Risk of migration: not all gregarious locust nymphs reach appropriate refuges.

Sedentary animals choose appropriate refuges against predators, while migratory ones may not necessarily do so. In ectotherms, refuge selection is critical during low temperatures, because they cannot actively evade predators. To understand how migratory ectotherms alter their defensive behaviors depending on refuge quality in cold temperatures, we evaluated migratory gregarious desert locust nymphs (Schistocerca gregaria) in the Sahara Desert, where daily thermal constraints occur. We recorded how roosting plant type (bush/shrub) and its height influenced two alternative defense behaviors (dropping/stationary) during cold mornings, in response to an approaching simulated ground predator. Most locusts in bushes dropped within the bush and hid irrespective of their height, whereas those roosting > 2 m height in shrubs remained stationary. These defenses are effective and match with refuge plant types because dynamic locomotion is not required. When nymphs roosted on shrubs < 1.5-m height, which was an unsafe position, nearly half showed both defensive behaviors, indicating that escaping decisions become ambiguous when the refuges are inappropriate. These results suggest that locusts display flexible defensive behaviors when finding appropriate refuges and selecting refuge before daily thermal limitations occur could be critical for migratory ectotherms, which is a risk associated with migration.

Initial study and phylogenetic analysis of hard ticks (Acari: Ixodidae) in Nantong, China along the route of avian migration.

The growing concern about migratory birds potentially spreading ticks due to global warming has become a significant issue. The city of Nantong in this study is situated along the East Asia-Australasian Flyway (EAAF), with numerous wetlands serving as roosting sites for migratory birds. We conducted an investigation of hard ticks and determined the phylogenetic characteristics of tick species in this city. We utilized three different genes for our study: the mitochondrial cytochrome oxidase subunit 1 (COX1) gene, the second internal transcribed spacer (ITS2), and the mitochondrial small subunit rRNA (12 S rRNA) gene. The predominant tick species were Haemaphysalis flava (H. flava) and Haemaphysalis longicornis (H. longicornis). Additionally, specimens of Haemaphysalis campanulata (H. campanulata) and Rhipicephalus sanguineus (R. sanguineus) were collected. The H. flava specimens in this study showed a close genetic relationship with those from inland provinces of China, as well as South Korea and Japan. Furthermore, samples of H. longicornis exhibited a close genetic relationship with those from South Korea, Japan, Australia, and the USA, as well as specific provinces in China. Furthermore, R. sanguineus specimens captured in Nantong showed genetic similarities with specimens from Egypt, Nigeria, and Argentina.

Parasitism on domestic cats by Amblyomma auricularium and serological evidence of exposure to Rickettsia amblyommatis.

The domestic cat is not considered a primary host for any specific tick species; however, it can be affected by some Ixodidae species, such as Rhipicephalus sanguineus sensu lato and Amblyomma spp. The study reports parasitism by Amblyomma auricularium and the detection of anti-Rickettsia spp. antibodies in domestic cats from a rural property in the Afrânio municipality, Pernambuco, Brazil. Amblyomma auricularium (24 nymphs, six females, and four males) and Amblyomma sp. (42 larvae) parasitized three cats, and 73 free-living ticks were captured in armadillo burrows: A. auricularium (36 nymphs, six females, five males) and Amblyomma sp. (26 larvae). Blood samples from cats were collected and the obtained plasma were subjected to indirect immunofluorescence assay (IFA) to detect antibodies against Rickettsia antigens. Thus, anti-Rickettsia spp. antibodies were determined (titers ranging from 128 to 512) and showed a predominant antibody response to Rickettsia amblyommatis or a very closely related genotype. This study reports the first infestation of nymphs and adults of A. auricularium on cats in a new area of occurrence in the semi-arid region of Northeastern Brazil and reports for the first time the presence of anti-Ricketsia antibodies in cats in the region, with R. amblyommatis as the probable infectious agent.

Prey stage preference of Amblyseius paraaerialis (Acari: Phytoseiidae) on varied life stages of the spider mites Tetranychus urticae, Tetranychus macfarlanei and Oligonychus biharensis (Acari: Tetranychidae) and exploring the mass rearing possibilities of this predatory mite on alternative diets.

