The effects of various carbohydrate diets on Aedes aegypti infected with Dirofilaria immitis.

Aedes aegypti infected with Dirofilaria immitis and uninfected mosquitoes were maintained on various carbohydrate diets (glucose, galactose, fructose, sucrose, trehalose, maltose, and melibiose). The value of each of these sugars in supporting survival of adult A. aegypti, and in supporting egg production, viability of eggs, and development of third-stage larvae of D. immitis in A. aegypti was analyzed. Fructose, glucose, maltose, sucrose, and trehalose provided the strongest support for survival of adult male, and infected and uninfected adult female A. aegypti. Galactose and melibiose provided the least support for survival of all groups of mosquitoes. The mean number of eggs laid per uninfected adult female A. aegypti was greatest when mosquitoes were maintained on glucose, melibiose, maltose, fructose, sucrose, and trehalose. The same was true for female mosquitoes infected with D. immitis; except for melibiose which provided poor support for egg production. In both Dirofilaria-infected and in uninfected mosquitoes, galactose supported the production of low mean numbers of eggs per adult female A. aegypti. High percentages of eggs laid by uninfected and by infected female mosquitoes fed glucose, melibiose, maltose, sucrose, and trehalose hatched. While galactose supported a high percentage of hatching in eggs laid by uninfected A. aegypti, a much lower percentage of eggs laid by infected female mosquitoes maintained on this same carbohydrate hatched. The lowest percentages of eggs that hatched were from among those laid by infected and by uninfected females fed fructose. The highest mean number of D. immitis larvae (L₃) were recovered from adult A. aegypti fed glucose, maltose, fructose, and sucrose; the second best sugar in this regard was trehalose. The lowest mean number of D. immitis larvae were isolated from female A. aegypti fed galactose and melibiose.     

Lifespan and patterns of accumulation and mobilization of nutrients in the sugar-fed phorid fly, Pseudacteon tricuspis

Abstract. The effect of sugar feeding on the survival of adult phorid fly Pseudacteon tricuspis is investigated. Flies fed 25% sucrose in aqueous solution continuously throughout their lifespan have greater longevity (mean ± SE longevity: female = 7.9 ± 0.8 days, male = 8.9 ± 0.9 days) than completely starved (provided no water and no sugar solution) flies, sugar-starved (provided water only) flies, or flies fed sugar solution only on their first day of adult life. Completely starved flies rarely lived beyond one day. Provision of water increases longevity by 2 days, and one full day of sugar feeding further increases longevity by an additional 1–2 days. Flies fed 50% sucrose have similar survivorship as those fed 25% sucrose. The temporal patterns of nutrient accumulation and utilization are also compared in P. tricuspis fed different diets: sugar-starved, sucrose-fed on the first day of adult life only, and sucrose-fed continuously. Adult P. tricuspis emerge with no gut sugars, and only minimal amounts of body sugars and glycogen. Although the levels of body sugars and glycogen decline gradually in sugar-starved flies, a single day of sugar feeding results in the accumulation of maximum amounts of gut sugars, body sugars and glycogen. High levels of these nutrients are maintained in female and male phorid flies fed on sucrose continuously over the observation period, whereas nutrient levels decline in flies fed only on the first day of life, beginning 1 day postfeeding. Female and male P. tricuspis emerge with an estimated 12.3 ± 2.3 and 7.2 ± 1 g of lipid reserves per fly, respectively. These teneral amounts represent the highest lipid levels detected in adult flies, irrespective of their diet, and are maintained over the life times of sucrose-fed female and male flies, but declined steadily in sugar-starved females. These data suggest that adult P. tricuspis are capable of converting dietary sucrose to body sugars and glycogen, but not lipids.     

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.     

Feeding behavior of Ceratitis capitata (Diptera,Tephritidae): influence of carbohydrate ingestion

Experiments were conducted on Ceratitis capitata larvae and adults to determine the influence of sugar (glucose and sucrose) ingestion on some aspects of the feeding behavior of this species. The results indicate that larval choice of a diet containing glucose or sucrose is not influenced by the rearing diet, by carbohydrate deprivation or by previous experience (induction). Carbohydrate deprivation did not alter the discrimination threshold of the larvae for sucrose. In adult females, the discrimination threshold for sucrose was unchanged when the flies were submitted to carbohydrate deprivation during the adult phase although ingestion by deprived females was 35% higher than ingestion by the control group. However, adults submitted to carbohydrate deprivation during the larval phase suffered a profound reduction in discrimination threshold for sucrose.     

