Showing papers in "Medical and Veterinary Entomology in 2009"

Effects of intraspecific larval competition on adult longevity in the mosquitoes Aedes aegypti and Aedes albopictus

Abstract: Larval competition is common in container-breeding mosquitoes. The impact of competition on larval growth has been thoroughly examined and findings that larval competition can lead to density-dependent effects on adult body size have been documented. The effects of larval competition on adult longevity have been less well explored. The effects of intraspecific larval densities on the longevity of adults maintained under relatively harsh environmental conditions were tested in the laboratory by measuring the longevity of adult Aedes aegypti (L.) and Aedes albopictus (Skuse) (Diptera: Culicidae) that had been reared under a range of larval densities and subsequently maintained in high- or low-humidity regimes (85% or 35% relative humidity [RH], respectively) as adults. We found significant negative effects of competition on adult longevity in Ae. aegypti, but not in Ae. albopictus. Multivariate analysis of variance suggested that the negative effect of the larval environment on the longevity of Ae. aegypti adults was most strongly associated with increased development time and decreased wing length as adults. Understanding how larval competition affects adult longevity under a range of environmental conditions is important in establishing the relationship between models of mosquito population regulation and epidemiological models of vector-borne disease transmission.

The invasive mosquito Aedes japonicus in Central Europe

Abstract: . Complaints about a biting pest led to the recognition of invasive Aedes (Finlaya) japonicus japonicus (Theobald) (Diptera: Culicidae) in Central Europe. Larval collections from cemetery vases revealed a colonized area of approximately 1400 km2 in northern Switzerland spreading into bordering Germany, suggesting that the mosquito has been established in this region for several years. Within this range, larvae of Ae. japonicus were recovered from more containers than the most common resident culicid species Culex pipiens. Possible introduction sites (used tyre yards and international airports) revealed few or no larvae, and the mode of introduction remains unclear. Given the vector potential of this species for arboviruses, implementation of surveillance and control measures should be considered.

Distribution and ecology of mosquitoes in a focus of dirofilariasis in northwestern Iran, with the first finding of filarial larvae in naturally infected local mosquitoes.

Abstract: A study of the distribution and ecology of mosquitoes (Diptera: Culicidae) in Ardebil Province of northwestern Iran, with special reference to the known dirofilariasis focus in Meshkinshahr County, was carried out in July-August 2005 and April-October 2006. In total, 17,533 adult mosquitoes and 3090 third- and fourth-instar larvae were collected on 14 occasions and identified using morphological characters and DNA sequence data. Twenty species belonging to seven genera were found: Anopheles claviger (Meigen), An. hyrcanus (Pallas), An. maculipennis Meigen, An. pseudopictus Grassi*, An. sacharovi Favre, An. superpictus Grassi, Aedes vexans (Meigen)*, Coquillettidia richiardii (Ficalbi)*, Culex hortensis Ficalbi, Cx. modestus Ficalbi, Cx. pipiens Linnaeus, Cx. theileri Theobald, Cx. torrentium Martini*, Cx. tritaeniorhynchus Giles, Culiseta longiareolata (Macquart), Cs. annulata (Schrank)*, Cs. subochrea (Edwards), Ochlerotatus caspius (Pallas) s.l.* (= Aedes caspius sensu auctorum), Oc. geniculatus (Olivier)* (= Aedes geniculatus sensu auctorum) and Uranotaenia unguiculata Edwards (asterisks indicate new occurrence records for the province). The most prevalent species in adult catches were An. maculipennis (52%), Cx. theileri (45%) and Cx. hortensis (1%); the most prevalent species caught as larvae were Cx. theileri (27%), Cx. hortensis (21%) and An. maculipennis (19%). Anopheles maculipennis, Cx. pipiens and Cx. theileri were most widely distributed in the province. The occurrence of Cx. torrentium in Iran is verified based on differential characters of fourth-instar larvae. Anopheles maculipennis and An. sacharovi of the Maculipennis Group were identified from their diagnostic ITS2 sequences. For the first time, cytochrome c oxidase I (COI) sequences were obtained from Iranian specimens of An. hyrcanus, An. pseudopictus, Cx. theileri and Oc. caspiuss.l. Culex theileri and An. maculipennis were found naturally infected with third-stage (infective) larvae of Dirofilaria immitis (Leidy) and Setaria labiatopapillosa (Alessandrini) (Spirurida: Onchocercidae), respectively, for the first time in Iran.

Risk indicators for the tick Ixodes ricinus and Borrelia burgdorferi sensu lato in Sweden.