Spider mites Tetranychus urticae, Tetranychus macfarlanei and Oligonychus biharensis are considered to be highly polyphagous in nature and causes severe damage to a wide range of plants around the world. Amblyseius paraaerialis is an efficient phytoseiid predator of spider mites with a potential to survive on both natural and alternative diets. Evaluation of predatory potential and prey stage preference provides valuable information on the efficacy of the predatory species in controlling mite population. Feeding experiments were conducted on mulberry leaf discs under the laboratory conditions of 30 ± 2 °C and 70 ± 5% relative humidity (RH). After 24 h of feeding experiment, the adult female predator exhibited a significant preference in feeding towards the eggs of T. macfarlanei (42.6%) and the larval stages of T. urticae (46%) and O. biharensis (25.3%). The mass rearing possibilities of A. paraaerialis was tested by tracking and comparing the developmental duration of individual life stages on varied food sources like, honey, castor (Ricinus communis) pollen, honey-pollen mixture and mixed life stages of T. urticae. The predator was failed to complete its development on honey and pollen when supplied separately. However it was successfully developed on honey-pollen mixture and mixed life stages of T. urticae. The developmental studies unravelled a shortest developmental duration and an extended adult longevity and lifespan of A. paraaerialis when reared on the alternative diet, thus opened up the mass rearing possibility of the predatory species under laboratory conditions.

Cascading impacts of overstory structure in managed forests on understory structure, microclimate conditions, and Ixodes scapularis (Acari: Ixodidae) densities.

Forest management practices designed to meet varied landowner objectives affect wildlife habitat and may interrupt the life-cycle stages of disease vectors, including the black-legged tick, Ixodes scapularis Say (Acari: Ixodidae). Ixodes scapularis transmits multiple pathogens including Borrelia burgdorferi, the causative agent of Lyme disease, which is the most common tick-borne disease in the United States. There is evidence that a range of active forest management practices (e.g., invasive plant removal, prescribed burning) can alter tick densities and pathogen transmission. However, few studies have investigated relationships between forest stand structural variables commonly manipulated by timber harvesting and tick ecology. Foresters may harvest timber to create certain forest structural conditions like the mean number of trees, or basal area, per hectare. This study used a spatially replicated experiment in a blocked design to compare forest stands with a range of overstory structures and document variations in the midstory, understory, and forest floor, as well as microclimate conditions within tick off-host habitat. Greater numbers of trees or basal area per hectare correlated with greater canopy closure but less understory cover, stabilized microclimate temperature, higher microclimate humidity, and greater I. scapularis nymph densities. A random forest model identified understory forest structure as the strongest predictor of nymph densities. There was no relationship between the number of trees or basal area per hectare and daily deer (Odocoileus virginianus Zimmermann) activity or nymphal infection prevalence. These findings provide a deeper understanding of tick-habitat associations within a forest stand and have the potential to inform forest management decisions.

Are the ladybugs Cryptolaemus montrouzieri and Exochomus quadripustulatus (Coleoptera: Coccinellidae) candidate predators of Toumeyella parvicornis (Hemiptera: Coccidae)?

BACKGROUND: Toumeyella parvicornis is an alien pest of recent introduction in Italy that infests stone pines (Pinus pinea L.), its main host plant in Europe. Infestations are currently controlled through endotherapic treatments, but the high costs and the long-term inefficacy highlight the need for alternative control strategies applicable in natural systems as well. An analysis of the effectiveness of autochthonous and naturalized predators is the first step to achieve this goal. This work focused on two candidate predators, Exochomus quadripustulatus and Cryptolaemus montrouzieri (Coleoptera: Coccinellidae), that may potentially control T. parvicornis. The analysis was carried out under laboratory-controlled and semi-field conditions. RESULTS: Laboratory tests were carried out to assess: (i) the predation rate of the ladybugs over different densities of pest preimaginal stages, and (ii) the effect of the presence of heterospecific and conspecific predators on the attractiveness of prey colonies. Semi-field experimentations were carried out by wrapping infested stone pine twigs with net sleeves and applying one of three treatments: (i) Exochomus quadripustulatus, (ii) Cryptolaemus montrouzieri, and (iii) control containing only the pest population. Both the ladybugs were attracted by T. parvicornis, offered as prey. Exochomus quadripustulatus was more attracted to conspecific and heterospecific ladybugs than Cryptolaemus montrouzieri and responded to prey more quickly. CONCLUSIONS: The results obtained could be useful for planning further experimentations to explore the potential use of these predators in biological control programs that may be applied in infested areas. Besides the use in an urban context, where pesticide use is strongly limited, the release of natural enemies may help safeguard stone pine forests. © 2024 Society of Chemical Industry.

