Influence of life history differences of two tachinid parasitoids of Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) on their interactions with glandula trichome/methyl ketone-based insect resistance in tomato
1992
Farrar, R.R. Jr | Kennedy, G.G. | Kashyap, R.K.
The effects of glandular trichome/methyl ketone (2-tridecanone and 2-undecanone) -based insect resistance in the wild tomato, Lycopersicon hirsutum f. glabratum C.H. Mull, accession PI 134417, on Archytas marmoratus (Townsend) and Eucelatoria bryani (Sabrosky) (Diptera: Tachinidae), both parasitoids of Helicoverpa (=Heliothis) zea (Boddie) (Lepidoptera: Noctuidae), were investigated in the laboratory. A. marmoratus deposits larvae (planidia) on the foliage of its host's food plant; planidia attach to passing hosts, penetrate the cuticle, and develop in the host pupae. E. bryani larviposits directly into its host; its larvae develop in the host larva. A. marmoratus planidia are killed by glandular trichomes of PI 134417 and also by trichomes of hybrid lines with no methyl ketones. The methyl ketones are toxic to planidia, but at least part of the effect is due to other factors, possibly physical entanglement. Both species can be affected indirectly by methyl ketones in the diet of the host. 2-Undecanone reduces the percentage of A. marmoratus larvae that mach pupation. This effect is evidently due to premature death and desiccation of the host pupa caused by 2-undecanone. 2-Tridecanone in host diets had no effect on A. marmoratus. In E. bryani, 2-tridecanone in the diet of the host reduced the number of parasitoids yielded by each parasitized host, although not the overall percentage of hosts parasitized. 2-Undecanone in the diet of the host had no effect on E. bryani.
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