Development and Dehiscence of Gametocysts of the Gregarine Pyxinia crystalligera Frenzel

SYNOPSIS. Association of gamonts of Pyxinia crystalligera takes place in the midgut of its beetle host, Dermestes vulpinus. At 25°C. the development of gametocysts to the point of liberation of sporocysts is completed between about 15 hours and 27 hours after the gametocysts are deposited with fecal material. Dehiscence is favored by relative humidities of 0% to 90%, but is not favored by a relative humidity of 100%. During the early development of the gametocysts outside the host, the crystals and paraglycogen granules in the cytoplasm of the associated gamonts become concentrated in large masses. The gametes are formed at the periphery of the gamonts. After fusion of the gametes takes place and the sporoblasts begin to develop, the residual cytoplasm containing the inclusions moves outward to form a continuous layer next to the gametocyst envelope, so that the sporoblasts become crowded into a central core. A few hours before dehiscence is initiated a clear area appears on the upper side of the gametocyst. The contents of the gametocyst begin to shrink away from the envelope except in the region of the clear area. Eventually the sporocysts emerge through the clear area and press against the envelope of the gametocyst, causing formation of a conical papilla in the envelope. With continued pressure from the sporocysts, the papilla ruptures at its tip, and the sporocysts emerge in a continuous thread until dehiscence is completed. The thread of sporocysts may attain a length of about 11 mm.     

Gregarines on a diet: the effects of host starvation on Gregarina confusa Janovy et al., 2007 (Apicomplexa: Eugregarinida) in Tribolium destructor Uyttenboogaart, 1933 (Coleoptera: Tenebrionidae) larvae

This study was designed to explore the nutritional relationship between Gregarina confusa (Apicomplexa: Eugregarinida) parasites and its coleopteran host, Tribolium destructor, by measuring the cytoplasmic density of gregarines in continuously fed larvae, starved larvae, and larvae refed after starvation. Cultures were maintained in a standard media (whole wheat flour:commercial wheat germ:yeast [30:10:1]). Larvae from control and experimental groups were dissected daily for 3 days then allowed to feed or starve for an additional 3 days. On day 6, the remaining experimental larvae were divided and placed into 2 groups; 1 group remained starved while larvae from the second group were fed a Wheaties flake. Photographs were taken of the parasites daily and analyzed using ScionImage. Gregarines from starved larvae were significantly longer and skinnier than those from fed controls, and there was also a significant difference between gregarine deutomerite cytoplasmic densities. Parasites from refed larvae regained cytoplasmic density within 24 hr and showed morphological similarities to those from fed larvae. This study shows that the Tribolium destructor-Gregarina confusa relationship can be manipulated easily through alterations of host diet and thus is an excellent model for use in the study of chemical relationships between parasites and their hosts.     

Metabolic changes in the African fruit beetle,Pachnoda sinuata,during starvation

Specimens of the fruit beetle Pachnoda sinuata were starved for up to 30 days. The weight of the beetles declined consistently throughout the starvation period. Concentrations of carbohydrates and alanine in flight muscles, fat body and haemolymph decreased rapidly after onset of starvation, while the concentration of proline remained high. Whereas the lipid concentrations in the haemolymph did not change significantly upon starvation, the lipid content in flight muscles and fat body decreased significantly.Beetles that had been starved for 14 days responded to injection of Mem-CC, the endogenous neuropeptide from its corpora cardiaca, with hyperprolinaemia and a decrease in the alanine level, but no such effect was monitored after prolonged starvation of 28 days. Regardless of the period of starvation, Mem-CC injection could not cause hypertrehalosaemia or hyperlipaemia, although carbohydrates were increased in fed beetles after injection.Flight ability of beetles that had been starved for 15 or 30 days was apparently not impaired. During such periods, beetles used proline exclusively as fuel for flight as evidenced by the increase in the level of alanine in the haemolymph and decrease of the level of proline; the concentrations of carbohydrates and lipids remained unchanged.Activities of malic enzyme and alanine aminotransferase (enzymes involved in transamination in proline metabolism), glyceraldehyde-3-phosphate dehydrogenase (enzyme of glycolysis), 3-hydroxyacyl-CoA dehydrogenase (enzyme of beta-oxidation of fatty acids) and of malate dehydrogenase (enzyme of Krebs cycle) were measured in fat body and flight muscles. In flight muscle tissue the maximum activity of NAD(+)-dependent malic enzyme increased, while that of glyceraldehyde-3-phosphate dehydrogenase decreased during starvation, and malate dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase and alanine aminotransferase were unchanged. In fat body tissue, activities of NADP(+)-dependent malic enzyme and 3-hydroxyacyl-CoA dehydrogenase increased during food deprivation and activities of glyceraldehyde-3-phosphate dehydrogenase, malate dehydrogenase and alanine aminotransferase remained unchanged.     

