Effects of six sugars on the longevity,fecundity and nutrient reserves of Microplitis mediator

Parasitoid adults can directly feed on floral nectar and honeydew containing monosaccharides and disaccharides. Oligosaccharides such as maltose, melezitose and raffinose are also found in honeydew but are rare in floral nectar. The effects of six different sugar resources on the longevity, fecundity and nutrient reserves of Microplitis mediator, a larval endoparasitoid in the cotton bollworm Helicoverpa armigera (Hübner) were determined in our laboratory. The results showed that both food and sex affected longevity of this wasp. Females and males of M. mediator fed with 1 M sucrose solution survived longer than controls fed with water (5.7- and 3.7-fold longer, respectively). When provided with sucrose, glucose or fructose solutions, the parasitoid generated 3.6- to 3.7-fold more offspring than controls, and 60–75% of these progenies were produced during the first 5 days. When separately given fructose, sucrose or glucose, this wasp accumulated fructose and total sugar at the highest level, which means a high sugar levels might lead to prolonging longevity and more offspring in M. mediator. In addition, compared with organisms fed galactose or raffinose, M. mediator fed sucrose or fructose accumulated high glycogen levels. Furthermore, in M. mediator, the lipid content declined with the advancing age. Females showed the slowest lipid metabolic rates when fed with sucrose, glucose, fructose, mannose and galactose solutions versus when fed with raffinose and control. In addition, only sucrose had a significant effect on lipid levels in males nearing the end of life.     

Effect of six carbohydrate sources on the longevity of a whitefly parasitoid Eretmocerus hayati (Hymenoptera: Aphelinidae)

Parasitoid adults often acquire carbohydrates by feeding on floral nectar and honeydew which provides them with energy and prolongs their life span. The concentration and type of saccharide in nectar and honeydew are variable by species of plant and insect. To explore the effects of various sugar type and concentrations on parasitoid fitness, we compared 5%, 10% and 20% (w/v) solutions of six different sugar resources (glucose, fructose, sucrose, trehalose, melezitose and honey) on the longevity of Eretmocerus hayati, a larval parasitoid of the whitefly Bemisia tabaci in China. Male and female longevity was increased by all of the sugar diets, but female wasps survived longer than the males when the same sugar diet was supplied. Female parasitoids feeding on 10% glucose and 10% honey increased longevity, respectively up to 6.2- and 5.9-fold longer than distil water; 5% honey and 10% fructose had the greatest effects on male longevity, up to 3.5- and 3.3-fold. All six sugar diets, no matter which concentration, significantly changed the survival curves. Glucose, sucrose and honey were optimal sugar diets for this wasp, and 10% was the optimal concentration. Our results could provide an insight into the nutritional requirements of E. hayati under laboratory conditions. Such information can be a basis to improve the longevity of this biological control agent by sugar feeding during the indoor mass-rearing process.     

Nectar to improve parasitoid fitness in biological control: Does the sucrose:hexose ratio matter?

The consumption of saccharide-rich foods such as floral nectar is crucial for the survival of many adult parasitoid wasps. The importance to parasitoids of nectar quality, with regards to its sucrose:hexose ratio, was investigated. Nectar, an aqueous solution of sugars, amino acids and other compounds, differs between plant species. Nectar composition is dominated by sucrose, glucose and fructose. Previous studies have shown that the ratio of sucrose to hexose (glucose+fructose) sugars can explain nectar associations in a range of flower visiting arthropods. It has been suggested that this ratio may be important in terms of parasitoid fitness. Analysis of floral nectar from fourteen plant species confirmed that the sucrose/hexose ratio significantly differed between species. An opportunity to select floral resources based on this measure of nectar quality arose and highlighted the potential to utilize native flowering plant species in place of the seven most commonly deployed, which are usually not native to the countries in which they are used.Results presented in this paper indicate, however, that the sucrose/hexose ratio is not a significant factor explaining parasitoid longevity. The hymenopteran parasitoids Diadegma semiclausum (Ichneumonidae) and Dolichogenidea tasmanica (Braconidae) were fed 40% w/w sugar solutions, differing in their sugar ratios. Solutions were classified as either sucrose-dominant (ratio >0.99), sucrose-rich (ratio 0.5–0.99), hexose-rich (ratio 0.1–0.499) or hexose-dominant (ratio <0.1). No significant differences in parasitoid longevity were found between the different treatments for either species. This suggests there is not an optimal sucrose/hexose ratio for parasitoid wasps, although a greater number of parasitoid species should ideally be tested to confirm if this is true for the wider parasitoid taxonomic groups.     

