Larvae Tenebrio Research Articles

Evaporative water loss, nitrogen excretion and osmoregulation in phyllomedusine frogs

1. Minimal rates of evaporative water loss in tree frogs of genusPhyllomedusa (P. pailona, P. iherengi, P. hypochondrialis) were only 5–10% those of representatives of two related genera,Agalychnis annae andPachymedusa dacnicolor (Table 1). 2. Phyllomedusa species,A. annae andP. dacnicolor all took up water rapidly (25–45% standard wt·hr−1) across the skin following prolonged water deprivation (Table 2). 3. When fed mealworms (Tenebrio larvae) and deprived of additional water, body fluid concentrations increased more slowly inPhyllomedusa species than in representatives of three other genera (Agalychnis, Pachymedusa andHyla) tested. Of thePhyllomedusa species,P. sauvagei showed by far the lowest rate of increase (Table 4). 4. The osmoregulatory ability of thePhyllomedusa species is primarily attributable to their ability to excrete urate. The fraction of total waste nitrogen production excreted as urate was 80% inP. sauvagei, ca. 45% inP. pailona andP. iherengi, and 24% inP. hypochondrialis. Urate excretion inAgalychnis, Pachymedusa andHyla was negligible (Tables 5 and 9). 5. Increased water intake did not alter the rate of urate production in the three species tested (P. sauvagei, P. hypochondrialis andA. annae) (Table 6). 6. Additional osmoregulatory benefit is derived byPhyllomedusa species from the binding of Na+, K+, and NH4+ to precipitated urate (Tables 5 and 7). 7. On a diet of mealworms, energy losses via the feces and nitrogen wastes ranged from 14 to 18% of intake in the four species ofPhyllomedusa and inP. dacnicolor, and were about equally divided between the two avenues (Tables 8 and 9). 8. These results suggest thatP. sauvagei could remain in water balance in nature on a diet of insects with little or no additional water intake.

Biosynthesis of ecdysones in isolated prothoracic glands and oenocytes of Tenebrio molitor in vitro

Isolated prothoracic glands from Tenebrio larvae synthesize in vitro α-ecdysone, but not β-ecdysone from 4- 14C-cholesterol. Isolated abdominal oenocytes from the larvae synthesize mainly β-ecdysone, but only little α-ecdysone. When prothoracic glands and oenocytes are cultured together, the α-ecdysone derived from the prothoracic glands is oxidized by the oenocytes to β-ecdysone. The newly synthesized hormones are not stored in the cells, but are secreted into the medium if sufficient amounts of non-labelled hormones are present. If no unlabelled hormones are added to the culture medium, the newly formed hormones are converted to a large extent into polar conjugates.

Detection of diffusible ions in insect osmoregulatory systems by electron probe X-ray microanalysis using scanning electron microscopy and a cryoscopic technique

A technique for using electron probe X-ray microanalysis for the detection of diffusible ions in frozen bulk specimens is described. The method has been applied to the study of insect osmoregulatory systems and preliminary results are presented using Ephydrella larvae (Ephydridae, Diptera) which normally live in salt water, and Tenebrio larvae (Tenebrionidae, Coleoptera). In Ephydrella larva, differences are demonstrated in (a) ionic composition of different regions of the gut, (b) the concentration of Na+ and Cl− in the hindgut lumen compared with blood, (c) Na+ and Cl− concentration in different cell types in the hindgut and (d) Na+ and Cl− concentrations in hindgut cells which are correlated with differences in environmental salinity. In Tenebrio larvae, the detection of high levels of K+ in the region of the leptophragmata cells of the Malpighian tubules lends support to the hypothesis that these cells recruit K+ from the haemolymph.