Abstract: The distributional area of the tick Ixodes ricinus (L.), the primary European vector to humans of Lyme borreliosis spirochaetes (Borrelia burgdorferi sensu lato) and tick-borne encephalitis virus, appears to be increasing in Sweden. It is therefore important to determine which environmental factors are most useful to assess risk of human exposure to this tick and its associated pathogens. The geographical distribution of I. ricinus in Sweden was analysed with respect to vegetation zones and climate. The northern limit of I. ricinus and B. burgdorferi s.l. in Sweden corresponds roughly to the northern limit of the southern boreal vegetation zone, and is characterized climatically by snow cover for a mean duration of 150 days and a vegetation period averaging 170 days. The zoogeographical distribution of I. ricinus in Sweden can be classified as southerly-central, with the centre of the distribution south of the Limes Norrlandicus. Ixodes ricinus nymphs from 13 localities in different parts of Sweden were examined for the presence of B. burgdorferi s.l. and found to be infected with Borrelia afzelii and Borrelia garinii. Tick sampling localities were characterized on the basis of the density of Borrelia-infected I. ricinus nymphs, presence of specific mammals, dominant vegetation and climate. Densities of I. ricinus nymphs and Borrelia-infected nymphs were significantly correlated, and nymphal density can thus serve as a general indicator of risk for exposure to Lyme borreliosis spirochaetes. Analysis of data from this and other studies suggests that high densities of Borrelia-infected nymphs typically occur in coastal, broadleaf vegetation and in mixed deciduous/spruce vegetation in southern Sweden. Ixodes ricinus populations consistently infected with B. burgdorferi s.l. can occur in: (a) biotopes with shrews, rodents, hares and birds; (b) biotopes with shrews, rodents, hares, deer and birds, and (c) island locations where the varying hare (Lepus timidus) is the only mammalian tick host.

Medical and Veterinary Entomology

Abstract: "Medical and Veterinary Entomology" is a comprehensive text and is primarily intended for graduate students and upper level undergraduates studying the medical and veterinary significance of insects and related arthropods The book will also appeal to a larger audience, specialists and non-specialists alike, including entomologists, parasitologists, biologists, epidemiologists, physicians, public health personnel, veterinarians, wildlife specialists and others looking for a readable, authoritative book on this topic The first two chapters provide overviews of medical-veterinary entomology and epidemiology, respectively These are followed by individual chapters devoted to each group of insects or arachnids of medical-veterinary importance and the health problems they can cause including their role as vectors of pathogens Each of these chapters provides an overview of the taxonomy, biology and ecology of the group, and is followed by separate sections on their medical and veterinary importance, then by a section on prevention and control and, finally, by a list of references and further reading It is written by nationally and internationally renowned contributing authors It contains up to date and new information that is easy to locate, with extensive subheadings and highlighted key words throughout text It includes extensive coverage of arachnids, including scorpions, solpugids, spiders, mites and ticks It is designed for teaching several courses including Medical Entomology, Veterinary Entomology or combined Medical-Veterinary Entomology courses

The effect of shade on the container index and pupal productivity of the mosquitoes Aedes aegypti and Culex pipiens breeding in artificial containers.

Abstract: The aim of this study was to assess whether certain attributes of larval breeding sites are correlated with pupal productivity (i.e. numbers of pupae collected per sampling period), so that these could be used as the focus for control measures to enhance control efficiency. Therefore, the objectives were to identify the months of highest pupal productivity of Aedes aegypti (L.) and Culex pipiens L. (Diptera: Culicidae) in an urban temperate cemetery in Argentina where artificial containers of < 6 L (flower vases) were the predominant breeding habitats, to compare various measures of the productivity of sunlit and shaded containers and to determine whether the composition of the containers affected pupal productivity. Over a period of 9 months, 200 randomly chosen water-filled containers (100 sunlit and 100 shaded), out of approximately 3738 containers present (approximately 54% in shade), were examined each month within a cemetery (5 ha) in Buenos Aires (October 2006 to June 2007). In total, 3440 immatures of Cx pipiens and 1974 of Ae. aegypti were collected. The larvae : pupae ratio was 10 times greater for the former, indicating that larval mortality was greater for Cx pipiens. Both mosquito species showed a higher container index (CI) in shaded than in sunlit containers (Ae. aegypti: 12.8% vs. 6.9% [chi(2) = 17.6, P < 0.001]; Cx pipiens: 6.3% vs. 1.8% [chi(2) = 24, P < 0.001]). However, the number and the density of immatures per infested container and the number of pupae per pupa-positive container did not differ significantly between sunlit and shaded containers for either species. Therefore, the overall relative productivity of pupae per ha of Ae. aegypti and Cx pipiens was 2.3 and 1.8 times greater, respectively, in shaded than in sunlit areas as a result of the greater CIs of containers in shaded areas. Neither the CI nor the number of immatures per infested container differed significantly among container types of different materials in either lighting condition. The maximum CI and total pupal counts occurred in March for Ae. aegypti and in January and February for Cx pipiens. The estimated peak abundance of pupae in the whole cemetery reached a total of approximately 4388 in the middle of March for Ae. aegypti and approximately 1059 in the middle of January for Cx pipiens. Spearman's correlations between monthly total productivity and monthly CI were significant at P < 0.001 for Ae. aegypti (r(s) = 0.975) and P < 0.01 for Cx pipiens (r(s) = 0.869). Our findings indicate that the efficacy of control campaigns against the two most important mosquito vectors in temperate Argentina could be improved by targeting containers in shaded areas, with maximum effort during species-specific times of year when pupal productivity is at its peak.

Prevalence of flea infestation in dogs and cats in Hungary combined with a survey of owner awareness.

