Juvenile hormones (JHs) are sesquiterpenoids synthesized by the corpora allata (CA). They play critical roles during insect development and reproduction. The first JH was described in 1934 as a "metamorphosis inhibitory hormone" in Rhodnius prolixus by Sir Vincent B. Wigglesworth. Remarkably, in spite of the importance of R. prolixus as vectors of Chagas disease and model organisms in insect physiology, the original JH that Wigglesworth described for the kissing-bug R. prolixus remained unidentified. We employed liquid chromatography mass spectrometry to search for the JH homologs present in the hemolymph of fourth instar nymphs of R. prolixus. Wigglesworth's original JH is the JH III skipped bisepoxide (JHSB3), a homolog identified in other heteropteran species. Changes in the titer of JHSB3 were studied during the 10-day long molting cycle of 4th instar nymph, between a blood meal and the ecdysis to 5th instar. In addition we measured the changes of mRNA levels in the CA for the 13 enzymes of the JH biosynthetic pathway during the molting cycle of 4th instar. Almost 90 years after the first descriptions of the role of JH in insects, this study finally reveals that the specific JH homolog responsible for Wigglesworth's original observations is JHSB3.
- MeSH
- biologická proměna * MeSH
- corpora allata chemie MeSH
- epoxidové sloučeniny chemie MeSH
- hemolymfa chemie MeSH
- kukla chemie fyziologie MeSH
- nymfa chemie fyziologie MeSH
- Rhodnius chemie fyziologie MeSH
- seskviterpeny chemie MeSH
- shazování tělního pokryvu fyziologie MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
The Channel Islands are British Crown dependencies located in the English Channel to the west of the Normandy coast in northern France. Whilst there have been studies investigating tick occurrence and distribution in different habitats on the mainland of the UK and in France, the Channel Islands have been relatively understudied. As such, little is known about whether the sheep tick, Ixodes ricinus, is present, and whether there is a potential risk of Lyme borreliosis on the Channel Islands. To ascertain the presence of I. ricinus on the three largest islands in the archipelago: Jersey, Guernsey and Alderney, surveys of ticks questing in the vegetation and ticks feeding on hosts were undertaken during April and May 2016. Across all three islands, the highest numbers of ticks were found in woodland habitats. Ixodes ricinus was the predominant questing tick species found on Jersey, and Ixodes ventalloi the most common questing tick species on Alderney and Guernsey, with little or no evidence of questing I. ricinus on either island. During field studies on small mammals, I. ricinus was the predominant tick species feeding on Jersey bank voles (Myodes glareolus caesarius), with Ixodes hexagonus the most common species infesting hedgehogs on Guernsey. We propose that the greater diversity of small mammals on Jersey may be important in supporting immature stages of I. ricinus, in contrast to Guernsey and Alderney. Morphological identification of tick species was confirmed by PCR sequencing based on amplification of the cytochrome c oxidase subunit one (cox1) gene (COI DNA barcoding). To date, there have been few records of human tick bites in the Channel Islands, suggesting that the current risk from tick-borne disease may be low, but continued reporting of any human tick bites, along with reporting of cases of Lyme borreliosis will be important for continued assessment of the impact of tick-borne diseases in the Channel Islands.