Energy Utilization in the Lizards Sceloporus graciosus and S. occidentalis

Three Sceloporus graciosus which gained weight (+ 0.37 g) during measurement assimilated 83-88 cal/g/day when maintained on a Tenebrio larvae diet. One S. graciosus which maintained constant body weight assimilated 73 cal/g/day. Five S. occidentalis that had a mean weight gain of 3.70 g had a mean energy assimilation of 36 cal/g/day. It was calculated that a male S. graciosus, feeding only on Tenebrio larvae, would ingest 78,000 cal during its first three years of life, of which 64,000 cal would be assimilated. Ap- proximately 61% (39,000 cal) of the total energy assimilated would be used in metabolism. * * * The subject of energy budgets and measurements of energy assimilation of reptile species has not been extensively studied. However some reports have appeared giving estimates of energy utilization. McNab (1963) using the respirometry data of Dawson and Bartholomew (1956) and the temperature data of Bogert (1949), calculated the daily energy expenditure of Sceloporus occidentalis. Johnson (1966) estimated the daily energy assimilation of three species of lizards. Alexander and Whitford (1968) calculated the energy requirements of a population of Uta stansburiana.

The relation of carnitine to the formation of phosphatidyl-beta-methylcholine by Tenebrio molitor L. larvae.

AbstractResults demonstrate thatTenebrio molitor larvae can incorporate β‐methylcholine into their phospholipids and that β‐methylcholine spares larval choline. Phosphatidyl‐β‐methylcholine is detected when larvae are reared on a diet in which choline is replaced by β‐methylcholine. Results indicate that, in contrast to housefly and blowfly larvae,Tenebrio larvae do not metabolize carnitine to β‐methylcholine. The same phospholipids were found with all rearing conditions. They were lecithin, sphingomyelin, phosphatidylethanolamine, phosphatidylserine and two others tentatively identified as cardiolipin and phosphatidylinositol. The ratio of lecithin to sphingomyelin and to the combined other phospholipids did not vary significantly, regardless of the rearing conditions. Larvae reared on diets lacking either choline or carnitine contained more lipid phosphorus per gram of tissue than those reared on a complete diet. The fatty acid composition of the neutral lipids was similar regardless of the rearing conditions. Oleic acid represented greater than 55% of the total fatty acids, and unsaturated fatty acids comprised 75–80% of the total. Palmitic acid was the predominant saturated fatty acid.

Temperature Regulation in Nestling Cactus Wrens: The Development of Homeothermy

The Cactus Wren is a permanent resident of semi-arid desert-scrub areas of the southwestern part of the United States and northem Mexico. In the Sonoran Desert near Tucson, Arizona, its breeding season usually extends from March to August, during which two and occasionally three broods of three or four young are raised. The Cactus Wren is an ideal subject for developmental studies because of its long nestling period ( 26 days ), convenient size, and accessibility. The development of structural and behavioral features of the Cactus Wren are described in detail by Anderson and Anderson ( 1961). and they were returned to their nests within 24 hours. Individuals were not used more than once. The young were fed ground beef and meal worms (Tenebrio larvae) and were maintained in a replete condition during the experiments. The ages of nestlings were usually known from our observations at nests and were confirmed by comparing wing length with a standard wing length growth curve ( Anderson and Anderson 1961) . Temperature regulation at ambient temperatures below 35°C was studied by placing nestlings in 260-ml plastic jars with air-tight lids. Air was passed through these containers at a.constant rate (one liter/min) after it was dried by passage through tubes of Drierite dessicant ( anhydrous calcium sulfate). Temperatures inside the containers were measured with indwelling mercury thermometers. The nestlings were isolate’d from the walls of the containers by nylon mesh so that a maximum amount of the body surface was exposed to the circulating air. A range of ambient temperatures was obtained by taking measurements at various times during the day throughout the breeding season. After the nestlings had been in the chambers for 45 minutes their body temperatures were measured by inserting a thermistor probe through the mouth deep into the proventriculus. Regulation at temperatures above 35°C was studied by placing nestlings in shallow paper cups in a constant temperature incubator ( ? 0.5C ). Body temperatures were measured over a three-hour interval at ambient temperatures of 36, 40, and 44°C. The relative humidity was not controlled but never exceeded 20 per cent. Temperatures of nestlings in the field were measured with orally inserted thermistors. Temperatures in the center of the nest cavities and in the shade outside the nests were measured with permanently fixed mercury thermometers.

