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 late 5th instar caterpillar of the cecropia silk moth (Hyalophora cecropia) spins a silken cocoon with a distinct, multilayered architecture. The cocoon construction program, first described by the seminal work of Van der Kloot and Williams, consists of a highly ordered sequence of events. We perform behavioral experiments to re-evaluate the original cecropia work, which hypothesized that the length of silk that passes through the spinneret controls the orderly execution of each of the discrete events of cocoon spinning. We confirm and extend by three-dimensional scanning and quantitative measurements of silk weights that if cocoon construction is interrupted, upon re-spinning, the caterpillar continues the cocoon program from where it left off. We also confirm and extend by quantitative measurements of silk weights that cecropia caterpillars will not bypass any of the sections of the cocoon during the construction process, even if presented with a pre-spun section of a cocoon spun by another caterpillar. Blocking silk output inhibits caterpillars from performing normal spinning behaviors used for cocoon construction. Surprisingly, unblocking silk output 24-hr later did not restart the cocoon construction program, suggesting the involvement of a temporally-defined interval timer. We confirm with surgical reductions of the silk glands that it is the length of silk itself that matters, rather than the total amount of silk extracted by individuals. We used scanning electron microscopy to directly show that either mono- or dual-filament silk (i.e., equal silk lengths but which vary in their total amount of silk extracted) can be used to construct equivalent cocoons of normal size and that contain the relevant layers. We propose that our findings, taken together with the results of prior studies, strongly support the hypothesis that the caterpillar uses a silk "odometer" to measure the length of silk extracted during cocoon construction but does so in a temporally regulated manner. We further postulate that our examination of the anatomy of the silk spinning apparatus and ablating spinneret sensory output provides evidence that silk length measurement occurs upstream of output from the spinneret.
- MeSH
- biobehaviorální přístup MeSH
- biologická proměna fyziologie MeSH
- bourec anatomie a histologie fyziologie MeSH
- chování zvířat fyziologie MeSH
- čití, cítění fyziologie MeSH
- hedvábí analýza chemie metabolismus MeSH
- kukla fyziologie MeSH
- Manduca anatomie a histologie fyziologie MeSH
- mikroskopie elektronová rastrovací MeSH
- senzorická zpětná vazba fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
An animal's fitness strongly depends on successful feeding, avoidance of predators and reproduction. All of these behaviours commonly involve chemosensation. As a consequence, when species' ecological niches and life histories differ, their chemosensory abilities need to be adapted accordingly. The intertidal insect Clunio marinus (Diptera: Chironomidae) has tuned its olfactory system to two highly divergent niches. The long-lived larvae forage in a marine environment. During the few hours of terrestrial adult life, males have to find the female pupae floating on the water surface, free the cryptic females from their pupal skin, copulate and carry the females to the oviposition sites. In order to explore the possibility for divergent olfactory adaptations within the same species, we investigated the chemosensory system of C. marinus larvae, adult males and adult females at the morphological and molecular level. The larvae have a well-developed olfactory system, but olfactory gene expression only partially overlaps with that of adults, likely reflecting their marine vs. terrestrial lifestyles. The olfactory system of the short-lived adults is simple, displaying no glomeruli in the antennal lobes. There is strong sexual dimorphism, the female olfactory system being particularly reduced in terms of number of antennal annuli and sensilla, olfactory brain centre size and gene expression. We found hints for a pheromone detection system in males, including large trichoid sensilla and expression of specific olfactory receptors and odorant binding proteins. Taken together, this makes C. marinus an excellent model to study within-species evolution and adaptation of chemosensory systems.
