fruit in which the eggs and larvae died in the fruit albedo. Survival of either species to the adult stage occurred in later season grapefruit. In oranges, no A. serpentina larvae survived compared with 150 A. ludens surviving to adults. Survival on both Citrus species was much lower for A. serpentina, only approximately 5% of eggs eclosed into larvae in grapefruit compared with approximatley 50% for A. ludens. In oranges approximately 16% of A. serpentina eggs eclosed compared with approximately 76% for A. ludens. In grapefruit, only one fourth as many A. serpentina larvae survived to the adult stage compared with A. ludens. Additional experiments were performed in a greenhouse on small, caged trees of la coma (Sideroxylon celastrinum H.B.K.), a Texas species of Sapotaceae. The A. serpentina females readily oviposited into these berries and normal adults emerged. The present low incidence of the adults, coupled with the high mortality during development of the larvae, suggests that Texas citrus is unlikely to support a breeding population of A. serpentina.

Grapefruit as a host for the West Indian fruit fly (Diptera: Tephritidae).

The most common hosts for the West Indian fruit fly, Anastrepha obliqua (Macquart) (Diptera: Tephritidae) are fruit in the family Anacardiaceae (mango [Mangifera L.] and mombin [Spondias L.] species). However, similar to many of the tropical fruit flies of major economic importance, this species attacks several other families of crop fruit, including Annonaceae (cherimoya, Annona cherimola Mill.), Myrtaceae (guava, Psidium L.), Oxalidaceae (carambola, Averrhoa carambola L.), Passifloraceae (granadilla, Passiflora quadrangularis Mill.), and Sapotaceae [mamey sapote, Pouteria sapota (Jacq.) H. E. Moore & Steam]. In the family Rutaceae the economically important genus Citrus has been reported and until recently considered a host for this fruit fly. In this study, we reviewed the taxonomy of A. obliqua, tested specific chemicals that may inhibit oviposition, compared egg-to-adult survival of A. obliqua on preferred hosts and on grapefruit (Citrus X paradisi Macfad.), and measured fruit tissue-specific developmental rates of A. obliqua and the known citrus breeding Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae), from egg to pupae. Our literature review shows much confusion concerning the taxonomy of this and related Anastrepha species, including synonymies and confusion with other species. The deterrent effect of the highest concentration of flavonoids for oviposition, although significant, was not absolute. Experiments carried out under laboratory conditions showed 15-40 times greater survival of A. ludens (whose preferred hosts include Rutaceae) on grapefruit compared with A. obliqua for both tree attached and harvested fruit. Experiments of survival of developing stages over time showed that the two species oviposit into different tissues in the fruit, and mortality is much higher for the West Indian fruit fly in the flavedo and albedo of the fruit compared with the Mexican fruit fly.

The Moneda Bug, emChrysodarecus/em emmoneta/em Breddin = emPlacocoris/em emviridis/em Mayr (Pentatomidae: Discocephalinae: Ochlerini).

The pentatomid genus Placocoris Mayr is removed from Pentatominae and placed in Discocephalinae: Ochlerini based on the trichobothrial arrangement. Within the Ochlerini Placocoris shares characteristics with a clade composed of Adoxoplatys and allies including the rostrum arising anteriorad, abdomen with tubercle at middle base received by a notch in the metasternum, bucculae confluent posteriorly, pronotum flat, and a double row of spines on the femora. It appears to share the same host plants with Neoadoxoplatys, species of bamboo. It is further concluded that the genus Chrysodarecus Breddin is a junior synonym of Placocoris Mayr.

Efficacy of a water-based botanical acaricide formulation applied in portable spray box against the southern cattle tick, Rhipicephalus (Boophilus) microplus (Acari: Ixodidae), infesting cattle.

Ectoparasitism result in annual losses to livestock producers estimated to reach billions of dollars in tropical and subtropical parts of the world where the southern cattle tick, Rhipicephalus (Boophilus) microplus, is established because this invasive pest is also a vector of pathogens causing bovine babesiosis and anaplasmosis. Reintroduction of R. microplus could be economically devastating for the cattle industry in the United States. Novel technologies are necessary to manage populations of R. microplus that are resistant to multiple classes of synthetic chemicals widely used as acaricides to control ticks infesting livestock, and to mitigate the environmental impact of these synthetic acaricides. Bioassays with a water-based formulation of a commercially available botanical acaricide (Essentria® IC3) at 6.25 % against a laboratory strain of R. microplus was 100 % lethal against unfed larvae, and 94 % mortality was recorded against engorged female ticks. These results prompted documentation of efficacy on infested cattle using an acaricide delivery system mimicking field conditions, which is required to consider the use of a product by integrated tick management programs. Twelve tick naïve cattle were artificially infested with unfed larvae on days -19, -12 and -5. On day -2, ticks from the left-side of the body of each animal were manually counted. Depending on pre-treatment tick counts the animals were assigned into three separate treatment groups: i) water (untreated control); ii) coumaphos 0.3 % in water (positive control); and iii) botanical acaricide 6.25 % in water. Five days after the last infestation, cattle were doused in a spray box and moved to individual stalls to collect tick data for calculation of treatment efficacy. The percentage control, based on the reproduction of surviving engorged female ticks after treatment with the 6.25 % Essentria in water-based spray was 70 % against R. microplus. Coumaphos treatment had a mean percent control of 100 %. Whereas this application of Essentria® IC3 cannot be recommended as a stand-alone method to eradicate R. microplus, the 6.25 % botanical acaricide water-based spray could be part of integrated tick management to control populations of R. microplus resistant to organophosphates like coumaphos and other classes of commercially available synthetic acaricides.

