Calcite formation induced by Ensifer adhaerens, Microbacterium testaceum, Paeniglutamicibacter kerguelensis, Pseudomonas protegens and Rheinheimera texasensis.

A wide range of bacterial species are able to induce calcium carbonate precipitation. Using our own laboratory-preserved strains, we have newly discovered that Ensifer sp. MY11e, Microbacterium sp. TMd9a1, Paeniglutamicibacter sp. MSa1a, Pseudomonas sp. GTc3, and Rheinheimera sp. ATWe6 can induce the formation of calcite crystals on an agar medium. Type strains of their closely related species (Ensifer adhaerens, Microbacterium testaceum, Paeniglutamicibacter kerguelensis, Pseudomonas protegens, and Rheinheimera texasensis) could also induce calcite formation. Although the initial pH value of the agar medium was 6.1, the pH of the agar media containing calcite, induced by cultivation of the 10 bacterial strains, increased to 8.0-8.4. The ammonification (oxidative deamination) of amino acids may been responsible for this increase in pH. The crystals formed both on and around the bacterial colonies. Furthermore, when these strains (excepting two Microbacterium strains) were cultivated on a cellulose acetate membrane filter (0.20 µm pore size) resting on the surface of the agar medium (i.e., in the membrane filter culture method), the crystals formed on the agar medium separate from the bacterial cells. These results indicate that the bacterial cells did not necessarily become nucleation sites for these crystals. We also investigated whether the studied strains could be applied to the biocementation of sand, and found that only two Ensifer strains were able to form large sand lumps.

Imidacloprid-induced pathophysiological damage in the midgut of Locusta migratoria (Orthoptera: Acrididae) in the field.

Neonicotinoids are modern insecticides widely used in agriculture worldwide. Their impact on target (nervous system) and non-target (midgut) tissues has been well studied in beneficial insects including honeybees under controlled conditions. However, their detailed effects on pest insects on the field are missing to date. Here, we have studied the effects of the neonicotinoid imidacloprid on the midgut of the pest insect Locusta migratoria caught in the field. We found that in the midgut of imidacloprid-exposed locusts the activity of enzymes involved in reactive oxygen metabolism was perturbed. By contrast, the activity of P450 enzymes that have been shown to be activated in a detoxification response and that were also reported to produce reactive oxygen species was elevated. Probably as a consequence, markers of oxidative stress including protein carbonylation and lipid peroxidation accumulated in midgut samples of these locusts. Histological analyses revealed that their midgut epithelium is disorganized and that the brush border of the epithelial cells is markedly reduced. Indeed, microvilli are significantly shorter, misshapen and possibly non-functional in imidacloprid-treated locusts. We hypothesize that imidacloprid induces oxidative stress in the locust midgut, thereby changing the shape of midgut epithelial cells and probably in turn compromising their physiological function. Presumably, these effects reduce the survival rate of imidacloprid-treated locusts and the damage they cause in the field.

Relationship between incomplete synapsis and chiasma localization.

One of the subjects within the meiotic field that has been actively investigated in the recent years is the temporal and functional relationships between meiotic recombination, cohesin loading and synaptonemal complex (SC) assembly. Although the study of meiotic mutants has shed some light, many questions remain to be answered. Here, we have studied this topic in the orthopteran Paratettix meridionalis, a species with telocentric chromosomes, which shows two unusual cytological features: pairing and synapsis of homologues during prophase I are restricted to the non-centromeric distal regions and extremely distal chiasma localization in metaphase I bivalents. In order to determine whether there is a relationship between both phenomena, we have used: (1) a spreading technique for following the ultrastructure of SC assembly and (2) immunofluorescence for SMC3 and SMC1alpha cohesin subunits, which mark the development of the axial element (a SC component); the histone gamma-H2AX, which mostly labels the sites of double-strand breaks; and the recombinase RAD51. Spermatocytes showed conspicuous polarization of both the maturation of cohesin axes and the initiation of meiotic recombination events. Consequently, it is proposed that maturation of cohesin axes, which begins in very distal regions, could drive the latter loading of recombinases to such regions. This restricted distribution of recombination events along homologues would finally be responsible for the incomplete pairing and synapsis observed in all autosomes of the complement and hence for chiasma localization.

Peptides of the adipokinetic hormone/red pigment-concentrating hormone family with special emphasis on Caelifera: primary sequences and functional considerations contrasting grasshoppers and locusts.