Effects of honeydew sugar composition on the longevity of Aphidius ervi

Feeding on sugar‐rich foods such as nectar and honeydew is important for survival of many adult parasitoids. Especially in agricultural systems, honeydew is often the most prevalent carbohydrate source. However, relative to plant nectar, honeydew may be relatively unsuitable, as a result of an unfavourable sugar composition or the presence of secondary plant compounds. We studied survival of the aphid parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) on honeydew collected from various aphid species feeding on potato (Solanum tuberosum L., cv. Desiree) (Solanaceae), wheat (Triticum aestivum L., cv. Bobwhite) (Poaceae), or artificial diet, as well as the sugar composition of the different honeydews. Honeydews from the tested aphid species on potato, wheat, or artificial diet were found to be relatively suitable food sources for adult A. ervi, although not always as suitable as a 2 M sucrose solution. There were differences in honeydew sugar composition among the different aphid species on the various host plants. Multivariate statistics showed that the factor ‘aphid species’ had a significant influence on the sugar composition of the honeydew, explaining 27% of the variation in the potato system and 89% in the wheat system. When exploring the relationship between carbohydrate composition of the honeydews from aphids on potato and wheat plants, and their nutritional value for A. ervi, data revealed that differences in parasitoid longevity can to some extent be explained by carbohydrate composition. Furthermore, our results confirm that sucrose and its hexose components glucose and fructose are very suitable carbohydrate sources for hymenopteran parasitoids and show that parasitoid survival on an equimolar solution of the two monosaccharides glucose and fructose does not exceed performance on the disaccharide sucrose.     

Evaluating potential sugar food sources from the olive grove agroecosystems for Prays oleae parasitoid Chelonus elaeaphilus

Chelonus elaeaphilus Silvestri (Hymenoptera: Braconidae) is a host-specific parasitoid of the olive moth, Prays oleae (Bernard), that can cause parasitism rates of up to 80% in Mediterranean olive groves. A laboratory study was carried out to assess the potential of sugars provided by wild plant species in olive grove agroecosystem to enhance the fitness of C. elaeaphilus. Insects were reared in a climate-controlled chamber at 25?±?2°C, 60?±?5% relative humidity (RH) with a photoperiod of 16:8 (L:D) h. Five naturally occurring wild plant nectar sugars (sucrose, fructose, glucose, maltose and mannose) were tested for their effect on insect longevity. The nectar sugar content of sucrose, fructose and glucose in 12 selected olive grove agroecosystem plant species was analysed and categorised on the basis of sugar ratios. Female insect longevity was increased when they were fed on both sucrose and glucose compared to either maltose or fructose, suggesting that sucrose-dominant nectars would bene?t this parasitoid. Sucrose was predominant in the nectar of five of the studied plant species (Silene gallica, Borago officinalis, Echium plantagineum, Lavandula stoechas and Lonicera hispânica). The results are discussed in terms of potential enhancement of the biological control of P. oleae.     

Plutella xylostella (diamondback moth) and its parasitoid Diadegma semiclausum show different gustatory and longevity responses to a range of nectar and honeydew sugars

Parasitoids as well as many of their herbivorous hosts, depend on carbohydrate‐rich food during the adult stage. Different types of nectar and honeydew vary with regard to their sugar composition. In order to successfully exploit a food source, the insect must show a positive gustatory response to its component sugars and be able to digest and metabolise them. Here we tested the herbivore Plutella xylostella L. (Lepidoptera: Plutellidae) and its parasitoid Diadegma semiclausum (Hellén) (Ichneumonidae: Campopleginae) with respect to their feeding response and longevity when provided with one of nine sugars (fructose, glucose, lactose, maltose, melibiose, melezitose, raffinose, sucrose, or trehalose). Both species responded to and showed a prolonged life span on a broad range of sugars. The impact of food supply on life span was about sixfold higher for the parasitoid than for the herbivore. In general, there was a good fit between gustatory response and achieved longevity, with some outliers. Both species showed only weak responses to melibiose, which significantly prolonged life span. The parasitoid showed a gustatory response to melezitose, which did not prolong its life span. The parasitoid and its herbivorous host responded differently to trehalose. These differences in gustatory response and longevity show the potential for application of selective sugar sources in conservation biological control. At the same time it also reveals a risk that the indiscriminate application of sugar sources may stimulate herbivory.     