Survey of Rickettsia spp. in ticks (Acari: Ixodidae) infesting opossums (Didelphis albiventris) and capybaras (Hydrochoerus hydrochaeris) from an urban park in southeastern Brazil.

Ticks are hematophagous arthropods and, during feeding, may transmit pathogens to vertebrate hosts, including humans. This study aimed to investigate the presence of Rickettsia spp. in ticks collected between 2010 and 2013 from free-ranging capybaras (Hydrochoerus hydrochaeris) and opossums (Didelphis albiventris) that inhabit Sabiá Park in Uberlândia, Brazil. Overall, 1,860 ticks were collected: 1,272 (68.4%) from capybaras (487 of the species Amblyomma sculptum, 475 adults and 12 nymphs; 778 Amblyomma dubitatum, 727 adults and 51 nymphs; and seven larva clusters of the genus Amblyomma); and 588 (31.6%) from opossums (21 A. sculptum, one adult and 20 nymphs; 79 A. dubitatum, all nymphs; 15 Ixodes loricatus, 12 adults and three nymphs; 457 Amblyomma sp. larva clusters; 15 Ixodes sp. larva clusters; and one Argasidae larva cluster). Out of 201 DNA samples tested for the presence of Rickettsia spp. DNA using polymerase chain reaction (PCR) 12 showed amplification of a gtlA gene segment that was specific to Rickettsia bellii, a bacterium non-pathogenic to humans. As there has been a report showing serological evidence of infections caused by Rickettsia species of the spotted fever group (SFG) in capybaras and opossums in the park, including Rickettsia rickettsii, the etiological agent of Brazilian spotted fever, and considering the presence of A. sculptum ticks, which are aggressive to humans, as well as these vertebrate hosts, which are amplifiers of R. rickettsii, it is important to monitor the presence of SFG rickettsiae in the Sabiá Park, which is visited daily by thousands of people.

Repellent activity of the non-host semiochemical (E)-2-octenal against Amblyomma sculptum and Amblyomma dubitatum ticks under field conditions.

Amblyomma ticks pose a significant public health threat due to their potential to transmit pathogens associated with rickettsial diseases. (E)-2-octenal, a compound found in donkeys (Equus asinus), exhibits strong repellent properties against Amblyomma sculptum nymphs under laboratory conditions. This study assessed the effectiveness of the (E)-2-octenal in wearable slow-release devices for personal human protection against Amblyomma ticks under natural conditions. Slow-release devices treated with (E)-2-octenal and untreated controls were prepared and tested on two volunteers walking through a tick-infested area in Goiania, Brazil. The experiment was conducted twice daily for three series of 10 days, with each volunteer wearing two devices attached to each leg, one on the ankle and one just above the thigh. Volunteers with control and treated devices exchanged them between rounds. Also, the daily release rate of (E)-2-octenal from the slow-release devices was determined in the laboratory, increasing significantly from 0.77 ± 0.14 µg/day on the first day to 9.93 ± 1.92 µg/day on the 4th day and remaining constant until the 16th day. A total of 5409 ticks were collected from both volunteers. Treated devices resulted in recovering fewer ticks (n = 1,666; 31%) compared to untreated devices (control: n = 3,743; 69%). (E)-2-octenal effectively repelled Amblyomma spp. larvae, A. sculptum adults, and exhibited pronounced repellency against A. dubitatum nymphs and adults. These findings suggest the potential of (E)-2-octenal delivered by wearable slow-release devices as a green-based repellent. Further improvements, however, are necessary to provide better protection for humans against A. sculptum and A. dubitatum in field conditions.

Predator-Prey Interaction Between Xylocoris sordidus (Hemiptera: Anthocoridae) and Enneothrips enigmaticus (Thysanoptera: Thripidae).