The presented work is a hybrid of an overview and an original research paper. First, we review briefly the structure, biosynthesis, release, mode of action and function of those peptides that constitute the adipokinetic/red pigment-concentrating family. Second, we collate the data on primary sequences available for caeliferan orthoptera, i.e. grasshoppers and locusts, and add a number of new data from previously unpublished work. The data are interpreted in conjunction with morphological and molecular biology data with respect to phylogenetic relationships of these various taxa. Finally, we discuss the differences between the adipokinetic response of grasshoppers and locusts to corpus cardiacum extract or synthetic adipokinetic hormone with regard to flight ability, phase polymorphism, age, presence of adipokinetic hormones, lipophorin system and other parameters. It appears that the higher hyperlipaemic response is always correlated with pronounced flight ability.

New Zealand Tree and Giant Weta (Orthoptera) Transcriptomics Reveal Divergent Selection Patterns in Metabolic Loci.

Exposure to low temperatures requires an organism to overcome physiological challenges. New Zealand weta belonging to the genera Hemideina and Deinacrida are found across a wide range of thermal environments and therefore subject to varying selective pressures. Here we assess the selection pressures across the weta phylogeny, with a particular emphasis on identifying genes under positive or diversifying selection. We used RNA-seq to generate transcriptomes for all 18 Deinacrida and Hemideina species. A total of 755 orthologous genes were identified using a bidirectional best-hit approach, with the resulting gene set encompassing a diverse range of functional classes. Analysis of ortholog ratios of synonymous to nonsynonymous amino acid changes found 83 genes that are under positive selection for at least one codon. A wide variety of Gene Ontology terms, enzymes, and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways are represented among these genes. In particular, enzymes involved in oxidative phosphorylation, melanin synthesis, and free-radical scavenging are represented, consistent with physiological and metabolic changes that are associated with adaptation to alpine environments. Structural alignment of the transcripts with the most codons under positive selection revealed that the majority of sites are surface residues, and therefore have the potential to influence the thermostability of the enzyme, with the exception of prophenoloxidase where two residues near the active site are under selection. These proteins provide interesting candidates for further analysis of protein evolution.

Structural, tribological, and mechanical properties of the hind leg joint of a jumping insect: Using katydids to inform bioinspired lubrication systems.

This study investigates the structural properties of the hind leg femur-tibia joint in adult katydids (Orthoptera: Tettigoniidae), including its tribological and mechanical properties. It is of particular interest because the orthopteran (e.g., grasshoppers, crickets, and katydids) hind leg is highly specialized for jumping. We show that the katydid hind leg femur-tibia joint had unique surfaces and textures, with a friction coefficient (µ) at its coupling surface of 0.053±0.001. Importantly, the sheared surfaces at this joint showed no sign of wear or damage, even though it had undergone thousands of external shearing cycles. We attribute its resiliency to a synergistic interaction between the hierarchical surface texture/pattern on the femoral surfaces, a nanograded internal nanostructure of articulating joints, and the presence of lubricating lipids on the surface at the joint interface. The micro/nanopatterned surface of the katydid hind leg femur-tibia joint enables a reduction in the total contact area, and this significantly reduces the adhesive forces between the coupling surfaces. In our katydids, the femur and tibia joint surfaces had a maximum effective elastic modulus (Eeff) value of 2.6GPa and 3.9GPa, respectively. Presumably, the decreased adhesion through the reduction of van der Waals forces prevented adhesive wear, while the contact between the softer textured surface and harder smooth surface avoided abrasive wear. The results from our bioinspired study offer valuable insights that can inform the development of innovative coatings and lubrication systems that are both energy efficient and durable. STATEMENT OF SIGNIFICANCE: Relative to body length, insects can outjump most animals. They also accelerate their bodies at a much faster rate. Orthopterans (e.g., grasshoppers, crickets, and katydids) have hind legs that are specialized for jumping. Over an individual's lifetime, the hind leg joint endures repeated cycles of flexing and extending, including jumping, and its efficiency and durability easily surpass that of most mechanical devices. Although the efficient functioning of insect joints has long been recognized, the mechanism by which insect joints experience friction/adhesion/wear, and operate efficiently/reliably is still largely unknown. Our study on the structural, tribological, and mechanical properties of the orthopteran hind leg joints reveals the potential of katydid bioinspired research leading to more effective coatings and lubrication systems.

De novo biosynthesis of arachidonic acid and 5,11,14-eicosatrienoic acid in the cricket Teleogryllus commodus.