Comparing the effects of five naturally occurring monosaccharide and oligosaccharide sugars on longevity and carbohydrate nutrient levels of a parasitic phorid fly, Pseudacteon tricuspis

Abstract.  The longevity and nutrient levels of Pseudacteon tricuspis provided with 1  m solutions of five naturally occurring sugars, fructose, glucose, sucrose, trehalose and melezitose, are compared. All but melezitose, result in significant increases in the longevity of P. tricuspis in comparison with sugar-starved flies (flies provided with water only). Sugar-starved female and male P. tricuspis have an average longevity of 3.3 and 4.1 days, respectively. Provision of free water in addition to sugar solution is necessary for optimum longevity by female and male flies. Longevity is increased by 2.4–2.6-fold by the two monosaccharides, fructose and glucose, and by 2.6–2.8-fold by the disaccharides, sucrose and trehalose. Phorid flies provided with the trisaccharide sugar, melezitose, had a marginal increase in lifespan (approximately 1 day), but this is not significantly different from the longevity of sugar-starved flies. Significantly greater levels of total sugars are detected in P. tricuspis fed the disaccharide sugars (sucrose, trehalose) or the monosaccharide sugars (fructose, glucose), compared with flies provided with melezitose (trisaccharide), or to sugar-starved flies. Fructose is not detected in sugar-starved flies, or in flies fed glucose or trehalose. However, high levels of fructose are detected in flies fed sucrose or fructose, whereas levels of fructose in melezitose-fed flies are intermediate. In general, significantly greater glycogen levels are detected in P. tricuspis fed sucrose, glucose, trehalose or fructose, compared with melezitose-fed or sugar-starved flies. Levels of total sugars and glycogen in sugar-fed flies are positively correlated with wing length, possibly indicating a higher accumulation of storage sugars by larger flies. These results are discussed in relation to the nutritional ecology of the phorid fly.     

Sugar receptors in Drosophila

The detection and discrimination of chemical compounds in potential foods are essential sensory processes when animals feed. The fruit fly Drosophila melanogaster employs 68 different gustatory receptors (GRs) for the detection of mostly nonvolatile chemicals that include sugars, a diverse group of toxic compounds present in many inedible plants and spoiled foods, and pheromones [1-6]. With the exception of a trehalose (GR5a) and a caffeine (GR66a) receptor [7-9], the functions of GRs involved in feeding are unknown. Here, we show that the Gr64 genes encode receptors for numerous sugars. We generated a fly strain that contained a deletion for all six Gr64 genes (DeltaGr64) and showed that these flies exhibit no or a significantly diminished proboscis extension reflex (PER) response when stimulated with glucose, maltose, sucrose, and several other sugars. The only considerable response was detected when Gr64 mutant flies were stimulated with fructose. Interestingly, response to trehalose is also abolished in these flies, even though they contain a functional Gr5a gene, which has been previously shown to encode a receptor for this sugar [8, 9]. This observation indicates that two or more Gr genes are necessary for trehalose detection, suggesting that GRs function as multimeric receptor complexes. Finally, we present evidence that some members of the Gr64 gene family are transcribed as a polycistronic mRNA, providing a mechanism for the coexpression of multiple sugar receptors in the same taste neurons.     

Food selection in adults and larvae of three species of Lepidoptera: a behavioural and electrophysiological study

Adults and larvae of Spodoptera littoralis, Heliothis virescens and Heliothis armigera were tested with a range of sugars, amino acids, sugar alcohols and allelochemics. Feeding behaviour was correlated with the electrophysiological responses of maxillary styloconic sensilla in the larvae and proboscis styloconic sensilla in the adult. The neural response was more vigorous in larvae than in adults but otherwise the spectra of responses were similar in the two life stages. Phagostimulants and antifeedants stimulated maximally different sensilla in larvae but not in adults. The responses of adult sensilla to sugars and amino acids were significantly correlated to behaviour in all three species, but only in H. armigera was there a similar correlation with the sugar alcohols and allelochemics.     