Life history response and age-specific tolerance to starvation in Brachionus plicatilis O.F. Müller (Rotifera)

To examine the life history response and age-specific tolerance to starvation in the rotifer Brachionus plicatilis O.F. Müller, we carried out two series of individual culture experiments. In the first experiment, rotifers were fed until each of the ages of 1-4 days, and were then starved during the rest of their lifetimes. The control group was fed throughout their lifespans. Rotifers stopped active reproduction just after the onset of food deprivation, and showed shorter subsequent survival times when they were starved at older ages. The finding that the larger the number of offspring produced before food deprivation, the shorter the subsequent lifetime under starvation, appeared to reflect a trade-off with the cost of reproduction. In the second experiment, newborns were starved until each of the ages of 1-5 days, and were fed thereafter. The lifespans of the rotifers starved up to the age of 3 days were not statistically different from those that were not starved. Although the starved rotifers began to reproduce once fed again, their lifetime fecundity decreased significantly from that of the non-starved group. Based on these results, it was suggested that the reproductive suppression caused by starvation would cause rotifers to have a longer lifespan to allow for future reproduction.     

Starvation and the Mating Success of Wild Male Mediterranean Fruit Flies (Diptera: Tephritidae)

Recent evidence suggests that the nutritional state of male Mediterranean fruit flies, Ceratitis capitata (Wied.) (medfly), is an important influence on various components of their reproductive biology, including mating success. The objective of the present study was to examine experimentally the effect of temporary starvation on the mating success of wild male C. capitata. Males were maintained on protein–sugar or sugar-only diets, and for each diet we compared the mating success of continuously fed males versus males starved for 18 or 24 h immediately before testing. In trials conducted on field-caged, host trees, males starved for 24 h obtained only about half as many matings as fed males for both diets. However, when the starvation period was 18 h, starved males reared on the protein–sugar diet mated significantly less frequently than fed males, whereas starved males reared on sugar mated as often as fed males. Measurements of male pheromone calling and female attraction revealed that reduced mating success likely reflected the decreased signaling activity of starved males.     

Resistance to adult banded cucumber beetle (Coleoptera: Chrysomelidae) in romaine lettuce

Four cultivars of lettuce, Lactuca sativa L., were evaluated for their resistance to the adult banded cucumber beetle, Diabrotica balteata LeConte, under laboratory conditions. When paired with each of the other three cultivars, leaf consumption in all possible combinations of short-term (48 h) two-choice tests among the cultivars was significantly reduced only for 'Valmaine'. However, in a 48-h no-choice situation, beetles fed Valmaine or 'Short Guzmaine' had similarly low leaf consumption, followed by 'Parris White', with the greatest consumption occurring on 'Tall Guzmaine'. In longer term experiments, female beetles fed Valmaine for 10, 13, or 16 d generally had lower survival and the lowest body weights compared with beetles fed any of the other three cultivars. No mature eggs were found in the ovaries of females fed Valmaine, whereas from 14% (Short Guzmaine, day 10) to 100% (Tall Guzmaine, day 13) of females fed the other cultivars produced mature eggs. In a starvation test, most D. balteata of either sex did not survive after 7 d with access only to water. Moreover, starved females did not produce mature eggs. Thus, food consumption by adult D. balteata is very important to their survival and reproductive performance, and it is likely that females fed Valmaine failed to produce mature eggs because they did not consume a sufficient amount of this cultivar. However, because Valmaine-fed beetles maintained their body weight and lived significantly longer than starved beetles, it appears that they can obtain some nourishment from their limited feeding on this cultivar. Overall, these results suggest that Valmaine, and to a lesser extent short Guzmaine (a cultivar produced by crossing Valmaine with two other cultivars), exhibit antixenosis-based resistance against D. balteata.     