Effects of aphid honeydew sugars on the longevity and fecundity of the aphidophagous gall midge Aphidoletes aphidimyza

The predatory gall midge Aphidoletes aphidimyza, which is used for augmentative biological control of aphids in greenhouses, uses aphid honeydew as an energy source. Currently, Rhopalosiphum padi on barley plants and Melanaphis sacchari on sorghum plants are used as the banker plant systems for A. aphidimyza to control Aphis gossypii on eggplant in Japan. We analyzed the sugar components of the honeydew of these three species by HPLC. The major components of honeydew were sucrose, fructose, and melezitose for A. gossypii; glucose and fructose for R. padi; and glucose, fructose, and melezitose for M. sacchari. Maltose and trehalose were minor components of the honeydew of these species. We investigated the influence of sugars, including three artificial aphid honeydews, six sugar components, and distilled water, on the longevity of unmated A. aphidimyza. Both females and males attained the greatest longevity on sucrose and artificial honeydew of A. gossypii. Mean longevities of both females and males were shortest when they were provided only with water. We conducted another experiment in which a mated female was released in a cage with an eggplant seedling infested with A. gossypii and fed with sucrose or only water. Females fed with sucrose lived significantly longer and had higher lifetime fecundity than those fed only water.     

Sugar feeding by the aphid parasitoid Binodoxys communis: how does honeydew compare with other sugar sources?

Parasitoids commonly forage in agricultural settings where the predominant sugar source is homopteran honeydew. The aphidiine braconid, Binodoxys communis, is an Asian parasitoid currently being released against the soybean aphid, Aphis glycines, in North American soybean fields. We conducted a number of laboratory experiments evaluating the quality of A. glycines honeydew as a sugar source for this parasitoid. Wasps readily fed on droplets of A. glycines honeydew, honey and 50% sucrose solution, but the length of feeding bouts on honey was significantly longer than on the other foods. Parasitoids lived significantly longer when fed honey or sucrose than honeydew, while starved wasps had the shortest lifespan. At 21+/-1 degrees C and 25+/-5% R.H., male B. communis that were fed honey lived for a maximum of 14 days, while females lived up to 20 days. Honeydew-fed wasps of both sexes lived approximately 3 days on average, which was 2-3 times longer than when they were only allowed access to water. Anthrone tests of whole insects showed that total sugar and glycogen levels of honey or sucrose-fed individuals were consistently higher than those fed honeydew or water. The glycogen levels of honeydew-fed wasps increased significantly after one day of feeding. HPLC analyses revealed that B. communis readily assimilates A. glycines honeydew oligosaccharides such as erlose, while others (e.g., raffinose) did not degenerate. Raffinose was present in much higher amounts in honeydew-fed wasps than in wasps fed other diets, so this sugar could be used as a 'signature' sugar for this species. Honeydew-fed wasps also had significantly lower fructose/(fructose+glucose) ratios than those from other diet treatments. Although A. glycines honeydew might be the main carbohydrate source within a soybean field, other sugar sources such as floral nectar appear to be more optimal foods for B. communis from a physiological standpoint. We discuss the results from the perspective of classical biological control of the soybean aphid in North America.     

Comparing floral nectar and aphid honeydew diets on the longevity and nutrient levels of a parasitoid wasp

We compared the effects of floral nectar from buckwheat, Fagopyrum esculentum Moench, and honeydew produced by the soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae), on longevity, nutrient levels, and egg loads of the parasitoid Diadegma insulare Cresson (Hymenoptera: Ichneumonidae). Diadegma insulare lived for 2 days in control treatments of water or clean soybean leaves, for 6–7 days with honeydew, and in excess of 2 weeks with buckwheat nectar. Potential reasons for the superiority of buckwheat nectar over soybean aphid honeydew for extending the longevity of parasitoids include: (i) parasitoids ingest more sugars from floral sources, (ii) oligosaccharides in honeydew have a lower nutritional value than nectar sugars, and (iii) honeydew has antagonistic compounds. Overall sugar levels were lower in honeydew‐ vs. nectar‐fed female wasps, suggesting a lower feeding rate, but other explanations cannot be excluded. Diadegma insulare eclosed with high levels of lipids and glycogen, and low levels of gut and storage sugars. All carbohydrates increased over the life of both nectar‐ and honeydew‐fed wasps, but remained low or decreased in starved wasps. Lipid levels declined over the lifespan of female wasps, but females fed floral nectar showed the slowest rate of lipid decline. Diet did not affect egg load, probably because the females were not given hosts in the experiment.     