- MeSH
- ekosystém MeSH
- klíště růst a vývoj fyziologie MeSH
- larva růst a vývoj fyziologie MeSH
- lidé MeSH
- nymfa růst a vývoj fyziologie MeSH
- rozšíření zvířat * MeSH
- veřejné zdravotnictví * MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Normanské ostrovy MeSH
Many temperate insects encounter temperatures low enough to freeze their body fluids. Remarkably, some insects are freeze-tolerant, surviving this internal ice formation. However, the mechanisms underlying freeze tolerance are not well-understood, in part due to a lack of tractable model organisms. We describe a novel laboratory model to study insect freeze tolerance, the spring field cricket Gryllus veletis (Orthopera: Gryllidae). Following acclimation to six weeks of decreasing temperature and photoperiod, G. veletis become freeze-tolerant, similar to those exposed to natural autumn conditions in London, Ontario, Canada. Acclimated crickets suppress their metabolic rate by c. 33%, and survive freezing for up to one week at -8 °C, and to temperatures as low as -12 °C. Freeze-tolerant G. veletis protect fat body cells from freeze injury in vivo, and fat body tissue from freeze-tolerant cricket survives brief freeze treatments when frozen ex vivo. Freeze-tolerant crickets freeze at c. -6 °C, which may be initiated by accumulation of ice-nucleating agents in hemolymph or gut tissue. Although we hypothesize that control of ice formation facilitates freeze tolerance, initiating ice formation at high subzero temperatures does not confer freeze tolerance on freeze-intolerant nymphs. Acclimation increases hemolymph osmolality from c. 400 to c. 650 mOsm, which may facilitate freeze tolerance by reducing ice content. Hemolymph ion concentrations do not change with acclimation, and we therefore predict that freeze-tolerant G. veletis elevate hemolymph osmolality by accumulating other molecules. Gryllus veletis is easily reared and manipulated in a controlled laboratory environment, and is therefore a suitable candidate for further investigating the mechanisms underlying freeze tolerance.
- MeSH
- aklimatizace * MeSH
- Gryllidae růst a vývoj fyziologie MeSH
- homeostáza MeSH
- nízká teplota * MeSH
- nymfa růst a vývoj fyziologie MeSH
- roční období MeSH
- zmrazování * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Ontario MeSH
BACKGROUND: Bed bugs (Heteroptera: Cimicidae) are a group of blood-feeding ectoparasites. They mainly specialize on bats and birds, but a few species are important human pests. They exhibit several unique adaptations for their parasitic lifestyle. Among those, bed bug aggregations represent a striking example of a sub-social structure. However, their benefits for the bed bugs as well as their potential for bed bug control are largely unexplored. Young nymphs are known to disperse from the aggregations much less than older ones or adults. We therefore found possible that the aggregation age structure is connected with success in finding host and tested the effect of presence of adults on nymphal feeding success. RESULTS: We tested the effect of presence of adults on feeding success of first-instar nymphs using an artificial feeding system. We found that presence of fed adults causes larger proportion of nymphs to feed. CONCLUSIONS: Based on our data, fed bed bugs seem to trigger the young nymphs to actively forage. Since the first instar is much less viable than later stages, our finding points to an adaptive behavior that economizes on foraging energy cost. In the context of bed bug control, knowledge on such behavior emphasizes the prevention of fed bed bugs from returning to harborages. Bed bug traps may thus be used not just as means of bed bug monitoring, but also as means of control.
- MeSH
- nymfa fyziologie MeSH
- štěnice fyziologie MeSH
- stravovací zvyklosti * MeSH
- věkové faktory MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Freeze tolerance, the ability to survive internal ice formation, facilitates survival of some insects in cold habitats. Low-molecular-weight cryoprotectants such as sugars, polyols and amino acids are hypothesized to facilitate freeze tolerance, but their in vivo function is poorly understood. Here, we use a combination of metabolomics and manipulative experiments in vivo and ex vivo to examine the function of multiple cryoprotectants in the spring field cricket Gryllus veletis. Cold-acclimated G. veletis are freeze-tolerant and accumulate myo-inositol, proline and trehalose in their haemolymph and fat body. Injecting freeze-tolerant crickets with proline and trehalose increases survival of freezing to lower temperatures or for longer times. Similarly, exogenous myo-inositol and trehalose increase ex vivo freezing survival of fat body cells from freeze-tolerant crickets. No cryoprotectant (alone or in combination) is sufficient to confer freeze tolerance on non-acclimated, freeze-intolerant G. veletis. Given that each cryoprotectant differentially impacts survival in the frozen state, we conclude that small cryoprotectants are not interchangeable and likely function non-colligatively in insect freeze tolerance. Our study is the first to experimentally demonstrate the importance of non-colligative cryoprotectant function for insect freeze tolerance both in vivo and ex vivo, with implications for choosing new molecules for cryopreservation.