Effect of diet and feeding history on flight of Colorado potato beetle, Leptinotarsa decemlineata

We evaluated the hypothesis that Colorado potato beetle (Leptinotarsa decemlineata Say) (CPB) flight frequency is related to diet, and that it changes with duration of food unavailability or exposure to poor quality food by exposing adult overwintered and summer CPB populations to an acceptable host plant (conventional foliage), a poor host (insect resistant transgenic foliage expressing Bacillus thuringiensis tenebrionis[Btt] Cry3a toxin) and no host. Exposure to poor host and no host treatments (with or without water) decreased mean daily flight frequencies and the overall number of overwintered CPB flying, but increased the mean daily flight frequency and number of summer population CPB that flew. Overwintered CPB did not react to an absence of plants at emergence whereas summer CPB increased mean daily flight frequencies when plants and water were not available. The flight response to insect resistant foliage was similar to that for starvation treatments in both populations indicating that flight may not be triggered by Btt toxins but by starvation brought on by feeding on poor quality food. Flight was observed in all treatments for the duration of the test with two exceptions; overwintered beetles fed insect resistant foliage ceased flying after day 17 and summer beetles starved without water ceased after day 8 of a 29‐day study.     

Capacity of Bembidion lampros and Tachyporus hypnorum to survive periods of starvation in early spring

The capacity of the polyphagous predators Bembidion lampros Herbst (Coleoptera; Carabidae) and Tachyporus hypnorum F. (Coleoptera; Staphylinidae) to survive starvation in early spring was investigated. The two species are of similar size and live in the same habitat. They have similar life cycles; where adults emerge in autumn, hibernate during winter and disperse during spring into arable fields where they reproduce and then die. Both species showed an ability to survive long periods of starvation after hibernation. However, B. lampros could live without food several weeks longer than T. hypnorum.Fat content was measured to estimate the energy reserves of beetles in the field. The fat content of B. lampros was at a constant level of 23% both when fed ad libitum in the laboratory and when collected in the field during spring. The fat content of B. lampros was reduced to a level of 7% when they died by starvation. Fat content of T. hypnorum was more variable both when fed ad libitum in the laboratory (17–33%), when collected in the field during the spring (20—26%) and when they died by starvation (10–20%).Neither the mean longevity of starved beetles nor the fat content of specimens collected in the field indicated that the beetles suffered high mortality due to a food shortage in early spring before movement into arable fields.     

Gregarina hylobii and Ophryocystis hylobii n. sp. (ophryocystidae,neogregarinida) parasitizing Hylobius abietis (Curculionidae,coleoptera)

Two sporozoan parasites, Gregarina hylobii and Ophryocystis hylobii n. sp., parasitizing the adults of natural populations of Hylobius abietis are described. The gregarine G. hylobii, a parasite of the gut of H. abietis, has been reexamined and its complete life cycle, including the solitary gamonts, gametocysts, and sporoducts is described. The life cycle of the neogregarine O. hylobii infecting the Malpighian tubules of host animals examined at light and electron microscope levels is discussed. Some data on the prevalence of infections and host-parasite relationships are also discussed.     

Septate Gregarines From Reticulitermes Flavipes and Reticulitermes Virginicus (Isoptera: Rhinotermitidae)

ABSTRACT. The gregarine parasites of Reticulitermes virginicus and Reticulitermes flavipes begin their development as trophozoites attached to the midgut epithelium by a small button-shaped epimerite. the epimerite is lost when the parasite becomes free-living in the gut lumen as a solitary gamont. Syzygy is late and was not observed. When full-grown, gamonts enter the hemocoel and fuse in pairs to form large gametocysts that are attached to the midgut of the termite by a duct. Thousands of sporocysts are formed within the original gametocyst. the mature sporocysts are released into the lumen of the midgut through the connecting duct. They are then passed out with the feces. These gregarines are believed to be identical to Gregarina termitis Leidy which was described from a single gamont and later erroneously placed in the genus Hirmocystis by Henry.     

