Joint action of l‐leucine and sodium phosphate buffer solutions as feeding stimulants for protein‐deprived females of the house fly Musca domestica

Abstract

Potentiation in joint action was demonstrated between solutions of L-leucine and sodium phosphate buffer (pH 6.3) as feeding stimulants for protein-deprived females of the house fly, Musca domesticu L. Both components alone elicited feeding. In two-choice feeding tests, mixtures consisting of equi-stimulating concentrations of the two components were taken in greater quantities than either component alone at twice the concentration in the mixture.The presence of 1x10-' M phosphate buffer markedly lowered the threshold for detection of L-leucine. The presence of phosphate buffer strengthened the preferences shown by flies given choices of concentrations of L-leucine differing by a factor of 2 and enabled them to display preferences at lower concentrations. M L-leucine increased, somewhat, the ability of flies to detect low concentrations of phosphate buffer. Its presence had relatively little effect on the strength of preference shown between two-fold differences in concentration of phosphate buffer when the higher concentration was 6 . 3~ M or less, but markedly strengthened the preferences when the higher concentration was 2.5X lo-' M or greater. Leucine increased the optimal concentration of phosphate buffer by a factor of more than 2 and converted 2 X lo-' M phosphate buffer from a mild feeding deterrent to a powerful feeding stimulant.The presence of 1 X

The patterning of compensatory sugar feeding in the Australian sheep blowfly

“…Surprisingly, however, no-one has yet recorded the patterning of intake in flies feeding ad libitum to see whether these mechanisms do in fact explain feeding behaviour. Such studies have proved to be of value in understanding the regulation of food intake in the locust (Blaney et al, 1973;Simpson, 1981Simpson, , 1982Simpson & Abisgolcl, 1985;Simpson & Ludlow, 1986) and the caterpillar of Manduca sexta (Reynolds et al, 198t1;Bowdan, 1988a, b).…”

Influence of sex and prior protein feeding on preferences by the housefly, Musca domestica, between sucrose solutions and solutions of l‐leucine or sodium phosphate buffer

“…The flies were from the same source as those used by Barton Browne & Kerr (1985). Females were provided, from the time of emergence, with dry sucrose and water (non-protein-fed females) or were given, in addition, 5% milk powder suspension for 48 h starting at 0900 h on the day after emergence (protein-fed females).…”

“…The test methods were as described in detail by Barton Browne & Kerr (1985). Briefly, groups of 6 house flies, in 1 100 ml glass jars were provided with two horizontal potometers containing the test solutions.…”

“…The findings of Robbins et al (1965) imply that the responses to the stimulatory amino-acids and nucleotides were an integral part of the response of the flies to casein hydrolysate, a material that is nutritionally adequate for ovarian maturation in this anautogenous fly. Those of Robbins et al (1965) and Barton Browne & Kerr (1985) suggest that a response to phosphate might also be involved in the recognition of such materials.…”

“…In an investigation of the chemo-sensory basis for feeding by non-protein-fed females of the housefly, Musca domestica L., on casein hydrolysate, Robbins et al (1965) identified a number of its constituent amino-acids and nucleotides as feeding stimulants and stated that their feeding stimulant activity was enhanced by the addition of phosphate buffer. Subsequently, Barton Browne & Kerr (1985) made a detailed examination of the responses of non-protein-fed female houseflies to l-leucine, one of the most powerful feeding stimulants identified by Robbins et al and sodium phosphate buffer. The findings of Robbins et al (1965) imply that the responses to the stimulatory amino-acids and nucleotides were an integral part of the response of the flies to casein hydrolysate, a material that is nutritionally adequate for ovarian maturation in this anautogenous fly.…”