The de novo biosynthesis of 5,11,14-eicosatrienoic acid (5,11,14-20:3), arachidonic acid (20:4(n - 6] and eicosadienoic acid (20:2(n - 6] and the elongation/desaturation of linoleic acid (18:2(n - 6] to 20:4(n - 6) and alpha-linolenic acid (18:3(n - 3] to eicosapentaenoic acid (20:5(n - 3] were demonstrated in adult males of the field cricket Teleogryllus commodus. Sodium [1-14C]acetate, [1-14C]18:2(n - 6) and [1-14C]18:3(n - 3) were injected into adult male crickets and after an incubation period, the testes and remaining tissues were extracted and the methyl esters obtained from the phospholipid and triacylglycerol fractions were analyzed. After 5 days of daily injections of [1-14C]acetate, the methyl esters of the triene and tetraene fatty acids from the testicular phospholipid fraction were purified by AgNO3-TLC and HPLC and analyzed by GLC, radio-HPLC, and radio-GLC of ozonolysis products. The results demonstrate the de novo biosynthesis of 20:2(n - 6), 20:4(n - 6) and an isomer of 20:3(n - 6) with double bonds in the 5,11,14 positions. the elongation/desaturation of 18:2(n - 6) to 20:4(n - 6) and 18:3(n - 3) to 20:5(n - 3) was demonstrated by analysis of the methyl esters derived from the testicular phospholipid fraction by radio-HPLC after injecting crickets with radiolabeled substrates.

The presence and distribution of crustacean cardioactive peptide in the central and peripheral nervous system of the stick insect, Baculum extradentatum.

Crustacean cardioactive peptide (CCAP)-like immunoreactivity was localized and quantified in the central and peripheral nervous system of the Vietnamese stick insect, Baculum extradentatum, using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA). The brain, frontal ganglion, suboesophageal ganglion and ventral nerve cord displayed neurons and processes with CCAP-like immunoreactivity. The brain, in comparison to the other parts of the central nervous system, contained the greatest amount of CCAP (167 +/- 18 fmol), and showed CCAP-like staining in neurons, neuropil regions and the central complex. There were also CCAP-like varicosities and processes associated with the corpus cardiacum. The alimentary canal of B. extradentatum contained CCAP with the largest amount localized in the midgut (1110 +/- 274 fmol CCAP equivalents). The midgut contained numerous endocrine-like cells which stained positively for CCAP, whereas the foregut and hindgut revealed an extensive network of CCAP-like immunoreactive axons and varicosities. Based on physiological assays, the hindgut of the stick insect was found to be sensitive to CCAP, showing dose-dependent increases in contractions with threshold at 10(-10) M CCAP and maximal response at 5 x 10(-7) M CCAP. There were negligible quantities of CCAP in the oviducts and no CCAP-like immunoreactivity was associated with the oviducts. CCAP had no effect on spontaneous contractions of the oviducts. The presence of CCAP in the central nervous system, the stomatogastric nervous system, the corpus cardiacum and the alimentary canal, suggest broad ranging roles for CCAP in B. extradentatum.

Heavy metal accumulation, heat shock protein expression and cytogenetic changes in Tetrix tenuicornis (L.) (Tetrigidae, Orthoptera) from polluted areas.

The orthopteran insect Tetrix tenuicornis, collected from polluted and unpolluted areas, was used to study heavy metal accumulation and its impact on stress protein levels and on changes in the number and morphology of chromosomes in mitotic and meiotic cells. During two consecutive years, insects were collected from polluted areas of zinc-lead mine spoils near Boleslaw (Poland) and from unpolluted areas near Busko and Staszów (Poland). T. tenuicornis from the polluted area showed 1.5, 4.03, 4.32 and 41.73 times higher concentrations of copper (Cu), zinc (Zn), lead (Pb) and cadmium (Cd), respectively, than insects of the same species collected from unpolluted areas. Insects exposed to heavy metals showed only small changes, and rather a decrease in the concentration of constitutive and inducible heat shock proteins Hsp70, the level of which increases under stress conditions. A cytogenetic study of T. tenuicornis revealed intra-population anomalies in chromosome number and morphology in mitotic and meiotic cells and the presence of an additional B chromosome in germinal cells. In 50% of females collected from polluted areas, mosaic oogonial mitotic chromosome sets and diploid, hypo- or hypertetraploid, tetraploid, and octoploid chromosome numbers were detected. In turn, 14.6% of males showed a heterozygous deficiency of chromatin in L2 and M3 bivalents in addition to the presence of B chromosomes.