The impact of food type, temperature and starvation on larval development of Balanus amphitrite Darwin (Cirripedia: Thoracica)

The impact of diatom food species (Chaetoceros calcitrans and Skeletonema costatum), temperature and starvation on the larval development of Balanus amphitrite was evaluated. Starvation threshold levels for different ages of larvae (0- to 5-day-old) fed with C. calcitrans and S. costatum and then starved at 5, 15 and 25 °C temperature were estimated as ultimate recovery hour (URH; denoting the starvation point in hours at the end of which larvae can recover and continue development). Effect of temperature on starvation threshold varied significantly with larval age and food species. The URH declined with larval age at 5 °C, but not at 15 and 25 °C. The URH and grazing rates were high for early instars fed on C. calcitrans, and for advanced instars fed on S. costatum. Carbon gain through feeding was maximum for 2-day-old larvae when fed with C. calcitrans and decreased with larval age. However, when fed with S. costatum carbon gain increased with larval age. This confirms that with development the utility of food types changes. The differences in the carbon gain can be attributed to differences in grazing rate due to variations in the size of the diatom cells, larval intersetular distance, diatom sinking rate and the photo-taxic behavior of larvae. Molting was observed at times when larvae were undergoing starvation and this could be viewed as stress-induced molting, and it differed with the larval age and food organisms.     

Feeding and activation of corpora allata in the cockroach Blattella germanica (L.) (Dictyoptera,Blattellidae)

Adult females of the cockroach Blattella germanica have clearly-defined feeding cycles related to oogenesis. In the first cycle, food ingestion precedes volumetric increase in the corpora allata, which in turn precedes juvenile hormone production, whereas starved females do not develop the corpora allata and produce very low amounts of juvenile hormone. When the second gonadotropic cycle is provoked by removing the ootheca, the first event observed is an increase in food consumption, followed by an increase in corpora allata volume and activity. However, this increase in corpora allata volume (and activity) does not occur if females are starved, thus indicating that the ootheca in the genital chamber inhibits primarily feeding, and indirectly corpora allata development and activity. Corpora allata volume in isolated heads from starved and decapitated females was able to increase to levels similar to fed controls, but this increase was abolished by allatostatin treatment. We suggest that a factor produced in the thoracico-abdominal compartment, which reaches the head mainly through a nervous pathway, is released during starvation and inhibits corpora allata development. This factor may stimulate allatostatin production or release, or may well be allatostatin itself.     

Physiological and metabolic adjustments of Hoplosternum littorale (Teleostei,Callichthyidae) during starvation

All animals face the possibility of limitations in food resources that could ultimately lead to mortality caused by starvation. The primary goal of this study was to characterize the various physiological strategies that allow fish to survive starvation. A multiparametric approach, including morphological biomarkers, blood plasma metabolites, oxidative stress and energy reserves, was used to assess starvation effects on the fish Hoplosternum littorale. Adult specimens were maintained at four experimental groups: control (fed ad libitum), and starved (not fed) fish for 7 and 28 days. Significant changes were observed not only after 28 days, but also after 7 days of starvation. In the shorter period, the hepatosomatic index as well as plasma triglycerides and glucose were significantly lower in starved fish than in the control ones. These results were accompanied by reduced lipid, glycogen and protein reserves in liver and diminished glycogen content in muscle, suggesting the need of these macromolecules as fuel sources. In addition, increased antioxidant enzyme activities were observed in gills, without evidence of oxidative stress in any of the evaluated tissues. Most significant differences were found in 28-days starved fish: total body weight together with the hepatosomatic index was lower when compared to control fish. The plasmatic metabolites tested (glucose, triglyceride, cholesterol and protein), all energy reserves in liver and glycogen content in muscle decreased in 28-days starved fish. Lipid oxidative damage was reported in liver, kidney and brain, and antioxidant enzymes (GST, GR, GPx and CAT) were activated in gills. According to the multivariate analysis, oxidative stress markers and metabolic parameters were key biomarkers that contributed in separating starved from fed fish. Our study allowed an integrated assessment of the fish response to this particular condition.     