Abstract: A survey was conducted in order to gain current information on flea species (Siphonaptera: Pulicidae) infesting dogs and cats living in urban and rural areas of Hungary, along with data on the factors that affect the presence, distribution and seasonality of infestation. In addition, owner awareness of flea infestation was evaluated. Practitioners in 13 veterinary clinics were asked to examine all dogs and cats attending the clinic and to collect fleas, when present, on 2 days in each month from December 2005 to November 2006. They also completed a questionnaire for each animal examined. A total of 319 dogs (14.1%) were found to be infested; the highest prevalence (27.1%) of infestation on dogs occurred in August and the lowest (5.4%) in May. Prevalence of fleas on cats was higher (22.9%); the highest (35.0%) and lowest (8.1%) prevalences occurred in July and April, respectively. Fleas were more prevalent in rural (387/1924 animals, 20.2%) than in urban (161/1343 animals, 12.0%) areas. Three species, Ctenocephalides felis (Bouche), Ctenocephalides canis (Curtis) and Pulex irritans L., were found. On dogs, the prevalence of C. canis alone was 53.0%, whereas that of C. felis alone was 36.0%. Only 19 specimens of P. irritans were found on 14 dogs from rural habitats only. Prevalence of C. felis only on cats was 94.3%; the remaining cats were infested with either C. canis or with mixed infestations of C. felis and C. canis. More than half (51.4%) of the owners of infested dogs and cats had not used flea control products in the past year or more, and five times as many owners in rural than urban areas had not used flea control products in the same period. Very few owners reported having attempted to kill fleas in their animals' environment; instead, they believed that fleas were acquired from other cats or dogs.

A carbon dioxide, heat and chemical lure trap for the bedbug, Cimex lectularius.

Abstract: A trap for the collection of bedbugs, Cimex lectularius Linnaeus (Hemiptera: Cimicidae), is described. The trap was baited with CO2 (50–400 mL/min), heat (37.2–42.2 °C) and a chemical lure comprised of 33.0 μg proprionic acid, 0.33 μg butyric acid, 0.33 μg valeric acid, 100 μg octenol and 100 μg L-lactic acid, impregnated into a gel. Laboratory studies, conducted in a square arena measuring 183 cm on each side, showed that traps with and without baits captured adult bedbugs, but traps with CO2 emissions of 50–400 mL/min caught significantly (P < 0.05) more bedbugs than traps without CO2. In an infested unoccupied apartment, traps with heat and with or without the chemical lure were tested without CO2 on 29 trap-days and with CO2 on 9 trap-days. The numbers of bedbugs captured were 656 and 5898 in traps without and with CO2, respectively. The numbers of bedbugs of all development stages captured were significantly greater in traps with CO2 (χ2 = 15 942, d.f. = 1, P < 10−9). A non-parametric two-way analysis of variance evaluation of six different traps with or without CO2, heat or a chemical lure monitored over 19 trap-days in an infested apartment showed that trap type was highly significant (n = 2833 bedbugs collected) (P < 10−7). The trap with CO2, heat and a chemical lure captured more bedbugs than the other traps, but only caught significantly more fourth and fifth instar nymphs than all other traps. Otherwise, the catches in this trap did not differ significantly from those caught by traps that contained CO2 and heat only. The total numbers of bedbugs collected for each trapping date (pooling all six traps) followed an exponential decline over the trapping period. This type of trap, which caught bedbugs in unoccupied apartments with and without furniture, and in an occupied apartment, may have utility in studying the ecology of bedbugs, in detecting bedbug infestations and in reducing numbers of bites by trapping host-seeking bedbugs.

Responses of the bed bug, Cimex lectularius, to temperature extremes and dehydration: levels of tolerance, rapid cold hardening and expression of heat shock proteins.

Abstract: This study of the bed bug, Cimex lectularius, examines tolerance of adult females to extremes in temperature and loss of body water. Although the supercooling point (SCP) of the bed bugs was approximately -20 degrees C, all were killed by a direct 1 h exposure to -16 degrees C. Thus, this species cannot tolerate freezing and is killed at temperatures well above its SCP. Neither cold acclimation at 4 degrees C for 2 weeks nor dehydration (15% loss of water content) enhanced cold tolerance. However, bed bugs have the capacity for rapid cold hardening, i.e. a 1-h exposure to 0 degrees C improved their subsequent tolerance of -14 and -16 degrees C. In response to heat stress, fewer than 20% of the bugs survived a 1-h exposure to 46 degrees C, and nearly all were killed at 48 degrees C. Dehydration, heat acclimation at 30 degrees C for 2 weeks and rapid heat hardening at 37 degrees C for 1 h all failed to improve heat tolerance. Expression of the mRNAs encoding two heat shock proteins (Hsps), Hsp70 and Hsp90, was elevated in response to heat stress, cold stress and during dehydration and rehydration. The response of Hsp90 was more pronounced than that of Hsp70 during dehydration and rehydration. Our results define the tolerance limits for bed bugs to these commonly encountered stresses of temperature and low humidity and indicate a role for Hsps in responding to these stresses.

Sand flea (Tunga spp.) infections in humans and domestic animals: state of the art.

Abstract: Tungiasis is a parasitic disease of humans and animals caused by fleas (Siphonaptera) belonging to the genus Tunga. Two species, Tunga penetrans (L.) and Tunga trimamillata, out of 10 described to date, are known to affect man or domestic animals; the other eight are exclusive to a few species of wild mammals. Tunga penetrans and T. trimamillata originated from Latin America, although the first species is also found in sub-Saharan Africa (between 20 degrees N and 25 degrees S). Hundreds of millions of people are at risk of infection in more than 70 nations, mostly in developing countries. The second species has been reported only in Ecuador and Peru. Males and non-fertilized females of Tunga are haematophagous ectoparasites; pregnant females penetrate the skin where, following dilatation of the abdomen, they increase enormously in size (neosomy) and cause inflammatory and ulcerative processes of varying severity. The importance of Tunga infection in humans concerns its frequent localization in the foot, which sometimes causes very serious difficulty in walking, thereby reducing the subject's ability to work and necessitating medical and surgical intervention. Tungiasis in domestic animals can be responsible for economic losses resulting from flea-induced lesions and secondary infections. Because tungiasis represents a serious problem for tropical public health and because of the recent description of a new species (Tunga trimamillata), it seems appropriate to review current knowledge of the morphology, molecular taxonomy, epidemiology, pathology, treatment and control of sand fleas of the genus Tunga.

