Immune protection of three serine protease inhibitors vaccine in mice against Rhipicephalus sanguineus.

Bioactive molecules in tick saliva are considered to be key to successful feeding and further the transmission of tick-borne pathogens. Problems such as pathogen transmission and animal weight loss result in tick infestation can cause tremendous economic losses to the livestock industry. Therefore, the development of a universal tick vaccine is urgently needed. In this paper, three serine protease inhibitor (serpin) proteins RMS-3, L7LRK7 and L7LTU1 were analyzed with bioinformatics methods. Subsequently the proteins were expressed and purified, and inoculated into Kunming mice for immune protection analysis. The amino acid sequence similarities between RMS-3, L7LRK7 and L7LTU1 were up to 90% in Rhipicephalus sanguineus. The recombinant RMS-3 + L7LRK7 + L7LTU1 showed anticoagulant reaction function and could inhibit the activity of CD4+ lymphocytes, when inoculated into Kunming mice. Additionally, After the immunized mice were challenged with Rhipicephalus sanguineus, the percentage of larvae and nymphs that were fully engorged dropped to 40.87% (P < 0.05) and 87.68% (P > 0.05) in the RmS-3 + L7LRK7 immune group, 49.57% (P < 0.01) and 52.06% (P < 0.05) in the RmS-3 + L7LTU1 group, and 45.22% (P < 0.05) and 60.28% (P < 0.05) in the RmS-3 + L7LRK7 + L7LTU1 immune group, in comparison with the control group. These data indicate that RmS-3 + L7LRK7 + L7LTU1 has good immune protection and has the potential to be developed into a vaccine against the larvae and nymphs of R. sanguineus.

A model for predicting the phenology of Philaenus spumarius.

The design and implementation of Philaenus spumarius control strategies can take advantage of properly calibrated models describing and predicting the phenology of vector populations in agroecosystems. We developed a temperature-driven physiological-based model based on the system of Kolmogorov partial differential equations to predict the phenological dynamics of P. spumarius. The model considers the initial physiological age distribution of eggs, the diapause termination process, and the development rate functions of post-diapausing eggs and nymphal stages, estimated from data collected in laboratory experiments and field surveys in Italy. The temperature threshold and cumulative degree days for egg diapause termination were estimated as 6.5 °C and 120 DD, respectively. Preimaginal development rate functions exhibited lower thresholds ranging between 2.1 and 5.0 °C, optimal temperatures between 26.6 and 28.3 °C, and upper threshold between 33.0 and 35 °C. The model correctly simulates the emergence of the 3rd, 4th, and 5th nymphal instars, key stages to target monitoring actions and control measures against P. spumarius. Precision in simulating the phenology of the 1st and 2nd nymphal stages was less satisfactory. The model is a useful rational decision tool to support scheduling monitoring and control actions against the late and most important nymphal stages of P. spumarius.

Evaluation of Peregrinus maidis transformer-2 as a target for CRISPR-based control.

The corn planthopper, Peregrinus maidis, is an economically important pest of corn and sorghum. Here we report the initial steps towards developing a CRISPR-based control method, precision guided sterile insect technique (pgSIT), for this hemipteran pest. Specifically, we evaluated the potential of transformer-2 (tra-2) as a target for sterilizing insects. First, we identified tra-2 transcripts within our P. maidis transcriptome database and performed RNA interference (RNAi) to confirm functional conservation. RNAi-mediated knockdown of Pmtra-2 in nymphs transformed females into pseudomales with deformed ovipositors resembling male claspers. While males showed no overt difference in appearance, they were indeed sterile. Importantly, the results were similar to those observed in another planthopper, Nilaparvata lugens. We also used CRISPR/Cas9 genome editing to assess the impact of tra-2 knockout in injectees. CRISPR-mediated knockout of Pmtra-2 had lethal effects on embryos, and hence not many injectees reached adulthood. However, mosaic knockout of Pmtra-2 did impact female and male fertility, which supports the use of tra-2 as a target for pgSIT in this hemipteran species.

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.