Correcting behaviour in mealworms ( Tenebrio) and the rejection of a previous hypothesis

1. 1. Tenebrio larvae when forced to make a turn in a maze show a tendency, already observed in other insects, to make a second opposite turn. If not forced to make a turn prior to a choice point, they will proceed straight ahead instead of taking one of the turns there. 2. 2. The frequency of this correcting behaviour increases as the distance from the start to the forced turn increases. 3. 3. The frequency of correcting decreases as the distance from the forced turn to the choice point is increased. This decrease is not a function of the time it takes to traverse that distance. 4. 4. Because of 2 and 3 above I have rejected “reactive inhibition” as an explanation of the behaviour observed. 5. 5. As in boxelder bugs, the tendency to alternate turns is apparently the result of an interaction between events occurring at the forced turn and an excitatory state accumulated prior to the forced turn.

Studies on the proteolytic activity of the beetles Tenebrio and Tribolium

The optimal conditions for total proteolytic activity in vitro of the midgut as well as whole-larva homogenates of Tenebrio molitor L. were determined as pH 6·2–6·4, 37°C for 20 min reaction, and 0·5% casein. The same were found for both Tribolium confusum Duval and T. castaneum Herbst except for the pH, which was in the range of 6·5–6·9. Larvae of Tribolium grown under a fluctuating temperature, with a mean of 24·5°C, showed a remarkably increased proteolytic activity, as compared to those grown under a constant temperature of 28°C. The crystalline soybean trypsin inhibitor partially inhibited proteolysis in Tenebrio larvae, whereas the C 1 fraction of soybeans inhibited some 70 per cent of this activity. Haemoglobin could not replace casein as a substrate. Moreover, when added to reaction mixtures containing optimal casein concentrations it inhibited proteolysis to a considerable extent. Likewise, larval growth of all three species was suppressed on basic diets supplemented with haemoglobin. The addition of methionine and/or isoleucine to the haemoglobin-supplemented diets could not overcome this suppression of growth. With a relative decrease in proteolytic activity during larval development there is a steady relative increase in amylolytic activity until both activities reach constant levels in the last instars.

Body Temperature, Oxygen Consumption, Evaporative Water Loss, and Heart Rate in the Poor-Will

The physiology of the Poor-will (Phalaenoptilus nuttallii) is of unusual interest. Not only is it one of the very few birds which can undergo long periods of dormancy comparable in most respects to mammalian hibernation, but over much of its summer range it is exposed to severe conditions of heat because of its habit of spending the daylight hours, even in the desert, sitting quietly in the open. During the past year we have had the opportunity to make a series of observations on two captive, adult PIoor-wills, one (P. n. hueyi) captured by Mr. Donald Schroeder in the Coachella Valley, Riverside County, California, and the other (P. n. californicus) found in a torpid condition in Eagle Rock, Los Angeles County, California, by Mrs. Gerald Massey. Both birds were maintained for many months in captivity and were fed on a diet of meal worms (Tenebrio larvae) and canned cat food. The limited information on the physiology of Poor-wills has previously been summarized (Bartholomew, Howell, and Cade, 1957; Howell and Bartholomew. 1959) and need not be reviewed here.

PORE CANALS AND RELATED STRUCTURES IN INSECT CUTICLE

The fine structure and the distribution of an esterase have been studied in the cuticle of Galleria larvae, Tenebrio larvae and pupae, and in the wax-secreting cuticle of the honey bee, and compared with those in the cuticle of the caterpillar of Calpodes. In Galleria and Tenebrio the pore canals are spaces passing through the lamellate endocuticle from the epithelium to the epicuticle. They contain a filament from the cells which may be concerned in their formation. The shape of the pore canal is probably determined by the orientation of the fibres making up the lamellae in the endocuticle and is not a regular helix. The pore canals also contain numerous filaments of another sort which pass on through the epicuticle and are believed to be the origin of the surface wax. They are particularly abundant in the pore canals of the honey bee wax-secreting cuticle and extend into the cell in long pockets surrounded by an envelope of the plasma membrane. The esterase is probably concerned with the final stage of wax synthesis, for its distribution is similar to that of the lipid filaments.

The stimulus to feeding in larvae of Tenebrio molitor L.