Pictorial dissection guide and internal anatomy of the cattle tick, Rhipicephalus (Boophilus) microplus (Canestrini).

Ticks are pests and vectors of diseases that are of public health and veterinary importance. The cattle tick, Rhipicephalus microplus (Canestrini, 1888), is one of the most studied tick species because of its impact on livestock health and production in the tropical and subtropical parts of the world, costing the cattle industry billions annually. Control methods have evolved throughout the years but so has R. microplus. Reliance upon chemical control has created a consistent need to develop new technologies to overcome the pesticide resistance that occurs as the ticks adapt. In order to utilize the more advanced tools such as RNAi or Crispr/Cas9 systems, tick tissues need to be isolated and manipulated. Unfortunately, there are a limited number of dissection guides available providing a detailed view of tick internal anatomy. This manual includes photomicrographs to guide the dissection of R. microplus adults, male and female. Topography and anatomical differences between the internal organs of unfed and gravid adult females are described. We were able to locate the crucial tissues for cattle tick physiology and lay out spatial and temporal guidelines for their identification and dissection. Examples of how this information can be used at the nexus between organismal and molecular research to innovate tick control technologies is discussed.

Ionizing radiation as a phytosanitary treatment against fruit flies (Diptera: Tephritidae): efficacy in naturally versus artificially infested fruit.

Some phytosanitary irradiation treatment research against tephritid fruit flies (Diptera: Tephritidae) has used artificially infested fruit with the unstated and untested assumption that the method adequately simulated a natural situation. We compare grapefruit, Citrus paradisi Macfayden, naturally infested by Mexican fruit fly, Anastrepha ludens (Loew), via oviposition until larvae reached the late third instar versus insertion of diet-reared third instars into holes made in grapefruits 24 h before irradiation; the latter technique has been used in other studies. Both infestation techniques resulted in statistically indistinguishable results, indicating that insertion of diet-reared third instar Mexican fruit fly into holes bored into grapefruit and subsequently sealed 24 h before irradiation would adequately represent natural infestation and could be used to develop a radiation phytosanitary treatment of the insect in grapefruit when prevention of adult emergence is used as the measure of efficacy. Nevertheless, it may not be advisable to extend this conclusion to other fruit fly/fruit combinations without doing appropriate comparison studies. Dissection of puparia from nonirradiated control insects that failed to emerge as adults showed a relatively even distribution of mortality among the developmental stages within the puparium. In contrast, dissection of puparia from irradiated third instars that did not emerge as adults revealed a sharp attenuation in development from cryptocephalic to phanerocephalic pupae demonstrating this transition to be the developmental step most affected by radiation.

Survival of off-host unfed Rhipicephalus (Boophilus) annulatus (Acari: Ixodidae) larvae in study arenas in relation to climatic factors and habitats in South Texas, USA.

The cattle fever tick, Rhipicephalus annulatus (Say), is an economically destructive arthropod because of its ability to vector bovine babesiosis. Cattle fever ticks can spend more than 90% of their life cycle as questing larvae, but the effect of climatic factors on their off-host behavior and survival is unclear. The goal of this study was to measure the effects of specific ecological factors on off-host larvae in nature. The study was conducted in a south Texas pasture over a 20-mo period, during which time larval populations were surveyed and ambient weather variables - relative humidity and temperatures - were recorded. Oviposition success and larval survival varied between cattle fever tick cohorts and was affected by relative humidity and canopied (with tree cover) versus exposed habitat. The results show that relative humidity and the interaction of relative humidity and inhabiting canopied habitats play a key role in oviposition success. Additionally, canopied habitats have a positive influence on off-host larval survival in the spring and summer.

Molecular screening for rickettsial bacteria and piroplasms in ixodid ticks surveyed from white-tailed deer (Odocoileus virginianus) and nilgai antelope (Boselaphus tragocamelus) in southern Texas.

