Larvae of Phormia regina (Meigen) (Diptera: Calliphoridae) were reared, in isolation, upon either lamb's liver or meridic diets that varied in protein- and carbohydrate-content. An artificial diet containing 53% protein (by mass of dry ingredients) resulted in the heaviest P. regina pupae and shortest development time when compared with larvae reared upon lamb`s liver and all other diets. In diets where the concentration of protein was less than that of carbohydrate, the level of carbohydrate became important. In a diet containing 22.6% protein it was neither the diet with the highest (51%) nor lowest (17%) concentration of carbohydrate that adversely affected development. Specifically, an intermediate level of carbohydrate (33.9%) resulted in an extended larval period, together with increased mortality and reduced pupal weights. Larvae reared in groups of 10 on either liver or a diet containing 53% protein were heavier than those reared in isolation. Group-rearing hastened development on liver, but not on the meridic diet. The results are discussed in relation to the nutritional ecology of saprophagous calliphorids.
A series of experiments were conducted to compare the susceptibility of P. regina larvae reared in isolation or in groups to the effects of diet-borne metabolic inhibitors: chlorogenic acid (CGA) and mimosine. Larvae were presented with diets containing 0.4 mM CGA or 0.4 mM CGA in combination with 22 mM lysine or methionine or with diets containing 1.5, 15 or 30 mM concentrations of mimosine. Methionine and CGA caused significantly reduced pupal weights when compared with larvae presented with lysine and CGA. All concentrations of mimosine resulted in 100% mortality with larvae unable to successfully complete pupation even at the lowest concentration. In general, larvae reared in groups were less susceptible to the toxic effects resulting from diet-borne metabolic inhibitors. The results are discussed in relation to the chemical factors that result from the feeding activity of saprophagous dipterans.