- MeSH
- biologická adaptace fyziologie MeSH
- bulbus olfactorius metabolismus fyziologie MeSH
- Chironomidae metabolismus fyziologie MeSH
- čich fyziologie MeSH
- čichové buňky metabolismus MeSH
- hmyz metabolismus fyziologie MeSH
- hmyzí proteiny metabolismus MeSH
- kladení vajíček fyziologie MeSH
- kukla metabolismus fyziologie MeSH
- larva metabolismus MeSH
- pohlavní dimorfismus * MeSH
- receptory pachové metabolismus MeSH
- sensilla metabolismus fyziologie MeSH
- vodní organismy metabolismus fyziologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Analysis of sublethal responses in cold-stressed insects can provide important information about fitness costs and a better understanding of the physiological mechanisms used to prevent and/or to cope with cold injury. Yet, such responses are understudied and often neglected in the literature. Here, we analyzed the effects of cold stress applied to larvae on the mortality/survival and fitness parameters of survivor adults of the vinegar fly, Drosophila melanogaster. Third instar larvae (either cold-sensitive or cold-acclimated) were exposed to either supercooling or freezing stress, both at -5 °C. A whole array of sublethal effects were observed, from mortality that occurs with some delay after cold stress, through delayed development to the pupal stage, to shortened life-span of the adult, and decreased female fecundity. Taking the sublethal effects into account improves the ecological meaningfulness of cold hardiness assay outcomes. For instance, we observed that although more than 80% of cold-acclimated larvae survive freezing to -5 °C, less than 10% survive until adulthood, and survivor females exhibit more than 50% reduction in their fecundity relative to controls. Female fecundity was positively correlated with dry mass and negatively correlated with total protein and glycogen stores. Hence, these parameters may serve as good predictors of survivor adult female fecundity. Further, we provide the concept of a two-component defense system, which (based on analysis of sublethal effects on fitness parameters) distinguishes between physiological mechanisms that help insects to resist (reduce or avoid) or tolerate (survive or repair) injuries linked to cold stress.
Diapause is a deep resting stage facilitating temporal avoidance of unfavourable environmental conditions, and is used by many insects to adapt their life cycle to seasonal variation. Although considerable work has been invested in trying to understand each of the major diapause stages (induction, maintenance and termination), we know very little about the transitions between stages, especially diapause termination. Understanding diapause termination is crucial for modelling and predicting spring emergence and winter physiology of insects, including many pest insects. In order to gain these insights, we investigated metabolome dynamics across diapause development in pupae of the butterfly Pieris napi, which exhibits adaptive latitudinal variation in the length of endogenous diapause that is uniquely well characterized. By employing a time-series experiment, we show that the whole-body metabolome is highly dynamic throughout diapause and differs between pupae kept at a diapause-terminating (low) temperature and those kept at a diapause-maintaining (high) temperature. We show major physiological transitions through diapause, separate temperature-dependent from temperature-independent processes and identify significant patterns of metabolite accumulation and degradation. Together, the data show that although the general diapause phenotype (suppressed metabolism, increased cold tolerance) is established in a temperature-independent fashion, diapause termination is temperature dependent and requires a cold signal. This revealed several metabolites that are only accumulated under diapause-terminating conditions and degraded in a temperature-unrelated fashion during diapause termination. In conclusion, our findings indicate that some metabolites, in addition to functioning as cryoprotectants, for example, are candidates for having regulatory roles as metabolic clocks or time-keepers during diapause.
- MeSH
- diapauza hmyzu fyziologie MeSH
- kukla růst a vývoj fyziologie MeSH
- larva růst a vývoj fyziologie MeSH
- metabolom * MeSH
- motýli růst a vývoj fyziologie MeSH
- nízká teplota * MeSH
- roční období MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Glyphosate is an herbicide that is used worldwide with potential environmental risks to nontarget organisms. We applied an age-stage, two-sex life table approach to assess the sublethal effects of short-term oral exposure to a glyphosate-based herbicide on the life table parameters and biocontrol potential of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). Aphids (Metopolophium dirhodum (Walker) (Sternorrhyncha: Aphididae)) treated with herbicide (an isopropylamine-salt of glyphosate) at low recommended, maximum recommended, and double the maximum recommended concentration for agricultural situations, and untreated controls were offered to the fourth instar of H. axyridis for 24 h. Development, consumption, and fecundity were measured daily until death. We detected minor differences in the hatching rate and mean generation time, whereas the longevity, fecundity, net reproductive rate, intrinsic rate of increase, finite rate of increase, and consumption were unaffected across treatments. We conclude that biocontrol potential of H. axyridis was not affected by acute oral intoxication by a glyphosate-based herbicide during the larval stage for 24 h under the study design.
