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The role of the foregut (crop and proventriculus) in mechanical processing of food has received little attention in insects. Using the Australian plague locust (Chortoicetes terminifera) and the black field cricket (Teleogryllus commodus) as models, the role of the crop in processing of wheat or rye grass was examined. Interior cuticular structures (spines) of the foregut were described using light and scanning electron microscopy, with locusts having sclerotised structures and crops of crickets being unsclerotised internally. Muscular bands on the exterior surface of the crop part of the foregut are similar in males of both species, but contractions and movements are more forceful in locusts. Passage rate from the foregut is much faster in locusts (3 h). Water within the crop is reduced compared with the water content of fresh grass within the foregut of locusts, but water is increased in cricket crops. Spines within the crops are small relative to the size of food particles in both species. Some spines of locusts contain metals. The slower passage rate from the crop of crickets may be limited by the proventriculus. Foregut structure and food processing facilitates the generalist diet of crickets, but may restrict locusts to consuming softer grasses.

Tropical seascapes are comprised of a range of patch habitat types, yet we have only a partial understanding of how local patch condition and seascape position may influence patterns of marine biodiversity, particularly for invertebrate taxa. We investigated how the epifaunal abundance and biomass of tropical Sargassum varied with canopy size (volume, total length and dry weight), local patch conditions (macroalgal composition, canopy structure and invertivorous fish biomass) and seascape setting (nearshore, lagoon and back reef) within the Ningaloo fringing reef ecosystem, Australia. A total of 49431 epifauna, dominated by crustaceans and molluscs, were extracted from the thalli of 81 tropical Sargassum polycystum individuals. Epifaunal abundance and biomass were most strongly correlated with host Sargassum canopy volume and dry weight, respectively. Epifaunal abundance and biomass also varied significantly among separate Sargassum meadow patches, with a significant interaction between canopy size and seascape position. Considerable site-level variations in epifaunal biomass density (mg per g Sargassum dry weight) were best predicted by either seascape context or local invertivorous fish biomass. Sargassum within meadows furthest from the back reef tended to have the highest epifaunal biomass (dominated by molluscs), while meadows closest to the back reef were dominated by crustacea. Sargassum within meadows with a high local abundance of invertivorous labrids and serranids tended to have the lowest epifaunal biomass. Strong Sargassum canopy size-epifauna relationships indicate that even small differences in canopy extent have major flow-on effects for the trophic function of tropical marine ecosystems by affecting the epifaunal secondary productivity available to higher-order consumers, such as fishes.

Plants can respond to insects that feed with stylet mouthparts using various processes that are initiated via the salicylic acid metabolic pathway. In Australia, scale insects of the genus Parthenolecanium can cause economic damage to grapevines as they feed on the vines and produce honeydew as a waste by-product, which supports the growth of black sooty mould on fruit and leaves, potentially affecting the plant growth and yield. Using rootlings of Sauvignon Blanc (SB, resistant) and Chardonnay (Char, susceptible), the growth and production of volatile organic compounds (VOCs) following exposure to scale insect infestations were measured under controlled greenhouse conditions. At harvest, the numbers of scale insects per five leaves were higher on plants infested at the start of the study compared with the control plants. Infested SB had increased dry root and shoot mass compared with the SB control, which was also the case with Char (control and infested). Leaf volatiles differed between cultivars in response to scale infestation. Benzyl alcohol decreased among infested SB plants compared with the other treatments. A change in the salicylic acid pathway as indicated by the change in benzyl alcohol may cause the increased growth in SB associated with the increased scale insect infestation.

Rovibrational spectroscopy is a fundamental component of most physical chemistry curricula. This article describes an adaption of the rovibrational spectroscopy of carbon dioxide experiment that can be used as a stand-alone experiment or in conjunction with a traditional hydrogen chloride experiment. The case is made that the laboratory investigation of carbon dioxide provides students with an alternative learning experience to hydrogen chloride experiments alone because the spectroscopic properties of carbon dioxide facilitate a wider discussion and integration of important physical chemistry concepts either directly or peripherally related to rovibrational spectroscopy. However, the motivation to use carbon dioxide is driven by green chemistry considerations. By applying a systems thinking approach to the green chemistry principle of reducing or eliminating toxic reagents, the proposed experiments use only ambient atmospheric carbon dioxide to completely eliminate any purchased reagent. Additionally, without the need for vacuum lines, pumps, traps, and IR gas cells to prepare a sample, instructors can discuss with students the concept of the total chemical footprint of an experiment in relation to not only the reagents but the equipment used to perform the experiment. The use of carbon dioxide also facilitates a discussion of issues related to climate change that reinforces the systems thinking methodology to green chemistry.