Sensitivity of antennal gustatory receptor neurones to aphid honeydew sugars in the carabid Anchomenus dorsalis

Using electrophysiology, the stimulating effect of 13 sugars and three sugar alcohols (each at a concentration of 100 mm ) to antennal gustatory receptor neurones (GRNs) is tested in the carabid beetle Anchomenus dorsalis (Pontoppidan, 1763) (Coleoptera, Carabidae). Maltose, sucrose, glucose and raffinose are the most stimulating sugars for the sugar‐sensitive neurone (SuN), evoking 6.7–18.6 spikes s^?1 in fed insects, whereas the others had little or no effect. The firing rate of the antennal GRNs is not affected by any of the tested sugar alcohols, dulcitol, inositol and sorbitol. Additionally, concentration/response curves for sucrose and maltose are obtained in the range 0.01–100 mm . The responses of beetles starved for 96 h to this range of sucrose are two‐ to three‐fold higher compared with those of fed beetles. The presence of a terminal α‐glucose unit is an important feature of the molecular structure determining the stimulating properties of the two disaccharides, maltose and sucrose, as well as glucose. The other monosaccharide unit of the molecule is also of great importance in determining the stimulating properties of various disaccharides. The sensitivity of the SuN to the four most prevalent aphid honeydew sugars suggests that A. dorsalis uses these chemicals as sensory cues when searching for aphids as prey.     

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.     

Dietary sugars affect cold tolerance of Drosophila melanogaster

In spite of the extensive knowledge of the biology and the genetics of Drosophila melanogaster, the mechanisms by which this fly builds up cold tolerance remain poorly understood. Recent studies have reported that acclimation-mediated acquisition of cold tolerance is associated with moderate accumulation of sugars in drosophilids. However, it is not known whether there is a genuine causative link between cold tolerance and body sugar accumulation in Drosophila flies. We thus tested whether increasing body sugars levels, via dietary enrichment, will promote the cold tolerance of D. melanogaster adults. We gradually augmented the concentration of four different sugars (sucrose, fructose, glucose and trehalose) in rearing diets and tested the basal cold tolerance (acute and chronic). Using SIM-GC/MS approach, we verified whether feeding of larvae and adults on sugar-enriched diets was associated with increasing body sugars. We also tested whether development, body mass, fat stores, metabolites composition and metabolic pathways were altered by these dietary manipulations. The data confirm an effective incorporation of all sugars. Contrary to the expectation, cold tolerance was negatively affected by exogenous sugars, especially when supplemented at high concentrations. Rearing on high-sugar doses induced system-wide metabolic alteration associated with carbohydrate metabolism imbalance, a developmental delay and a fresh mass reduction. Our data show that high dietary sugars create a metabolic imbalance and negatively affect cold tolerance. This study provides an intriguing connection between nutritional conditions and thermal trait. It also underlines that careful attention should be given to dietary factors when studying thermal traits.     

Sugars in crop plants

We review current knowledge of the most abundant sugars, sucrose, maltose, glucose and fructose, in the world's major crop plants. The sucrose‐accumulating crops, sugar beet and sugar cane, are included, but the main focus of the review is potato and the major cereal crops. The production of sucrose in photosynthesis and the inter‐relationships of sucrose, glucose, fructose and other metabolites in primary carbon metabolism are described, as well as the synthesis of starch, fructan and cell wall polysaccharides and the breakdown of starch to produce maltose. The importance of sugars as hormone‐like signalling molecules is discussed, including the role of another sugar, trehalose, and the trehalose biosynthetic pathway. The Maillard reaction, which occurs between reducing sugars and amino acids during thermal processing, is described because of its importance for colour and flavour in cooked foods. This reaction also leads to the formation of potentially harmful compounds, such as acrylamide, and is attracting increasing attention as food producers and regulators seek to reduce the levels of acrylamide in cooked food. Genetic and environmental factors affecting sugar concentrations are described.     