The peanut thrips, Enneothrips enigmaticus (Thysanoptera: Thrypidae), is an important pest of the peanut (Arachis hypogaea) in South America. Due to concerns about the environment and human health induced by the extensive use of pesticides in the management control of pests, environmentally and friendlier tactics must be targeted. Thus, this study investigates, for the first time, the behavior of Xylocoris sordidus (Hemiptera: Anthocoridae) as a biological control agent for E. enigmaticus. The methodology included no-choice tests to assess whether the predation rate varies according to the developmental stage of the prey, as well as the predator's developmental stage with the highest predation capacity. Additionally, an analysis of the functional response of adult and 5th instar nymphs of X. sordidus exposed to different densities of E. enigmaticus nymphs (1, 2, 4, 8, 16, and 32) was conducted. The results confirm the predation of peanut thrips by X. sordidus, with a higher predation rate in the nymphal stages of the prey. There was no difference in predation capacity between predator nymphs and adults, and exhibiting a type II functional response. Therefore, the potential of X. sordidus as a biological control agent for E. enigmaticus is confirmed, showing the importance of adopting measures to preserve this predator in peanut crops.

Composition and transstadial retention of the salivary glands in Ornithodoros hermsi (Acari: Argasidae).

Following several days of blood feeding by larval and nymphal ixodid (hard) ticks, the salivary glands degenerate and are completely replaced in the next life stage. Yet, what happens during the molt of immature argasid (soft) ticks after their rapid and small bloodmeal has remained a mystery. Multiple studies of nymphal Ornithodoros hermsi Wheeler (Acari: Argasidae) ticks infected with the relapsing fever spirochete Borrelia hermsii suggested the salivary glands in these ticks may not disintegrate after feeding. Therefore, cohorts of second-stage O. hermsi nymphs were fed and examined daily after the bloodmeal by fresh dissections and weekly by histological cross-sections of the entire tick. The composition of the salivary glands was typical for argasid ticks in having agranular (Type I) and granular (Type II) acini, the latter being surrounded by a myo-epithelial sheath. In all 197 ticks examined from 1 to 63 days after feeding, morphologically intact salivary glands were present. During apolysis, 5 ticks had extralimital clusters of granular acini adhering to otherwise intact glands. Our observations demonstrate that the salivary glands of nymphal O. hermsi do not disintegrate after feeding and new acini are produced during the molt for incorporation into the existing glands. Cumulatively, these findings suggest a fundamental difference in the transstadial development of argasid and ixodid ticks.

Prevalence and risk factors of Linguatula spp. in slaughter animals in Tabriz, Iran, and methods for nymphal stage inactivation.

Linguatula is a food born zoonotic parasite in which carnivores and herbivores serve as final and intermediate hosts, respectively. Human infection with Linguatula spp. occurs following consumption of raw or undercooked infected internal organs of the intermediate host and/or consumption of water and/or vegetables contaminated with eggs released from final hosts. The aim of this study was to determine prevalence and risk factors of Linguatula spp. in sheep, cattle, buffalo, goats and camels slaughtered at the Tabriz abattoir, Iran. In addition, effect of temperature and sodium chloride (NaCl) on survival time of Linguatula spp. nymphs was assessed. For this purpose, 25,520 mesenteric lymph nodes from 2552 animals and the livers and lungs from 656 animals were collected randomly and examined. To evaluate the effect of temperature and NaCl on the survival of Linguatula spp. nymphs in infected livers and lungs, 30 g of each liver and lung with dimensions of 2 × 3 × 4 cm, were exposed to temperatures of -20, 10, 50, 60 and 72 °C and NaCl concentrations of 5 %, 10 %, 15 % and 20 % for 3, 6, 12, 24, 48 and 72 h, in triplicate. Based on the mesenteric lymph nodes, 25.7 % (656 of 2552 animals) were infected with Linguatula spp. Of the 656 liver and lungs assessed, 141 (21.5 %) and 62 (9.5 %) were infected with Linguatula spp., respectively. The rate of infection of mesenteric lymph nodes in all animals was significant with age (P < 0.05), with more older animals infected. In regards to sex, except for camels, more female animals were infected than male animals (P < 0.05). There was a significant difference in survival of nymphs based on temperature and/or NaCl and time (P < 0.0001). At 72 h, all temperatures assessed except 10 °C, resulted in all nymphs being inactivated. Sodium chloride was more effective against Linguatula spp. nymphs in livers than in lungs with 100 % efficacy only achieved against nymphs in livers at 20 % concentration after 48 h and at 10 and 15 % concentration after 72 h. Based on these results, heating and application of common salt as a food preservative in meat products reduces the survival time of Linguatula spp. nymphs and their use could decrease the risk of food-born microorganisms.