Analysis of the translational capacity of the male accessory gland during aging in Acheta domesticus.

The protein synthesizing capacity of the male cricket accessory gland was inspected for changes associated with aging by analysis of organs from young (2 weeks post-imaginal molt), middle-aged (4 and 6 weeks) and senescent (8 weeks) animals. Total RNA content and the percentage of ribosomes in polysomes show an increase up to 4 weeks and then a steady decline. The rates of protein synthesis by young and old glands incubated in vitro were comparable, although the old glands were significantly less efficient in precursor uptake and therefore showed lower incorporation levels. The overall picture appears to be one of a steady but unspectacular decline in protein synthesizing capacity in aging animals. The quality of the secretory proteins formed by young and old glands was inspected by SDS--polyacrylamide gel electrophoresis and by isoelectric focusing, using both wide and narrow pH-range gels. While some differences in the banding patterns of isoelectric focusing gels were detected, they were eliminated by the inclusion of Triton X-100 in the gels. No other evidence for age-associated qualitative or quantitative changes was detected, strongly suggesting that proteins from young and old glands are identical.

Neurons reactive to antibodies against serotonin in the stomatogastric nervous system and in the alimentary canal of locust and crickets (Orthoptera, Insecta).

Immunoreactive neurons in the stomatogastric nervous system and in the alimentary tract of the locust Schistocerca gregaria and the crickets Gryllus bimaculatus and Acheta domesticus have been examined using antibodies against serotonin (5-hydroxytryptamine; 5-HT). For comparative anatomical analysis cobalt chloride infusion was applied. The innervation of the visceral muscles was studied electron microscopically. In all three species the majority of the 5-HT-immunoreactive cell bodies of the stomatogastric nervous system occur in the frontal ganglion in which 30-40% of the total number of cell bodies react with anti-5-HT. In the occipital ganglion only two to four cell bodies (1-2%) are 5-HT-immunoreactive. Single immunoreactive cell bodies were observed in the ventricular ganglia in only a few preparations. The 5-HT-immunoreactive neurons in the frontal ganglion are pseudounipolar or multipolar. The main process of the 5-HT-immunoreactive neurons of the frontal ganglion descend along the entire stomatogastric nervous system. Some arborizations of these processes ascend into the brain and others supply the neuropil of all stomatogastric ganglia. Side branches leave the stomatogastric nervous system and form a plexus along the surface of the entire intestinal tract from where 5-HT-immunoreactive fibers supply: all muscle layers of the muscularis; the external dilator muscles of the foregut and probably some somatic muscles, neurohaemal organs and Malpighian tubules (excretory system). Serotonin-immunoreactive fibers further proceed into salivary gland and the retrocerebral complex (corpora cardiaca and corpora allata). The retrocerebral glandular complex and the hindgut receive additional immunoreactive neurons from the central nervous system. Electron microscopic analysis of nerves innervating the muscle layers of the alimentary tract revealed one type of 5-HT-immunoreactive and one or two types of non-5-HT-immunoreactive fibers. All fiber types contact the sarcolemma of muscle fibers without any obvious synaptic membrane specializations. The 5-HT-immunoreactive fibers are in some regions in close contact with the haemolymph. These regions can be regarded as sites of neurohormonal release. The distribution of serotonin-immunoreactive neurons suggests that 5-HT acts as a neurotransmitter and/or modulator on intestinal muscles and some somatic muscles and glandular cells, and as a neurohormone released from neurohaemal sites into the body fluid.

The biosynthetic pathway of ecdysone: studies with vitellogenic ovaries of Locusta migratoria (Orthoptera).

Ovaries of adult females of Locusta migratoria synthesize impressive amounts of the steroid hormone ecdysone (and related ecdysteroids) during the late phases of vitellogenesis. The present study, aimed at elucidating the sequence of the biosynthetic steps that lead from cholesterol to ecdysone, has taken benefit of this remarkable biological model by using a double approach: (1) isolation and physico-chemical identification of endogenous biogenetic intermediates; (2) metabolic study of labelled putative precursor molecules. The data presented in this paper lead us to propose the following sequence of events: conversion of cholesterol to 3 beta-hydroxy-5 beta-cholest-7-en-6-one (via several intermediates not identified in this study) followed by 14 beta-hydroxylation to 3 beta, 14 alpha-dihydroxy-5 beta-cholest-7-en-6-one; hydroxylation on the side-chain at C-25 and C-22 (in this order) to 2-deoxyecdysone; hydroxylation at C-2 to ecdysone.