Functional response of Franklinothrips vespiformis (Thysanoptera: Aeolothripidae) to eggs and nymphs of Bemisia tabaci (Hemiptera: Aleyrodidae).

The Middle East Asia Minor 1 biotype of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is a greenhouse and field crop pest of global significance. The objective of this study was to assess the potential of the generalist predatory thrips, Franklinothrips vespiformis Crawford (Thysanoptera: Aeolothripidae), as a biological control agent for B. tabaci. This was achieved by determining the functional responses of F. vespiformis larvae and adults to the egg and nymphal stages of B. tabaci under laboratory conditions. Analyses consisted of 10 replicates of each predator and prey stage combination on bean leaf discs for a 24-h period. Following logistic regression analyses to determine the functional response type exhibited, response parameters were estimated with nonlinear least squares regression using Roger's equation. Results showed that F. vespiformis larvae and adults exhibited a Type II functional response when feeding on immature B. tabaci. The handling times (Th) of F. vespiformis larvae and adults were magnitudes higher for B. tabaci nymphs than they were for eggs, which were in part driven by the higher attack rates (a) observed on eggs. The maximum attack rate (T/Th) for B. tabaci eggs and nymphs exhibited by first-stage larvae, second-stage larvae, and adult F. vespiformis increased with increasing predator age. Results from this study suggest that F. vespiformis larvae and particularly adults are promising biological control agents for B. tabaci and are efficient predators at both low and high prey densities.

Effects of rodent abundance on ticks and Borrelia: results from an experimental and observational study in an island system.

BACKGROUND: Lyme borreliosis is the most common tick-borne disease in Europe and is often caused by Borrelia afzelii, which is transmitted by Ixodes ricinus ticks. The prevalence and abundance of infected ticks fluctuate in time and space, influencing human infection risk. Rodents are reservoir hosts for B. afzelii and important feeding hosts for larval ticks. In the study reported here, we examined how variation in rodent abundance is associated with B. afzelii infection prevalence in ticks, the density of nymphs (DON) and the density of infected nymphs (DIN) in the following year. We further analysed the relationships between the abundance of infected rodents and nymphal infection prevalence (NIP) and DIN. METHODS: We conducted a study that combined experimental and observational approaches on 15 islands (10 small islands and 5 large islands) in Finland. On all of the islands, ticks and rodents were monitored and sampled during the summer of 2019, with the monitoring of tick abundance and sampling continuing into the spring of 2020. On five of the 10 small islands, captured rodents were removed from the island ("removal" islands), and on the other five small islands, captured rodents were released back to the trapping site after marking and sampling ("control" islands). On the five large islands, captured rodents were released back to the trapping site after marking and sampling. The presence of B. afzelii from nymph and rodent samples was examined. RESULTS: The results of the experimental study showed that neither treatment (removal), rodent abundance index nor abundance index of infected rodents in 2019 was associated with DON, NIP or DIN in 2020. Based on data from the observational study, the NIP in 2020 decreased with increasing rodent abundance index and abundance index of infected rodents in 2019. However, the DIN in 2020 was not associated with the rodent abundance index or the abundance index of infected rodents in 2019. In addition, in the observational study, DON in 2020 increased with increasing rodent abundance index. CONCLUSIONS: Our results suggest that low rodent abundance during the tick activity period is not sufficient for reducing the disease hazard and, hence, rodent removal may not be a feasible control measure in natural ecosystems.

Revision of Thraulus Eaton 1881 (Ephemeroptera: Leptophlebiidae: Choroterpinae).