Sensitivity to bites by the bedbug, Cimex lectularius.

Abstract: Bedbugs are a public health problem and can cause significant economic losses, but little is known about the effects of bites on humans We reviewed case reports and published papers on bedbug bites to assess the empirical basis of the commonly cited figure that only approximately 80% of the population are sensitive to bedbug bites We found the sensitivity estimate to be based on only one study carried out 80 years ago However, this study did not account for the now well-established fact that only repeated exposure to external allergens leads to skin reactions In our sample, 18 of 19 persons showed a skin reaction after bedbug exposure, but in most cases only after repeated controlled exposure With repeated exposure, the latency between bite and skin reactions decreased from approximately 10 days to a few seconds Our results are relevant for the hospitality industry, where apparently increasing infestation rates are likely to lead to an increase in the number of tourists and hotel employees exposed to bedbugs Medical and public health professionals may expect to see an increase in the prevalence of people with bedbug bite sensitivity The significance of the delayed reaction time of skin to bites may also have implications in litigation cases where people seek compensation

Efficacy and safety of catnip (Nepeta cataria) as a novel filth fly repellent.

Abstract: Catnip (Nepeta cataria) is known for its pseudo-narcotic effects on cats. Recently, it has been reported as an effective mosquito repellent against several Aedes and Culex species, both topically and spatially. Our laboratory bioassays showed that catnip essential oil (at a dosage of 20 mg) resulted in average repellency rates of 96% against stable flies, Stomoxys calcitrans (L.) and 79% against houseflies, Musca domestica (L.), respectively. This finding suggested that the application of repellent could be used as part of filth fly management. Further evaluations of catnip oil toxicity were conducted to provide a broad-spectrum safety profile of catnip oil use as a potential biting and nuisance insect repellent in urban settings. Acute oral, dermal, inhalation, primary dermal and eye irritation toxicity tests were performed. The acute oral LD(50) of catnip oil was found to be 3160 mg/kg body weight (BW) and 2710 mg/kg BW in female and male rats, respectively. The acute dermal LD50 was > 5000 mg/kg BW. The acute inhalation LD50 was observed to be > 10,000 mg/m3. Primary skin irritation tested on New Zealand white rabbits showed that catnip oil is a moderate irritant. Catnip oil was classified as practically non-irritating to the eye. In comparison with other U.S. Environmental Protection Agency-approved mosquito repellents (DEET, picaridin and p-menthane-3,8-diol), catnip oil can be considered as a relatively safe repellent, which may cause minor skin irritation.

A lethal ovitrap-based mass trapping scheme for dengue control in Australia: II. Impact on populations of the mosquito Aedes aegypti.

Abstract: In Cairns, Australia, the impacts on Aedes aegypti L. (Diptera: Culicidae) populations of two types of 'lure & kill' (LK approximately 15, 1/premise) and larval control (container reduction and methoprene treatment) and (ii) larval control alone, and (iii) untreated control. Female Ae. aegypti populations were monitored for 4 weeks pre- and post-treatment in all three areas using BGSs and sticky ovitraps (SOs) or non-lethal regular ovitraps (ROs). In the dry season, 206 SLOs and 15 BGSs set at 54 and 15 houses, respectively, caught and killed an estimated 419 and 73 female Ae. aegypti, respectively. No significant decrease in collection size of female Ae. aegypti could be attributed to the treatments. In the wet season, 243 SLOs and 15 BGSs killed approximately 993 and 119 female Ae. aegypti, respectively. The mean number of female Ae. aegypti collected after 4 weeks with SOs and BGSs was significantly less than the control (LSD post-hoc test). The third mass-trapping intervention was conducted using the BLO during the wet season in Cairns. For this trial, three treatment areas were each provided with BLOs (>500, approximately 4/premise) plus larval control, and an untreated control area was designated. Adult female Ae. aegypti were collected for 4 weeks pre- and post-treatment using 15 BGSs and 20 SOs. During this period, 53.2% of BLOs contained a total of 6654 Ae. aegypti eggs. Over the intervention period, collections of Ae. aegypti in the treatment areas were significantly less than in the control area for BGSs but not SOs. An influx of relatively large numbers of young females may have confounded the measurement of changes in populations of older females in these studies. This is an important issue, with implications for assessing delayed action control measures, such as LOs and parasites/pathogens that aim to change mosquito age structure. Finally, the high public acceptability of SLOs and BLOs, coupled with significant impacts on female Ae. aegypti populations in two of the three interventions reported here, suggest that mass trapping with SLOs and BLOs can be an effective component of a dengue control strategy.

Seasonal abundance of anopheline mosquitoes and their association with rainfall and malaria along the Matapí River, Amapí, Brazil.