- MeSH
- biologická kontrola škůdců MeSH
- brouci účinky léků růst a vývoj fyziologie MeSH
- glycin analogy a deriváty toxicita MeSH
- insekticidy toxicita MeSH
- kukla účinky léků růst a vývoj fyziologie MeSH
- larva účinky léků růst a vývoj fyziologie MeSH
- mšice chemie růst a vývoj MeSH
- nymfa chemie růst a vývoj MeSH
- potravní řetězec * MeSH
- predátorské chování účinky léků MeSH
- zvířata MeSH
- zvláštnosti životní historie * MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Spodoptera litura (F.), one of the most devastating pests in many Asian countries, is normally controlled by relying on chemical insecticides. To encourage an integrated pest management approach, we determined the economic injury level (EIL) for S. litura on peanut, Arachis hypogaea L., by larval infestation with late instars at different crop growth stages. The cumulative consumption rate of the fifth- and sixth-instars was used as the relative unit for the "Spodoptera injury equivalent" (SIE). The yield of marketable pods significantly decreased from 6.19 to 1.63 g.plant-1 as larval infestation intensity increased throughout the entire cropping season. When supplemented with timely applications of the insecticide, indoxacarb, an oxadiazine insecticide, the EIL values obtained in the larval infestation trial ranged from 3.26 to 13.47 SIE per 20 plants depending on the timing of initial infestation. The economic threshold (ET) for late instars, i.e., multiplying the EIL by 0.75, could not be utilized as a control timing index for the outbreak of injurious larvae population because of the time-lag. When the occurrence of natural mortality in the egg to pupal stage was considered, the ETs were adjusted to reflect the average survivorship. ETs of 27.3, 55.9, 51.3, and 112.6 eggs.m-2 were recommended at the early vegetative growth, blooming/pegging, pod-setting, and pod-filling stages, respectively, for initiating control measures. By simulating the pest population with the program, Timing-MSChart, we integrated the stage-specific EILs and ETs with the life-table data of S. litura on peanut and then proposed a demography-based control timing.
- MeSH
- Arachis * růst a vývoj MeSH
- býložravci * MeSH
- dezinsekce metody MeSH
- insekticidy MeSH
- kukla růst a vývoj fyziologie MeSH
- larva růst a vývoj fyziologie MeSH
- oxaziny MeSH
- populační dynamika MeSH
- Spodoptera růst a vývoj fyziologie MeSH
- tabulky života MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The last instar larva and pupa of Eucoeliodes mirabilis (A. Villa & G. B. Villa, 1835) (Curculionidae: Ceutorhynchini) are described using drawings and SEM images and are compared and keyed with already described larvae of 58 other ceutorhynchinae taxa. The larval body has an effective combination of morphological adaptations that assist a unique biological defensive strategy. All larval stages of E. mirabilis feed ectophytically on leaves of Euonymus europaeus L. (Celastraceae), and the larval body is covered with a thick faecal shield. The fixation of this protective shield on the larval back is performed by a peculiar dorsal microsculpture composed of a dense carpet of microtrichia on the thorax and abdomen, which serves effectively as a velcro system. Because of this strategy, macrosetae on the larval and pupal body of E. mirabilis are completely reduced. Larvae of E. mirabilis also have distinct morphological adaptations for protecting the spiracles against intrusion of faeces and avoiding occlusion of the tracheal system: a) microtrichia around spiracles are slightly shorter, distinctly stronger and are arranged with high-density and in clusters and b) spiracles are protected by an external safety valve. This strategy of E. mirabilis larvae is unique, although somewhat similar to that of Criocerinae and Blepharida-group leave beetles (Galerucinae) (both Coleoptera: Chrysomelidae), but with distinctly different morphological adaptations.
