Physiology of feeding-preference patterns of female black blowflies (Phormia regina Meigen): Modification in responsiveness to salts subsequent to salt feeding

Behavioural experimentation on Phormia regina shows that females previously fed only sucrose, and thus in a state of yeast preference, will ingest single-salt-sucrose mixtures in volumes similar to that of 10% yeast (Rachman et al., 1982). In particular, females will ingest NaCl 0.1 M in 0.2 M sucrose in volumes not statistically different from 10% yeast. In the experiments reported here, groups of females were given ad libitum access to both 0.2 M sucrose and NaCl 0.1 M in 0.2 M sucrose from days 0–4 after eclosion. Potassium and sodium salts were added to 0.2 M sucrose over a spectrum of concentrations and presented to the flies on day 6. The flies rejected all single-salt-sucrose mixtures offered. Even when the pre-test sodium salt was changed to a potassium salt during days 0–4, the flies still rejected the single-salt-sucrose mixtures offered subsequently. However, when sodium and potassium salts were mixed together in 0.2 M sucrose, females ingested the solutions in amounts similar to 10% yeast. Several different concentrations of the double-salt-sucrose solutions were ingested in volumes not statistically different from 10% yeast. Results support the underlying hypothesis that activity in the salt-sensitive chemosensory neurones is involved in protein preference.     

Physiology of feeding preference patterns of female black blowflies (Phormia regina Meigen)

Summary The relative effectiveness of 0. 1 M sucrose and 10% yeast extract in eliciting feeding by femalePhormia regina has been shown to be related to the fly's carbohydrate reserve levels. Females that have had ad lib. access to 0.1 M sucrose (S flies, standard condition) take larger drinks of 10% yeast than 0.1 M sucrose starting at three days of age, indicating that 10% is the more effective feeding stimulus. Females that have had ad lib. access to 0.1 M sucrose and 10% yeast (S/Y flies, standard condition) always drink more 0.1 M sucrose than 10% yeast (Fig. 1). S/Y (standard condition) flies appear to respond to the yeast as if it were dilute carbohydrate: the volumes of 0.1 M sucrose and 10% yeast that they drink fluctuate in parallel. S (standard condition) flies respond to the yeast differently: starting day 3, their drink volumes of 10% yeast increase as drink volumes of 0.1 M sucrose decrease.The elevation of the volume of 0.1 M sucrose drunk by flies whose carbohydrate reserve levels have been depleted by diet, starvation or flight (Figs. 2–4) supports the hypothesis that some physiological state or process related to carbohydrate metabolism regulates the fly's responsiveness to yeast extract. Possible mechanism by which the fly translates carbohydrate reserve level into feeding preference are discussed. Available evidence points to a CNS phenomenon, probably involving the stomatogastric nervous system. The pattern of the selective feeding cycle of femalePhormia can be explained in terms of the accumulation and utilization of carbohydrate reserves.This work was supported by a Spencer Foundation Predoctoral Fellowship from Princeton University and by NSF Grant number BNS 76-02172 to Dr. Vincent G. Dethier. I am grateful to the Departments of Zoology and Entomology of the University of Massachusetts, Amherst, for the use of their facilities. Many thanks to Drs. V.G. Dethier, Elizabeth Bowdan and David Falk for critical discussion and assistance.     

Antennal gustatory perception and behavioural responses in Trissolcus brochymenae females

Trissolcus brochymenae (Hymenoptera: Platygastridae) is an egg parasitoid that could be used to control stink bugs like Murgantia histrionica (Heteroptera: Pentatomidae), a pest of brassicaceous crops. Before laying their eggs, parasitoid females spend considerable time examining the substrate with their antennae, which are also used during feeding and mating behaviours. This suggests that contact chemoreception plays a prominent role in many aspects of parasitoid ecology. Therefore, we examined the sensitivity of antennal taste sensilla chaetica to several classical tastants including those that are appetitive or aversive. In addition we studied the taste preferences of wasps when presented with these chemicals alone or mixed. The sensilla chaetica of T. brochymenae responded to serial concentrations of sucrose, salts, and quinine, but no concentration-dependent effect was observed when testing sinigrin, a secondary metabolite found in many brassicaceae. However, both sinigrin and quinine inhibited responses to 0.1 M sucrose when mixed with this sugar. Behavioural taste preference assays confirmed that wasps showed a dose dependent preference for sucrose over agarose. In addition, a behavioural avoidance of sucrose solutions containing quinine was observed. This effect was not observed when sinigrin was used as a feeding deterrent. In the two-choice tests the wasp did not discriminate between sucrose solutions mixed with salts and sucrose alone. Further no preference for salts or sinigrin compared to agarose alone was observed. This work represents the first step towards the identification of gustatory receptor neurons implicated in the detection of different types of chemical cues in egg parasitoids.     

