Short-range phenotypic divergence among genetically distinct parapatric populations of an Australian funnel-web spider.

Speciation involves divergence at genetic and phenotypic levels. Where substantial genetic differentiation exists among populations, examining variation in multiple phenotypic characters may elucidate the mechanisms by which divergence and speciation unfold. Previous work on the Australian funnel-web spider Gray (2010; , 285-392; Mygalomorphae: Hexathelidae: Atracinae) has revealed a marked genetic structure along a 110-kilometer transect, with six genetically distinct, parapatric populations attributable to past glacial cycles.

Effects of substrate salinity on oviposition, embryonic development and survival in the Australian plague locust, Chortoicetes terminifera (Walker).

The Australian plague locust, Chortoicetes terminifera (Walker), is an important agricultural pest that oviposits into soil across vast semi-arid and arid regions. This study aimed to determine whether gravid female locusts can discriminate among substrates of increasing salinity (0, 4, 8, 12, 16, 20, 24, and 28ppt NaCl) when attempting oviposition, and quantify the effects of saline substrate on direct developing egg viability, and subsequent hatchling nymph body weight and survival. Gravid female locusts increasingly excavated and withdrew prior to completing oviposition in substrates of increasing salinity, but similar numbers of completed egg pods were observed across treatments.

Embryonic diapause in the Australian plague locust relative to parental experience of cumulative photophase decline.

The Australian plague locust Chortoicetes terminifera (Walker) exhibits facultative embryonic diapause during autumn. To approximate natural photoperiod changes during late summer and autumn, locust nymphs were reared under different total declines in laboratory photophase (-0.5, -0.

Cold tolerance of the Australian spur-throated locust, Austracris guttulosa.

The cold tolerance of overwintering adult Spur-throated locusts, Austracris guttulosa, was examined using measures of supercooling point relative to gender, environmental acclimation and feeding state as well as mortality for a range of sub-zero temperature exposure treatments. Freezing was lethal and supercooling points ranged from -6 to -12.8°C, but were statistically independent of fresh mass, body water content, acclimation, and/or gut content in fed and starved individuals.

Efficacy of vaporised ethyl formate/carbon dioxide formulation against stored-grain insects: effect of fumigant concentration, exposure time and two grain temperatures.

Background: The ethyl formate/carbon dioxide (CO(2)) formulation Vapormate is a rapid-acting fumigant being developed for the control of stored-grain insects. The effects have been investigated of concentration, exposure times of 1, 3, 24 and 72 h and two grain temperatures, 15 and 25 degrees C, on its efficacy against mixed-stage cultures of Sitophilus oryzae (L.) Tribolium castaneum (Herbst) and strongly phosphine-resistant Rhyzopertha dominica (F.

Field evaluation of vaporised ethyl formate and carbon dioxide for fumigation of stored wheat.

Background: Vapormate is a cylinderised non-flammable mixture of ethyl formate (16.7% by weight) and carbon dioxide (CO(2)) that has been developed as a rapid fumigant of stored grain. Four field trials were undertaken on wheat in 50 t farm silos to demonstrate the feasibility of dynamic application.

Effect of opioid compounds on feeding and activity of the cockroach, Periplaneta americana.

Opioid peptides have been implicated in regulation of feeding in invertebrates. Studies have suggested that receptors for opioids are present in cockroaches and that these receptors play roles in affecting both behaviour and feeding. We examined the effect of micro, delta, and kappa opioid receptor agonists and antagonists on feeding, mass changes and activity in the cockroach, Periplaneta americana.

Cold tolerance of first-instar nymphs of the Australian plague locust, Chortoicetes terminifera.

The cold tolerance of first-instar nymphs of the Australian plague locust, Chortoicetes terminifera, was examined using measures of total body water content, supercooling point and mortality for a range of sub-zero temperature exposure regimes. The supercooling points for starved and fed nymphs were -13.1+/-0.

Neural regulation of discontinuous gas exchange in Periplaneta americana.

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.

Effects of phosphine on the neural regulation of gas exchange in Periplaneta americana.

Phosphine is used for fumigating stored commodities, however an understanding of the physiological response to phosphine in insects is limited. Here we show how the central pattern generator for ventilation in the central nervous system (CNS) responds to phosphine and influences normal resting gas exchange. Using the American cockroach, Periplaneta americana, that perform discontinuous gas exchange (DGE) at rest, we simultaneously measure ventilatory nervous output from the intact CNS, VCO(2) and water loss from live specimens.

Physiology complements population structure of two endemic log-dwelling beetles.

Given rapid, global land modification and the likelihood of major global climate changes, it is becoming increasingly important to understand the physiological limits and capabilities of species to allow more accurate prediction of species' distributions under different scenarios of climate and landscape management. We studied whether the different habitat requirements of two species of tenebrionid beetles in temperate eucalypt forest could explain their patterns of dispersal and gene flow by applying flow-through respirometry to analysis of their physiological responses to different, ecologically relevant temperatures. Both Adelium calosomoides and Apasis puncticeps showed sensitivity to increasing temperatures (in terms of water loss), but Ap.

Cyclic gas exchange in the giant burrowing cockroach, Macropanesthia rhinoceros: effect of oxygen tension and temperature.

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.

Effects of temperature and oxygen availability on water loss and carbon dioxide release in two sympatric saproxylic invertebrates.

Water loss and VCO(2) relative to temperature and oxygen tension was investigated in a log-dwelling onychophoran (Euperipatoides rowelli) and a sympatric, un-described millipede species using flow-through respirometry. Onychophorans possess a tracheal system featuring permanently open spiracles. Total body water loss was consistently very high in E.