. The Australian zoologist. Zoology; Zoology; Zoology. A. C. COURTICE and R. A. I. DREW (Drew et al. 1983). The acid conditions not only confirm that bacteria cannot grow in these organs, as symbiotic bacteria would need to do, but also indicate that the flies do not contain proteinase enzymes to hydrolyse ingested protein. Most insect proteinases are active under neutral or alkaline conditions (Gilmour 1961). Fitt (1983) has shown that bacteria that secrete proteinases, when fed to fruit fly larvae, are pathogenic and destroy the stomach wall. Since hydrolysed protein is essential in the diet
. The Australian zoologist. Zoology; Zoology; Zoology. A. C. COURTICE and R. A. I. DREW (Drew et al. 1983). The acid conditions not only confirm that bacteria cannot grow in these organs, as symbiotic bacteria would need to do, but also indicate that the flies do not contain proteinase enzymes to hydrolyse ingested protein. Most insect proteinases are active under neutral or alkaline conditions (Gilmour 1961). Fitt (1983) has shown that bacteria that secrete proteinases, when fed to fruit fly larvae, are pathogenic and destroy the stomach wall. Since hydrolysed protein is essential in the diets of both adults and larvae, it seems most likely that these are ingested through a diet of bacteria which autolyse in the acid condi- tions and release their cell contents into the alimentary canal. The conditions which promote the growth of leaf surface bacteria at Mt. Glorious are clearly transitory. By mid-summer filamentous fungi become dominant on leaf surfaces of stone fruit trees and foliar applications of inorganic nitrogen are required if susceptible cultivars are not to succumb to pathogens which mark the end point of the succession on these trees. Although ornamental peach trees are very numerous in the Brisbane region, and are always heavily infested by D. tryoni and D. neohumeralis, increases in fruit fly numbers at Mt. Glorious, following their emergence in January, are usually small (Fig. 1). Both the movement of marked flies away from the mountain and the absence of a second spring swarm after the very wet winter of 1983 suggest that teneral fruit flies migrate towards regions having a recent history of drought and concomitant accumulation of soil nitrogen. 5000 4000- .5! 3000- - 2000- 1000- 1981-82. SEP OCT NOV DEC JAN FEB MAR Fig. 1. Cumulative totals of Dacus tryoni (Froggatt) plus Dacus neohumeralis Hardy caught in four cuelure traps on Mt. Glorious during the 1980-1, 1981-2 and 1982-3 spring- summer seasons. 264 Aust. Zool. 21(3). 1984. Please note that th
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1914
