Seasonal dynamics of the brown dog tick,Rhipicephalus sanguineus,on a confined dog population in Italy

This study evaluated the seasonal dynamics of Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) on naturally infested dogs in a private shelter in southern Italy. From March to May 2008, 39 autochthonous mixed‐breed young dogs and 10 beagles were enrolled in the study. From March 2008 until March 2009, every 21 ± 2 days, 11 body sites of each dog were checked for ticks. At each follow‐up, the number of ticks, their developmental stage, sex and location on the dog's body were recorded. Adult ticks were found throughout the year, but immatures were absent in January and February. The adult tick population increased from July to August, whereas the load of immatures increased in early July and peaked in September, which suggests that R. sanguineus develops one generation per year in this area. The mean number of immature ticks per infested dog was higher than that of adults from March to October 2008. Ears, interdigital areas and armpits were the most frequent attachment sites of adult ticks. At the last follow‐up, a total of 2266 ticks were collected and identified as R. sanguineus. The results suggest that R. sanguineus develops one generation per year in the study area, but that it infests dogs in all seasons. This information should be taken into account when planning control programmes against this tick species and the pathogens it transmits.     

Identification of a mutation in the para-sodium channel gene of the cattle tick Rhipicephalus (Boophilus) microplus associated with resistance to synthetic pyrethroid acaricides

Resistance against synthetic pyrethroid (SP) products for the control of cattle ticks in Australia was detected in the field in 1984, within a very short time of commercial introduction. We have identified a mutation in the domain II S4-5 linker of the para-sodium channel that is associated with resistance to SPs in the cattle tick Rhipicephalus (Boophilus) microplus from Australia. The cytosine to adenine mutation at position 190 in the R. microplus sequence AF134216, results in an amino acid substitution from leucine in the susceptible strain to isoleucine in the resistant strain. A similar mutation has been shown to confer SP resistance in the whitefly, Bemisia tabaci, but has not been described previously in ticks. A diagnostic quantitative PCR assay has been developed using allele-specific Taqman^® minor groove-binding (MGB) probes. Using the assay to screen field and laboratory populations of ticks showed that homozygote allelic frequencies correlated highly with the survival percentage at the discriminating concentration of cypermethrin.     

Distribution of domestic triatominae and stratification of Chagas Disease transmission in Oaxaca, Mexico

Mexico has 18 species of Triatomine bugs (Hemiptera: Reduviidae) reported to be vectors of Trypanosoma cruzi. Chagas Disease is widespread in Mexico, with up to 3.5% seropositivity of human transfusion blood. The State of Oaxaca has the longest history of endemic Chagas Disease, based on acute and chronic case reports, and of entomological surveys in the country. However, the State health care services need more information on current risks of vector transmission. In order to identify and characterize areas of transmission in Oaxaca and to stratify the vector potential, the distribution of domestic Triatominae was surveyed during 1996-98 in collaboration with the primary health care services and local communities. Villages were studied in 11% of 570 municipalities in Oaxaca. Eight triatomine species were found in domestic and peri-domestic habitats: Triatoma barberi Usinger, T. bolivari Carcavallo et al., T. dimidiata (Latreille), T. mazzottii Usinger, T. nitida Usinger, T. pallidipennis (Stal), T. phyllosoma (Burmeister) and Rhodnius prolixus Stal. For each triatomine species in Oaxaca, the range of distribution and habitat characteristics are described. Habitat partitioning, principally based on altitude and mean annual precipitation, limited the overlap of distribution between species. Relatively consistent altitude of human settlements facilitates the dispersion of individual species within microregions. Entomological indices of house infestation were used to estimate that approximately 50% of the human population (1,874,320 inhabitants) would be at risk of vector transmission, with a minimum of 134,320 infected people and 40,280 chronic cases of Chagas Disease currently in Oaxaca.     

The Dynamics of an Avoidance Behavior by Ixodid Ticks to Liquid Water

Life stages of different tick species avoid walking on a wet surface surrounding a dry patch by systematically returning to the dry each time they contact the wet surface beyond the border with the tip of a first leg tarsus. Sequential analysis of the border behaviors shows that repetitive contact with the water increases the probability of walks astride the border. Ticks accept this unilateral contact with the water for longer intervals and eventually walk on to the wet surface after a combination of a short patch walk followed by a border walk which is longer than the foregoing ones. Staying time on a small circular patch is shorter than on a large one, arising probably from faster adaptation of peripheral receptors following a higher frequency of border contacts. However, an equal number of border reactions on patches of different sizes and shapes suggests that a counter in the CNS may also influence dry patch departure.     

