It is well known that many phytophagous insects use plant chemistry in the process of host selection. For example, it has been shown that plants from the family Brassicaceae contain glucosinolates (secondary metabolites) that can act as attractants or deterrents to insect herbivores either in their intact form or when broken down into hydrolysis products. Previous studies have also demonstrated that for some phytophagous insects, a female’s natal environment (preimaginal or eclosion experiences) may affect host oviposition preferences. However, to our knowledge, information is lacking regarding how intraspecific differences in a natal host subsequently affect these preferences. This question was addressed using near-isogenic lines of Arabidopsis thaliana in oviposition bioassays done in the laboratory. Larvae of the generalist Trichoplusia ni and the specialist Plutella xylostella were reared on A. thaliana genetic lines producing different hydrolysis products: the isothiocyanate-producing Col-0, the nitrile-producing 35S:ESP and the double myrosinase knockout tgg1 tgg2. Eclosing adult females from each natal genotype were then used in oviposition bioassays, which included all possible paired combinations of the three genetic lines.
Results/Conclusions In general, we found that regardless of natal plant genotype, P. xylostella preferred to oviposit on plants producing hydrolysis products (i.e., Col-0 and 35S:ESP), whereas T. ni females preferred to oviposit on the double myrosinase mutant tgg1 tgg2, which has no detectable levels of hydrolysis products, over lines containing isothiocyanates (Col-0). However, T. ni showed no preference between tgg1 tgg2 and 35S:ESP. Despite these general trends, in some cases, there was a significant interaction between natal plant genotype and oviposition preference. This suggests that female choice may, at least, be partly influenced by natal host chemistry due to differences at the intraspecific level, via experiences from the larval stage or during eclosion.