The feeding behaviour of larvae of Tenebrio molitor has been studied from the standpoint of the modern concept that phytophagous insects may require a phagostimulant for normal feeding. It is shown that Tenebrio larvae discriminate between different parts of the wheat grain, preferring the bran, and that when this is all consumed the total amount eaten falls markedly. Evidence is offered that this is not a nutritional effect but a true response to a feeding stimulus. Tenebrio larvae will not eat powdered cellulose even when previously starved, but the addition of only 2 1 2 per cent flour causes them to eat the mixture. If the particles are fine enough the larvae cannot avoid eating cellulose in addition to the nutritive constituent. Yet they are still able to exercise some discrimination, for calculations from the increase in true body weight proves that the percentage of flour in the material actually ingested is higher than the percentage in the mixture offered. Complete discrimination can be effected if the stimulant constituent consists of larger particles. The response-promoting substance is localized in the inner layers of the bran. The feeding response is not evoked by simple proteins, carbohydrates or fats. Among natural substances other than wheat flour, very strong responses are evoked by dried yeast and by fishmeal.

The Waterproofing Mechanism of Arthropods

ABSTRACT The relationship between the temperature of the cuticle and its permeability to water has been determined for a number of different terrestrial arthropods. In most of these animals the waterproofing wax loses its great impermeability to water very abruptly at a particular transition temperature; that temperature varies appreciably with the individual, but appears to be characteristic of any one species at a particular age within a particular instar. No change in permeability with temperature was found in Tipula sp. taken from soil, in which the cuticle was greatly damaged ; above 48° C. the permeability of the cuticle of Schistocerca nymphs changes rapidly with increasing temperature, but this change is not abrupt. In the permeability/temperature curves for larvae of Pieris, Tenebrio, Calliphora and Nematus, pupae of Calliphora and adults of Schistocerca, Ixodes and Ornithodorus only one transition discontinuity is found. In all these animals the wax maintains almost constant permeability up to the point of transition, above which permeability increases very rapidly with temperature. Immediately after moulting, Rhodnius nymphs and pupae of Tenebrio and Pieris also reveal only one transition point; this occurs at a comparatively low temperature. But when cement is secreted over the primary wax layer, a second and higher transition point is found which is independent of the first point. The lower transition temperature seems constant in position during the life of an instar, but the upper point occurs at progressively higher temperatures as the instar ages. The evidence suggests that these animals have two special waterproof layers of wax, the one with high transition temperature occurring on the outer surface of the cement. This outer layer could arise by the migration of wax from the primary layer (with lower transition temperature) through the cement to the outer surface, there to lose volatile components and waterproof the surface. In every animal investigated a permanent increase in permeability is produced by heating a wax layer above its transition point; after such treatment no transition point can be found. From calculations of the absolute permeability of the various wax layers, and from the behaviour of the wax, it is suggested that all epicuticular waxes are laid down with some special molecular arrangement and that in very waterproof insects this may extend throughout the thickness of the wax layers; in less waterproof insects only a portion of the wax layer (as in the cockroach) may be specially organized. Very slight mechanical damage promotes increased transpiration through the cuticle. Stationary adsorptive dusts applied directly to a primary wax layer do not affect permeability; applied to wax above the cement, they promote rates of evaporation in excess of the value exhibited by the same cuticle having a primary wax layer alone. This phenomenon is discussed in relation to the distribution of water within the transpiring cuticle.

The Co-ordination of Growth in the Tracheal System of Insects

ABSTRACT The tracheae in Rhodnius and many other insects are parallel-sided tubes which branch in such a way that the cross-section of the diffusion path remains constant. Growth in length results mainly from stretching the trachea in the preceding instar. Growth in diameter of the tracheae varies with feeding and the organ supplied. The proportions of the tracheal system are maintained by co-ordination of the growth of the main tracheae and new terminal branches. This is brought about by the property of tracheae which enables them to react to stimuli for growth only upon the spiracle side of the point of application. The stimuli for growth probably originate from the tissues and from the nodes. They determine first the diameter of the tracheae farthest away; that is, the tracheae begin to form at the spiracles. The nodes controlling the diameter of the lateral tracheae are influenced by the blood. Growth in the tracheal system of Tenebrio larvae varies inversely with the oxygen tension both above and below atmospheric.