A Preliminary Study on the Antigenic Proteins of Linguatula serrata Nymphal Stage in Sheep with Visceral Linguatulosis.

Scant information is available on the immunological aspect of Linguatula serrata causing linguatulosis in humans and animals. The present study aimed to analyze the content of crude somatic extracts and excretory-secretory products of L. serrata nymphs to detect the immune response of sheep and immunogenic proteins of the parasite. After collecting the nymphs, somatic extracts were prepared by sonication. Excretory secretory products were prepared by the incubation of nymphs in RPMI medium at 37°C with 5% CO2. Somatic and excretory-secretory proteins were isolated using SDS-PAGE. The immunogenic properties of the resulting proteins were determined using immunoblotting and positive sera from sheep infected with visceral linguatulosis. The total content of somatic extracts and excretory-secretory products of L. serrata nymphs analyzed by SDS-PAGE (12% gel) revealed two protein patterns with more than 18 and 9 strong bands, respectively. Immunoblots using sera samples of sheep infected with the parasite, somatic extracts and excretory-secretory products demonstrated 12 and 3 antigenic proteins with molecular weights mostly in the range of 24-100 kDa and an antigen more than 180 kDa. Three common immunodominant antigenic proteins with molecular weights of 38 and 57, as well as an antigen of more than 180 kDa, were detected in the somatic extracts and excretory-secretory products of L. serrata nymphs in sheep with visceral linguatulosis. These antigens can be considetered prime candidates for future serodiagnosis and immunoprotective studies of the parasite.

Seasonal changes in questing efficiency of wild Amblyomma americanum (Acari: Ixodidae) nymphs.

Understanding the factors which influence host-seeking behavior of ticks is essential to determine the risk they pose as a vector of pathogens. While many studies have evaluated the impact of environmental variables on tick behavior, few have examined how seasonal changes in physiological status may further modify patterns of activity. In this study, we measured differences in questing behavior of mid spring- and early summer-caught Amblyomma americanum nymphs held under standardized laboratory conditions. As both groups represent the same cohort of overwintered nymphs, we hypothesized that age-related changes in the older summer ticks may influence questing behavior. In each season, we collected nymphs from field and forest habitats in northeast Missouri, after which we placed each nymph individually in a desiccating vertical questing apparatus with a hydrating microenvironment at the base. On the day following collection, we recorded the height of each nymph in the apparatus bi-hourly from 04:00 to 22:00 and calculated the vertical displacement between consecutive observations. Despite displaying no differences in mean questing height throughout the experiment, active ticks collected in the summer group (n = 89) travelled greater cumulative distances between desiccating and hydrating microenvironments than those collected in the spring (n = 119). This suggests that questing efficiency decreases in summer nymphs to accommodate increased time allocation towards rehydration. While we observed no direct association between body size and distance travelled, body size of the nymphal population also decreased significantly from spring to summer. Overall, our results demonstrate that there are seasonal changes in how A. americanum responds to environmental conditions. To more accurately predict host-seeking behavior of ticks across seasons, models should incorporate physiological parameters of the active ticks in a given population.

Composition and abundance of midgut surface proteins in the Asian citrus psyllid, Diaphorina citri.