- MeSH
- aklimatizace * MeSH
- dlouhověkost MeSH
- Gryllidae růst a vývoj fyziologie MeSH
- hemolymfa fyziologie MeSH
- kryoprotektivní látky metabolismus MeSH
- metabolomika MeSH
- nízká teplota * MeSH
- nymfa růst a vývoj fyziologie MeSH
- prolin metabolismus MeSH
- trehalosa metabolismus MeSH
- tukové těleso fyziologie MeSH
- zmrazování MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
An indoor terrarium population of Amblyomma geoemydae was established subsequent to the import of a single yellow-marginated box turtle Cuora flavomarginata. This indoor tick population revealed an unexpected resistance against de-ticking trials, with persistence between 2010 and 2015, when the ticks were successfully eliminated. Ticks were collected from the bodies and shells of turtles, as well as from terraria soil. Species diagnosis of ticks was carried out according to distinguishable morphological characters and supported by molecular analysis using DNA-barcoding. Introduced exotic ticks are potential vectors of pathogens and can have an impact on wildlife, domestic animals and the human population. This case emphasizes the need for sharp surveillance and control measures on imported reptiles.
- MeSH
- infestace klíšťaty parazitologie prevence a kontrola veterinární MeSH
- Ixodidae klasifikace genetika růst a vývoj fyziologie MeSH
- larva klasifikace genetika růst a vývoj fyziologie MeSH
- nymfa klasifikace genetika růst a vývoj fyziologie MeSH
- roční období MeSH
- taxonomické DNA čárové kódování veterinární MeSH
- zavlečené druhy MeSH
- želvy * MeSH
- zvířata v ZOO MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Rakousko MeSH
Overwintering insects are categorized either as freeze tolerant or freeze avoiding (supercooling) based on their ability or inability, respectively, to tolerate the formation of ice in their body. The freeze tolerant insects set their supercooling point (SCP) higher for winter to stimulate freezing at higher temperatures, while freeze avoiding insects survive winter in a supercooled state by depressing their SCP. Some supercooling insects, however, were found to survive in frozen state when freezing occurred through inoculation by external ice at mild subzero temperatures. Here, we assessed the potential relevance of inoculative freezing and freeze tolerance strategy in an insect that was so far considered as a classical example of a 'supercooler', the linden bug (Pyrrhocoris apterus). Microclimatic conditions of the overwintering microhabitat of P. apterus (leaf litter layer with buffered temperature fluctuations, mild sub-zero extremes, high humidity, and presence of ice) present a potentially high risk of inoculative freezing. We found that P. apterus is highly susceptible to inoculation by external ice. The temperature at which inoculative freezing occurred (above -3°C) was much higher compared to SCP (-16 °C to -20 °C in winter). The insects were inoculated through body openings and across cuticle and were able to survive after freezing. There was, however, a distinct critical ice fraction, corresponding to 38.7-42.8% of total body water, beyond which survival rapidly decreased to zero. We found that P. apterus adaptively reduces the actual ice fraction below critical ice fraction for winter season. Since many insect species overwinter in habitats similar to that of P. apterus, the ability to tolerate freezing after inoculation by external ice crystals could be much more common among 'supercooling' insects than it is currently appreciated.
Alienoptera is an insect order recently described from mid-Cretaceous amber [1] and is phylogenetically nested in the Dictyoptera lineage. Alienoptera currently comprises three species: Alienopterus brachyelytrus[1], Alienopterella stigmatica[2] and Caputoraptor elegans[3]. The most interesting is Caputoraptor elegans, which was recently described in Current Biology by Bai and colleagues [3] and which has an unusual cephalo-thoracic device formed by wing-like extensions of the genae and the corresponding edges of the pronotum. Bai and colleagues [3] suggested that the cephalo-thoracic apparatus may have been used to hold the female and male together during copulation. According to this possible function, the cephalo-thoracic apparatus of the female would fit together with the spread forewings of the male while the female was on the back of the male during copulation. This function was proposed based on examination of females and nymphs, and the authors stated that it could be falsified if a male with a similar apparatus were discovered. After examining a male nymph of this species (Figure 1), I here suggest that the cephalo-thoracic apparatus was not used for copulation but was instead used for predation and feeding.