Feeding responses by female Pieris brassicae butterflies to carbohydrates and amino acids

Most Lepidoptera feed during the adult stage on carbohydrate‐rich food sources, primarily floral nectar. However, little is known about the factors leading to the acceptance of a possible food source. It is reported that butterflies select for nectar rich in sucrose and amino acids. This suggests that the insects have developed a sensitivity to these nectar compounds. We tested females of the large cabbage white, Pieris brassicae L. (Lepidoptera: Pieridae) for their responses to 10 different nectar‐ or honeydew‐sugars after either tarsal or proboscis stimulation. In no‐choice experiments, food‐deprived P. brassicae showed the strongest response to sucrose, followed by fructose. Other sugars, including galactose, glucose, maltose, mannose, melezitose, melibiose, raffinose and trehalose, did not elicit a feeding response. Mixtures of essential or common non‐essential amino acids did not stimulate feeding. In a choice situation, P. brassicae preferred sucrose over fructose, whereas they accepted a sucrose and amino acid solution equally to a plain sucrose solution. The results indicate that for P. brassicae, feeding is mainly elicited by sucrose and fructose.     

The nutritional value of aphid honeydew for non-aphid parasitoids

Intake of sugar-rich foods by adult parasitoids is crucial for their reproductive success. Hence, the availability of suitable foods should enhance the efficacy of parasitoids as biological control agents. In situations where nectar is not readily available, homopteran honeydew can be a key alternative food source. We studied the impact of honeydew feeding on the longevity of the larval endoparasitoids Cotesia marginiventris, Campoletis sonorensis and Microplitis rufiventris, all natural enemies of important lepidopteran pests. Females of these wasps lived longer when feeding on honeydew produced by the aphid Rhopalosiphum maidis on barley compared to control females provided with water only. However, they lived shorter than females fed with a sucrose solution. Further investigations with C. marginiventris showed that access to honeydew also increases the number of offspring produced, but less so than access to a sucrose solution. Moreover, it was found that females of this species need to feed several times throughout their life in order to reach optimal longevity and reproductive output. Analyses of the sugars in the honeydew produced by R. maidis on barley revealed that it contains mainly plant-derived sugars, but also several aphid-synthesized sugars. The sugar composition of the honeydew changed as a function of aphid colony size and time a colony had been feeding on a plant. In general, the higher the aphid infestation, the smaller the percentage of aphid-synthesized sugars in the honeydew. Experiments with honeydew sugar mimics allowed us to reject the hypothesis that the relatively poor performance of the parasitoid on a honeydew diet was due to the sugar composition. Instead, the results from additional feeding experiments with diluted honeydew showed that the nutritional value of pure honeydew is primarily restricted by its high viscosity. The possible consequences of these findings for biological pest control are discussed.     

Do hummingbirds have a sweet-tooth? Gustatory sugar thresholds and sugar selection in the broad-billed hummingbird Cynanthus latirostris

Nectar is a solution of mainly three sugars: sucrose, glucose and fructose. Studies have demonstrated that pollinators have preferences according to the sugar composition presented in their diet, and these preferences may be caused by sugar assimilation capacities. However, sugar flavor could also play an important role for sugar preferences of nectar-feeding animals. We evaluated the sugar gustatory thresholds of the broad-billed hummingbird Cynanthus latirostris for sucrose, glucose, fructose and a 1:1 mixture of glucose-fructose. We presented eight C. latirostris to paired feeders containing either a sugar solution or pure water. Additionally, we conducted sugar preference tests at three different concentrations (146, 730 and 1022 mmol L^− 1), to relate sugar preferences with sugar gustatory thresholds. C. latirostris had different gustatory thresholds for the three different sugars tested. At low sugar concentrations (146 mmol L^− 1), sugar selection followed the gustatory thresholds. Hummingbird sugar preference patterns can be affected by different mechanisms, both pre- and post-ingestive. At low concentrations gustatory thresholds may play an important role to determine sugar selection. However, at intermediate and high concentrations, sugar assimilation rates, and velocity of food processing generated by osmotic constraints, can be the mechanisms that explain the sugar selection of these animals.     