The genus Thraulus is widespread throughout much of the Eastern Hemisphere. Since Eaton established Thraulus in 1881, 62 species have, at one time or another, been placed in this genus. Thirty-eight of those species were eventually moved to other genera. Any comprehensive study of the remaining species, based on the published literature, is difficult as they were described by many authors, using different criteria, over a period of 142 years. The purpose of this study was to redescribe this genus, based on previously described species and nine new species, and to provide a format for future taxonomic and morphological studies of Thraulus. Redescriptions of most species were based on direct examination of external morphological characters. Descriptions or diagnoses of species, whose types were unavailable for study, were made using the original published description and additional information provided by authors of several of those species. The following species were studied: Thraulus amravati Vasanth, Subramanian & Selvakumar, 2022; T. bellus Eaton, 1881; T. bishopi Peters & Tsui, 1972; T. cuspidatus Vasanth, Subramanian & Selvakumar, 2022; T. demoulini Peters & Tsui, 1973; T. fasciatus (Kimmins, 1956); T. fatuus Kang & Yang, 1994; T. femoratus Li, Liu & Zhou, 2006; T. gopalani Grant & Sivaramakrishnan, 1985; T. jacobusi Isack, Srinivasan, Sivaruban & Barathy, 2022; T. macilentus Kang & Yang, 1994; T. malabarensis Vasanth, Subramanian & Selvakumar, 2022; T. mudumalaiensis Soman, 1991; T. plumeus Selvakumar, Vasanth & Subramanian, 2022; T. semicastaneus (Gillies, 1951); T. thiagarajani Balasubramanian & Muthukatturaja, 2019; T. thraker Jacob, 1988; T. torrentis (Gillies, 1964); T. turbinatus (Ulmer, 1909); T. umbrosus Kang & Yang, 1994; and T. vellimalaiensis Vasanth, Subramanian & Selvakumar, 2022. Nine new species of Thraulus are described: T. connubialis sp. nov., Malaysia; T. cursus sp. nov., Japan; T. eatoni sp. nov., Indonesia; T. ishiwatai sp. nov., Japan; T. madagasikarensis sp. nov., Madagascar; T. nihonensis sp. nov., Japan; T. opifer sp. nov., Australia; T. parentalis sp. nov., Malaysia; and T. petersorum sp. nov., Malaysia. Thraulus can be distinguished from all other genera of Leptophlebiidae by the following combination of characters: In the imagos, 1) upper portion of eyes oval-suboval, major axes diverge anteriorly; 2) vein MA fork of fore wings symmetrical; 3) vein MP fork of fore wings asymmetricala cross vein connects base of MP2 to MP1, MP fork closer to base of wing than Rs fork; 4) strongly oblique cross vein extends between veins R4+5 and MA1 just apical to fork of vein MA; 5) 2 cubital intercalary veins in fore wings; 6) costal projection on hind wings well-developed, bluntly rounded to acutely pointed; 7) claws dissimilarone blunt and pad-like, the other apically hooked; 8) penes long, relatively straight, narrow, parallel, usually contiguous mesally but not fused, apex may have lateral projections; 9) sternum 7 of female with posterior margin straight or shallowly concave or convex mesally; and 10) sternum 9 of females rounded apically. In addition, penile spines occur on most species. In the nymphs, 1) lateral margins of clypeus parallel; 2) width of labrum subequal to width of clypeus; 3) 2 dorsal rows of setae on labrum; 4) venter of labrum with 1 row of short stout setae on either side of midline near anterior margin, rows curve mesally; 5) hypopharynx with small, rounded, posterolateral projections on arms of superlingua; 6) large spine on posterolateral corners of terga 69, 79 or 89; 7) gills 17 dissimilar: gill 1 composed of 1 or 2 subulate lamellae or a dorsal subulate lamella and a ventral fimbriate oval lamella, and gills 27 composed of dorsal and ventral oval lamellae with fimbriate margins. Two species continue to be nomen dubiumT. siewertii (Weyenbergh, 1883) and T. vogleri (Weyenbergh, 1883). Thraulus grandis Gose, 1980 is considered nomen nudum. A review of published phylogenetic studies involving Thraulus is provided. With the species discussed in this paper, along with reports of additional new species to be described, Thraulus has the potential to be included among the more specious genera of Ephemeroptera.

Investigations on the immature stages of some species of Eulecaniinae (Hemiptera: Coccomorpha: Coccidae).