A number of planetary bodies, including Triton and Pluto, and a number of Kuiper Belt objects contain nitrogen ices on their surfaces. Nitrogen ices were also used in laboratory experiments as a matrix isolation material before noble gases could be condensed. Planetary bodies with nitrogen ices then may act as giant matrix isolation experiments, trapping reactive species onto the surface and concentrating them. Upon sublimation, these reactive species are much more likely to encounter each other or another molecule to react with. A pilot study was conducted to test the feasibility of testing the chemistry occurring during the sublimation of nitrogen ices. A high vacuum laboratory setup was used to create ices at ∼6 K (±0.5 K). Ices were deposited under microwave radiation to create radicals to simulate what might be present in the tenuous atmospheres of these planetary bodies. The ices consisted of a mixture of 1:1:100 carbon source + H2O + N2, where the carbon source was either CO or CH4. Reagents and pr...

The loss of hollow-bearing trees is a key threat for many hollow-dependent taxa. Nesting boxes have been widely used to offset tree hollow loss, but they have high rates of attrition, and, often, low rates of usage by target species. To counter these problems, chainsaw carved hollows (artificial cavities cut into trees) have become a popular alternative, yet little research has been published on their effectiveness. We examined the usage of 150 chainsaw carved hollows by cavity-dependent fauna in the central west of New South Wales using observations from traditional inspection methods and remote cameras. Between October 2017 and April 2019, we detected 21 species of vertebrates (two reptile, one amphibian, 10 bird, and eight mammal species) inside chainsaw carved hollows, but the number of species detected was dependent on the chosen monitoring method. We detected six species inside hollows during physical inspections, whereas remote cameras detected 21 species entering hollows. Cameras detected eight species using hollows as breeding sites, whereas physical inspections detected just four species. Cameras detected two threatened mammals (squirrel glider (Petaurus norfolcensis) and greater glider (Petauroides volans)) raising young inside hollows, yet we failed to detect these species during physical inspections. For birds, the two methods yielded equivalent results for detection of breeding events. Overall, our study showed that few cavity-dependent species used chainsaw carved hollows as breeding sites. This highlights how artificial hollows are not a substitute for retaining naturally occurring hollows in large trees and revegetation programs.

We describe a pair of labial gland lobes on either side of the retrocerebral complex in the head of the Australian black field cricket, Teleogryllus commodus Walker. As the retrocerebral complex includes the corpora cardiaca and corpora allata, hormones secreted by these glands can be absorbed by these lobes. These lobes of the labial gland are connected to the thoracic lobes via a relatively long duct that enters the main duct draining the thoracic lobes. Measurement of the flow rate of dye from head to thorax in the ducts is rapid, suggesting that these glands may serve as a transport system into the thoracic region. Both serotonin and adipokinetic hormone are shown to be present in the lobes near the retrocerebral complex and the ducts of the thoracic lobes, but whether this connection between the head and thorax acts as a hormone transporter is still unclear., Graphical Abstract Graphical AbstractIn the black field cricket (Teleogryllus commodus), one pair of salivary lobes are located on either side of the corpora cardiaca and corpora allata, connected to the thoracic salivary glands by a long narrow duct. We suggest that this might be one way of transferring hormones from the retrocerebral complex directly into the thoracic region.

This article describes the use of a spreadsheet to reinforce basic calculus that is expected of all university-level chemistry majors. The example provided shows a calculation using Excel to estimate, using a Riemann summation, the radiant exitance of a hot object using Planck’s Law of Blackbody Radiation. The approach reinforces the elementary calculus topic of integrating an area under a curve in an applied chemistry setting and, additionally, requires students to understand how units propagate through integrals in order to calculate correct numerical values. This manual calculation in Excel is pedagogically more satisfying than using black-box type software to calculate areas under curves, and is widely available to almost all students through the use of Excel (or similar spreadsheets software packages).

Scales of the genus Parthenolecanium have become pests in some grapevine growing regions of Australia but not in the wine region in and around Canberra, Australian Capital Territory, Australia. Previous work suggests that population size of scales on certain cultivars varied, with one potential reason for observed differences being the number of scales surviving winter. Parthenolecanium persicae (Fabricius, 1776) overwinters as a third-instar nymph under the bark of grapevines. We investigated whether differences in bark thickness and thermal insulation contributed to survivorship and the extent to which the scales could tolerate cold temperatures. The thickness of bark and the temperature difference across the bark varied among cultivars studied (Shiraz, Chardonnay, Tempranillo, Riesling, Viognier), but these parameters were not correlated among cultivars. Third-instar scales could survive −15°C in dry conditions but froze and were killed when wet and temperatures were cooled to −10°C. Neither the differences in bark thickness nor scale cold tolerance could explain differences in infestations among cultivars observed previously. Grapevine scale outbreaks in various Australian grape-growing regions may coincide with changes in climate as a result of increased winter survival.