Taste responses of Drosophila melanogaster

The amounts of sugar solution consumed by Drosophila melanogaster flies were determined. Starved and desiccated flies of a wild type strain (QA) consume 7?9 × 10^?2 λ of a 0.3 M sucrose solution per fly during the first hour and less later. They consume more of the 0.3 M sucrose solution than of the more diluted and the more concentrated solutions. In preference-aversion tests the flies discriminated between water and various sugar solutions, and between different sugar concentrations. Contrary to other fly species these flies did not prefer 0.05 M fructose over 0.05 M glucose. 0.3–0.5 M NaCl added to 0.1 M sucrose turned a preference over 0.01 sucrose into an aversion. A mutant, Lot-94, selected for its increased consumption of a 1 M NaCl solution was found to consume more of all test solutions. The amount of NaCl that had to be added to 0.1 M sucrose to turn the preference over 0.01 M sucrose by the mutant flies into aversion was not different from that found for the wild type flies.     

Long Term Feeding Patterns Highlight Preference for Sucrose in the Fruit Fly <Emphasis Type="Italic">Anastrepha serpentina</Emphasis> When Given a Choice over Other More Nutritious Food Sources

Insects are known to be able to regulate food ingestion according to its nutrient composition rather than its energetic content. Several studies have found that individuals can feed selectively when given the opportunity, and balance the intake of different nutrients so as to optimize fitness. However, there are cases in which individuals do not strictly adopt this pattern of optimal nutrient balancing. This study examined the periodicity of feeding on different food substrates and also water by adult individuals of Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) over a 38-day observation period analyzing daily feeding patterns, feeding time, and sequences of feeding events. Two artificial food substrates, one rich in protein (hydrolyzed yeast) and one rich in carbohydrates (sucrose), and one natural diet (open sapodilla fruit) were offered alone or paired (sucrose vs. open fruit or sucrose vs. yeast) to newly emerged individuals during 38 days or until death. Water was also provided in all cases. Our results provide new and interesting insights on long-term individual dietary preferences and feeding periodicity in a tropical fruit fly, including water consumption. In general, flies exhibited different feeding patterns according to the diet, but preferred to feed on sucrose when offered a choice of sucrose and yeast. This preference was evident from the outset of the trial. When sucrose was offered together with an open fruit, the latter was preferred. However, there were conspicuous individual differences in temporal feeding patterns among flies fed the same diet, including variability in the number of consecutive days some individuals did not consume any food or water (up to five days in some cases). Individuals fed with sucrose only exhibited the lowest survival and those fed with sucrose-open fruit the highest. We discuss these feeding choices and their possible causes, including individual differences in the gut microbiota and nutritional reserves of newly emerged flies.     

Tarsal taste neurons of Helicoverpa assulta (Guenée) respond to sugars and amino acids, suggesting a role in feeding and oviposition

Helicoverpa assulta and Helicoverpa armigera are sibling species with different host-plant ranges. We have previously reported electrophysiological and behavioral responses of H.armigera to sugars and amino acids. Here we describe a parallel study performed on H. assulta and compare the results obtained with the two species. In females, fourteen gustatory chemosensilla, identified on one ventrolateral side of the fifth tarsomere were stimulated with sucrose, glucose, fructose, maltose, myo-inositol, and the twenty common amino acids, using the tip-recording technique. The taste receptor neurons in eight chemosensilla were identified sensitive to the sugars, myo-inositol, Lys, Glu, Arg, Trp, and Ser which all induced proboscis extension reflex (PER) when tarsi were stimulated. There was a positive correlation between electrophysiological activities and PER responses triggered by sucrose. No stimulatory effect on oviposition was observed with sugar or amino acid mixtures. In males, three chemosensilla showed responses to the four sugars, but generally weaker than in females. The major difference of the two species was the variety of amino acids triggering electrophysiological responses. The stimulatory effect of sugars and amino acids on H.assulta was also generally weaker than that on H. armigera.     