Sugar concentration and timing of feeding affect feeding characteristics and survival of a parasitic wasp

The availability of food sources is important for parasitoid survival, especially for those that inhabit ecosystems where nectar and honeydew are spatially or temporally scarce. Therefore, the value of even a single meal can be crucial for survival. Psyttalia lounsburyi is a parasitoid, and biological control agent, of the olive fruit fly, Bactrocera oleae. In order to improve our understanding of the basic nutritional ecology of P. lounsburyi and its role in survival we evaluated the effect of a single sucrose meal on the longevity of female and male wasps. We measured the duration of feeding, volume ingested, sucrose consumption, energy content, and longevity of wasps provided with different concentrations of sucrose (0.5, 1, and 2 M) at different times after emergence (0, 1, 2 or 3 days after emergence). Our results showed that longevity was significantly influenced by sucrose concentration and timing of feeding. For females, feeding on sucrose increased the likelihood of survival to varying degrees, ranging from 32.3% to 95.4%, compared to water-only controls. The longest duration of feeding was observed for the highest sucrose concentrations and oldest wasps. The amount of sugar ingested and energy uptake increased, up to a point, as sugar concentration increased. Our results suggest that P. lounsburyi derived greatest benefit from the intermediate concentration (1 M) of sucrose provided 2 or 3 days after emergence. Our study emphasizes the importance of finding balance between increasing longevity and limiting the duration of feeding, and concomitant uptake of nutrients, that is fundamental for survival of the wasp in nature.     

Effect of different dietary resources on longevity, carbohydrate metabolism, and ovarian dynamics in two fruit fly parasitoids

A growing body of literature reports the importance of non-prey food sources in boosting fitness of arthropod natural enemies, thus further contributing to their pest control efficacy. Although resources such as nectar, pollen, or honeydew have received a fair amount of research attention, little is known about the role of fruit juices. Under natural conditions, Tephritid fruit fly parasitoids enjoy ample access to fallen or damaged fruits and their saccharide-rich juices, and wasp fitness can potentially benefit in multiple ways from access to these resources. In this study, we compared the effect of fruit juice with other food resources on multiple fitness parameters in parasitoids that commonly forage on fallen, damaged fruits: the braconid Diachasmimorpha longicaudata and figitid Aganaspis pelleranoi. Parasitoids were subject to simple or combined diets of guava juice (Psidium guajava), honey and pollen, and their effect on wasp longevity, ovarian dynamics and (body) carbohydrate levels was assessed. For both species, adult longevity proved lowest on simple diets of water, guava juice, or pollen, while greatest longevity was attained on honey or combined diets. For D. longicaudata, egg load did not differ between the various diets, while A. pelleranoi egg load was higher for individuals that had access to honey or pollen, but did not differ between newly emerged wasps and those fed guava juice. In both parasitoid species, total sugars, fructose, and glycogen levels were highest in wasps fed with honey or combined diets and lowest under (simple) guava juice, pollen, or water diets. In conclusion, D. longicaudata and A. pelleranoi attained superior longevity and body nutrient levels with access to high-sucrose sugar sources, such as honey, but benefited comparatively little from access to guava juice. Our work hints the role of high-sucrose foods such as (extra-) floral nectar or artifical sugar sprays in boosting fitness of fruit fly parasitoids. We further discuss the relevance of these findings for fruit fly biological control, in crops such as guava.     

The influence of hosts, temperature and food sources on the longevity of Trichogramma platneri