The hydroxyl radical (OH) is important in both tropospheric and stratospheric chemical processes that occur in Earth’s atmosphere. The OH radical can also strongly hydrogen-bond to form complexes with other atmospheric constituents, like water molecules. Consequently, there is potential for altered reaction dynamics/kinetics as a result of this complexation. Without direct measurements of the abundances of such complexes in Earth’s atmosphere, we have adopted a theoretical approach to determine such abundances. Electronic structures, enthalpies and free Gibbs energies of formation of OH, H2O and H2O-HO were calculated at CCSD(T) and QCISD(T) levels of theory with either 6–311++G(2d,2p) or aug-cc-pVTZ basis. Statistical thermodynamic concepts were then used to assess the abundance of the complex as function of altitude.

This review of Pluto laboratory research presents some of the recent advancements and motivations in our understanding enabled by experimental simulations, the need for experiments to facilitate models, and predictions for future laboratory work. The spacecraft New Horizons at Pluto has given a large amount of scientific data already rising to preliminary results, spanning from the geology to the atmosphere. Different ice mixtures have now been detected, with the main components being nitrogen, methane, and carbon monoxide. Varying geology and atmospheric hazes, however, gives us several questions that need to be addressed to further our understanding. Our review summarizes the complexity of Pluto, the motivations and importance of laboratory simulations critical to understanding the low temperature and pressure environments of icy bodies such as Pluto, and the variability of instrumentation, challenges for research, and how simulations and modeling are complimentary.

Background and Aims Frosted scale is a sap-sucking insect pest that feeds on several commercial Vitis vinifera cultivars across several wine regions of Australia. The ability to develop and the impact of its feeding activity on grapevines have not been documented. We have closed this knowledge gap through a study that examined the development and feeding effect of frosted scale on Pinot Noir, Riesling and Sauvignon Blanc. Methods and Results A replicated glasshouse experiment was established by allocating the potted rootlings of the three cultivars into two treatment regimes, control (uninfested) and treated (infested with frosted scale) grapevines in the summer months between November 2011 and March 2012. Frosted scale population was relatively high on Riesling, moderate on Pinot Noir and least on Sauvignon Blanc. The presence of frosted scale significantly reduced leaf chlorophyll concentration and the number of internodes per vine. An increasing number of scales did not significantly affect the chlorophyll concentration in any cultivar. An increasing number of scales did significantly decrease the number of internodes per vine. The proportion of dropped leaves in all cultivars exposed to frosted scale was higher than that of control plants. Riesling dropped more leaves than Pinot Noir or Sauvignon Blanc. Conclusions An increase in first and second instar populations of frosted scale feeding mainly on grapevine leaves was observed. This feeding may reduce leaf chlorophyll and the number of internodes per vine. Pinot Noir, Riesling and Sauvignon Blanc were all susceptible to frosted scale feeding under glasshouse conditions, but individual cultivar performance varied. Significance of the Study Grapegrowers could expect frosted scale population and loss of vine vigour to increase on highly susceptible cultivars, such as Riesling. Further studies regarding cultivar differences in response to frosted scale feeding are necessary to clarify these results.

The chemistry of hydroxyl (OH) radicals plays a key role in the radiolysis and photolysis of water-rich ices of astrochemical origin. Other radical species such as hydroperoxy (HO2) radicals are also potentially important in oxygen cycles that exist on icy satellite surfaces due to the stoichiometric loss of H from radiation-processed water-ices. Both OH and HO2 are likely key intermediates in the formation of H2O in the ISM. Despite the importance of such species, laboratory measurements of OH and HO2 in water-ices are sparse. This is due to a combination of low abundances and overlapping spectral features that makes detection using infrared spectroscopy difficult. There have been several reports in the literature claiming detection of both OH and HO2 in laboratory water-ices. In the present work OH radicals are formed in the gas-phase prior to deposition with water to attempt to trap them stably in water-ice at 6 K. The present work does not find any IR spectral detection of OH in ices prepared by this method. Chemical reactions are likely the sink of OH that limits detection in additiontospectraloverlapwithH2O.Theimplicationsofthisforastrochemistryarediscussed herein. Additional experiments have been performed using the matrix-isolation technique to determine the intrinsic band strengths of the infrared absorption of the OH radical and the related H2O–HO complex. These could be used to quantify OH radical in non-water-ices where spectral interference from H2O is absent.

Plant secondary metabolites can affect insect feeding but responses are species-specific. Sideroxylonal-A (a formylated phloroglucinol) has been shown to inhibit feeding in several vertebrate and invertebrate herbivores. To investigate whether sideroxylonal-A affected feeding in sawfly larvae, Perga affinis affinis, we fed larvae eucalypt leaves containing various concentrations of sideroxylonal-A, and measured frass production as an indicator of consumption. We found that: (1) at least 80% of the sideroxylonal-A ingested by larvae was stored in the diverticulum; (2) less than 1% was excreted in frass; (3) feeding was unaffected by the concentration of sideroxylonal-A; and (4) larvae produced more frass on natal host leaves than on non-natal host leaves.