Effects of disodium octaborate tetrahydrate on survival, behavior, and egg viability of adult muscoid flies (Diptera: Muscidae).

Disodium octaborate tetrahydrate (Na2B8O13(.)4H2O) was mixed with sugar and fed to adult Musca domestica L. and Fannia canicularis (L.) to determine concentration-mortality relationships. LC50s (48-h exposure) were 5.7% for M. domestica and 1.0% for F. canicularis. Rates of 1 and 2% were used to test effects on M. domestica mortality and egg hatch over an 8-d period. Reduced egg hatch was evident after 1 d of feeding on the treated mixtures and was greatest (less than 10% egg hatch) after flies fed only on treated mixtures for 2 d. A partial rebound in egg hatch occurred after 3-4 d of feeding on treated diet. Sperm motility in females fed treated sugar was apparently normal. Fertile egg placed on treated poultry manure did not hatch, indicating embryonic death, which also may have been involved in the low hatch of eggs observed from treated flies. When flies were exposed to treated sugar for 2 d then returned to untreated diet, delayed mortality effects and reduced egg hatch persisted for at least 3 d. Behavioral assays (feeding) with M. domestica demonstrated that flies rejected borate-sugar mixtures in favor of sugar alone when the concentration of borate was greater than 2%. Given a choice of treated and untreated poultry manure for oviposition, flies also rejected the treated manure. The potential of borates in adult bait formulations or applied to developmental substrates for fly control is discussed.     

Consumption of sugars by Anastrepha suspensa (Diptera: Tephritidae)

We were interested in determining the feeding response of the Caribbean fruit fly, Anastrepha suspensa Loew (Diptera: Tephritidae), to various sugar concentrations to develop an improved bait for adults. We compared the consumption of 0.01-1.00 M concentrations of glucose, fructose, raffinose, and sucrose in no-choice tests for 24-h- and 6-d-old male and female flies. Sucrose was the most consumed sugar or within the most consumed group of sugars at 0.02-0.20 M concentrations. There were no differences in consumption among sugars at 0.01, 0.40, and 1.00 M. Consumption generally increased with increasing sugar concentration except that sucrose consumption peaked at 0.20 M. Twenty-four-hour females consumed less fructose than other sugars; 24-h males consumed more sucrose than fructose or raffinose, with an intermediate response to glucose. Females in the 6-d group consumed more sucrose than the other three sugars, whereas 6-d males exhibited no difference in consumption among sugars. In choice tests, flies consumed more sugar solution than water, but the difference between 0.20 M fructose and water was not significant for 24-h males or 24-h females. In choice tests between 0.20 M fructose and 0.20 M sucrose, both 24-h and 6-d females showed a preference for fructose. Males of both age classes showed no preference. These results indicate that the responses of flies to different sugars can vary by sugar, gender, and age.     

Nutritional balancing in fruit flies: performance of wild adult females of Anastrepha obliqua (Diptera: Tephritidae) fed on single-food or food-pair treatments

The aim of the present study was to investigate the effects of different artificial diets, in which sucrose and brewer's yeast were offered separately (food-pair treatment) or mixed (single-food treatment), on the regulation of nutrient ingestion and the performance of wild adult females of Anastrepha obliqua. The amount of diet consumed by females of A. obliqua increased as the concentration of yeast in the diet increased, revealing a phagostimulant effect of yeast. The amount of sucrose ingested was constant in all groups, showing that these flies regulate the ingestion of sucrose. Longevity and production of eggs/female were similar in both groups. Our results suggest that A. obliqua females regulate the ingestion of nutrients to obtain an adequate performance. Dietary self-selective behavior was more efficient for the females of A. obliqua than feeding on a single-food, because the self-selecting flies ingested less food and had a similar performance as the ones fed on the single-food treatment.     

