Melibiose

About: Melibiose is a research topic. Over the lifetime, 1002 publications have been published within this topic receiving 27300 citations. The topic is also known as: Melibiose.

Gustatory response and longevity in Aphidius parasitoids and their hyperparasitoid Dendrocerus aphidum

Abstract: Aphid parasitoids are commonly used in the biological control of aphids. However, their success in biological control largely depends on the availability of carbohydrate-rich food as an energy source for maintenance and reproduction. Therefore, as these resources have become rare in modern agricultural systems, external sugar sources like flowering plants or artificial sugar solutions are more and more used to provide the biocontrol agents with the necessary sugars. When developing such artificial food sources, it is essential to carefully select the sugars that best support the target parasitoids without benefiting non-target insects, such as pest insects or hyperparasitoids. Here, we investigated the gustatory response and longevity of two commonly used aphid parasitoids (Aphidius colemani and Aphidius matricariae) and their hyperparasitoid Dendrocerus aphidum when provided with one of eight plant- and/or insect-derived sugars (fructose, galactose, glucose, melibiose, melezitose, rhamnose, sucrose and trehalose). Our results showed that the studied insect species consumed the largest amounts of sugars that are most commonly found in honeydew (sucrose, fructose, glucose and melezitose) and also survived best when feeding on these sugars. Both Aphidius spp. survived well on melibiose, whereas D. aphidum performed poorly on this sugar. When melibiose was offered in a mixture with glucose, a significant reduction in longevity was observed for D. aphidum when compared to glucose only, while this was less pronounced for Aphidius spp. This knowledge can be exploited in tailoring food sources to selectively support Aphidius parasitoids, enhancing the biological control of aphids.

Trisaccharides of Lolium and Festuca.

Abstract: IN the course of an investigation into the distribution of water-soluble carbohydrates in seeds of the Gramineae1, it was observed that two species of grass (Lolium perenne L. and Festuca pratensis Huds.) contained in their caryopses substantial amounts of a trisaccharide which was not detected in any of the thirty other wild grasses and cereals examined. This non-reducing trisaccharide (Fig. 1, X) had a specific rotation of + 90.5° (without recrystallization), yielded equal amounts of galactose, glucose and fructose on acid hydrolysis and was readily broken down to fructose and a reducing disaccharide in the presence of invertase or very dilute acid. This ease of hydrolysis suggests that the trisaccharide resembles raffinose in containing a terminal β-fructofuranoside residue. Iodine oxidation2 indicated that the galactose residue was at the non-reducing end of the disaccharide, and electrophoretic mobility of the disaccharide in borate was intermediate between the mobilities of laminari-biose and melibiose. Movement in borate is allied to the mode of linkage of sugar residues3, disaccharides containing 1,2 or 1,4 linkages being of much lower mobility than those containing 1,3 or 1,6 linkages. The disaccharide under consideration would therefore appear to contain either a 1,3 or a 1,6 linkage. Although the electrophoretic behaviour in borate does not distinguish between α and β linkages, the high positive rotation of the trisaccharide suggests that the galactose and glucose residues are α-linked, and, since 6-glucose-α-galactoside is melibiose, it seems probable that the newly isolated disaccharide is 3-glucose-α-galactoside. The trisaccharide from Lolium perenne and Festuca pratensis is therefore tentatively described as α-D-galactopyranosyl-3-α-D-glucopyranosy 1-2- β-D- fructofuranoside.

Bacterial Oxidation of Lactose and Melibiose

Abstract: DURING an investigation of bacteria isolated from blocks of whale meat, two distinct strains of paracolon bacteria (Blx, urease-positive; and C6, urease-negative) were obtained, the sugar metabolism of which was interesting. Tested in the normal way with Durham tubes, these organisms produced acid from lactose within 5–12 days at 30° C. and were accordingly recorded as late lactose fermenters. Tested by Hugh and Leifson's1 method, both strains fermented cellobiose, maltose, sucrose, trehalose, galactose, glucose, mannitol and sorbitol, producing acid and gas anaerobically within 48 hr. at 30° C. Lactose, melibiose and glycerol, however, were not fermented but oxidized, that is, acid was produced from these sugars within 48 hr. under aerobic conditions only.

Carbohydrate Digestion by the Larval Midgut of Heliothis zea

Abstract: Ten of 13 selected substrates were hydrolyzed by crude extracts of midguts from larvae of Heliothis zea (Boddie). Sucrose was the most readily hydrolyzed; raffinose, melezitose, trehalose, glycogen, starch, melibiose, maltose, inulin, and α-methyl glucoside were less readily hydrolyzed. Cellulose, cellobiose, and lactose were not hydrolyzed. The p H optimum for each substrate was determined. Thin-layer chromatography showed that a β-fructosidase occurs in the midgut. Sucrase activity and p H of gut contents were determined each day for 5- to 11-day-old larvae.