Abstract: Three communities separated by 1.5-7.0 km, along the Matapi River, Amapa State, Brazil, were sampled monthly from April 2003 to November 2005 to determine relationships between seasonal abundance of host-seeking anophelines, rainfall and malaria cases. Out of the 759 821 adult female anophelines collected, Anopheles darlingi Root (Diptera: Culicidae) was the most abundant (56.2%) followed by An. marajoara Galvao & Damasceno (24.6%), An. nuneztovari Gabaldon (12.4%), An. intermedius (Chagas) (4.4%) and An. triannulatus (Neiva and Pinto) (2.3%). Vector abundance, as measured by human landing catches, fluctuated during the course of the study and varied in species-specific ways with seasonal patterns of rainfall. Anopheles darlingi and An. triannulatus were more abundant during the wet-dry transition period in June to August, whereas An. marajoara began to increase in abundance in February in two villages, and during the wet-dry transition in the other village. Anopheles nuneztovari and An. intermedius increased in abundance shortly after the rains began in January to February. A generalized linear mixed model (GLMM) analysis of 32 consecutive months of collections showed significant differences in abundance for each species by village and date (P < 0.0001). Correlations between lagged rainfall and abundances also differed among species. A strong positive correlation of An. darlingi abundance with rainfall lagged by 4 and 5 months (Pearson's r = 0.472-0.676) was consistent among villages and suggests that rainfall may predict vector abundance. Significant correlations were detected between numbers of malaria cases and abundances of suspected vector species. The present study shows how long-term field research may connect entomological and climatological correlates with malaria incidence.

Influence of biotope on the distribution and peak activity of questing ixodid ticks in Hungary.

Abstract: In order to update the occurrence of hard tick species in Hungary, 3442 questing ticks were collected from the vegetation by the dragging/flagging method in 37 different places in the country, between March and June of 2007. Ixodes ricinus (L.) turned out to be ubiquitous. Dermacentor marginatus (Schulzer) was absent from sam- pling sites in the southwestern part of the country, but in most places was concomitant and contemporaneous with Dermacentor reticulatus (Fabricius). These two species, as well as I. ricinus , occurred up to an altitude of 900 - 1000 m a.s.l. Haemaphysalis iner- mis (Birula) and Haemaphysalis concinna (Koch) were not confined to any parts of the country, unlike Haemaphysalis punctata (Canestrini & Fanzago) which was found in only one region. The local prevalence of the latter species was also significantly lower than those of the former two in the same habitat (fringes of meadows, paths in forests). Dermacentor spp. and H. inermis were represented only by adults. In most species fe- males were collected more frequently than males, except in H. concinna and H. punctata . Temporal differences between the peak activity of I. ricinus and Dermacentor spp. on dry pastures appeared to equalize on meadows in mountain forests, and a similar phe- nomenon was observed for the three Haemaphysalis spp. when collected along forest paths with fresh, green vegetation.

Data quality in thermal summation development models for forensically important blowflies.

Abstract: To highlight some issues regarding data quality that are significant in estimating post-mortem intervals (PMI) from maggots, the developmental constants of thermal summation models for development of Chrysomya megacephala Fabricius (Diptera: Calliphoridae) were calculated from incidental data gathered from 12 published studies, and from data generated specifically for the purpose in a single experiment. The focused experiment involved measuring the timing of five developmental landmarks at nine constant temperatures with a sampling resolution of 6-12 h, which is characteristic of other published studies. Combining data from different studies produced inconsistent results because of statistical noise introduced by (at least) disparities in temporal precision, descriptive statistics, geographical location and rearing diets. A robust experimental design to estimate a developmental model should involve at least six constant temperatures, starting at about 7 degrees C above the relevant developmental zero (D0) and going almost to the upper critical temperature, and a temporal sampling interval with a relative precision of about 10%, which requires sampling about every 2 h until hatching, about every 3 h until first ecdysis and about every 6 h until second ecdysis.

Molecular evidence for tick-borne encephalitis virus in ticks in South Korea.

Abstract: To investigate whether tick-borne encephalitis viruses (TBEVs) are present in South Korea, Korean ixodid ticks were tested for TBEV RNA. Ticks (n = 2460) were collected from wild and domestic animals or by flagging at forest and grassland in 12 regions of five provinces in 2005-06. Four species in two genera were identified, yielding 197 sample pools (1-20 ticks per pool); from these, 12 envelope protein gene fragments of TBEV were amplified by reverse transcriptase-nested polymerase chain reaction (RT-nested PCR). Ten of the 2104 adult ticks (0.4%) and two of the 356 nymph ticks (0.2%) were positive for the envelope (E) gene of TBEV. Twelve TBEV RNA-positive samples were detected in Gyeonggi and Gangwon provinces. Phylogenetic analysis showed that the E genes of the TBEV isolates were clustered with the Western European subtype (98% identity). This study suggests that TBEVs may exist in Korea.

Models of development for blowfly sister species Chrysomya chloropyga and Chrysomya putoria.

Abstract: Developmental curves for the sister species Chrysomya chloropyga (Wiedemann, 1818) and Chrysomya putoria (Wiedemann, 1830) (Diptera: Calliphoridae) were established at eight and 10 different constant temperatures, respectively, using developmental landmarks and body length as measures of age. The thermal summation constants (K) and developmental threshold (D(0)) were calculated for five developmental landmarks using a previously described method. Isomorphen and isomegalen diagrams were also constructed for the purpose of estimating postmortem intervals (PMIs). Chrysomya chloropyga had an average developmental threshold value (D(0)) of 10.91 degrees C (standard error [SE] = 0.94 degrees C, n = 5), significantly lower than that of C. putoria (13.42 degrees C, SE = 0.45 degrees C, n = 5) (paired t-test: t = - 4.63, d.f. = 8, P < 0.00). Similarly, K values for C. chloropyga were larger than those for C. putoria for all developmental events except onset of the wandering phase. These are the first data that can be used to calculate minimum PMIs and predict population growth of C. chloropyga and C. putoria in Africa; the data indicate that developmental data for one of these species cannot be used as surrogate data for the sister species.