The Asian citrus psyllid, Diaphorina citri, is the vector of Candidatus Liberibacter asiaticus (CLas), the presumed causative agent of citrus greening disease. For successful transmission, CLas must cross the gut barrier, requiring interaction with proteins on the midgut epithelium. We compared the relative abundance of gut surface proteins for both adult and nymph D. citri, as nymphs are particularly susceptible to CLas infection. To enrich for gut surface proteins, brush border membrane vesicles were prepared from dissected guts, and proteins identified from triplicate samples run on a timsTOF mass spectrometer. A total of 1516 and 1219 proteins were identified from D. citri adults and nymphs respectively. Based on bioinformatics analysis software and manual curation, 112 adult and 87 nymph proteins were predicted to localize to the surface of the microvilli and were further categorized into integral membrane and glycosylphosphatidylinositol (GPI)-anchored proteins. Proteins exploited by insect pathogens such as aminopeptidase, alkaline phosphatase, cadherin, ABC transporters, and carboxypeptidase were among the most abundant proteins on the gut surface. In addition to providing insights into hemipteran gut physiology, the D. citri gut surface proteome will inform novel approaches to interfere with CLas interaction with the psyllid gut to prevent the spread of citrus greening. BIOLOGICAL SIGNIFICANCE: The Asian citrus psyllid (ACP), D. citri is one of the most serious pests of citrus worldwide. ACP transmits the pathogenic bacterium that causes citrus greening or huanglongbing (HLB), which has resulted in severe economic losses in global citriculture. The putative causative agent of this disease, the gram-negative bacterium Candidatus Liberibacter asiaticus (CLas), is vectored by the Asian citrus psyllid, D. citri, in a persistent and circulative manner. CLas must interact with gut surface proteins in order to enter midgut epithelial cells. However, the specific proteins exploited by CLas have yet to be identified. The characterization of the most abundant proteins on the surface of the D. citri gut provides insight into candidate receptors for CLas and other pathogens of D. citri. We hypothesize that pathogens of D. citri exploit the most abundant proteins on the surface of the gut for entry into the host insect. Importantly, the abundant gut surface proteins will provide the basis for novel approaches to disrupt CLas-D. citri interactions, with the goal of preventing further economic loss to the citrus industry.

Body shape and fluctuating asymmetry following different feeding sources and feeding time in a triatomine, Triatoma pallidipennis (Stål, 1892).

Even when an animal has a generalist diet, different food sources can impact its body shape and fluctuating asymmetry (a stress indicator; FA). To test this, we varied the food source (mammalian, avian or defibrinated mammalian blood; and control animals - ad libitum feeding) and the time of feeding (every 8 days, 45 days and ad libitum) having the Chagas triatomine vector, Triatoma pallidipennis (Stål, 1892), as a study animal which has presumable generalist feeding habits. This factorial design was applied since first instar animals until adulthood. As response variables, we measured body shape and FA in adults of both sexes, using a two-dimensional geometric morphometrics protocol. The highest variance in body shape was explained by diet (17%), followed by sex nested within diet (12%). Males had less morphological differentiation than females: females with defibrinated blood provided every 45 days differentiated more, while those that fed on mammalian blood every 8 days differed less. Distances among the averages of the FA component related to shape indicated greater distances between avian blood provided every 45 days and mammalian blood provided every 8 days, as well as between the two groups fed on avian blood (feeding every 8 and 45 days), followed by avian and defibrinated blood, both fed every 8 days. These results indicate that blood source and feeding time have significant effects on the body shape, and FA in females and both sexes. Thus, despite general feeding habits, avian blood showed a greater impact on shape and FA in triatomines. This may select for triatomines to use mammal blood rather than avian blood if they have the chance to do so.

Occurrence of juvenile Dermacentor reticulatus ticks in three regions in Poland: the final evidence of the conquest.