Soluble proteins in chemosensory organs of phasmids.

Soluble proteins of low molecular weight have been purified from chemosensory organs of five species of Phasmids. On the basis of their N-terminal amino acid sequences, two classes can be identified. Polypeptides of 14 and 15 kDa, expressed in the antennae and legs of Eurycantha calcarata and Extatosoma tiaratum, as well as in the antennae of Carausius morosus, bear a close similarity (around 45% identity) with a soluble protein associated with the sensilla coeloconica of Drosophila melanogaster. Two proteins of 19 and 18 kDa, isolated from the antennae and the maxillary palpi, respectively, of Acrophylla wuelfingi, are 59 and 75% identical, in their N-terminal region, to a 19 kDa antennal protein of Carausius morosus. Similarity between members of the two classes is not significant, being limited to two to three identical amino acids in the most favorable cases. Finally, a 17 kDa protein, specifically expressed in the antennae of Sipyloidea sipylus, did not show any homology with other proteins. The expression in sensory organs and the characteristics of these proteins may suggest a function in chemosensory transduction.

Apolar ecdysteroid esters in adult female crickets, Gryllus bimaculatus.

Six hours after injection of 0.5 microCi 3H-ecdysone into the hemocoele of adult female crickets, several labelled compounds could be separated from hemolymph and tissues by silicic acid column chromatography, TLC, and HPLC. The amount of conjugated, polar ecdysteroids was low in all tissues, whereas apolar metabolites were predominant in all tissues. The apolar compound A2, which is the most abundant in quantity, could be hydrolyzed by porcine liver esterase, yielding ecdysone and various long chain fatty acids. This represents a new class of apolar ecdysteroid conjugates not yet found in other insects.

Amino acids and memory consolidation in the cricket. I: Changes in the titer of free amino acids in nervous tissue after learning.

The involvement of certain amino acids in the memory consolidation process was investigated in the cricket Pteronemobius sp. Thirsty crickets were trained to constantly turn to one side of a symmetrical Y-shaped maze using reinforcement with water. Controls were trained to turn to both sides of the maze according to a random program. Animals were sacrificed immediately after training and free amino acid fractions were isolated from whole brain, subesophagic, prothoracic, mesothoracic and metathoracic ganglia homogenates and analyzed by high pressure liquid chromatography. A complex pattern of variation in the titer of amino acids emerged after learning, where the changes differed among the various ganglia. The most conspicuous change was an increase in the levels of urea and an amino acid-like compound related to the urea cycle, in all ganglia except the subesophagic one, if compared to controls. Arginine increased in the subesophagic ganglion, but decreased significantly in the metathoracic ganglion. The variation of ganglionic amino acid levels and its possible relation to mnemonic processes is discussed.

Opiate receptor in praying mantis: effect of morphine and naloxone.

A praying mantis displays a "frightening reaction" called deimatic reaction (DR), any time that it is faced with a patterned visual stimulus that represents a potential damage for the insect. Results of the present paper show that the DR could be also elicited by an actual noxious (an electrical shock) and that this response is similar to that elicited by a potential nociceptive stimulus (a patterned visual stimulus). The DR elicited by the electric shock was used as a model for studying the analgesic effect of opiates. The mantis was placed in an apparatus that allowed us to give the insect an electrical shock and to measure the strength of its DR. During a first session the voltage threshold necessary to induce a full DR was determined, and then, the insect was injected with a certain solution. The voltage threshold was tested one, two and four hours after injection. Mantises that were injected with only distilled water showed no changes in their voltage threshold during the three tests. Injections of 300, 350 and 400 micrograms/g of morphine-HCl increased the voltage threshold in both a time-dependent and a dose related manner. A dose of 350 micrograms/g of morphine-HCl produced 50% of response inhibition after two hours of injections and is referred to as the median antinoxious dose ( AD50 ). Sixteen micrograms/g of naloxone given in conjunction with an AD50 of morphine, partially blocked the effect of morphine during the first hour and fully blocked it during the second hour. Thirty-two micrograms/g of naloxone fully blocked the morphine effect during the first and the second hour. However, more than 48 micrograms/g of naloxone alone also increased the voltage threshold in insects, similar to those described for vertebrates.