Stimulation of the labellar sugar receptor of the fleshfly by mono- and disaccharides

Responses of the labellar sugar receptor of the fleshfly, Boettcherisca peregrina, were studied over a wide range of concentrations of several sugars (sucrose, maltose, glucose, fructose, and mannose) in single solutions and in mixtures. The results suggest (a) that the receptor sites are not completely differentiated for glucose and for fructose combination, (b) that the receptor site is composed of two subunits. Such suggestions are based on the classical model, where the response is proportional to the number of the sites, two subunits of each site being simultaneously occupied with one molecule of disaccharides or two molecules of monosaccharides. It is shown, however, that an allosteric model gives a somewhat better interpretation of the experimental results.     

Cyclic AMP-protein kinase A and Snf1 signaling mechanisms underlie the superior potency of sucrose for induction of filamentation in Saccharomyces cerevisiae

Under specific environmental conditions, the yeast Saccharomyces cerevisiae can undergo a morphological switch to a pseudohyphal growth pattern. Pseudohyphal differentiation is generally studied upon induction by nitrogen limitation in the presence of glucose. It is known to be controlled by several signaling pathways, including mitogen-activated protein kinase, cyclic AMP-protein kinase A (cAMP-PKA), and Snf1 kinase pathways. We show that the alpha-glucoside sugars maltose and maltotriose, and especially sucrose, are more potent inducers of filamentation than glucose. Sucrose even induces filamentation in nitrogen-rich media and in the mep2Δ/mep2Δ ammonium permease mutant on ammonium-limiting medium. We demonstrate that glucose also inhibits filamentation by means of a pathway parallel to the cAMP-PKA pathway. Deletion of HXK2 shifted the pseudohyphal growth pattern on glucose to that of sucrose, while deletion of SNF4 abrogated filamentation on both sugars, indicating a negative role of glucose repression and a positive role for Snf1 activity in the control of filamentation. In all strains and in all media, sucrose induction of filamentation is greatly diminished by deletion of the sucrose/glucose-sensing G-protein-coupled receptor Gpr1, whereas it has no effect on induction by maltose and maltotriose. The competence of alpha-glucoside sugars to induce filamentation is reflected in the increased expression of the cell surface flocculin gene FLO11. In addition, sucrose is the only alpha-glucoside sugar capable of rapidly inducing FLO11 expression in a Gpr1-dependent manner, reflecting the sensitivity of Gpr1 for this sugar and its involvement in rapid sucrose signaling. Our study identifies sucrose as the most potent nutrient inducer of pseudohyphal growth and shows that glucose inactivation of Snf1 kinase signaling is responsible for the lower potency of glucose.     

A genetic tool kit for cellular and behavioral analyses of insect sugar receptors

Arthropods employ a large family of up to 100 putative taste or gustatory receptors (Grs) for the recognition of a wide range of non-volatile chemicals. In Drosophila melanogaster, a small subfamily of 8 Gr genes is thought to mediate the detection of sugars, the fly''s major nutritional source. However, the specific roles for most sugar Gr genes are not known. Here, we report the generation of a series of mutant sugar Gr knock-in alleles and several composite sugar Gr mutant strains, including a sugar blind strain, which will facilitate the characterization of this gene family. Using Ca²⁺ imaging experiments, we show that most gustatory receptor neurons (GRNs) of sugar blind flies (lacking all 8 sugar Gr genes) fail to respond to any sugar tested. Moreover, expression of single sugar Gr genes in most sweet GRNs of sugar-blind flies does not restore sugar responses. However, when pair-wise combinations of sugar Gr genes are introduced to sweet GRNs, responses to select sugars are restored. We also examined the cellular phenotype of flies homozygous mutant for Gr64a, a Gr gene previously reported to be a major contributor for the detection of many sugars. In contrast to these claims, we find that sweet GRNs of Gr64a homozygous mutant flies show normal responses to most sugars, and only modestly reduced responses to maltose and maltotriose. Thus, the precisely engineered genetic mutations of single Gr genes and construction of a sugar-blind strain provide powerful analytical tools for examining the roles of Drosophila and other insect sugar Gr genes in sweet taste.     