The dependence on adult female morphology for the determination of soft scale insect species (Hemiptera: Coccomorpha: Coccidae) creates several problems. In this paper, various nymphal stages of soft scale insects from the Ankara district of Trkiye and Israel, belonging to Coccidae: subfamily Eulecaniinae, namely Eulecanium cerasorum (Cockerell), E. ciliatum (Douglas), E. tiliae (Linnaeus), Paleolecanium bituberculatum (Signoret), Physokermes piceae (Schrank) and Rhodoccus perornatus (Cockerell & Parrott) were studied. The morphology of all the nymphal stages of these species is described and illustrated, and identification keys are provided to each instar. The results show that nymphal stages can be used to accurately identify soft scale insect species.

A review of the genus Neogreenia MacGillivray (Hemiptera: Coccomorpha: Qinococcidae) with descriptions of two new species.

The species of Neogreenia MacGillivray (Hemiptera: Coccomorpha: Qinococcidae) are reviewed. The genus is distributed in the Oriental and Palaearctic Regions and now contains seven species. The present study provides updated generic descriptions of all the developmental stages and a brief account of the biology and life cycle of Neogreenia. The genotype, Neogreenia zeylanica (Green, 1896), is redescribed. The following are described and illustrated for the first time: the second-instar nymph, third-instar female, and male third-instar nymph and pupa of N. zizyphi Tang; the second-instar nymph of N. lonicera Wu & Nan; and the second-instar nymph of N. sophorica Wu. Two new species are described and illustrated: Neogreenia ficus Zheng & Wu, sp. n. based on the adult female and Neogreenia tangi Zheng & Wu, sp. n. based on all female instars. These new species bring the total number of described species of Neogreenia to seven. An identification key to all the developmental stages of Neogreenia, and identification keys to species based on adult females and available nymphal instars are provided.

Biological development of Saccharicoccus sacchari () (Hemiptera: Pseudococcidae) on sugarcane in different temperatures.

The pink sugarcane mealybug Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Pseudococcidae) occurs practically in all sugarcane producing regions Saccharum spp. (Poaceae) causing damage. Little information is available about insect's biology under Brazilian conditions. In this work, biological development of pink sugarcane mealybug was studied at temperatures of 23 °C ± 2 °C and 28 °C ± 2 °C without photophase and relative humidity of 80%. Number and viability of eggs, incubation time, duration of the last oviposition, duration of each nymphal instar, viability of the nymphs, start of oviposition and longevity of the females were recorded. Biological development of insects was stipulated by the SAS University Edition software, version 9.4. There were differences in the life cycle of the pseudococcid at both temperatures evaluated. Females of S. sacchari had three nymphal instars and reproduce asexually. Asexual reproduction occurs in the field and under controlled conditions. By increasing the temperature increases, insect lived longer and the presence of the winged male in Brazil indicates the possibility of sexual reproduction of the species.

Investigations of the tick burden on passeriform, water-associated and predatory birds reveal new tick-host associations and habitat-related factors of tick infestation.

BACKGROUND: Previous studies on the tick infestation of birds in the Carpathian Basin focused on songbirds (Passeriformes). Thus, the primary aim of the present work was to extend the scope of previous studies, i.e. to include aquatic (water-associated) bird species in a similar context, especially considering that these birds are usually long-distance migrants. METHODS: Between March 2021 and August 2023, 11,919 birds representing 126 species were checked for the presence of ticks. From 352 birds belonging to 40 species, 905 ixodid ticks were collected. Tick species were identified morphologically and/or molecularly. RESULTS: Ticks from avian hosts belonged to seven species: Ixodes ricinus (n = 448), I. frontalis (n = 31), I. festai (n = 2), I. arboricola (n = 36), I. lividus (n = 4), Haemaphysalis concinna (n = 382) and Dermacentor reticulatus (n = 2). Nymphs of I. ricinus occurred with a single activity peak around March-May, whereas its larvae typically infested birds in May, June or July. By contrast, H. concinna usually had its activity maximum during the summer (nymphs in June-July, larvae later in July-August). Interestingly, two ornithophilic species, I. frontalis and I. arboricola, were most active around winter months (between October and April). A significantly lower ratio of aquatic birds was found tick-infested than songbirds. Several new tick-host associations were revealed, including I. ricinus from Greylag Goose (Anser anser) and D. reticulatus from Great Egret (Ardea alba) and Sedge Warbler (Acrocephalus schoenobaenus). Ticks were collected for the first time in Europe from two species of predatory birds as well as from Little Bittern (Ixobrychus minutus). Bird species typically inhabiting reedbeds were most frequently infested with H. concinna, and most ticks localized at their throat, as opposed to forest-dwelling avian hosts, on which I. ricinus predominated and ticks were more evenly distributed. CONCLUSIONS: In the evaluated region, aquatic birds appear to be less important in tick dispersal than songbirds. However, newly revealed tick-host associations in this category attest to their hitherto neglected contribution. The results suggest that the habitat type will have significant impact not only on the species composition but also on the feeding location of ticks on birds.

