2-tridecanone-glandular trichome-mediated

Tridecanone—Glandular Trichome-Mediated Insect Resistance in Tomato Effect on Parasitoids and Predators of Helwthis zeo... 

Tridecanone/glandular trichome-mediated resistance of L hirsutum f. glabratum PI 134417 to sexta and decemlineata adversely affects an array of parasitoids and predaceous insects that are important natural enemies of the tomato fruitworm, zea. These natural enemies represent a diversity of life histories and are affected by the defenses of PI 134417 in different ways. Because the resistance of PI 134417 decreases the parasitization rates and increases mortality of immatures of the three parasitoid species... 

The diversity and magnitude of the negative tritrophic level effects of 2-tridecanone/glandular trichome-mediated resistance suggest that the deployment of tomato cultivars possessing this resistance, but no additional resistance to other important arthropod pests, could have undesirable pest management consequences. 

Tridecanone also conditions resistance to the Colorado potato beetle, Leptinotarsa decemlineata (Say), causing mortality of young larvae which disrupt the glandular trichomes (47-51), PI 134417 also possesses factors associated with leaf lamellae that kill decemlineata larvae during the late instars. These factors are mechanistically distinct from 2-tridecanone-mediated resistance (51-52),... 

Unlike 2-tridecanone-mediated resistance, which is inherited recessively (45) and kills early instar larvae, the lameliar-based resistance is a dominant or incompletely dominant character. Its presence is observed when larvae are fed PI 134417 foliage from which glandular trichomes have been removed, or Fi hybrid (L, esculentum x PI 134417) foliage, which does not possess 2-tridecanone-mediated resistance (52),... 

Because 2-tridecanone-mediated resistance to sexta and L. decemlineata is genetically distinct from the lamellar-based resistance to zea, it would be possible to develop tomato cultivate resistant to sexta and decemlineata but susceptible to zea. On such cultivate, the 2-tridecanone-mediated induction of elevated tolerance to some insecticides might make control of zea more difficult (55, 58). The severity of H. zea as a pest problem on such cultivate would be further exacerbated if 2-tridecanone associated with the resistant foliage seriously interfered with insect parasitoids and predators important in suppressing natural populations of zea. Because of its occurrence in the foliar glandular trichomes, and because of its broad spectrum toxicity to insects, we considered it likely that parasitoids and predaceous insects searching the resistant foliage for prey would be exposed to potentially toxic levels of 2-tridecanone. 

In field cage studies in which zea larvae on several plant lines were exposed to adult parasitoids (one plant line per cage), percent paras itization by both species was significantly lower on BC2, (a backcross ((L, esculentum x PI 134417) x PI 134417) line with intermediate levels of 2-tridecanone and glandular trichome density), and PI 134417 than on L. esculentum and the Fi hybrid (L. esculentum X PI 134417) (Table ViTT. This pattern reflects levels of 2-tridecanone-mediated resistance to sexta. These data indicate that fewer zea larvae are parasitized on the more resistant plant lines but do not indicate whether this is due to elevated densities of glandular trichomes or methyl ketones, or both. 

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