The Life Cycle of Ganymedes oaklandi n. sp., an Acephaline Gregarine of Gammarus fasciatus (Say)*

SYNOPSIS. Ganymedes oaklandi n. sp. (Ganymedidae) from the intestine of Gammarus fasciatus (Say) is described, and its life cycle is given. In the trophic stage the gregarine is acephaline, with an elongated cylindrical body slightly tapered anteriorly, and is up to 298 × 64 μ. The gametocysts are up to 121 × 99 μ, and are covered with a secreted thick sticky gelatinous coat. The spores are released from the gametocyst by rupturing of the cyst wall. The spore body is spherical, approximately 6 μ in diameter, and has 4 episporal rays about 20 μ long.     

The influence of changes in food availability on the activities of key degradative and metabolic enzymes in the liver and epaxial muscle of the golden perch

This study investigated the influence of feeding frequency on the activities of important degradative enzymes and potentially rate-limiting enzymes in glycolysis and gluconeogenesis in the liver and white epaxial muscle of Macquaria ambigua . Adult animals were either fed daily to satiety (fed), deprived of food for up to 180 days (starved), or starved for 150 days then fed daily to satiety for 30 days (starved/fed). The activities of lipolytic, glycogenolytic and glycolytic enzymes in the livers of starved fish were maintained as long as liver energy stores were available, but became significantly reduced following their exhaustion indicating a decline in metabolism in response to prolonged starvation. The response of epaxial muscle metabolism to changes in food availability was different to that of the liver, as no significant change in the activities of muscle lipolytic or glycogenolytic enzymes were observed in response to starvation. Muscle tissue metabolism was reduced after 60–90 days of starvation, but then returned to prestarvation levels.     

Juvenile Hormone and Insulin Regulate Trehalose Homeostasis in the Red Flour Beetle,Tribolium castaneum

Insulin/IGF-1 signaling (IIS) has been well studied for its role in the control of life span extension and resistance to a variety of stresses. The Drosophila melanogaster insulin-like receptor (InR) mutant showed extended life span due to reduced juvenile hormone (JH) levels. However, little is known about the mechanism of cross talk between IIS and JH in regulation of life span extension and resistance to starvation. In the current study, we investigated the role of IIS and JH signaling in regulation of resistance to starvation. Reduction in JH biosynthesis, JH action, or insulin-like peptide 2 (ILP2) syntheses by RNA interference (RNAi)-aided knockdown in the expression of genes coding for juvenile hormone acid methyltransferase (JHAMT), methoprene-tolerant (Met), or ILP2 respectively decreased lipid and carbohydrate metabolism and extended the survival of starved beetles. Interestingly, the extension of life span could be restored by injection of bovine insulin into JHAMT RNAi beetles but not by application of JH III to ILP2 RNAi beetles. These data suggest that JH controls starvation resistance by regulating synthesis of ILP2. More importantly, JH regulates trehalose homeostasis, including trehalose transport and metabolism, and controls utilization of stored nutrients in starved adults.     

Effects of repeated cycles of starvation and refeeding on lungs of growing rats.

Adult male rats were subjected to four cycles of mild starvation (2 wk) and refeeding (1 wk) and were compared with a fed group. Starvation was induced by giving rats one-third of their measured daily food consumption. During each starvation cycle, rats lost approximately 20% of their body weight. Despite catch-up growth and overall weight gain, starved rats had lower final body weight than fed rats. Lung dry weight and lung volumes were also reduced in the starved group. The mechanical properties of air- and saline-filled lungs did not change significantly with repeated cycles of starvation. Mean linear intercept was similar in the two groups, but alveolar surface area was reduced in the starved rats. Total content of crude connective tissue and concentration per lung dry weight of hydroxyproline and crude connective tissue were reduced in starved rats. We conclude that lung growth is retarded in growing rats subjected to repeated cycles of mild starvation and refeeding, as manifested by smaller lung volume and reduced alveolar surface area. Because alveolar size is unchanged, a reduced number of alveoli is most likely responsible for decreased lung volumes.     