A lethal ovitrap-based mass trapping scheme for dengue control in Australia: I. Public acceptability and performance of lethal ovitraps

Abstract: We report on the first field evaluation of the public acceptability and performance of two types of lethal ovitrap (LO) in three separate trials in Cairns, Australia. Health workers were able to set standard lethal ovitraps (SLOs) in 75 and 71% of premise yards in the wet and dry season, respectively, and biodegradable lethal ovitraps (BLOs) in 93% of yards. Public acceptance, measured as retention of traps by residents, was high for both trap types, with <9% of traps missing after 4 weeks. Traps retaining water after 4 weeks were 78 and 34% for the two SLO trials and 58% for the BLOs. The 'failure rate' in the 535 BLOs set in the field for 4 weeks was 47%, of which 19% were lost, 51% had holes from probable insect chewing, 23% were knocked over, 7% had dried by evaporation and 1% were split. There was no significant difference in the failure rate of BLOs set on porous (grass, soil and mulch) versus solid (tiles, concrete, wood and stone) substrates. The SLOs and the BLOs were readily acceptable to ovipositing Aedes aegypti L. (Diptera: Culicidae); the mean number of eggs/trap was 6 and 15, for the dry season and wet season SLO trial, respectively, and 15 for the BLO wet season trial. Indeed, 84-94% of premise yards had egg positive SLOs or BLOs. A high percentage of both wet and dry season SLOs (29 and 70%, respectively) and BLOs (62%) that were dry after 4 weeks were egg positive, indicating the traps had functioned. Lethal strips from SLOs and BLOs that had been exposed for 4 weeks killed 83 and 74%, respectively, of gravid Ae. aegypti in laboratory assays. These results indicate that mass trapping schemes using SLOs and BLOs are not rejected by the public and effectively target gravid Ae. aegypti. The impact of the interventions on mosquito populations is described in a companion paper.

Flies in the ointment: a morphological and molecular comparison of Lucilia cuprina and Lucilia sericata (Diptera: Calliphoridae) in South Africa.

Abstract: Complementary nuclear (28S rRNA) and mitochondrial (COI) genes were sequenced from blowflies that phenotypically resembled Lucilia cuprina (W.), Lucilia sericata (Meigen) or exhibited characters of both species. The aim was to test a long-held hypothesis that these species hybridize under natural conditions in South Africa (Ullyett, 1945). Blowflies were obtained predominantly from the Cape Town metropolitan area, but reference samples were acquired for L. sericata from Pretoria. Several L. cuprina-like flies were shown to possess a conflicting combination of nuclear and mitochondrial genes that has also been seen in Hawaiian specimens. Homoplasy, sampling of pseudogenes, hybridization and incomplete lineage sorting are discussed as possible hypotheses for the pattern and the latter is concluded to represent the most likely explanation.

Detection and identification of Bartonella sp. in fleas from carnivorous mammals in Andalusia, Spain

Abstract: A total of 559 fleas representing four species (Pulex irritans, Ctenocephalides felis, Ctenocephalides canis and Spilopsyllus cuniculi) collected on carnivores (five Iberian lynx Lynx pardinus, six European wildcat Felis silvestris, 10 common genet Genetta genetta, three Eurasian badger Meles meles, 22 red fox Vulpes vulpes, 87 dogs and 23 cats) in Andalusia, southern Spain, were distributed in 156 pools of monospecific flea from each carnivore, and tested for Bartonella infection in an assay based on polymerase chain reaction (PCR) amplification of the 16 S-23 S rRNA intergenic spacer region. Twenty-one samples (13.5%) were positive and the sequence data showed the presence of four different Bartonella species. Bartonella henselae was detected in nine pools of Ctenocephalides felis from cats and dogs and in three pools of Ctenocephalides canis from cats; Bartonella clarridgeiae in Ctenocephalides felis from a cat, and Bartonella alsatica in Spilopsyllus cuniculi from a wildcat. DNA of Bartonella sp., closely related to Bartonella rochalimae, was found in seven pools of Pulex irritans from foxes. This is the first detection of B. alsatica and Bartonella sp. in the Iberian Peninsula. All of these Bartonella species have been implicated as agents of human diseases. The present survey confirms that carnivores are major reservoirs for Bartonella spp.

Species-specific mitochondrial gene rearrangements in biting midges and vector species identification.

Abstract: Partial mitochondrial gene sequences of 16 Culicoides species were determined to elucidate phylogenetic relations among species and to develop a molecular identification method for important virus vector species. In addition, the analysis found mitochondrial gene rearrangement in several species. Sequences of the mitochondrial genome region, cox1-trnL2-cox2 (1940-3785 bp) of 16 Culicoides and additional sequences were determined in some species, including whole mitochondrial genome sequences of Culicoides arakawae. Nine species showed common organization in this region, with three genes cox1-trnL2-cox2 and a small or no intergenic region (0-30 bp) between them. The other seven species showed translocation of tRNA and protein-coding genes and/or insertion of AT-rich non-coding sequences (65-1846 bp) between the genes. The varied gene rearrangements among species within a genus is very rare for mitochondrial genome organization. Phylogenetic analyses based on the sequences of cox1+cox2 suggest a few clades among Japanese Culicoides species. No relationships between phylogenetic closeness and mitochondrial gene rearrangements were observed. Sequence data were used to establish a polymerase chain reaction tool to distinguish three important vector species from other Culicoides species, for which classification during larval stages is not advanced and identification is difficult.