Mortality of Rhagoletis indifferens exposed to hydrolyzed protein baits and spinosad in the absence and presence of yeast extract

Western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is the major quarantine pest of sweet cherry, Prunus avium (L.) L. (Rosaceae), in the Pacific northwest of the USA and in British Columbia in Canada. Although spinosad bait (GF‐120 NF Naturalyte® Fruit Fly Bait) is used for the control of R. indifferens in this region, the effects of alternate food sources on fly responses to this bait have not been studied. In this study, experiments were conducted to determine mortalities of flies exposed to hydrolyzed protein baits in the presence of sugar only and sugar + yeast extract food. All baits contained Entrust® (termed ‘spinosad alone’). When flies were exposed to GF‐120 with or without added ammonia compounds (uric acid, ammonium acetate, and ammonium carbonate) for 48 h, mortalities were higher in the presence of sugar only than in the presence of sugar + yeast extract, but when flies were exposed to spinosad alone, mortalities were similar in presence of either of the two foods. In another experiment comparing GF‐120, Nu‐Lure, Mazoferm, Baker's yeast extract, and spinosad alone, mortalities in the GF‐120, Mazoferm, and Baker's yeast extract treatments were higher in the presence of sugar only than in the presence of sugar + yeast extract, but in the Nu‐Lure and spinosad alone treatments, mortalities were similar in the presence of either of the two foods. Overall results suggest that the indirect effects of yeast extract food on mortality are dependent on bait type and that mortalities caused by spinosad alone and baits are similar. Nu‐Lure and spinosad alone may have an advantage over other treatments for fly control, because their effects do not appear to be affected by the presence of nitrogenous food.     

Trends in lipid and protein contents during medfly aging: an harmonic path to death

Survival and egg-laying trends were investigated in Mediterranean fruit flies (Ceratitis capitata) adults maintained on a sucrose-only diet, or on a full diet that consisted of a 3:1 sucrose and yeast hydrolizate mixture. In addition, we followed the total individual lipid and protein contents of aging flies in a cohort. Survival trends and life expectancy parameters at eclosion for males and females on full diet and for males on sucrose only were very similar. In contrast, the mortality of females on sucrose only was high early in life, but then slowed down. Egg-laying was ten times greater in female flies on full diet than in flies on sucrose only. Lipid contents in males and females on both types of diets were very similar, and harmonically oscillated with an amplitude of approximately 10 days. Successive crests of lipids tended to be smaller with the ageing of the cohort, and lipids contents significantly dropped at very advanced ages and close to the maximal age of the whole cohort. Protein contents of flies maintained on a full diet were high and stayed at a constant level throughout the entire life of the cohort. Protein levels in males and females on sucrose only dropped drastically during the first days of adult life, but then stayed stable at a low level until advanced ages. We propose that the synchronous rhythmic oscillation in lipid contents of male and female flies seems to be independently set by an internal clock. Protein reserves are allocated according to the access to protein food sources and these levels of protein are closely associated to egg production and mortality. Our results are discussed in view of resource allocation during reproduction and senescence.     

Additive and interactive effects of nutrient classes on longevity, reproduction, and diet consumption in the Queensland fruit fly (Bactrocera tryoni)

Insect lifespan is often closely linked to diet, and diet manipulations have been central to studies of ageing. Recent research has found that lifespan for some flies is maximised on a very low yeast diet, but once all yeast is removed, lifespan drops precipitously. Although effects of yeast availability on lifespan are commonly interpreted in terms of protein, yeast is a complex mix of nutrients and provides a rich source of vitamins, minerals and sterols. Elucidating which components of yeast are involved in this lifespan drop provides insights into more specific nutritional requirements and also provides a test for the commonplace interpretation of yeast in terms of protein. To this end, we fed Queensland fruit flies (Bactrocera tryoni) one of eight experimental diets that differed in the nutrient group(s) found in yeast that were added to sucrose: none, vitamins, minerals, amino acids, cholesterol, vitamin+mineral+cholesterol (VMC), vitamin+mineral+cholesterol+amino acids (VMCA), and yeast. We measured survival rates and egg production in single sex and mixed sex cages, as well as nutrient intake of individual flies. We found that the addition of minerals increased lifespan of both male and female flies housed in single sex cages by decreasing baseline mortality. The addition of just amino acids decreased lifespan in female flies; however, when combined with other nutrient groups found in yeast, amino acids increased lifespan by decreasing both baseline mortality and age-specific mortality. Flies on the yeast and VMCA diets were the only ones to show significant egg production. We conclude that the drop in lifespan observed when all yeast is removed is explained by missing micronutrients (vitamins, minerals and cholesterol) as well as the absence of protein in females, whereas minerals alone can explain the pattern for males. These results indicate a need for caution when interpreting effects of dietary yeast as effects of protein.     