Density and behavior of capybara (Hydrochoerus hydrochaeris) ticks (Acari: Ixodidae) Amblyomma sculptum and Amblyomma dubitatum with notes on Rickettsia bellii infection: Assessing human exposure risk.

In several urban and peri­urban areas of Brazil, populations of Amblyomma sculptum and Amblyomma dubitatum ticks are maintained by capybaras (Hydrochoerus hydrochaeris). In some of these areas, this host and these tick species are associated with Brazilian spotted fever (BSF), a lethal human disease caused by the bacterium Rickettsia rickettsii. In this work, we evaluated the risk of human exposure to these tick species using four collection techniques to discern host-seeking behavior. The study was carried out in 10 urban sites inhabited by capybaras in Uberlândia, a BSF-free municipality in southeastern Brazil. Ticks were collected in areas of 400 m2 at each site and at three seasons. Within the same municipality, the distance and speed of A. sculptum nymphs moving towards the CO2 traps were evaluated. In a sample of ticks Rickettsia DNA was investigated. During the study period, 52,953 ticks were collected. Among these, 83.4 % were A. sculptum (1,523 adults, 10,545 nymphs and 32,104 larvae) and 16.6 % were A. dubitatum (464 adults, 2,153 nymphs and 6,164 larvae). An average annual questing tick density of 4.4/m² was observed, with the highest density recorded at one site in autumn (31.8/m²) and the lowest in summer at another site (0.03/m²). The visual search yielded the highest proportion of A. sculptum larvae, constituting 47 % of the total and 63.6 % of all A. sculptum larvae. In contrast, CO2 traps collected a greater proportion of nymphs and adults of A. sculptum ticks. In the case of A. dubitatum, the CO2 trap was the most efficient technique with 57.7 % of captures of this species, especially of nymphs (94.5 % of captures) and adults (97.8 % of captures). Ticks' ambush height on vegetation (9 to 77 cm), observed by visual search 30 times, yielded a total of 20,771 ticks. Of these, 28 (93 %) were A. sculptum ticks, with only two (7 %) identified as A. dubitatum ticks. Among A. sculptum ticks, the nymph was the most attracted stage to humans and larva in the case of A. dubitatum. Amblyomma sculptum adults and nymphs were significantly more attracted to humans than those of A. dubitatum, but A. dubitatum larvae were significantly more attracted than the same stage of A. sculptum. The maximum distance and speed of horizontal displacement for A. sculptum nymphs were five meters and 2.0 m/h, respectively. The only species of Rickettsia detected in ticks, exclusively in A. dubitatum, was R. bellii. Importantly, it was observed that the higher the proportion of A. sculptum in the community of ticks, the lower the rate of infection of A. dubitatum by R. bellii. In conclusion, host-seeking behavior differed between the two tick species, as well as between stages of the same species. A greater restriction of A. dubitatum ticks to the soil was observed, while larvae and nymphs of A. sculptum dispersed higher in the vegetation. The behavior presented by A. sculptum provides greater opportunities for contact with the hosts, while A. dubitatum depends more on an active search for a host, the hunter behavior. Taken together, these observations show that a human being crossing an area infested with A. sculptum and A. dubitatum ticks will have almost exclusive contact with A. sculptum larvae and/or nymphs. Humans in a stationary position (sitting, lying or immobile) are exposed to both tick species, but they are more attractive to adults and mainly nymphs of A. sculptum compared to the corresponding stages of the tick A. dubitatum. The negative effect of A. sculptum on A. dubitatum infection by R. bellii deserves further studies.