Could the bug Triatoma sherlocki be vectoring Chagas disease in small mining communities in Bahia, Brazil?

Abstract: Searches for Chagas disease vectors were performed at the type locality from which Triatoma sherlocki Papa et al. (Hemiptera: Reduviidae: Triatominae) was described in the municipality of Gentio do Ouro, in the state of Bahia, Brazil, and in a small artisan quarry-mining community approximately 13 km distant in a remote area of the same municipality. The latter site represents a new locality record for this species. Adults, nymphs and exuviae of T. sherlocki were found in 21% of human dwellings, indicating that the species is in the process of domiciliation. Prevalence of Trypanosoma cruzi infection in collected bugs was 10.8%. Simple predictive approaches based on environmental similarity were used to identify additional sites likely suitable for this species. The approach successfully predicted an additional five sites for the species in surrounding landscapes. Ecological and entomological indicators were combined to discuss whether this scenario likely represents an isolated case or an emerging public health problem.

The distribution of Hyalomma spp. ticks from domestic ruminants in Iran.

Abstract: . The distribution of Hyalomma species on domestic animals was studied in four zoogeoghraphical zones. Nine hundred and ninety-two Hyalomma ticks were collected from sheep, goats, cattle and camels. A total of seven tick species consisting of: Hyalomma anatolicum Koch, 1844 (28.93%), H. excavatum Koch, 1844 (12.5%), H. asiaticum Schulze & Schlottke, 1930 (13.5%), H. marginatum Koch, 1844 (27.01%), H. detritum Schulze, 1919 (9.67%), H. schulzei Olenev, 1931 (4.03%) and H. dromedary Koch, 1844 (4.33%) were recorded. The results indicated that H. anatolicum, H. asiaticum, H. marginatum and H. detritum were present in all zones whereas H. excavatum was absent in Zone I. The result also showed that H. dromedari was presented in Zones III and IV whereas H. schulzei was present in Zones II and III. During this study, the tick species collected are candidates for investigation as vectors of pathogenic organisms in Iran.

Insecticide resistance and detoxifying enzyme activity in the principal bancroftian filariasis vector, Culex quinquefasciatus, in northeastern India.

Abstract: The insecticide resistance status of Culex quinquefasciatus Say (Diptera: Culicidae) to DDT and deltamethrin across army cantonments and neighbouring villages in northeastern India was investigated. In India, DDT is still the insecticide of choice for public health programmes. In military stations, pyrethroids, especially deltamethrins, are used for insecticide-treated nets (ITNs). Recent information on the levels of resistance to DDT and deltamethrin in mosquito populations of northeastern India is scare. Continued monitoring of insecticide resistance status, identification of the underlying mechanisms of resistance in local mosquito populations and the establishment of a baseline data bank of this information are of prime importance. Insecticide susceptibility assays were performed on wild-caught adult female Cx. quinquefasciatus mosquitoes to the discriminating doses recommended by the World Health Organisation (WHO) to DDT (4%) and deltamethrin (0.05%). Across all study sites, mortality as a result of DDT varied from 11.9 to 50.0%, as compared with 91.2% in the susceptible laboratory strain (S-Lab), indicating that Cx. quinquefasciatus is resistant to DDT. The species was found to be 100% susceptible to deltamethrin in all study sites except Benganajuli and Rikamari. Knock-down times (KDT) in response to deltamethrin varied significantly between study sites (P < 0.01) from 8.3 to 17.8 min for KDT(50) and 37.4 to 69.5 min for KDT(90). All populations exceeded the threshold level of alpha-esterase, beta-esterase and glutathion S-transferase (GST) established for the S-Lab susceptible strain, and all populations had 100% elevated esterase and GST activity, except Missamari and Solmara. Beta-esterase activity in Field Unit II (96.9%) was less than in any of the other populations. Benganajuli had the highest activity level for all the enzymes tested. There was a significant correlation between all enzyme activity levels and insecticide resistance phenotype by populations (P < 0.05). The results presented here provide the first report and baseline information of the insecticide resistance status of Cx. quinquefasciatus in northeastern India, and associated information about biochemical mechanisms that are essential for monitoring the development of insecticide resistance in the area.

Enabling technologies to improve area-wide integrated pest management programmes for the control of screwworms.