Gustatory perception and metabolic utilization of sugars by<Emphasis Type="Italic"> Myrmica rubra</Emphasis> ant workers

The suitability of various nectar and honeydew sugars as a food source for the polyphagous ant species M. rubra (L.) was studied. The sugars used included monosaccharides (fructose, glucose, galactose, mannose, rhamnose), disaccharides (sucrose, maltose, trehalose, melibiose, lactose) and trisaccharides (melizitose, raffinose, erlose). Single-sugar solutions were tested on ant workers in a long-term laboratory bioassay in which acceptance of the solutions and ant survival were recorded. The acceptance of the sugars was confirmed in a second bioassay in which feeding time was established. Enzymatic hydrolysis of sucrose, maltose and melibiose was investigated through HPLC analyses of workers fed these disaccharides. Sugar acceptance and feeding time were related to ant survival. Considering the monosaccharide units of which the sugars are composed, fructose seems especially suitable as a short-term energy source, while glucose appears to be used both directly and for storage. The presence of a galactose unit appears to reduce sugar suitability. It is suggested that the workers possess invertase and maltase and to a lesser degree also galactosidase. The gustatory perception is correlated with the profitability of sugars in further metabolic processes.     

Ingestion of sugar diets correlates with spike activity in labellar chemosensilla of the flesh-fly, Neobellieria (= Sarcophaga ) bullata

Abstract .Female 2-day-old Neobellieria (= Sarcophaga ) bullata (Parker) (Diptera: Sarcophagidae) were exposed to different concentrations of sucrose, glucose and fructose in a single-choice potometer, and the volume ingested in the first hour was measured. Nerve spike activity in response to the same sugars was recorded from medium labellar taste hairs of similar flies by tip-recording. Two classes of chemosensory cells responded to sucrose, glucose and fructose. Cell 1 showed an increasing spike activity with sugar concentration, whereas cell 2 did not; cell 1 was identified as the 'sugar cell'.
For both spike activity in cell 1 and feeding, sucrose was the most stimulatory sugar. The dose–response curves for glucose and fructose crossed over at about 200 m m . At higher concentrations, glucose was more stimulatory for both cell 1 and for feeding, and at lower concentrations, fructose. The pattern of spike activity supports a separate location on the sensory cells of receptors for pyranose and fructose forms of sugar. The strong correlation between volume ingested and spike activity indicates that sugar feeding is controlled by sensory input from the 'sugar' cells of labellar chemosensilla. Moreover, the results suggest that the flies do not distinguish between these sugars except by apparent 'sweetness'.     

Physiological effect of sugars on various digestive enzymes ofSpodoptera littoralis larvae

Summary Feeding of Styropor lamellae treated with 0.25 M maltose, sucrose, raffinose or melezitose byS. littoralis larvae induced amylase activity to 5–6 fold and invertase and protease activity to 2–3 that of the control. Melibiose induced amylase activity to about 4-fold and invertase and protease activity to 188% and 173%, respectively, that of the control. -lactose stimulated the various digestive enzymes to various extents; cellobiose had practically no effect. Glucose and fructose induced the various digestive enzymes to about the same level but to a much higher extent than galactose.The feeding rate of the various sugar compounds except maltose, correlates well with their stimulating activity on the digestive enzymes. Maltose, which induced the larval digestive enzymes to about the same level as that of sucrose, elicited a considerably lower feeding response. The excretion index of sugars stimulating digestive enzymes and eliciting a feeding response, such as maltose, sucrose, raffinose and melezitose, is considerably lower than that of the other sugars.In a comparative test, sucrose, maltose and raffinose induced the various digestive enzymes to about the same level as their equivalent monosaccharide components. However, -lactose and cellobiose, which have the same components as melibiose and maltose but differ in their configuration, affect the various enzymatic systems weakly.Contribution from The Volcani Center, Agricultural Research Organization, Bet Dagan, Israel. 1972 Series, No. 2171-E. Definitions. Feeding response: express the intake of sugar plus insert Styropor carrier. Excretion index: ratio between weight of fecal pellets and Styropor lamellae consumed.The authors wish to thank Mr. K. R. S. Ascher for fruitful discussions, Dr. A. Genizi for statistical analysis of the results, Mrs. Sara Yablonski and Mrs. Shulamit Cohen for skillful technical assistance, and Mrs. Shoshana Hadad for insect rearing.     