Bacteria as food had no effect on fecundity during domestication of the fruit fly,Bactrocera tryoni

Adult Bactrocera tryoni from different generations of domestication were given various diets to determine whether either or both the bacteria Klebsiella oxytoca and Klebsiella pneumoniae could provide a source of proteinaceous material sufficient to allow the female flies to produce mature oocytes and eggs or alternatively, whether the bacteria could act as a beneficial supplementary food when given in addition to the usual laboratory proteinaceous food that consisted of a paste of sucrose and yeast autolysate. Overall, there was no evidence from any generation studied that female flies could produce eggs or mature oocytes on a bacterial diet above the levels attained with access to culture medium without bacteria. Similarly, there was no evidence that bacterial supplementation to a diet that included a paste of sucrose and yeast autolysate was more beneficial than when the paste was the sole source of proteinaceous food. There was an increase in mature oocytes per female with the number of generations of culture but the extent of increase was greater when sugar/yeast paste was included in the diet. There was no evidence that mixtures of either bacterium species in nutrient broth or the broth itself was attractive to female B. tryoni over a distance of a few centimetres when the tested flies were caged at low density but flies of later generations did feed when offered either type of food at very close range.     

Sexual development of wild and mass‐reared male Queensland fruit flies in response to natural food sources

Diet has a profound influence on the fitness of adult tephritid flies. Mass‐reared flies are provided yeast hydrolysate as a rich source of nutrition that supports rapid sexual development and mating success. In contrast, wild tephritid flies often live in environments where food may be hard to find, and these are the conditions that sexually immature mass‐reared sterile males encounter when released into the field during sterile insect technique campaigns. The effect of natural food sources (bat guano, bird droppings, citrus pollen, and wheat pollen) on the sexual development of adult mass‐reared fertile, mass‐reared sterile, and wild male Queensland fruit flies, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), was determined by measuring ejaculatory apodeme size. Inclusion of yeast hydrolysate in the adult diet was associated with faster growth of the ejaculatory apodeme in comparison with all other diets. Effects of diet were far less pronounced in mass‐reared males, which may indicate reduced nutritional requirements, whereas the ejaculatory apodeme of wild males fed on natural sources of food or sucrose alone did not increase in size over the first 20 days of adult life.     

Performance and feeding behavior of Ceratitis capitata: comparison of a wild population and a laboratory population

Experiments were carried out to test the performance and some aspects of feeding behavior in two populations of Ceratitis capitata (a population reared in the laboratory for 16 years, i.e., approximately 160 generations, and a wild one obtained from infested coffee, Coffea arabica grains). Two types of food were used in the experiment: an artificial yeast diet used for laboratory rearing and papaya (Carica papaya), a natural host of the fly. The performance parameters tested were percent emergence, time to emergence, adult female size, and egg production during the pre-oviposition phase (first five days of adult life). The behavioral aspects tested were food preference by newly hatched larvae, induction, estimated ingestion of the two diets, whether the larvae placed on one diet stayed there or moved to the other diet, and acceptance of food for oviposition. The results indicated that the performance of the wild population was superior when the flies fed on papaya, whereas the performance of the laboratory population was similar with the two diets; the wild population showed a strong preference for papaya in all choice experiments, whereas the laboratory population showed no diet preference; the females of the wild population only oviposited on pieces of papaya that had not been peeled, and did not oviposit in the artificial diet; the females of the laboratory population oviposited indiscriminately on unpeeled and peeled papaya and on the artificial diet.     