Larvae of Manduca sexta are parasitised by the braconid wasp, Cotesia congregata. In this study we examined whether contraction activity of the semi-isolated foregut was affected by parasitism. Parasitised larvae fed significantly less compared with unparasitised control larvae, therefore starved unparasitised animals were used as controls. Rate and force of foregut contraction in control caterpillars significantly increased with days of starvation. However, only contraction force in foreguts of parasitised larvae increased over time following infection. The presence of food in the foregut of caterpillars starved 7 days suggested that food moved anteriorly from the midgut and that contraction became antiperistaltic, but only normal peristalsis occurred in parasitised caterpillars. Rate and force of gut contractions may be controlled independently and starvation did not truly mimic the effects of the parasitoids. Dissection of caterpillars with emerged wasps indicated that 47% had a single wasp larva wedged between the brain and foregut. Removal of this wasp caused an increased rate of foregut contraction of the caterpillar. Brain removal resulted in an increased rate of foregut contraction only for unparasitised insects. Sectioning of the recurrent nerve temporarily eliminated foregut contraction, but the contraction began again in 250 s in parasitised caterpillars prior to wasp emergence, compared with over 500 s for unparasitised controls and parasitised caterpillars following wasp emergence.

A new procedure using a student-friendly least-squares multiple linear-regression technique utilizing a function within Microsoft Excel is described that enables students to calculate molecular constants from the vibronic spectrum of iodine. This method is advantageous pedagogically as it calculates molecular constants for ground and excited I2 states simultaneously, directly from equations of energy for vibronic transitions. In addition, this method calculates the standard errors of the molecular constants and allows students to comment on the accuracy of the data.

A new model is presented on how chemically driven cryovolcanism might contribute to episodic outgassing at the icy moon Enceladus and potentially elsewhere including Europa and Kuiper Belt Objects. Exposed water ices can become oxidized from radiolytic chemical alteration of near-surface water ice by space environment irradiation. In contact with primordially abundant reductants such as NH3, CH4, and other hydrocarbons, the product oxidants can react exothermically to produce volatile gases driving cryovolcanism via gas-piston forces on any subsurface liquid reservoirs. Radiolytic oxidants such as H2O2 and O2 can continuously accumulate deep in icy regoliths and be conveyed by rheological flows to subsurface chemical reaction zones over million-year time scales indicated by cratering ages for active regions of Enceladus and Europa. Surface blanketing with cryovolcanic plume ejecta would further accelerate regolith burial of radiolytic oxidants. Episodic heating from transient gravitational tides, radioisotope decay, impacts, or other geologic events might occasionally accelerate chemical reaction rates and ignite the exothermic release of cumulative radiolytic oxidant energy. The time history for the suggested "Old Faithful" model of radiolytic gas-driven cryovolcanism at Enceladus and elsewhere therefore consists of long periods of chemical energy accumulation punctuated by much briefer episodes of cryovolcanic activity. The most probable sequence for detection of activity in the current epoch is a long evolutionary phase of slow but continuous oxidant accumulation over billions of years followed by continuous but variable high activity over the past 10(exp 7)-10(exp 8) years. Detectable cryovolcanic activity could then later decline due to near-total oxidation of the rheologically accessible ice crust and depletion the accessible reductant abundances, as may have already occurred for Europa in the more intense radiation environment of Jupiter's magnetosphere. Astrobiological potential of Enceladus could correspondingly be higher than at Europa due to a less extreme state of oxidation and greater residual abundance of organics.

The chemistry and spectroscopy of proton-irradiated H2O + O2 ices have been investigated in relation to the production of oxidants in icy satellite surfaces. Hydrogen peroxide (H2O2), ozone (O3), and the hydroperoxy (HO2) and hydrogen trioxide (HO3) radicals have all been observed, and their temperature and dose dependent production trends have been measured. We find that O2 aggregates form during the growth of H2O + O2 ice films, and the presence of these aggregates greatly affects the HO2 and H2O2 yields. In addition, we have found that the position of the spectral maximum of the ν3 vibration of O3 shifts with ice composition, giving an indication of the degree of dispersion of O3 molecules within the ice. We discuss the relevance of these measurements to icy satellite surfaces.