Nutritional Value-Dependent and Nutritional Value-Independent Effects on Drosophila melanogaster Larval Behavior

Gustatory stimuli allow an organism not only to orient in its environment toward energy-rich food sources to maintain nutrition but also to avoid unpleasant or even poisonous substrates. For both mammals and insects, sugars-perceived as "sweet"-potentially predict nutritional benefit. Interestingly, even Drosophila adult flies are attracted to most high-potency sweeteners preferred by humans. However, the gustatory information of a sugar may be misleading as some sugars, although perceived as "sweet," cannot be metabolized. Accordingly, in adult Drosophila, a postingestive system that additionally evaluates the nutritional benefit of an ingested sugar has been shown to exist. By using a set of seven different sugars, which either offer (fructose, sucrose, glucose, maltodextrin, and sorbitol) or lack (xylose and arabinose) nutritional benefit, we show that Drosophila, at the larval stage, can perceive and evaluate sugars based on both nutrition-dependent and -independent qualities. In detail, we find that larval survival and feeding mainly depend on the nutritional value of a particular sugar. In contrast, larval choice behavior and learning are regulated in a more complex way by nutrition value-dependent and nutrition value-independent information. The simplicity of the larval neuronal circuits and their accessibility to genetic manipulation may ultimately allow one to identify the neuronal and molecular basis of the larval sugar perception systems described here behaviorally.     

Overlapping substrate specificity for sucrose and maltose of two binding protein-dependent sugar uptake systems in Streptococcus mutans

Sugar metabolism by Streptococcus mutans is associated with tooth decay. The most abundant sugars in the human diet are sucrose and maltose, a derivative of starch. Previously, we reported a binding protein-dependent transport system (msm) in S. mutans that transports sucrose and maltose, but its associated enzymes do not metabolize maltose. By searching the S. mutans genomic sequence for a maltose system (mal), we found a gene cluster encoding proteins with homology to those of msm and the Escherichia coli maltose system. Mutants were constructed by deleting msm or mal, or both, and tested for sugar utilization. Deletion of the mal system diminished the ability of S. mutans to ferment maltose, but deletion of only the mal transporter genes or msm showed reduced utilization of chromogenic maltosides. Maltose, sucrose, glucose, fructose, mannose, and N-acetyl glucosamine inhibited utilization of chromogenic maltosides by the wild-type strain and mutants. In conclusion, the two binding protein-dependent systems in S. mutans appear to transport collaboratively their common substrate sugars, notably sucrose and maltose.     

Larval starvation reduces responsiveness to feeding stimuli and does not affect feeding preferences in a butterfly

It is commonly assumed that holometabolic insects such as Lepidoptera rely primarily on larval storage reserves for reproduction. Recent studies though have documented a prominent role of adult-derived carbohydrates for butterfly reproduction. Moreover, a few studies have shown that adult butterflies may also benefit from adult-derived amino acids, at least when larval storage reserves are reduced. Given that in holometabolous insects larval deficiencies are carried over into the adult stage, reduced storage reserves have the potential to modulate adult feeding preferences and responses in order to allow for a successful compensation. We tested this hypothesis here in the fruit-feeding butterfly Bicyclus anynana using larval food stress to manipulate storage reserves. Alcohols (methanol, ethanol, butanol, propanol), sugars (maltose, glucose, fructose, sucrose), and acetic acid acted as feeding stimuli, while butterflies did not respond to other substances such as amino acids, yeast, salts, or vitamins. Contrary to expectations, stressed butterflies showed a weaker response than controls to several feeding stimuli. In preference tests, butterflies preferred sugar solutions containing proline, arginine, glutamic acid, acetic acid, or ethanol over plain sugar solutions, but discriminated against salts. However, there were no general differences among starved and control butterflies. We conclude that larval food-stress does not elicit compensatory feeding behavior such as a stronger preference for amino acids or other essential nutrients in B. anynana. Instead, the stress imposed by a period of starvation yielded negative effects.