Quantitative and qualitative effects of larval diet on male scent secretions of Estigmene acrea, Phragmatobia fuliginosa, and Pyrrharctia isabella (Lepidoptera: Arctiidae)

In feeding experiments with insects reared in the laboratory, the presence of the dihydropyrrolizines hydroxydanaidal and danaidal in the male scent organs (coremata) of the arctiids, Estigmene acrea (Drury), Phragmatobia fuliginosa (L.), and Pyrrharctia isabella (J.E. Smith), was shown to depend on the presence of a source of pyrrolizidine alkaloids (PAs) in the larval diet. A behavioral bioassay showed that the coremata of PA-denied Pyrrharctia male progeny of PA-denied parents were pheromonally inactive, whereas those of PA-denied male progeny of PA-supplied parents (male and/or female) were often active.