- MeSH
- fylogeneze MeSH
- jantar MeSH
- nymfa anatomie a histologie růst a vývoj fyziologie MeSH
- predátorské chování * MeSH
- švábi anatomie a histologie růst a vývoj fyziologie MeSH
- zkameněliny anatomie a histologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- dopisy MeSH
- práce podpořená grantem MeSH
Insecticides usually present in low concentrations in streams are known to impair behaviour and development of non-target freshwater invertebrates. Moreover, there is growing awareness that the presence of natural stressors, such as predation risk may magnify the negative effects of pesticides. This is because perception of predation risk can by itself lead to changes on behaviour and physiology of prey species. To evaluate the potential combined effects of both stressors on freshwater detritivores we studied the behavioural and developmental responses of Chironomus riparius to chlorantraniliprole (CAP) exposure under predation risk. Also, we tested whether the presence of a shredder species would alter collector responses under stress. Trials were conducted using a simplified trophic chain: Alnus glutinosa leaves as food resource, the shredder Sericostoma vittatum and the collector C. riparius. CAP toxicity was thus tested under two conditions, presence/absence of the dragonfly predator Cordulegaster boltonii. CAP exposure decreased leaf decomposition. Despite the lack of significance for interactive effects, predation risk marginally modified shredder effect on leaf decomposition, decreasing this ecosystem process. Shredders presence increased leaf decomposition, but impaired chironomids performance, suggesting interspecific competition rather than facilitation. C. riparius growth rate was decreased independently by CAP exposure, presence of predator and shredder species. A marginal interaction between CAP and predation risk was observed regarding chironomids development. To better understand the effects of chemical pollution to natural freshwater populations, natural stressors and species interactions must be taken into consideration, since both vertical and horizontal species interactions play their role on response to stress.
- MeSH
- Chironomidae účinky léků růst a vývoj fyziologie MeSH
- hmyz účinky léků růst a vývoj fyziologie MeSH
- insekticidy toxicita MeSH
- larva účinky léků růst a vývoj fyziologie MeSH
- listy rostlin MeSH
- nymfa účinky léků růst a vývoj fyziologie MeSH
- olše MeSH
- ortoaminobenzoáty toxicita MeSH
- potravní řetězec * MeSH
- predátorské chování * MeSH
- stravovací zvyklosti účinky léků MeSH
- vážky růst a vývoj fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Vector-borne pathogens establish systemic infections in host tissues to maximize transmission to arthropod vectors. Co-feeding transmission occurs when the pathogen is transferred between infected and naive vectors that feed in close spatiotemporal proximity on a host that has not yet developed a systemic infection. Borrelia afzelii is a tick-borne spirochete bacterium that causes Lyme borreliosis (LB) and is capable of co-feeding transmission. Whether ticks that acquire LB pathogens via co-feeding are actually infectious to vertebrate hosts has never been tested. We created nymphs that had been experimentally infected as larvae with B. afzelii via co-feeding or systemic transmission, and compared their performance over one complete LB life cycle. Co-feeding nymphs had a spirochete load that was 26 times lower than systemic nymphs but both nymphs were highly infectious to mice (i.e., probability of nymph-to-host transmission of B. afzelii was ~100%). The mode of transmission had no effect on the other infection phenotypes of the LB life cycle. Ticks that acquire B. afzelii via co-feeding transmission are highly infectious to rodents, and the resulting rodent infection is highly infectious to larval ticks. This is the first study to show that B. afzelii can use co-feeding transmission to complete its life cycle.
- MeSH
- arachnida jako vektory mikrobiologie fyziologie MeSH
- klíšťata mikrobiologie fyziologie MeSH
- krmivo pro zvířata mikrobiologie MeSH
- lymeská nemoc mikrobiologie přenos MeSH
- myši MeSH
- nymfa mikrobiologie fyziologie MeSH
- stadia vývoje MeSH
- zdroje nemoci mikrobiologie MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