A survey of ixodid ticks parasitizing white-tailed deer (Odocoileus virginianus) and nilgai antelope (Boselaphus tragocamelus) was completed during the 2018-2019 public hunt season on the Laguna Atascosa National Wildlife Refuge (Cameron County, Texas) and the East Foundation's El Sauz Ranch in nearby Willacy County (Texas). Anocenter nitens was the predominant tick species identified with 5% of these ticks collected from nilgai. All life stages were encountered in high numbers on white-tailed deer, indicating that deer may be a primary host in this region. Amblyomma maculatum and Amblyomma inornatum were identified from both hosts, while Ixodes scapularis was encountered only on white-tailed deer. This is the first published record of A. inornatum on nilgai. A subset of ticks was used in PCR assays to detect Rickettsia spp., family Anaplasmataceae, Borrelia spp., and Theileria-Babesia spp. Borrelia spp. were not detected in any of the ticks analyzed. Rickettsia parkeri was detected in three A. maculatum adult ticks from deer, Rickettsia sp. endosymbiont sequences were present in all I. scapularis ticks, and Rickettsia amblyommatis was detected in three A. inornatum adult ticks from deer. Sequence analysis of Anaplasmataceae-positive amplicons from A. nitens and A. maculatum had low percent identity to published Anaplasma spp. sequences, suggesting a unique Anaplasma sp. may be circulating in the population. Anaplasma platys was detected from A. nitens larvae and an Ehrlichia sp. Delta strain was present in A. maculatum, both of unknown pathogenicity towards deer. Theileria cervi was detected in all stages of A. nitens ticks, and positive ticks originated from 27 of 31 deer and a single nilgai sampled from throughout the survey site. The primary vector for T. cervi is absent from this region, suggesting T. cervi is possibly maintained by a different tick species.

Partial characterization of the voltage-gated sodium channel gene and molecular detection of permethrin resistance in Rhipicephalus annulatus (Say, 1821).

The cattle tick, Rhipicephalus annulatus (Say) is a vector of bovine babesiosis and responsible for direct and indirect losses to cattle producing areas located in temperate and subtropical dry regions. Resistance against pyrethroids has been reported for this species in Asia and Africa, but never before in North America. An outbreak strain, Rio Lado, collected close to the border between Mexico and the United States, in Maverick County, Texas, showed low level of resistance to permethrin, a pyrethroid pesticide. We used genomic material from different strains of cattle ticks collected within the Permanent Quarantine Zone (Rio Lado, Vega and Klein Grass strains) to partially characterize the coding gene of the voltage-gated sodium channel (Na-channel), target-site of pyrethroid pesticides, and search for putative mutations associated with resistance using quantitative PCR high resolution melt (HRM) analysis. The two amplified fragments, corresponding to domains II and III of the Na-channel, were 100 % identical to its ortholog in Rhipicephalus microplus (Canestrini). No nucleotide polymorphisms in the Na-channel gene were observed in the pyrethroid-resistant Rio Lado strain, when compared to the susceptible strains Klein Grass and Vega. This study reports the first case of pyrethroid resistance in R. annulatus collected in the United States. Also, we provide new genomic data for this species of tick that allows for the development of a new method to screen for mutations associated with pyrethroid resistance.

Efficacy of Novaluron + Pyriproxyfen (Tekko Pro) Insect Growth Regulators Against Amblyomma americanum (Acari: Ixodidae), Rhipicephalus (Boophilus) annulatus, Rhipicephalus (Boophilus) microplus, and Rhipicephalus sanguineus.

Ixodids are globally distributed pests that transmit many disease agents. Increasing resistance to conventional acaricides raises the need for alternative tactics. Novaluron and pyriproxyfen are insect growth regulators (IGRs) that have variable potencies against acarines. We conducted in vitro and in vivo experiments to assess novaluron + pyriproxyfen (marketed as Tekko Pro) against four ixodid species. Laboratory assays on the brown dog tick, Rhipicephalus sanguineus (Latreille) (Ixodida: Ixodidae), and the lone star tick, Amblyomma americanum (L.) (Ixodida: Ixodidae), reduced metabolic activity in larvae and nymphs. Concentrations of novaluron + pyriproxyfen dried on filter paper impeded molting of larval R. sanguineus (less effective against nymphs). Molting A. americanum larvae were reduced by >95% using 4 and 8 µg/cm2 eliminated molting; nymphal molting was reduced but not halted even at 16 µg/cm2. On calves, novaluron + pyriproxyfen stopped larval A. americanum metabolic function 1 d post-treatment and larvae did not molt. When larvae were released 30 d after treatment, metabolic activity was reduced by 95% and molting was reduced by 94%. Southern cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini) (Ixodida: Ixodidae), larvae released 1 d after treatment on calves were 99% prevented from reaching adulthood. The treatment did not interfere with larval development when larvae were released 52 d after treatment. The cattle fever tick, Rhipicephalus (Boophilus) annulatus (Say) (Ixodida: Ixodidae), failed to reach adulthood when larvae were released on calves a day after treatment (residual activity was not assessed for R. annulatus). These IGRs, and possibly others, offer an alternative to conventional acaricides for ixodid control on cattle.