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25-Azacholesterol and 25-azacoprostane significantly increased the larval period of southwestern corn borer in a dose dependent fashion from 1 to 300 ppm in the diet. Male larvae were much more resistant than female larvae to the growth-inhibiting effects of the azasteroids. Both azasteroids caused melanization of larvae and inhibited moulting, but did not produce larval-pupal intermediates. The azasteroids caused a reduction in pupal and adult weight at higher concentrations, more so in females than in males. Pupal periods and adult longevity were shortened, and adult wing malformation occurred with the highest azasteroid concentrations. Egg production and hatchability decreased with increasing azasteroid concentrations in larval diets.

1. 1. Cholesterol was the major sterol in southwestern corn borer, Diatraea grandiosella , last instar larvae reared on corn plants or artificial diets containing predominantly sitosterol, and lesser amounts of other phytosterols. 2. 2. Cholesterol progressively increased in pupae and adults in relation to s sitosterol and other dietary sterols which suggested biosynthesis from phytosterol precursors. 3. 3. Total sterols decreased in adults after eclosion and oviposition. 4. 4. Eggs contained about 61% cholesterol and the remainder campesterol while the spent adults had only small amounts of cholesterol.

Southwestern corn borer larvae, Diatraea grandiosella Dyar, were reared on artificial diets containing individual sterols (cholesterol, sitosterol, or stigmasterol) in concentrations ranging from 0.05 to 0.2%. Female larvae developed to pupae more rapidly as sitosterol and stigmasterol were increased in the diets. Increased cholesterol concentrations did not affect the larval period significantly, and development was not as rapid as with the phytosterols. Female larvae developed at significantly slower rates in all diets than did males, except at the highest concentrations of sitosterol and stigmasterol. Female pupae and adults were significantly heavier than the males, and pupal and adult weight increased as sterol concentrations increased. Number of eggs laid per fertilized female and egg hatchability were significantly increased as concentrations of the three sterols were increased in the larval diets. Sitosterol-reared females produced more eggs than did females reared on other sterols but egg hatchability was not significantly different among sterols.

1. 1. Southwestern corn borer larvae, Diatraea grandiosella Dyar, were reared on an artificial diet containing either [4-14]cholesterol or [4-14C]sitosterol mixed with purified carrier sterol as the only sterol source. The uptake and carryover of [14C]sterols were investigated during development and reproduction. 2. 2. Larvae accumulated and carried over larger quantities of sterols to pupae and adults when reared on the sitosterol than on the cholesterol diet. However, there was no difference in the sterol content of the eggs produced by the adults from both diets. 3. 3. Females had larger sterol stores than males and partially transported these into eggs. 4. 4. Sitosterol was metabolized during development to cholesterol, which was deposited in the eggs.