Abstract: The economic devastation caused in the past by the New World screwworm fly Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) to the livestock industry in the U.S.A., Mexico and the rest of Central America was staggering. The eradication of this major livestock pest from North and Central America using the sterile insect technique (SIT) as part of an area-wide integrated pest management (AW-IPM) programme was a phenomenal technical and managerial accomplishment with enormous economic implications. The area is maintained screwworm-free by the weekly release of 40 million sterile flies in the Darien Gap in Panama, which prevents migration from screwworm-infested areas in Columbia. However, the species is still a major pest in many areas of the Caribbean and South America and there is considerable interest in extending the eradication programme to these countries. Understanding New World screwworm fly populations in the Caribbean and South America, which represent a continuous threat to the screwworm-free areas of Central America and the U.S.A., is a prerequisite to any future eradication campaigns. The Old World screwworm fly Chrysomya bezziana Villeneuve (Diptera: Calliphoridae) has a very wide distribution ranging from Southern Africa to Papua New Guinea and, although its economic importance is assumed to be less than that of its New World counterpart, it is a serious pest in extensive livestock production and a constant threat to pest-free areas such as Australia. In the 1980s repeated introductions and an expansion of Old World screwworm populations were reported in the Middle East; in the 1990s it invaded Iraq and since late 2007 it has been reported in Yemen, where a severe outbreak of myiasis occurred in 2008. Small-scale field trials have shown the potential of integrating the SIT in the control of this pest and various international organizations are considering using the release of sterile insects as part of an AW-IPM approach on a much wider scale. Wohlfahrtia magnifica (Schiner) (Diptera: Sarcophagidae) is a screwworm of temperate regions, which, although of limited agricultural importance, has invaded several new locations in the past few years. This special issue reports on the results of a 6-year project funded by the Joint Food and Agriculture Organization of the United Nations/International Atomic Energy Agency (FAO/IAEA) Programme of Nuclear Techniques in Food and Agriculture entitled 'Enabling Technologies for the Expansion of the SIT for Old and New World Screwworm'. A major goal of the project was to better understand population genetic variation in screwworms as an aid to the identification of isolated populations. The project also addressed issues related to genetic sexing, cuticular hydrocarbons, population dynamics, genetic transformation and chromosome analysis.

Traumatic myiasis in dogs caused by Wohlfahrtia magnifica and its importance in the epidemiology of wohlfahrtiosis of livestock

Abstract: In the province of Al Hoceima, northern Morocco, and on two farms in Hungary, dogs were inspected for the presence of traumatic myiasis. Nine and four infested dogs were found in Morocco and Hungary, respectively. All the larvae and adults reared from them in the laboratory were identified as Wohlfahrtia magnifica (Schiner) (Diptera: Sarcophagidae). To our knowledge, these are the first cases of wohlfahrtiosis in dogs to be reported in these countries. All infested animals lived close to livestock, where wohlfahrtiosis was endemic. Infested body sites included limbs (six cases), external genitalia (two), ears (three), nose (one) and neck (one). Developing larvae caused severe welfare problems and tissue destruction in most cases. Although the number of cases reported here is small, wohlfahrtiosis in dogs may be very important from an epidemiological perspective because farm and stray dogs can act as both reservoirs and carriers of this parasitic fly species. Therefore, education of dog owners concerning the risk factors in endemic regions is recommended in order to reduce the prevalence of wohlfahrtiosis in dogs and thereby in livestock. Both owners and veterinarians should pay regular attention to any wounds and to the natural orifices of dogs, especially during the fly seasons.

Nutritional stress affects the tsetse fly's immune gene expression.

Abstract: Tsetse-transmitted trypanosomiasis poses a serious threat to human and animal health in sub-Saharan Africa. The majority of tsetse flies (Glossina spp.) in a natural population will not develop a mature infection of either Trypanosoma congolense or Trypanosoma brucei sp. because of refractoriness, a phenomenon that is affected by different factors, including the tsetse fly's immune defence. Starvation of tsetse flies significantly increases their susceptibility to the establishment of a trypanosome infection. This paper reports the effects of nutritional stress (starvation) on (a) uninduced baseline levels of gene expression of the antimicrobial peptides attacin, defensin and cecropin in the tsetse fly, and (b) levels of expression induced in response to bacterial (Escherichia coli) or trypanosomal challenge. In newly emerged, unfed tsetse flies, starvation significantly lowers baseline levels of antimicrobial peptide gene expression, especially for attacin and cecropin. In response to trypanosome challenge, only non-starved older flies showed a significant increase in antimicrobial peptide gene expression within 5 days of ingestion of a trypanosome-containing bloodmeal, especially with T. brucei bloodstream forms. These data suggest that a decreased expression of immune genes in newly hatched flies or a lack of immune responsiveness to trypanosomes in older flies, both occurring as a result of fly starvation, may be among the factors contributing to the increased susceptibility of nutritionally stressed tsetse flies to trypanosome infection.

Population structure and geographical subdivision of the Leishmania major vector Phlebotomus papatasi as revealed by microsatellite variation.

Abstract: Multi-locus microsatellite typing (MLMT) has been employed to infer the population structure of Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) sandflies and assign individuals to populations. Phlebotomus papatasi sandflies were collected from 35 sites in 15 countries. A total of 188 P. papatasi individuals were typed using five microsatellite loci, resulting in 113 different genotypes. Unique microsatellite signatures were observed for some of the populations analysed. Comparable results were obtained when the data were analysed with Bayesian model and distance-based methods. Bayesian statistic-based analyses split the dataset into two distinct genetic clusters, A and B, with further substructuring within each. Population A consisted of five subpopulations representing large numbers of alleles that were correlated with the geographical origins of the sandflies. Cluster B comprised individuals collected in the Middle East and the northern Mediterranean area. The subpopulations B1 and B2 did not, however, show any further correlation to geographical origin. The genetic differentiation between subpopulations was supported by F statistics showing statistically significant (Bonferroni-corrected P < 0.005) values of 0.221 between B2 and B1 and 0.816 between A5 and A4. Identification of the genetic structure of P. papatasi populations is important for understanding the patterns of dispersal of this species and to developing strategies for sandfly control.