Patterns of gas exchange among terrestrial arthropods are highly variable from continuous to discontinuous with discretely partitioned phases. The underlying initiation and co-ordination of these patterns is relatively poorly understood. Here we present a novel method for the simultaneous measurement of central nervous system (CNS) activity of the metathoracic ganglion and VCO(2) in medium to large sized live terrestrial arthropods. Using Periplaneta americana at four oxygen levels (40%, 21%, 10% and 2% at 25 degrees C; n=6 per treatment), we present minimally invasive visualization of nervous output relative to typical resting discontinuous gas exchange (DGE) data for the first time. DGE was maintained when cockroaches were exposed to hyperoxia or moderate hypoxia, but was lost in severe hypoxia. CNS activity was manifested in three signal types: large CNS output coinciding with peak CO(2) production during a burst, moderate CNS output coinciding with CO(2) sawtoothing and fluttering, and minimal CNS activity during the closed phase of DGE in normoxia. Large and moderate CNS outputs were associated with observed abdominal pumping and congruent CO(2) peaks. At 10% oxygen, VCO(2) was significantly elevated during the inter-burst period in association with almost constant moderate CNS output between the periodic large CNS output. At 2% oxygen, DGE and large CNS output are lost to continuous CO(2) release and largely continuous moderate CNS output. As previously reported for this species, a central pattern generator for ventilation in the metathoracic ganglion is supported and we infer the presence of localized oxygen chemoreceptors based on clear CNS response to a change in oxygen tension.

The giant burrowing cockroach, Macropanesthia rhinoceros, is endemic to north-eastern Australia and excavates a permanent burrow up to 1m deep into soil. Using flow-through respirometry, we investigated gas exchange and water loss at three different oxygen tensions (21%, 10% and 2% at 20 degrees C) and temperatures (10, 20 and 30 degrees C at 21% oxygen). M. rhinoceros employ cyclic gas exchange (CGE) making the species by far the largest insect known to engage in discontinuous ventilation. CGE featured rhythmic bursts of CO(2) dispersed among inter-burst periods of reduced output. CGE was most commonly observed at 20 degrees C and degraded at10% oxygen. Mild hypoxia (10% oxygen) resulted in a lengthening of the burst period by approximately two-fold; this result is complementary to oxygen consumption data that suggests that the burst period is important in oxygen uptake. When exposed to severe hypoxia (2% oxygen), CGE was degraded to a more erratic continuous pattern. Also, during severe hypoxia, total water loss increased significantly, although CO(2) release was maintained at the same level as in 21% oxygen. During CGE, an increase in temperature from 10 to 20 degrees C caused both water loss and CO(2) output to double; from 20 to 30 degrees C, CO(2) output again doubled but water loss increased by only 31%.

Under controlled conditions of 25°C and 14 h light, adult Pezothrips kellyanus (Bagnall) were observed to have a peak mating time at 17:00 h, this almost coinciding with the time of minimum feeding. Filter papers on which males had walked attracted both sexes, the attraction being strongest when the odour was collected during the mating period and subsequently offered during this period. Field observations indicate that males aggregate and that females approach such aggregations for mating. In Australia, in the vicinity of citrus orchards, this thrips is associated particularly with non-Australian perfumed white flowers. However, recent collecting indicates that the species is widespread in south-eastern coastal areas far distant from citrus cultivation, in the flowers of an Australian native plant, Myoporum insulare. Despite this host plant evidence, morphological evidence continues to suggest retention of the species in the northern hemisphere genus Pezothrips Karny, and thus the country of origin of the pest remains in doubt.

Theoretical studies of the H2O.O2 complex have been carried out over the past decade, but the complex has not previously been experimentally identified. We have assigned IR vibrations from an H2O.O2 complex in an inert rare gas matrix. This identification is based upon theoretical calculations and concentration dependent behavior of absorption bands observed upon co-deposition of H2O and O2 in argon matrixes at 11.5 +/- 0.5 K. To aid assignment, we have used a harmonically coupled anharmonic oscillator local mode model with an ab initio calculated dipole moment function to calculate the OH-stretching and HOH-bending frequencies and intensities in the complex. The high abundance of H2O and O2 makes the H2O.O2 complex likely to be significant in atmospheric and astrophysical chemistry.

The Monterey pine aphid, Essigella californica Essig, is a recent incursion into Australia. Its sudden and rapid spread into commercial Pinus radiata D. Don plantations has caused concern to the forestry industry. Laboratory-based development studies showed that the apterous morph has three instars rather than the four typical of aphids. This difference was validated by an analysis of field-collected samples. The adaptive significance of this finding is discussed in relation to other aspects of this species’ life history.

Acoustic displays are pervasive and conspicuous forms of sexual advertisement used by animals to attract mates. Evidence suggests that individuals may use environmental cues and/or the presence of other displaying animals to select the best times for display to optimize the chances of mating. Less well-known is how the physical and social environment might interact to affect the actual content of the display itself. We examined the effects of social environment and temperature on calling rate in a frog Crinia signifera. We found that both variables interacted to affect call rate but only among continuous callers. Call rate increased with temperature in individuals calling continuously on their own but no relationship was found in frogs calling continuously in the presence of others, either in a duet or in a group calling situation. We suggest that the temperature sensitivity of calling rate in frogs could depend on the social environment of the caller. As such, we suggest caution in generalizing about the way temperature affects calling rates in frogs and encourage greater consideration of how physical and social environments might interact to influence the signal content of acoustic displays.