Spatial distribution of Triatoma dimidiata peridomestic colonies modulated by distance between susceptible microhabitat patches.

Triatoma dimidiata is a vector of the hemoparasite Trypanosoma cruzi, the causal agent of Chagas disease. It settles reproductive colonies in the peridomicile of the premises. The peridomicile is comprised of a random set of artificial and natural features that overlap and assemble a network of microenvironmental suitable sites (patches) that interact with each other and favor the structure and proliferation of T. dimidiata colonies. The heterogeneity of patch characteristics hinders the understanding and identification of sites susceptible to colonization. In this study, a classification system using a random forest algorithm was used to identify peridomiciles susceptible to colonization to describe the spatial distribution of these sites and their relationship with the colonies of T. dimidiata in ten localities of Yucatan. From 1,000 peridomiciles reviewed, the classification showed that 13.9 % (139) of the patches were highly susceptible (HSP), and 86.1 % (861) were less susceptible (LSP). All localities had at least one HSP. The occupancy by patch type showed that the percentage of total occupancy and by colonies was higher in the HSP, while the occupancy by adult T. dimidiata without evidence of nymphs or exuviae (propagules) was higher in the LSP. A generalized additive model (GAM) revealed that the percentage of occupied patches increases as the abundance of individuals in the localities increases however, the percentage of occupied patches in LSP is lower than occupied in HSP. Distance analyses revealed that colonies and propagules were located significantly closer (approximately 200 m) to a colony in a HSP than any colony in a LSP. The distribution of T. dimidiata in the localities was defined by the distribution of patch type; as the occupancy in these patches increased, a network of peridomestic populations was configured, which may be promoted by a greater abundance of insects inside the localities. These results reveal that the spatial distribution of T. dimidiata individuals and colonies in the peridomicile at the locality scale corresponds to a metapopulation pattern within the localities through a system of patches mediated by distance and level of the vectors' occupancy.

Sensory pathway in aquatic basal polyneoptera: Antennal sensilla and brain morphology in stoneflies.

Aquatic insects represent a great portion of Arthropod diversity and the major fauna in inland waters. The sensory biology and neuroanatomy of these insects are, however, poorly investigated. This research aims to describe the antennal sensilla of nymphs of the stonefly Dinocras cephalotes using scanning electron microscopy and comparing them with the adult sensilla. Besides, central antennal pathways in nymphs and adults are investigated by neuron mass-tracing with tetramethylrhodamine, and their brain structures are visualized with an anti-synapsin antibody. No dramatic changes occur in the antennal sensilla during nymphal development, while antennal sensilla profoundly change from nymphs to adults when switching from an aquatic to an aerial lifestyle. However, similar brain structures are used in nymphs and adults to process diverging sensory information, perceived through different sensilla in water and air. These data provide valuable insights into the evolution of aquatic heterometabolous insects, maintaining a functional sensory system throughout development, including a distinct adaptation of the peripheral olfactory systems during the transition from detection of water-soluble chemicals to volatile compounds in the air. From a conservation biology perspective, the present data contribute to a better knowledge of the biology of stoneflies, which are very important bioindicators in rivers.

Dynamics of cuticle-associated transcript profiles during moulting of the bed bug Cimexlectularius.