Dietary Modulation of Drosophila Sleep-Wake Behaviour

Background

A complex relationship exists between diet and sleep but despite its impact on human health, this relationship remains uncharacterized and poorly understood. Drosophila melanogaster is an important model for the study of metabolism and behaviour, however the effect of diet upon Drosophila sleep remains largely unaddressed.

Methodology/Principal Findings

Using automated behavioural monitoring, a capillary feeding assay and pharmacological treatments, we examined the effect of dietary yeast and sucrose upon Drosophila sleep-wake behaviour for three consecutive days. We found that dietary yeast deconsolidated the sleep-wake behaviour of flies by promoting arousal from sleep in males and shortening periods of locomotor activity in females. We also demonstrate that arousal from nocturnal sleep exhibits a significant ultradian rhythmicity with a periodicity of 85 minutes. Increasing the dietary sucrose concentration from 5% to 35% had no effect on total sucrose ingestion per day nor any affect on arousal, however it did lengthen the time that males and females remained active. Higher dietary sucrose led to reduced total sleep by male but not female flies. Locomotor activity was reduced by feeding flies Metformin, a drug that inhibits oxidative phosphorylation, however Metformin did not affect any aspects of sleep.

Conclusions

We conclude that arousal from sleep is under ultradian control and regulated in a sex-dependent manner by dietary yeast and that dietary sucrose regulates the length of time that flies sustain periods of wakefulness. These findings highlight Drosophila as an important model with which to understand how diet impacts upon sleep and wakefulness in mammals and humans.     

Supplemental diets containing yeast,sucrose, and soy powder enhance the survivorship,growth, and development of prey-limited cursorial spiders

We examined the effects of a supplemental diet mixture (SDM) and its individual ingredients (sucrose, yeasts, and toasted soy flour) on the survivorship, growth, and development of a cursorial spider, Hibana futilis Banks (Anyphaenidae). Some treatments included limited numbers of Helicoverpa zea eggs, a favored prey. This approach highlighted the relative nutritional contributions of the supplemental diet ingredients, especially under conditions of prey limitation, and showed whether these spiders could be reared on minimal prey augmented with supplemental diet. Spiders fed either 5 or 15 eggs became prey-limited during their first and second molts, respectively. When deprived of prey but provisioned with either sucrose or SDM, spiders persisted as first instar nymphs for weeks, but while sucrose-fed nymphs never molted, those fed SDM typically molted 2–3 times. When SDM was added to the diet, spiders that had fed on as few as 50 eggs could reproduce successfully. Binary mixtures of sucrose plus either baker’s yeast (Saccharomyces cerevisiae Meyen ex E.C. Hansen) or toasted soy flour were more effective in promoting growth and development in prey-limited spiders than any of the three ingredients of SDM alone. Active baker’s yeast was more effective than dried powdered brewer’s yeast at supporting development. These results suggest two possibilities for managing cursorial spiders: (1) Supplemental diet mixtures could be applied as a food spray to promote their conservation in crops; and, (2) A mass rearing diet could be made from a minimal amount of prey plus two or three inexpensive, supplemental diet ingredients.     

Mortality and oviposition of western cherry fruit fly (Diptera: Tephritidae) exposed to different insecticide baits for varying periods in the presence and absence of food

Spinosad bait is used to control western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), by killing flies before they oviposit. However, effects of different insecticide baits on management of reproductively mature flies are largely unknown. Objectives here were to determine mortality and oviposition of reproductively mature R. indifferens exposed to different insecticide baits for varying periods in the presence and absence of dried yeast extract and sucrose food. Spinosad bait (spinosad in a mix of protein, sugar, and other ingredients) was compared with acetamiprid, thiamethoxam, and imidacloprid in sucrose or Nu-Lure + sucrose bait. When flies were exposed to treatments and then offered cherries, Prunus avium (L.) L., for oviposition or when they were exposed to treatments and cherries simultaneously, both thiamethoxam bait and imidacloprid bait resulted in higher mortality and lower oviposition than spinosad bait and acetamiprid bait. Exposures to thiamethoxam bait and imidacloprid bait for six and 24 h were similarly effective, but 6-h exposures to spinosad bait and acetamiprid bait were less effective than 24-h exposures. There was little difference between sucrose and Nu-Lure + sucrose baits. When food was present, thiamethoxam bait and imidacloprid bait caused greater mortality and lower oviposition than spinosad bait and acetamiprid bait, but when food was absent, patterns were less consistent. Because of its ability to kill flies sooner after it is exposed to flies when food is present or absent, thiamethoxam or imidacloprid in sucrose or Nu-Lure bait may reduce infestations in cherries more than spinosad bait when mature R. indifferens are present in orchards.     