Seasonal Distribution of Ticks in Four Habitats near the Demilitarized Zone,Gyeonggi-do (Province), Republic of Korea

This study describes the seasonal distribution of larvae, nymph, and adult life stages for 3 species of ixodid ticks collected by tick drag and sweep methods from various habitats in the Republic of Korea (ROK). Grasses less than 0.5 m in height, including herbaceous and crawling vegetation, and deciduous, conifer, and mixed forests with abundant leaf/needle litter were surveyed at United States (US) and ROK operated military training sites and privately owned lands near the demilitarized zone from April-October, 2004 and 2005. Haemaphysalis longicornis Neumann adults and nymphs were more frequently collected from April-August, while those of Haemaphysalis flava Neumann and Ixodes nipponensis Kitaoka and Saito were collected more frequently from April-July and again during October. H. longicornis was the most frequently collected tick in grass habitats (98.9%), while H. flava was more frequently collected in deciduous (60.2%) and conifer (57.4%) forest habitats. While more H. flava (54.1%) were collected in mixed forest habitats than H. longicornis (35.2%), the differences were not significant. I. nipponensis was more frequently collected from conifer (mean 8.8) compared to deciduous (3.2) and mixed (2.4) forests.     

A novel defensin‐like peptide from salivary glands of the hard tick,Haemaphysalis longicornis

A novel defensin‐like antimicrobial peptide named longicornsin was isolated from the salivary glands of the hard tick, Haemaphysalis longicornis, using a 10‐kDa cut‐off Centriprep filter and reversed‐phase high‐performance liquid chromatography (RP‐HPLC). Its amino acid sequence was determined as DFGCGQGMIFMCQRRCMRLYPGSTGFCRGFRCMCDTHIPLRPPFMVG by Edman degradation. The cDNA encoding longicornsin was cloned by cDNA library screening. The predicted protein from the cDNA sequence was composed of 78 amino acids including a mature longicornsin. It showed similarity with defensin‐like peptides from other ticks by BLAST search. Different from most other tick defensin‐like peptides, longicornsin had a C‐terminal extension. Purified longicornsin exerted potent antimicrobial activities against bacteria and fungi. Interestingly, it even showed strong antimicrobial ability against drug‐resistant microorganisms and Helicobacter pylori. The results of this study indicated that longicornsin is a potential candidate for novel antimicrobial drug design.     

Introduction of Non-Native Ticks Collected from Fresh Migratory Bird Carcasses on a Stopover Island in the Republic of Korea

When free-ranging birds are accidentally killed or die, there may be greater potential for their associated ticks to detach, seek alternate hosts, and become established. We examined 711 carcasses of 95 avian species for ticks at a stopover island of migratory birds in the Republic of Korea where only Ixodes nipponensis and I. persulcatus were previously reported from local mammals and vegetation. A total of 16 ticks, I. turdus and Haemaphysalis flava, were collected from 8 fresh carcasses belonging to 5 avian species. Despite their known abundance on migratory birds and mainland Korea, these species had not colonized the isolated insular ecosystem possibly due to the low abundance and diversity of local hosts. The results imply that increasing human impact, such as the anthropogenic mortality of migratory birds and the introduction of non-native mammalian hosts, will increase the potential invasion and colonization risk of ticks. This finding also suggests that tick surveillance consisting of fresh carcasses of dead migratory birds may provide additional information, often ignored in surveillance of ticks on live birds, for the potential introduction of non-native ticks and associated pathogens affecting animal and human health.     

Attachment kinetics of the adult tick Amblyomma variegatum to cattle

At the beginning of the 1999 rainy season, three traditional cattle herds were monitored for 48 days while grazing in the bushy savannah of southwestern Burkina Faso. Cattle in each herd were caught on several occasions each day and the attached ticks were counted. This confirmed that Amblyomma variegatum Fabricius (Acari: Ixodidae) adults picked up in the pastures mainly attach to the interdigital areas (87% of the 791 ticks captured), and reach the predilection sites later (chest and udder/inguinal area) when the animals lie down. As many females as males attached to the hosts, but the seasonal distribution was very heterogeneous, with only a few females attaching as long as the humidity rate remained low. It is suggested that this prevents eggs from being laid when conditions are not optimal for their survival and that of the larvae. Ticks attached all day but the number picked up hourly and daily varied greatly according to their density on the pasture. As a general trend, confirmed by another study carried out in 2005, the number of ticks picked up daily increased from less than one tick/animal/day, before the onset of the rainy season, to 6.5 (+/- 1.5) ticks/animal/day on average during the infestation peak, which lasted 6-8 weeks, until early or mid-July. The number then decreased to less than one tick/animal/day from the end of July onwards. The infestation on the predilection sites followed the same trend, with a daily tick burden increase of three to five A. variegatum adults, depending on herd and year, during the infestation peak.     

Babesia ugwidiensis,a new species of Avian piroplasm from Phalacrocoracidae in South Africa

A new species of haematozoa, Babesia ugwidiensis sp. nov. from a cormorant is described. This is the first species of piroplasm to be recorded from the Phalacrocoracidae and the relationship of this parasite to other Babesia spp. from marine hosts is discussed.