Feeding experiments were conducted with Trichogramma platneri Nagarkatti (Hymenoptera: Trichogrammatidae) reared from the Angoumois grain moth, Sitotroga cerealella (Oliver) (Lepidoptera: Gelechiidae). T. platneri provisioned with host eggs do not live any longer than T. platneri without host eggs. Longevity of T. platneri is inversely related to temperature declining from 53 days at 10 °C to 3 days at 35 °C for honey-fed parasitoids and from 9 days at 10 °C to 1 day at 35 °C for unfed parasitoids. Sugar sources are necessary to prolong longevity of T. platneri, but a source of amino acid did not promote longevity. Honey solutions greater than 10%, and 43% fructose and sucrose solutions increased longevity 10–13 fold to 15–20 days in comparison to water when fed daily to T. platneri. Parasitoids fed only at the onset of the trial had greater longevity than unfed parasitoids but had a shorter longevity than parasitoids fed daily, due to the evaporation of the sugar solutions and consumption of the honey. Aphid honeydew is a suitable field-available sugar source supporting longevity up to 10 days, but is not as good as other sugar sources. Stabilizing additives did not reduce evaporation of a dilute sugar solution nor prolong longevity of T. platneri. Simulating a daily dew fall by misting vials, to redissolve the crystallized food residues left after providing food at the onset of the trial, failed to increase parasitoid longevity.     

Sugar and amino acid composition of ant‐attended nectar and honeydew sources from an Australian rainforest

Abstract Ants (Hymenoptera: Formicidae) consume a broad spectrum of liquid food sources including nectar and honeydew, which play a key role in their diet especially in tropical forests. This study compares carbohydrates and amino acids from a representative spectrum of liquid sources used by ants in the canopy and understorey of a tropical rainforest in northern Queensland, Australia. Eighteen floral nectars, 16 extrafloral nectars, two wound sap and four homopteran honeydew sources were analysed using high performance liquid chromatography. Wounds comprised flower abscission scars on Normanbya normanbyi L. H. Bailey and bitemarks on Cardwellia sublimis F. Muell. where ants were actively involved in wounding. Discriminant analysis was performed to model differences between food sources in sugar and amino acid concentration and composition. All characteristics varied significantly among plant species. Honeydew contained a broader spectrum of sugars (including melezitose, raffinose, melibiose, lactose and maltose) than nectar (sucrose, glucose, fructose), but certain extrafloral nectars had similar amino acid profiles and, like honeydew sources, were often monopolized by ants. Most common amino acids across the sources were proline, alanine and threonine among 17 α‐amino acids identified. Interspecific variability concealed characteristic differences in sugar and amino acid parameters between nectar, honeydew and wound sap across all plants, but these types differed significantly when found on the same plant. Among all sources studied, only a few flower nectars were naturally not consumed by ants and they were significantly less attended than sugar controls in feeding trials. These nectars did not differ in sugars and amino acids from ant‐attended flower nectars, suggesting the activity of repellents. Apart from these exceptions, variability in amino acids and carbohydrates is proposed to play a key role in ant preferences and nutrition.     

Effect of six sugars on the longevity,oviposition performance and nutrition accumulation in an endoparasitoid,Meteorus pulchricornis (Hymenoptera: Braconidae)

The effects of six sugar resources (fructose, glucose, sucrose, trehalose, raffinose and honey) on the longevity, oviposition performance and nutrition levels of Meteorus pulchricornis, a thelytokous larval endoparasitoid of the common cutworm Spodoptera litura were examined under laboratory conditions. Female adults of M. pulchricornis fed 1 M fructose, glucose, trehalose or sucrose solutions survived longer than those fed on other sugar solutions or water. When provided with honey or sucrose solutions, the female parasitoids laid more offspring than those fed other sugar diets or the control. The body size of offspring driven from honey-, fructose-, sucrose-, and glucose-fed females, along with water-fed group, were larger than the trehalose- and raffinose-fed females. However, the emergence rates of all offspring generated from different sugars- and water-fed females were similar. When separately given honey, sucrose or fructose, M. pulchricornis females accumulated fructose at a higher level than the other groups. Parasitoid wasps fed trehalose solution accumulated the highest level of total sugar. Glycogen levels and lipid content were highest at emergence and then decreased across all diets. In addition, females fed on trehalose had the highest level of glycogen compared to other sugar diets and water control regardless of emergency level. Females fed trehalsoe, fructose, and glucose solutions had a higher level of lipid than those fed other sugar solutions and water at life end. The outcome of this study can benefit both laboratory rearing and management interventions that improve sugar sources for the parasitoid in the field.     