Site of synthesis and phylogenetic distribution of a hemolymph trophic factor of the tobacco hornworm, Manduca sexta.

Identification of fifth instar larval Manduca sexta fat body and epidermis as sites of synthesis of a hemolymph protein (hemolymph trophic factor or HTF) was achieved using in vitro 3H-leucine incorporation into protein and subsequent immunoprecipitation of tissue homogenates. Fat body is the primary site of HTF synthesis with a maximal rate on Day 1; epidermis is a secondary site with peak synthesis on Day 0. In vitro radiolabelling followed by TCA precipitation of general protein of fat body and epidermal homogenates suggest that fat body actively elaborates protein on Days 0-5 with peak rates on Days 1 and 4, while epidermis is active on Days 0-5 with a peak rate on Day 3. Based on Anti-HTF ELISA estimates, HTF [500 to 1000 micrograms/ml] was found in the hemolymph of representatives of the insect orders Blattodea, Hemiptera, Orthoptera, and Lepidoptera and in the class Crustacea, but not in the class Merostomata. These studies suggest a possible fundamental role for HTF among modern arthropods in cuticular deposition involving both epidermis and fat body. The physiological role of HTF is undetermined.

Structure of the cuticle of the common house cricket with reference to the location of lipids.

Cuticle segments from the thorax, abdomen, and jumping legs of the house cricket, Acheta domesticus, were examined using histological techniques for light microscopy, scanning and transmission electron microscopy, and direct examination of frozen-fractured cuticle. The surface of untreated cuticle is covered by a lipid film which obscures fine surface detail. Standard EM preparative procedures, as well as washing the cuticle with ethanol before examination, remove this film exposing previously covered openings to dermal gland ducts and wax canals. An epicuticle, exocuticle, mesocuticle, endocuticle, and a deposition layer were present in all transverse sections of cuticle. Light microscopy showed that the exocuticle and mesocuticle are heavily impregnated with lipids, whereas there is little lipid associated with the endocuticle. Frozen-fractured cuticle clearly shows the 'plywood' structure of the meso- and endocuticle, while the exocuticle fractures as if it were a solid sheet. The epicuticle is composed of a dense homogeneous layer, cuticulin, outer epicuticle, and the outer membrane. Superficial wax was detected only in cuticle samples prepared using vinylcyclohexane dioxide as a polar dehydrant. The results were used to construct a comprehensive model of the cuticle of A. domesticus.

The transfer of lipid in insects from the epidermal cells to the cuticle.

The structure of the pore canals and the tubular filaments they contain are described in a series of insects and types of cuticle. In all these cuticles the tubular filaments arise from the plasma membrane of the epidermal cells and they contain argentaffin material, regarded as sclerotin precursors, and lipid-staining material, regarded as wax precursors. These materials are transferred to the inner epicuticle and are exuded over the surface of the outer epicuticle to form the waterproofing layer as described in the preceding paper. They are also transported to those parts of the endocuticle destined to form hard exocuticle. There are no terminations of tubular filaments in the soft cuticle of Manduca larva, in the soft expanding cuticle of Rhodnius, and in the non-sclerotized post-ecdysial endocuticle of Tenebrio. Apis. etc. In the puparium of Calliphora lipid appears to be added by the epidermal cells directly and not by way of tubular filaments. It is confirmed that lipid is a component of sclerotized cuticle.

Effects of gamma radiation and temperature on the biological assimilation and retention of 137Cs by Acheta domesticus (L.).

Cesium-137 retention was determined for brown crickets, Acheta domesticus, which had been irradiated with 0, 1000, 2500 and 5000 rad gamma radiation and maintained at 20, 25 and 30 degrees C. Parameters examined for temperature and dose effects were (1) per cent 137Cs assimilated into body tissues (p2), (2) rate of isotope passage through the gut (k1) and (3) rate of elimination of assimilated 137Cs (ks). Increases in temperature and gamma dose resulted in a general decrease in per cent 137Cs assimilated pe day (p2). The first-component elimination coefficient (k1) was not significantly affected (P less than or equal to 0.05) by either temperature or dose changes. Biological elimination coefficients for assimilated 137Cs (k2) increased with increasing temperature between doses of 0 and 2500 rad. Above 2500 rads however, increases in temperature had no noticeable effects on the rate of assimilated 137Cs excretion. At higher dose levels, radiation was the dominant factor influencing the parameter k2.