Studies on isolated cell components. IV. The effect of various solutions on the isolated rat liver nucleus

1. The effects of morganic ions, electrolyte concentration, and pH on the appearance and volume of the isolated rat liver nucleus have been studied. Nuclei were isolated by differential centrifugation in a buffered salt-sucrose mixture at pH 7.1. Nuclear volumes were determined photographically. 2. In solutions of NaCl, of KCl, and in potassium phosphate buffers the nuclear volume decreased markedly with an increase in concentration from 0.001 M to 0.05 M but remained essentially constant with further increase in concentration to 1.0 M. The effects of CaCl(2) and MgCl(2) differed from those of NaCl and KCl in that a smaller volume was obtained in concentrations less than 0.15 M, and in the case of CaCl(2) an increase in volume was obtained in more concentrated solutions. The volume changes are considered to be due primarily to ionic effects on the nuclear colloids rather than to osmotic behavior. 3. Treatment of nuclei with DNAase prevented the characteristic volume changes resulting from ion effects, suggesting the importance of DNA in nuclear volume changes. 4. The optical changes in isolated nuclei in various concentrations of KCl, NaCl, CaCl(2), MgCl(2), and in potassium phosphate buffers as observed under phase contrast illumination are described. CaCl(2) gave the most marked nuclear changes from the conditions in the uninjured cell and caused shrinkage and granulation in 0.001 M concentration. The effects of CaCl(2) were also manifested in 0.88 M sucrose, in mixtures with monovalent salts, and in serum. Changes in nuclear volume and optical appearance which occurred in salt solutions and in 0.1 N HCl were readily reversible. 5. Nuclear volume remained constant between pH 8.91 and 5.12 and decreased in more acid solutions. 6. Sucrose had no appreciable osmotic effect, and in hyperosmotic solution. (0.88 M) nuclei showed swelling and rupture comparable to that in distilled water. 7. The results are considered in relation to the requirements of nuclear isolation media. 8. Rat liver nuclei isolated in a buffered salt-sucrose medium by differential centrifugation exhibited a pattern of size distribution similar to that of fixed nuclei but were of considerably larger volume. The ratio of the volumes of the peak frequencies of the two chief size groups was 1:1.9.     

Effect of male inflorescence of Castanea mollissima on the reproductive development and lifetime of Bactrocera minax

Previous work reveals that newly emerged adult Chinese citrus flies, Bactrocera minax (Enderlein), emerges from the ground in the mosaic-type citrus orchard of the hilly terrain landform dispersed into adjacent forest, and the newly emerged adult flies fed on male inflorescence of the Chinese chestnut, Castanea mollissima Blume (Fagaceae). The potential impact of male inflorescence of C. mollissima on the longevity, and survival of adult females and males, the ovarian development of adult females, and the abdominal index, ovarian index, and egg length of the fourth ovarian grade of living females, as well as the flowering process of the male inflorescence of the Chinese chestnut, were studied with the three methods of rearing (normal rearing, hungry rearing, and bagging rearing). For all three rearing treatments, the longevity of all adults could live up to 38 days, there were similar time dynamics for the average survival of female and male adult flies. Of the total females, 32.1%–100% females with bagging rearing could attain the fourth ovarian grade like those in rearing and hunger rearing. The abdominal index, ovarian index, and egg length of the fourth ovarian grade of 27–39 days’ old living females with bagging rearing (it corresponds to the late flower withering period), were 75.1%, 49.8% and 89.6% of those with normal rearing, and 73.2%, 60.6% and 90.8% of those with hungry rearing, respectively. The male inflorescence of C. mollissima can satisfy the nutritional requirements of adult B. minax, enabling their survival and normal reproduction. This study can provide references for development and application of artificial feed and food attractants of adult B. minax.