BACKGROUND: Two populations of Dermacentor reticulatus ticks (Western and Eastern) in Poland are among the most dynamic tick populations in Central Europe. Expansion and settlement of ticks in new localizations depend on the presence of suitable hosts, for both adult and juvenile ticks. METHODS: The current study was planned to complement our previous studies on questing adult ticks and was focused on a collection of juvenile D. reticulatus ticks from rodents from three regions in Poland, defined by the presence/absence of adult ticks (regions of the Western and Eastern tick population and the gap area between them) to confirm the existence of stable populations. Rodent trapping was conducted in open habitats (fallow lands, wasteland and submerged meadows) in 2016-2018 in June, July and/or August to encompass seasonal peaks of larvae and nymph activity. RESULTS: Altogether, three tick species were collected, 2866 D. reticulatus, 2141 Ixodes ricinus and 427 Haemaphysalis concinna. Dermacentor reticulatus was the most common (72.3%) and abundant (mean 17.94 ± 2.62 ticks/rodent) tick species on rodents from the Eastern region; in the Western region infestation of rodents was only 6.8%. Ixodes ricinus was found in all three regions and was the only tick species collected from rodents from the gap area. Haemaphysalis concinna was noted only in the Western region. The highest infestation of juvenile D. reticulatus was recorded on voles (Myodes and Microtus spp.), infestation of I. ricinus was the highest on Apodemus mice, and the majority of H. concinna ticks were collected from root voles Alexandromys oeconomus. CONCLUSIONS: Our study confirmed a stable population of D. reticulatus in Eastern and Central Poland and a lower prevalence and mean abundance of this tick species among rodents from the Western region. A lack of juvenile D. reticulatus on rodents in Niewiadów confirmed the existence of the gap area, free of D. reticulatus ticks.

Duration of tick attachment necessary for transmission of Anaplasma phagocytophilum by Ixodes scapularis (Acari: Ixodidae) nymphs.

This study assessed the duration of tick attachment necessary for a successful transmission of Anaplasma phagocytophilum by an infected I. scapularis nymph. Individual nymphs were placed upon BALB/c mice and allowed to feed for predetermined time intervals of 4 to 72 h. Ticks removed from mice at predetermined intervals were tested by PCR for verification of infection and evaluation of the bacterial load. The success of pathogen transmission to mice was assessed by blood-PCR at 7, 14 and 21 days postinfestation, and IFA at 21 days postinfestation. Anaplasma phagocytophilum infection was documented in 10-30 % of mice, from which ticks were removed within the first 20 h of feeding. However, transmission success was ≥70% if ticks remained attached for 36 h or longer. Notably, none of the PCR-positive mice that were exposed to infected ticks for 4 to 8 h and only half of PCR-positive mice exposed for 24 h developed antibodies within 3 weeks postinfestation. On the other hand, all mice with detectable bacteremia after being infested for 36 h seroconverted. This suggests that although some of the ticks removed prior to 24 h of attachment succeed in injecting a small amount of A. phagocytophilum, this amount is insufficient for stimulating humoral immunity and perhaps for establishing disseminated infection in BALB/c mice. Although A. phagocytophilum may be present in salivary glands of unfed I. scapularis nymphs, the amount of A. phagocytophilum initially contained in saliva appears insufficient to cause sustainable infection in a host. Replication and, maybe, reactivation of the agent for 12-24 h in a feeding tick is required before a mouse can be consistently infected.

Domestic dogs as amplifying hosts of Rickettsia rickettsii for Amblyomma aureolatum ticks.

Brazilian spotted fever (BSF) is an acute infectious disease caused by the bacterium Rickettsia rickettsii, which is transmitted by different tick species. Due to deleterious effects caused on ticks, the horizontal transmission of R. rickettsii through amplifying hosts is crucial for its maintenance in tick populations among BSF-endemic areas. The tick Amblyomma aureolatum is the main vector of R. rickettsii in the São Paulo metropolitan area; nevertheless, it is not known which vertebrate could act as an amplifying host for this tick species. Herein, we evaluated the potential of domestic dogs - primary hosts for A. aureolatum adults in BSF-endemic areas - to act as amplifying hosts. For this purpose, A. aureolatum non-infected adults were allowed to feed on two groups of dogs: the control group (G1), composed of one dog not exposed to R. rickettsii; and, the infected group (G2), composed of three dogs infected with R. rickettsii via tick parasitism. All G2-dogs became ill, seroconverted to R. rickettsii, and rickettsial DNA was detected in 87% of the engorged females that fed on them. Transovarial transmission rate was estimated to be 25% and infected larvae successfully transmitted R. rickettsii to guinea-pigs, confirming transovarial transmission and vector competence. No rickettsial DNA was detected in individual samples of eggs or larvae, which precluded the estimation of filial infection rate, but implies that it was low. Our results suggest that domestic dogs act as amplifying hosts of R. rickettsii for A. aureolatum ticks in BSF-endemic areas in Brazil.

