Response of Lobesia botrana (Lepidoptera: Tortricidae) to Levels of Sugar and Protein in Artificial Diets

Abstract

Laboratory rearing experiments with artificial diets demonstrated a definite prolongation of the larval stage of Lobesia botrana (Denis & Schiffermueller) with increasing dietary levels of glucose. Both males and females had a threshold of 2.3% glucose; higher glucose levels did not produce further increases in size. Generally, faster developmental rates accompanied greater pupal weights, and females produced more eggs on diets with certain glucose levels. Glucose, fructose, maltose, and trehalose were all efficient sugar sources. Sucrose was somewhat inhibitory at the doses used. Individual rearing of larvae confirmed the importance of sugar, particularly during early larval development. whereas the protein supplied by brewer’s yeast was important during late larval development. When brewer’s yeast in the diet was decreased below 1.3% or increased above 8.3%, duration of the larval stage was prolonged, larval mortality was increased, and fecundity was decreased. Among the diets tested, the one with a protein/sugar ratio of 1:1.2 produced the heaviest and most fecund adults in the shortest time.