- MeSH
- Celastraceae parazitologie MeSH
- feces MeSH
- fyziologická adaptace * MeSH
- kukla anatomie a histologie fyziologie ultrastruktura MeSH
- larva anatomie a histologie fyziologie ultrastruktura MeSH
- listy rostlin parazitologie MeSH
- nosatcovití anatomie a histologie fyziologie ultrastruktura MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
The heartbeat of diapausing pupae of the flesh fly Sarcophaga crassipalpis was investigated using electrocardiographic methods including gravimetry, thermography, and optocardiography. During deep diapause, characterized by minimum metabolic activity, the heart exhibited discontinuous bouts of exclusively unidirectional, anterograde pulsations (40-60 contractions/min) that lasted only a few seconds. These bouts of cardiac pulsations were separated by periods of rest lasting 5-30 min. During infradian peaks of metabolic activity (4-day cycles) that occur throughout diapause, periods of rest were shortened and frequency of the anterograde heartbeat increased more than two-fold. Throughout diapause, the heart consistently exhibited a simple, bi-phasic pattern of pulsations generated by bouts of anterograde heartbeats interspersed with periods of cardiac rest. When the fly broke diapause and initiated pharate adult development, a new tri-phasic pattern was observed: the new pattern incorporated heartbeat reversal, as noted by the appearance of retrograde pulsations that directed hemolymph in a posterior direction. These retrograde heartbeats occurred exclusively in the abdominal portion of the dorsal vessel and were not observed in the head or thorax. The transition to pharate adult development was also accompanied by the appearance of extremely strong extracardiac pulsations that served a respiratory function. Although these pulsations made it more challenging to record heartbeat patterns in pharate adults, we observed progressive shortening of the resting periods and a continual increase in the rate of both anterograde and retrograde pulsations, a trend that was further magnified in the adult fly (anterograde contractions up to 300/min and retrograde contractions approximately 125/min). These results imply that the circulatory function of the heart is homeostatically regulated and is responsive to developmental changes and the diverse metabolic rate demands of larvae, diapausing pupae, pharate adults and adult flies.
- MeSH
- cykly aktivity MeSH
- diapauza hmyzu * MeSH
- hemolymfa fyziologie MeSH
- kukla fyziologie MeSH
- Sarcophagidae růst a vývoj MeSH
- srdeční frekvence MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Isaria fumosorosea (syn. Paecilomyces fumosoroseus) is potentially useful for the biological control of economically important agricultural and forest insect pests. We evaluated efficacy of two strains of this entomopathogenic fungus against last instar larvae and pupae of Egyptian cotton leafworm, Spodoptera littoralis. The first strain was Apopka 97 which is an active ingredient of commercial biopesticide PreFeRal WG (Biobest, Belgium). The second strain was isolated from Cameraria ohridella and is currently deposited under number CCM 8367 as a patent culture in the Czech Collection of Microorganisms in Brno. Blastospores of both strains were obtained after 120 hours submerged cultivation in grow media using orbital shaker. The concentration of blastospores was adjusted to 5 x 10(7) spores/ml of suspension. Soaking agent Tween 80 was added to the suspension at concentration 0.02%. Lethal effects of both fungal strains on S. littoralis were evaluated using standard dip test. Treated insects were individually placed into plastic Petri dishes (diam. 9 cm) and kept at constant laboratory conditions (temperature 23 degrees C, R.H. approx. 100%, 16L:8D photoperiod). Virulence of the strains was expressed as percentages of cumulative daily mortality corrected for mortality in the control variant. Obtained results revealed higher virulence of CCM 8367 blastospores to the last instar larvae of S. littoralis (93.1% mortality) on the 7th day after the treatment compared to Apopka 97 (65.5% mortality). Even more obvious difference was found in pupae, where corrected mortality of CCM 8367-treated pupae was 80.0% while mortality in Apopka 97-treated pupae reached only 3.3% on the 8th day after the treatment. We can conclude that the strain I. fumosorosea CCM 8367 has strong insecticidal effects on S. littoralis and has a potential to be implemented as a novel biocontrol agent.
- MeSH
- biologická kontrola škůdců MeSH
- časové faktory MeSH
- Hypocreales genetika patogenita MeSH
- kukla mikrobiologie fyziologie MeSH
- larva mikrobiologie fyziologie MeSH
- Paecilomyces genetika patogenita MeSH
- Spodoptera mikrobiologie fyziologie MeSH
- virulence MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