Digestive enzyme profiles reveal digestive capacity and potential energy sources in fed and starved spiny lobster (Jasus edwardsii) phyllosoma larvae

The impact of starvation on the digestive enzyme (protease, trypsin, lipase and amylase) activities of Stage I and IV Jasus edwardsii phyllosoma larvae was used to identify the nutrients metabolised or conserved during food deprivation, highlighting the most critical energy reserves. Protease activities increased significantly in both Stages I and IV phyllosoma, suggesting that protein catabolism provided energy during food deprivation. Lipase activity decreased significantly in starved Stages I and IV larvae indicating that lipid may be spared for fuelling later developmental moults. The use of protein, while sparing lipid, may provide immediate energy but not at the expense of long-term lipid energy stores which are known to be important during their lengthy larval phase. The preferential use of protein during short-term periods of starvation suggests that particular attention must be given to providing sufficient protein in artificial diets at all times. Amylase activity in starved Stage I larvae was lower than in fed animals, suggesting that the starved animals are not gaining sufficient carbohydrate. However, amylase activity was similar in fed and starved Stage IV larvae, possibly due to the catabolism of accumulated glycogen stores that were not sufficiently developed in Stage I animals.     

Effect of food shortage and temperature on oxygen consumption in the lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

Abstract.  Temperature and food availability are limiting factors for the establishment of tropical insects in temperate countries. In the alien pest beetle, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), starvation and temperature have a significant impact on metabolic rate with oxygen consumption ranging from 0.5 µmol/g fresh mass (FM)/h at 12 °C to 3.4 µmol/g FM/h at 24 °C. At 12 °C, oxygen consumption decreased continuously during an entire period of starvation. However, at 16, 20 and 24 °C, beetles display a marked hyperactivity that leads to an increase in the oxygen consumption level during the first week of starvation, followed by a steep decrease until the end of the starvation period. Oxygen consumption either does not decline in fed beetles (observed at higher temperatures) or declines at a much shallower rate than in starved beetles (observed at cooler temperatures). During the first week of refeeding, Oxygen consumption rose steeply at 16, 20 and 24 °C before levelling off to the initial value ( t ₀). At 12 °C, no compensation process was observed during recovery. This study reveals that an important threshold in the biology of A. diaperinus lies between 12 and 16 °C, leading to the onset of reduced locomotor activity and the promotion of survival to the detriment of reproduction. This 'sit and wait' behaviour is proposed as an adaptive strategy (i.e. inactivity and lower oxygen consumption coupled with low energetic requirements and high recovery abilities). Such behaviour and the observed hyperactivity were rarely described in insects before the present study. Together, the previous and present results suggest that A. diaperinus populations are likely maintained in temperate regions by immigration from warmer situations.     

Temporal changes in digestive enzyme activities in the gastrointestinal tract of European eel (Anguilla anguilla) (Linneo 1758) following feeding

Changes occurring after feeding in the digestive enzyme activities of European eel were investigated to provide some insights into the digestive physiology of this fish. Total and specific proteases, amylase and lipase activities were measured using standard biochemical assays over a 24 h cycle in fed eels, compared to starved ones, under the same rearing conditions. In the gastrointestinal tract of fed eels quantitative changes started 4 h after feeding and continued later on; conversely, in starved eels enzyme activities remained unchanged over time. In fed eels, total and specific protease activities showed an overall increasing trend in the intestine, while in the stomach they progressively decreased to values 22–50% lower than those measured at the pre-feeding time; this behaviour probably reflected the progression of digesta along the intestinal tract. The prolonged secretory response of European eel to food ingestion proved its extended activity in the digestive process.