Proboscis behavioral response of four honey bee Apis species towards different concentrations of sucrose,glucose, and fructose

Honey bees forage for pollen and nectar. Sugar is an important stimulus for foraging and a major source of energy for honey bees. Any differential response of bees to different concentrations of sugary nectar can affect their foraging. The sugar responsiveness of Apis species (Apis dorsata, Apis florea, and Apis cerana) was determined in comparison to that of Apis mellifera by evaluating the proboscis extension response (PER) with eight serial concentrations (0.00001, 0.0001, 0.001, 0.01, 0.1, 0.5, 1.0, and 1.5 M) of sucrose, glucose and fructose. Nectar foragers of bee species (A. dorsata, A. florea, A. cerana, and A. mellifera) exhibited an equal response for sucrose, glucose, and fructose, with no significant differences in their PER at all tested concentrations of these sugars within the same species. The inter-species comparison between Apis species revealed the differential responsiveness to the different concentrations of sugars, and the lowest concentration at which a response occurs was considered as the response threshold of these bee species for sugar solutions. A. mellifera presented significantly higher responsiveness than A. dorsata to low concentrations (0.00001, 0.0001, 0.001, 0.01, and 0.1 M) of sucrose, glucose and fructose. A. mellifera displayed a significantly higher response to water than A. dorsata. A. florea and A. mellifera presented no significant difference in their responsiveness to sucrose, glucose, and fructose at all tested concentrations, and their water responsiveness was also significantly at par but relatively higher in A. mellifera than in A. florea. Likewise, the responsiveness of A. cerana and A. mellifera to different concentrations of sucrose, glucose and fructose was significantly at par with no difference in their water responsiveness. This study represents preliminary research comparing the response of different honey bee species to three sugar types at different concentrations. The results imply that the native species are all better adapted than A. mellifera under local climate conditions.     

Effect of Bemisia tabaci honeydew and its carbohydrates on search time and parasitization of Encarsia bimaculata

Abstract:  The search time of Encarsia bimaculata Heraty et Polaszek was examined and recorded by using filter paper discs in Petri dish arenas impregnated with Bemisia tabaci (Gennadius) honeydew or its component carbohydrates. Our data show that E. bimaculata used honeydew as a contact kairomone to locate its host. Females responded quantitatively to the honeydew and the search time in the treated patches increased. This increase was concentration-dependent with regard to the amount of honeydew applied, but it levelled off 0.05 g/ml onwards. The response of E. bimaculata to honeydew decreased with increasing time after application and was significantly reduced 8 days after treatment. The parasitoid females were also arrested in patches treated with glucose, fructose, trehalulose and trehalose; trehalose elicited the highest response in the parasitoids. However, sucrose and low concentrations of melezitose did not elicit a significant effect. Glucose, sucrose, fructose, trehalose and trehalulose increased the longevity of the parasitoid females by a factor of 8.4, 8.1, 6.3, 6.1 and 4.2, respectively. Melezitose and 0.15 g/ml natural honeydew, however, had no effect on parasitoid lifespan. The effects of aqueous spray of honeydew sugars on egg to adult survivorship and parasitization of B. tabaci by E. bimaculata significantly differed when compared with controls only in cases where mixtures of glucose + fructose and trehalose and fructose + trehalose were applied.     

Nutritional suitability of individual carbohydrates and amino acids for adult Pieris brassicae

Abstract Many adult Lepidoptera are dependent on carbohydrate-rich solutions such as nectar and honeydew. These food sources can contain a range of carbohydrates as well as low levels of other compounds, including free amino acids, proteins and lipids. Little is known about the nutritional value of individual nectar sugars and amino acids for adult Lepidoptera. Ten sugars occurring in nectar and honeydew were tested with respect to their effects on a number of Pieris brassicae life-table parameters. In similar experiments it was investigated whether the butterfly derives nutritional benefits from mixtures of common non-essential or essential amino acids when provided either in water or in a sucrose solution. Food sources were found to have a significant effect on butterfly fertility, longevity, lifetime fecundity and daily oviposition rate. Whereas a number of sugars significantly increase longevity, melibiose and melezitose reduce P. brassicae longevity. Butterfly fecundity is compromized significantly by sucrose and melibiose. Glucose is the only sugar that has a positive effect on both longevity and fecundity as well as a number of oviposition parameters. Amino acids seem to have no or only a minor effect on the life-table parameters tested. However, when provided in sucrose, they appear to compensate for the negative effect of pure sucrose on fecundity. A comparison with an earlier study on the gustatory response of P. brassicae shows that there is only a weak correlation between the nutritional value of sugars and amino acid mixtures and their perceptibility.