In this review we provide the data needed to interpret remote spectroscopic studies of O2 molecules embedded in the icy surfaces of outer solar system bodies. O2 produced by radiolysis has been seen in the gas phase and as the so-called ‘solid O2’ trapped in the icy surfaces of Ganymede, Europa and Callisto. It may also have been indirectly observed on a number of objects by its radiolysis product, O3. These observations indicate the importance of O2 for understanding the chemical processes occurring on icy outer solar system surfaces. Therefore, the published absorption spectra of gaseous, liquid and solid O2 and of O2 embedded in H2O ice are reviewed in some detail. Particular emphasis has been placed on the presentation of transition probabilities for the various O2 spectral series so that their relative importances can be assessed when they are used for modelling the radiation chemistry occurring in such environments.

Many species of insects eat Eucalyptus foliage despite its relatively low nutritional value and the many plant secondary metabolites (PSMs) present, for example, terpenes, phenols and formylated phloroglucinols (FPGs). Formylated phloroglucinols are a new class of PSMs that act as antifeedants for possums and koalas. What physiological processes are present that permit insects to eat eucalypt foliage and how do PSMs influence insect feeding or digestion? Some trees seem to be repeatedly infested with eucalypt-feeding insects, possibly as a result of previous chemosensory cues remaining from parental selection of a plant. Avoidance or storage of PSMs permit jarrah leafminers (Perthida glyphopa) and sawflies (Perga sp.) to consume eucalypt foliage without dealing with the majority of these compounds. Some PSMs can be metabolized by polysubstrate membrane oxidases as found in caterpillars or sawflies that feed on eucalypts. High midgut pH may be advantageous for nutrient extraction and PSM metabolism, and midgut pH ranges between 8.5 and 8.9 for caterpillars of Hyalarcta huebneri. Plant secondary metabolites may not be absorbed as a result of the combined presence of the peritrophic matrix and endogenous surfactants. Excretion of PSMs can be as metabolites or intact compounds. Both putative metabolites and sideroxylonal-A, an FPG, are present in the faeces of larvae of the case moth, H. huebneri. The presence of sideroxylonal-A in the food had an effect on the presence of 5-hydroxytryptamine (5HT) in the central nervous system of caterpillars, as larvae fed leaves with a high concentration of sideroxylonal-A had relatively more 5HT in the brain and central nervous system ganglia than larvae fed leaves containing a low concentration. Further work is necessary to clarify how PSMs are handled by eucalypt-feeding insects and what effect FPGs have on feeding and digestion.

We studied the control of salt gland secretion in hatchling Chelonia mydas. The threshold salt load to activate salt secretion was between 400 mumol NaCl 100 g bodymass (BM)-1 and 600 mumol NaCl 100 g BM-1, which caused an increase in plasma sodium concentration of 13% to 19%. Following a salt load of 2700 mumol NaCl 100 g BM-1, salt gland secretion commenced in 12 +/- 1.3 min and reached maximal secretory concentration within 2-7 min. Maximal secretory rate of a single gland averaged 415 mumol Na 100 g BM-1 h-1. Plasma sodium concentration and total osmotic concentration after salt loading were significantly higher than pretreatment values within 2 min. Adrenalin (25 micrograms kg BM-1) and the cholinergic agonist methacholine (1 mg kg BM-1) inhibited salt gland activity. Atropine (10 mg kg BM-1) reversed methacholine inhibition and stimulated salt gland secretion when administered with a subthreshold salt load. Arginine vasotocin produced a transient reduction in sodium secretion by the active gland, while atrial natriuretic factor, vasoactive intestinal peptide and neuropeptide Y had no measurable effect on any aspect of salt gland secretion. Our results demonstrated that secretion of the salt gland in C. mydas can be modified by neural and hormonal chemicals in vivo and that the cholinergic and adrenergic stimulation of an exocrine gland do not appear to have the typical, antagonist actions on the chelonian salt gland.

The physicochemical environment of insect digestive systems affects digestion because of its importance in both enzyme activity and its direct reducing potential. Although the regulation of lepidopteran midgut pH has been widely studied, nothing has been reported concerning the regulation of gut pH in Orthoptera. In this study we measured the pH of the crop, proventriculus, caeca, midgut and anterior hindgut of the cricket, Teleogryllus commodus Walker, to determine whether gut pH was regulated. pH of the crop was between 5.1 and 5.8 for crickets fed on a variety of diets, but was neutral in starved animals. In both starved and fed animals, the alimentary canal increased in pH incrementally between the crop and anterior hindgut, reaching pH 8–8.5 in the latter. Haemolymph pH was slightly alkaline in fed animals (7.5) and acidic in starved animals (6.8). Transgut potential measurements and calculation of the equilibrium Nernst potential showed that the crop was not in equilibrium for H+, and we believe that this results from acidic secretions from the salivary glands. Neutralization of crop acid in fed and unfed animals resulted from anterior fluid movement, into the proventriculus in fed crickets and into the crop in starved individuals.