Characteristics of the Stipa Comata‐Bouteloua Gracilis‐Bouteloua Curtipendula Association in Northern Colorado

1. The effects of mold in the cultures of Tenebrio molitor on pupal and adult weights are given, and these weights are compared with weights of pupal and adult beetles reared in normal cultures without mold. 2. The results of a few observations are given of the interactions among the several grain inhabitants that may occur with Tenebrio molitor: the flour beetles of the genus Tribolium, the flour moth Ephestia, and mites of the genus Acarus. Of these, Tribolium appears to be more detrimental to populations of Tenebrio, but the mites show the greatest fluctuations in population density. 3. Analyses of the reactions of Tenebrio larvae and adults to various conditions of light, dark, and the presence of the insecticide paradichlorobenzene (PDB) are given. Various combinations of these conditions indicate that the apparently inherent photonegativity of the species is a stronger directing force in the behavior and orientation of Tenebria than is its negativity to the lethal chemical PDB. 4. Humidity experiments showed that the animal does not usually aggregate in the dark, but under various conditions of light, dark, moisture and dryness, aggregations were seen to form as negative responses. 5. Observations of the widespread phenomenon of letisimulation (death feigning) are described. The adults are more inclined to exhibit this behavior than are the larvae or pupae. 6. The tendency of Tenebrio to acclimate to unnatural circumstances has been described. This was shown in the responses to light intensity, poisonous chemicals, and mechanical stimulation by handling.

The effect of some derivatives and structural analogs of carnitine on the nutrition of Tenebrio molitor

Various compounds structurally related to carnitine were tested on carnitine-deficient Tenebrio larvae to determine whether they would replace carnitine or act as inhibitors. The sulfonic acid and triethyl analogs demonstrated weak carnitine activity. The activity of the O-acetyl derivative and the ethyl ester was almost as high as that of the parent compound. γ-Butyrobetaine was found to inhibit carnitine in a competitive manner, with an inhibition index of 100 to 1000. Compounds other than noted above were found to be both inactive and nontoxic to larvae. It appears that the length of the carbon chain between the onium and carboxyl group, the presence of the onium group, and the presence of a free or easily freed β-hydroxyl group are the most influential factors in determining the physiological activity of carnitine.

Xanthine Oxidase of the Clothes Moth, Tineola Bisselliella, and Some Other Insects

Xanthine oxidase activity in Tineola larvae averages 200� /!moles of uric acid per g whole larva (wet weight) per hr and in Tenebrio, Lucilia, Anthrenocerus, Ephestia, and Anthrenus larvae activity ranges between 13�4 and 1�3. The optimum pH for Tineola xanthine oxidase lies between pH 7�7 and 8� 0, and the optimum concentration of xanthine is at or below 1�3 X 10-3M. Methylene blue in concentrations up to 5�3 X 1O-3M has no toxic effect on this enzyme, and the lower concentrations of methylene blue have a limiting effect. Cyanide and 6-pteridyl aldehyde inhibit Tineola xanthine oxidase. The insect xanthine oxidases are demonstrated to be dehydrogenases. DPN, and pyruvate and DPN together, stimulate uric acid production by Tineola xanthine oxidase in the absence of methylene blue. In Tenebrio larvae there is a higher concentration of xanthine oxidase in the midgut and fat-body than in the remaining tissues.

The response of marine worms to unilateral tension of their musculature.

It has been shown that in Lumbricus1 and Nereis2 the anterior segments of the animal respond to passive bending of the posterior part, by active turning of the head in a direction parallel with the new orientation of the tail. This has been termed the homostrophic reflex. The receptors for the reflex are distributed throughout the animal but the efferent nerves are limited in their origin to the anterior 20 segments in Lumbricus, and to the first 2 or 3 segments in Nereis. The afferent impulses travel forward by way of the ventral nerve cord. Bending of the head end does not affect the direction of backward locomotion, hence the mechanism of the homostrophic reflex exhibits polarity. Similar observations3 have been recorded for Diplopods and for the larvae of Tenebrio molitor.A systematic study has shown the homostrophic reflex to play a part in the behavior of a number of nereid worms of the Mediterranean, namely, Eunice gigantea, Eunice siciliensis, Holla parthenospeia, Nephthis scolopendroides, Sthenela...