Increased plant volatile production affects oviposition, but not larval development, in the moth Helicoverpa armigera

Abstract

SUMMARYIt is well established that herbivorous insects respond to changes in plant odour production, but little attention has been given to whether these responses relate to direct fitness costs of plant volatile production on insect growth and survival. Here, we use transgenic Nicotiana tabacum (tobacco) plants that produce relatively large amounts of the volatile (S)-linalool to study whether the responses of egg-laying herbivorous insects to linalool production relate directly to the growth and survival of offspring. In choice tests, fewer eggs were laid on transgenic plants compared with non-transformed controls, indicating that increased linalool emissions have a deterrent effect on Helicoverpa armigera oviposition. Larval survival and larval mass after feeding on transgenic leaves, however, was comparable to non-transformed controls. (S)-linalool, whether in volatile or sequestered form, does not appear to have a direct effect on offspring fitness in this moth. We discuss how the ecology of this polyphagous moth species may necessitate a high tolerance for certain volatiles and their related non-volatile compounds, and suggest that responses by adult female H. armigera moths towards increased linalool production may be context specific and relate to other indirect effects on fitness.Supplementary material available online at

Terpenoids in plant and arbuscular mycorrhiza-reinforced defence against herbivorous insects

“…Genetic manipulation of plants for terpenoid emission is a promising method to alter tritrophic interactions. In recent years, transgenic plants producing terpenoids have been used to repel herbivores (Aharoni et al, 2003), deter oviposition (McCallum et al, 2011) and attract predators (Bouwmeester et al, 2003;Kappers et al, 2005;Beale et al, 2006) and parasitoids (Schnee et al, 2006). The physiological cost of terpenoid production has been assumed to be minor, given their low molecular weight and the relatively low concentrations emitted (Dicke and Sabelis, 1990;Halitschke et al, 2000).…”

CYP76C1 (Cytochrome P450)-Mediated Linalool Metabolism and the Formation of Volatile and Soluble Linalool Oxides in Arabidopsis Flowers: A Strategy for Defense against Floral Antagonists

“…However, constitutive or induced/engineered linalool emission can also serve in plant defense (Junker et al, 2011;McCallum et al, 2011;Xiao et al, 2012), and linalool can also attract antagonistic flower visitors such as thrips (Koschier et al, 2000). In addition, herbivoreinduced emission of linalool has been found to affect multitrophic interactions in several systems, where it attracts herbivores as well as their predators and parasitoids Turlings et al, 1995;Xiao et al, 2012).…”

Systemic defense priming byPseudomonas putidaKT2440 in maize depends on benzoxazinoid exudation from the roots

“…More recently, ref. 30 reported contradictory data, and showed that increased emission of (+)-Linalool from transgenic tobacco plants deters oviposition by the moth Helicoverpa armigera, but has no effect on larval development or feeding. 30 Since we did not investigate the chirality of linalool identified in our experiments it is not possible to predict the likely effect of increased emission upon insect behavior.…”