Ticks (Acari: Ixodidae) on marsh deer (Blastocerus dichotomus) at a conservation center: infestation and Rickettsia parkeri infection dynamics along nine years.

The objective of this work was to evaluate the relationship between the populations of the ticks Amblyomma triste Koch, 1844, Rhipicephalus microplus (Canestrini, 1888), Amblyomma sculptum Berlese, 1888, the pathogenic bacteria Rickettsia parkeri and a marsh deer (Blastocerus dichotomus) population after its removal from a pristine environment. For this purpose, ticks were collected from the cervical region of deer at the Marsh Deer Conservation Center in Promissão, São Paulo State, Brazil for nine consecutive years (2000 - 2008). Deer in captivity at the Center were kept in 2,000 m² paddocks surrounded by two-meter-high fences in the Tiete-river marsh. In total, 1,012 ticks of 26 deer were collected. Prevalence of the species A. triste among tick-infested hosts was the highest in the first triennium but decreased to the second and further to the third triennium. In contrast, the R. microplus prevalence amidst infested host population, increased from the first to the third triennium and was the species that attained the highest infestation intensity. Amblyomma sculptum was the tick with the lowest infestation prevalence and intensity throughout the period. The change in the proportion between the two most prevalent species was attributed to the new environment, specifically its restricted size and within it a dry area more suitable for R. microplus. DNA of 424 ticks processed in 276 pools was tested for Rickettsia genetic material by polymerase chain reactions (PCR). Twenty samples of the study were positive for the rickettsial gltA gene. Of these, 18 were from A. triste ticks and revealed the presence of the ompA spotted fever group gene as well. Eleven samples were sequenced and showed 100% identity with R. parkeri sensu stricto. Two samples from R. microplus did not amplify ompA gene neither yielded product in a PCR specific for Rickettsia bellii. Sequencing of the gltA gene in the DNA of these two ticks was also 100% identical with R. parkeri s.s. In conclusion, the changes in the deer environment modified the tick populations but maintained, at least temporary, R. parkeri bacteria in A. triste ticks. Rhipicephalus microplus was refractory to the R. parkeri infection and bacterial DNA in this tick species indicated DNA spill over from other tick species. It was demonstrated that captive marsh deer may sustain cattle tick populations on its own. This would hardly occur under pristine conditions because of the inadequacy the marsh deer´s naturally humid habitat for the cattle tick. However, deer transportations of R. microplus ticks from one farm to another may occur whenever habitat loss pushes this wild animal towards farms.

Defense Suppression through Interplant Communication Depends on the Attacking Herbivore Species.

In response to herbivory, plants emit volatile compounds that play important roles in plant defense. Herbivore-induced plant volatiles (HIPVs) can deter herbivores, recruit natural enemies, and warn other plants of possible herbivore attack. Following HIPV detection, neighboring plants often respond by enhancing their anti-herbivore defenses, but a recent study found that herbivores can manipulate HIPV-interplant communication for their own benefit and suppress defenses in neighboring plants. Herbivores induce species-specific blends of HIPVs and how these different blends affect the specificity of plant defense responses remains unclear. Here we assessed how HIPVs from zucchini plants (Cucurbita pepo) challenged with different herbivore species affect resistance in neighboring plants. Volatile "emitter" plants were damaged by one of three herbivore species: saltmarsh caterpillars (Estigmene acrea), squash bugs (Anasa tristis), or striped cucumber beetles (Acalymma vittatum), or were left as undamaged controls. Neighboring "receiver" plants were exposed to HIPVs or control volatiles and then challenged by the associated herbivore species. As measures of plant resistance, we quantified herbivore feeding damage and defense-related phytohormones in receivers. We found that the three herbivore species induced different HIPV blends from squash plants. HIPVs induced by saltmarsh caterpillars suppressed defenses in receivers, leading to greater herbivory and lower defense induction compared to controls. In contrast, HIPVs induced by cucumber beetles and squash bugs did not affect plant resistance to subsequent herbivory in receivers. Our study shows that herbivore species identity affects volatile-mediated interplant communication in zucchini, revealing a new example of herbivore defense suppression through volatile cues.