25 research outputs found
Performance of a North American Field Population and a Laboratory Colony of the Potato Tuberworm, Phthorimaea operculella, on Foliage of Resistant and Susceptible Potato Clones
Foliar resistance of two potato clones was tested against a Columbia Basin field population (CBFP) and a Colorado laboratory colony (COLC) of the potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae). The first clone was a cross of a cultivated potato, Solanum tuberosum L. (Solanales: Solanaceae), and a wild potato, Solanum berthaultii Hawkes (Q 174-2); the second clone was cv. Allegany, S. tuberosum L.. In no-choice assays, defoliation by P. operculella larvae of COLC and CBFP did not differ on Allegany and Q174-2. Larval weight and production of COLC and CBFP colonies were similarly reduced on Q174-2 compared to cv. Allegany, although larval weights and production of the CBFP population were slightly less affected by the host. Larval production by the COLC on Allegany was greater than that on Q174-2, while that of the CBFP on Allegany and Q174-2 did not differ. However, production of P. operculella larvae by the CBFP on Q174-2 during no-choice assays was greater than that in choice tests, indicating reduced host preference. Most of the larvae recovered from either host were fourth instars, followed by third instars. Although the levels of resistance expressed by Q174-2 potato clone to the two P. operculella populations differed in magnitude, nearly all of P. operculella performance criteria measured in this study were adversely affected by Q174-2 foliage compared to the commercial potato cultivar, cv. Allegany
Volatile diterpene emission by two Mediterranean Cistaceae shrubs
Mediterranean vegetation emits a wide range of biogenic volatile organic compounds (BVOCs) among
which isoprenoids present quantitatively the most important compound class. Here, we investigated
the isoprenoid emission from two Mediterranean Cistaceae shrubs, Halimium halimifolium and Cistus
ladanifer, under controlled and natural conditions, respectively. For the first time, diurnal emission
patterns of the diterpene kaurene were detected in real-time by Proton-Transfer-Reaction-Timeof-
Flight-Mass-Spectrometer. Kaurene emissions were strongly variable among H. halimifolium
plants, ranging from 0.01 ± 0.003 to 0.06 ± 0.01 nmol m−2 s−1 in low and high emitting individuals,
respectively. They were in the same order of magnitude as monoterpene (0.01 ± 0.01 to 0.11 ± 0.04
nmol m−2 s−1) and sesquiterpene (0.01 ± 0.01 to 0.52 nmol m−2 s−1) emission rates. Comparable
range and variability was found for C. ladanifer under natural conditions. Labelling with 13C-pyruvate
suggested that emitted kaurene was not derived from de novo biosynthesis. The high kaurene content
in leaves, the weak relationship with ecophysiological parameters and the tendency of higher emissions
with increasing temperatures in the field indicate an emission from storage pools. This study highlights
significant emissions of kaurene from two Mediterranean shrub species, indicating that the release of
diterpenes into the atmosphere should probably deserve more attention in the futureinfo:eu-repo/semantics/publishedVersio