The bed bug Cimex lectularius is a worldwide human pest. The sequenced genome allows molecular analyses of all aspects of bed bug biology. The present work was conducted to contribute to bed bug cuticle biology. As in other insect species, the C. lectularius cuticle consists of the three horizontal layers procuticle, epicuticle and envelope. To analyse the genes needed for the establishment of the stratified cuticle, we studied the expression pattern of 42 key cuticle-related genes at the transition of the penultimate nymphal stage to adult animals when a new cuticle is formed. Based on gene expression dynamics, in simplified model, we distinguish two key events during cuticle renewal in C. lectularius. First, upon blood feeding, modulation of ecdysone signalling culminates in the transcriptional activation of the transcription factor Clec-Ftz-F1 that possibly controls the expression of 32 of the 42 genes tested. Second, timed expression of Clec-Ftz-F1 seems to depend also on the insulin signalling pathway as RNA interference against transcripts of the insulin receptor delays Clec-Ftz-F1 expression and stage transition. An important observation of our transcript survey is that genes needed for the construction of the three cuticle layers are largely expressed simultaneously. Based on these data, we hypothesise a considerable synchronous mechanism of layer formation rather than a strictly sequential one. Together, this work provides a basis for functional analyses of cuticle formation in C. lectularius.

The inappropriate application of imidacloprid destroys the ability of predatory natural enemies to control pests in the food chain: A case study of the feeding behavior of Orius similis on Frankliniella occidentalis.

Insecticides are an indispensable and important tool for agricultural production. However, the inappropriate application of insecticides can cause damage to the food chain and ecosystem. Orius similis is an important predatory and natural enemy of Frankliniella occidentalis. Imidacloprid is widely used to control pests, but will inevitably exert adverse effects on O. similis. In order to determine the effect of different imidacloprid treatments on the ability of O. similis to prey on the 2nd-instar nymphs of F. occidentalis, we determined the toxicity and predation of imidacloprid on different stages of O. similis under contact and ingestion treatments. In addition, we used the Holling disc equation to evaluate the ability of O. similis to search and exhibit predatory activity following contact and ingestion treatments. Analysis showed that the highest LC10 and LC20 values for imidacloprid contact and ingestion toxicity treatment were 17.06 mg/L and 23.74 mg/L, respectively. Both imidacloprid treatments led toa reduction in the predatory of O. similis on prey. The functional responses of the 3rd to 5th instar nymphs, along with female and male O. similis adults to the 2nd-instar nymphs of F. occidentalis were consistent with the Holling type II response following contact and ingestion with imidacloprid. However, following imidacloprid treatment, the handing time (Th) of O. similis with single F. occidentalis was prolonged and the instantaneous attack rate (a) was reduced after imidacloprid treatment. The predatory capacity (a/Th) of female O. similis adults when treated with the LC10 concentration of imidacloprid by ingestion was 52.85; this was lower than that of the LC10 concentration of imidacloprid in the contact treatment (57.67). The extent of predation of O. similis on the 2nd-instar nymphs of F. occidentalis was positively correlated with prey density, although the search effect was negatively correlated with prey density. The most extensive search effect was exhibited by adult O. similis females. Simulations with the Hessell-Varley interference model showed that an increase in the number of O. similis would reduce search efficiency regardless of whether they were treated with imidacloprid or not. Thus, O. similis, especially female adults, exhibited strong potential for controlling the 2nd-instar nymphs of F. occidentalis. The toxicity of ingestion following treatment with the same concentration of imidacloprid in O. similis was greater than that of contact treatment. When using O. similis to control F. occidentalis in the field, we should increase the number of female adults released, and prolong the interval between imidacloprid treatment and O. similis exposure. This strategy will improve the control ability of O. similis, coordinate both chemical and biological control, reduce the impact of pesticides on the environment, and improve the efficiency of agricultural production.

Variation in Avian Predation Pressure as a Driver for the Diversification of Periodical Cicada Broods.

AbstractPeriodical cicadas live 13 or 17 years underground as nymphs, then emerge in synchrony as adults to reproduce. Developmentally synchronized populations called broods rarely coexist, with one dominant brood locally excluding those that emerge in off years. Twelve modern 17-year cicada broods are believed to have descended from only three ancestral broods following the last glaciation. The mechanisms by which these daughter broods overcame exclusion by the ancestral brood to synchronously emerge in a different year, however, are elusive. Here, we demonstrate that temporal variation in the population density of generalist predators can allow intermittent opportunities for new broods to invade, even though a single brood remains dominant most of the time. We show that this mechanism is consistent, in terms of the type and frequency of brood replacements, with the distribution of periodical cicada broods throughout North America today. Although we investigate one particularly charismatic case study, the mechanisms involved (competitive exclusion, Allee effects, trait variation, predation, and temporal variability) are ubiquitous and could contribute to patterns of species diversity in a range of systems.

