Interaction of larval age and dietary formaldehyde on the susceptibility of tufted apple budmoth (Lepidoptera: Tortricidae)to Bacillus thuringiensis

Abstract

Laboratory tests of Bacillus thuringiensis var. kurstaki (strain HD-1) against Platynota idaeusalis reared on a semisynthetic diet showed that the LC 50 values for neonates and 9-day-old larvae showed no significant difference in susceptibility; however, 14-day-old larvae were significantly more susceptible than neonates or 9-day-old larvae. There was no evidence of any interaction between 14-day-old larvae reared on the semisynthetic diets with and without formaldehyde and B. thuringiensis toxicity at any assessment reading. Likewise the toxicity of B. thuringiensis to 14-day-old larvae reared on apple leaves did not differ from the B. thuringiensis toxicity of 14-day-old larvae reared on semisynthetic diets with and without formaldehyde.