1. Chironomidae, sampled by interception of drifting cast pupal exuviae, responded to inputs of acid, heavy metal-rich waters in a seasonally flowing tropical stream in northern Australia. 2. Responses included gain of distinctive (indicative) taxa, loss of some species typical of pristine conditions, and increase in species richness. 3. Experimental manipulation (upstream diversion) of a mine adit entry showed that these responses were the result of change in water quality. 4. The higher species richness at low pH, which is contrary to temperate studies, may be explained by the large tropical (Australian and south-east Asian) pool of species tolerant of naturally occurring acidic aquatic habitats. 5. The structure and responses of the exuvial-assessed chironomid community matched long-term larval data.

The endangered grassland earless dragon, Tympanocryptis pinguicolla, is present in two geographic locations in Australia: the Australian Capital Territory and adjacent New South Wales (NSW) near Canberra (~580 m above sea level) and Monaro Plains, NSW, near Cooma (~950 m above sea level). The lizards live in native grassland, an endangered ecological community, and although the population ecology of the animal has been examined, the importance of habitat for thermoregulatory patterns is unknown. We studied whether lizards from the two locations differ in their seasonal patterns of thermoregulation by measuring skin and chest temperatures using both radio-telemetry and temperature measurement in the field, as well as thermal preferences in a laboratory thermal gradient. These results are compared with the operative temperatures (Te) in various microhabitats in the two regions to determine to what extent lizards are thermoregulating. We demonstrate that these lizards do not maintain a constant body temperature, but allow Tb to vary between 13 and 39°C when active in the field, although the grand mean for 50% basking temperatures ranged between 32 and 36°C in the laboratory gradient. Temperatures in the various microhabitats can exceed 40°C, but lizards appeared to avoid those temperatures by seeking shelter in either burrows or the base of grass tussocks. Lizards could choose microhabitats that would permit maintenance of body temperatures above 30°C in most seasons, but did not do so. As high body temperature is not selected in field conditions for either population, other processes (e.g. predation) may be more important for determining Tb maintenance.

Grape phylloxera Daktulosphaira vitifoliae (Fitch) is regarded as the most economically important insect pest of commercial grapevines Vitis worldwide. Root-feeding stages are the most economically damaging. Phylloxera has been managed effectively since the use of resistant rootstocks in the late nineteenth century. The more recent genetic characterisation and partial characterisation of the internal anatomy of D. vitifoliae has improved our knowledge of its life cycle, genetic diversity, physiology and geographic distribution of holocyclic and anholocyclic populations. Although the Phylloxeridae has a basal phylogenetic relationship to the Aphidoidea and provides an interesting comparative model, it has received far less research focus on its fundamental biological characteristics. Using existing techniques and recent advances in molecular, genomic and metabolomic techniques could address the knowledge gaps and lead to the development of improved management options.

SUMMARY 1. Periodic collecting of floating cast pupal cuticles of chironomids (exuviae) in two tropical northern Australian streams demonstrates (i) spatial heterogeneity in species composition across a wide stream, (ii) temporal heterogeneity in the maximum abundance of each species, and that (iii) species accumulate as a function of sample size and duration of sampling, 2. Spatial heterogeneity is ascribed to variation in larval microhabitat across the wide stream, combined with short exuvial drift duration and restricted upstream mixing. 3. Temporal heterogeneity is ascribed to diel periodicity in adult emergence and, as with spatial heterogeneity, to the short floating life. 4. The consequences of spatial and temporal variation for the sampling of exuvial drift are discussed in relation to the objectives of particular programmes. Thus, if the objective is assessment of chironomid species composition for inventory purposes such as faunistics or conservation, the large sample sizes attained by 24-h sampling are necessary and appropriate. However, for rapid assessment that requires comparable samples at different sites, species numbers may be optimized by temporally and spatially restricted sampling of the maximal emergence period, which in this study is at dusk, or by subsampling from a 24-h sample.