Life history data of a Triatoma protracta nahuatlae, T. sinaloensis, and their laboratory hybrids (Hemiptera: Reduviidae).

Chagas disease is one of the most significant vector-borne diseases in Mexico. The presence of "sylvatic" triatomine vectors of Trypanosoma cruzi (Chagas) inside human dwellings necessitates estimating their vectorial capacity. To estimate this capacity in Triatoma protracta nahuatlae (Ryckman), Triatoma sinaloensis (Ryckman), and their laboratory hybrids, 6 biological parameters were examined. Triatoma sinaloensis exhibited the shortest development time (155 days), with a median of 12 blood meals. Mortality rates varied from 35% to 45% in the 3 studied cohorts. All 3 cohorts were aggressive, initiating feeding within 0.5-1 min, and had similar feeding periods ranging from 10 to 18 min. A majority (75.3-97.9%) of the hybrids defecated when feeding, immediately after feeding, or in less than 1 min post-feeding. In contrast, only 7-42% of nymphs of T. sinaloensis defecated during the same period. Our results regarding the 6 parameters studied confirm the potential role of T. p. nahuatlae as an efficient vector of T. cruzi. Triatoma sinaloensis, on the other hand, exhibited limited vectorial capacity primarily due to its poor defecation behavior. Continued surveillance of these "sylvatic" triatomine populations is necessary to prevent an epidemiological problem.

The great gerbil (Rhombomys opimus) as a host for tick species in Gurbantunggut Desert.

BACKGROUND: Rodents play an important role in the life cycle of ixodid and argasid ticks, particularly as hosts of larvae and nymphs. The great gerbil (Rhombomys opimus), the preferred prey item of several carnivores (e.g. the red fox and marbled polecat), is the dominant rodent species in the Gurbantunggut Desert in northwestern China. The aim of this study was to investigate tick species associated with different hosts in the habitat of great gerbils, including wildlife and livestock. METHODS: During 2018-2023, ticks were removed from 326 great gerbils, two red foxes (Vulpes vulpes), three marbled polecats (Vormela peregusna), 35 pastured sheep (Ovis aries), and one long-eared desert hedgehog (Hemiechinus auritus) in the Gurbantunggut Desert. Ticks were identified according to standard morphological keys. Then, they were further analyzed by molecular and phylogenic methods based on two mitochondrial markers, 16S rDNA and cytochrome c oxidase subunit I (COI) genes. RESULTS: A total of 889 ticks were collected, representing five species. These included Hyalomma asiaticum (n = 425: 24 larvae, 79 nymphs and 322 adults), Rhipicephalus turanicus (n = 153: 2 nymphs and 151 adults), Haemaphysalis erinacei (n = 298: 4 larvae, 7 nymphs and 287 adults), Ixodes acuminatus (n = 7: 4 nymphs and 3 adults) and Ornithodoros tartakovskyi (6 adults). Based on COI sequences, molecular and phylogenetic analyses showed that (i) I. acuminatus from great gerbils and marbled polecats clustered with I. acuminatus reported from Europe; (ii) O. tartakovskyi found in northwestern China belonged to an independent clade; (iii) Hy. asiaticum, R. turanicus and Ha. erinacei had 100% sequence identities to conspecific ticks sampled previously in China. CONCLUSIONS: The great gerbil is an important host for the developmental stages of I. acuminatus, O. tartakovskyi, Ha. erinacei, Hy. asiaticum and R. turanicus, thus supporting the life cycle of several tick species which, as adults, parasitize predators (red fox and marble polecat) as well as pastured sheep and hedgehogs in the Gurbantunggut Desert. Ixodes acuminatus and O. tartakovskyi were found for the first time on great gerbil and marbled polecat, respectively.