Two sympatric species of saltwater-dwelling Ephydrella larvae inhabit saline waters ranging between 0.9 and 2.0 mol l −1 NaCl. When larvae with anal microcannulae were exposed to media of varying salinity, both species were found to be capable of excreting rectal fluid (urine) which was hyperosmotic or isosmotic to the media whilst maintaining the haemolymph osmotic concentration at a relatively constant value. Over environmental osmotic concentrations ranging from 43–5850 mOsm kg −1 , the osmotic concentration of rectal fluids from E. breviseta varied between 36 and 4800 mOsm kg −1 and was relatively close to isosmoticity with the external medium. The fluid from E. marshalli varied between 180 and 8700 mOsm kg −1 and was hyperosmotic to the medium. The osmotic concentration of rectal fluid in both species is almost entirely accounted for by Na + and the assumed Cl − counterion. K + was in relatively low concentration in the rectal fluid but was considerably higher than in the haemolymph. In external media of low NaCl concentrations the rectal fluid from both species was hyposmotic to the haemolymph and at high concentrations the rectal fluids were hyperosmotic to the haemolymph. A consideration of drinking rates and Na + excretion indicates that E. marshalli is in sodium balance in a medium of 1 mol l −1 NaCl but not in 0 or 3 mol l −1 NaCl. This coincides with a significantly higher drinking rate in 1 mol l −1 NaCl.

Oxygen is seen in the reflectance spectra of the icy surfaces of Ganymede and Europa via absorption bands at 627 and 573 nm. Here we show that the trapped O2 associated with these spectral features can be produced via radiation-induced decomposition of hydrogen peroxide dimers contained in hydrogen peroxide inclusions in these icy satellite surfaces.

Thin-film water ice samples are doped with reactive species, such as OH and HO(2) and both singlet and triplet O atoms, which are produced in a discharge, in order to trace the reactions that form oxidants such as H(2)O(2) and O(2), in relation to the icy surfaces of satellites in the outer solar system. The present experiments show that, while reactions of OH formed in the discharge produce H(2)O(2), the majority of H(2)O(2) is formed via other pathways, with reactions of singlet O atoms being the most likely candidate. Strong evidence comes from thermal processing of the ices and using the matrix-isolation technique to quantify the OH abundance in the discharge, which is far below the required amount to account for the relatively high H(2)O(2) abundances measured. Reactions of HO(2) are also of possible significance but appear to be less dominant in the formation of H(2)O(2) than singlet O.

Laboratory studies pertinent to the chemistry of ices with and without additional ingredients such as organics is critical to our understanding of how solar system icy bodies from comets and Kuiper Belt Objects far away in the outer solar system to the ices on Earth, much closer to the sun. This chapter reviews our present day understanding of the fundamental processes that occur in water-rich ices, containing organic impurities. In particular, the role of radiation – photons, electrons, and ions on the chemical evolution of solar system ices, including the newly discovered photoionization in ices, are reviewed.

Matrix isolation FTIR experiments have shown that methanol is a major product when argon gas doped with water and methane is exposed to an electrical discharge and condensed to a solid matrix at 11 K. Experiments with (2)H, (17)O and (18)O-labeled isotopologues show the mechanism for the methanol production is likely to be insertion of an excited oxygen atom in the (1)D state into a C-H bond of a methane molecule. In light of these experiments, the possibility of oxygen atom insertion into methane should be considered as a possible mechanism for the production of methanol in interstellar ices.

Very little information is available regarding the nervous and/or humoral control of foregut peristalsis associated with feeding in insects. Using the cricket, Teleogryllus commodus Walker, we have examined the effect of feeding and the chemicals, proctolin and 5-hydroxytryptamine (5-HT), on contraction of isolated foreguts. Both diet and the presence of food in the crop influence the pattern of contraction. Proctolin and 5-HT increase contraction in a dose-dependent manner between 1 pmol l −1 and 1 μmol l −1 . Comparison of the effects of proctolin (10 nmol l −1 and 1 μmol l −1 ) and 5-HT (1 μmol l −1 ) indicated that 5-HT always had the greatest stimulatory effect. The difference between the two chemicals resulted from stimulation of crop peristalsis by 5-HT. Gut contractions continued to be elevated after replacement of 5-HT by normal saline, althought this residual effect was reduced when the ingluvial ganlia were removed. An increase in spontaneous contractile activity of the foregut was observed when the foregut remained connected to the midgut/hindgut. Addition of the isolated midgut to the saline bathing the foregut resulted in changes in the contraction pattern within 10 s. This work indicates that feedback from the midgut and chemicals released either from the central or stomatogastric nervous systems influence foregut contraction.

Insects are an important and abundant component of the aquatic habitat They are used as indicators of water quality and provide food for fish and birds. The composition and abundance of insect assemblages are known to change with pH. The physiological mechanisms used by insects to cope with extreme environmental pH and regulate extracellular pH are virtually unknown. Evolutionarily, the movement into water from land has consequences with respect to gas transfer, as air has 20-40 times more oxygen per unit volume than water. Two functional respirator, systems have dezveloped within the aquatic insects to extract oxygen from water: water breathers, which use morphological gills; and air breathers, which obtain air from a bubble attached to the body or directly from the atmosphere. This article summarizes research to date pertaining to acid-base regulation in these two functional groups of aquatic insects and compares them with other aquatic ectotherms. Excretion appears capable of handling base removal in t...