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Population-related variation in plant defense more strongly affects survival of an herbivore than its solitary parasitoid wasp.

Harvey JA, Gols R - J. Chem. Ecol. (2011)

Bottom Line: Moreover, development was prolonged and biomass was reduced on herbivore-induced plants.However, GS chemistry could not explain the reduced performance on induced plants since only indole GS concentrations increased in response to herbivory, which did not affect insect performance based on multivariate statistics.This result suggests that, in addition to aliphatic GS, other non-GS chemicals are responsible for the decline in insect performance, and that these chemicals affect the parasitoid more strongly than the host.

View Article: PubMed Central - PubMed

Affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands. j.harvey@nioo.knaw.nl

ABSTRACT
The performance of natural enemies, such as parasitoid wasps, is affected by differences in the quality of the host's diet, frequently mediated by species or population-related differences in plant allelochemistry. Here, we compared survival, development time, and body mass in a generalist herbivore, the cabbage moth, Mamestra brassicae, and its solitary endoparasitoid, Microplitis mediator, when reared on two cultivated (CYR and STH) and three wild (KIM, OH, and WIN) populations of cabbage, Brassica oleracea. Plants either were undamaged or induced by feeding of larvae of the cabbage butterfly, Pieris rapae. Development and biomass of M. brassicae and Mi. mediator were similar on both cultivated and one wild cabbage population (KIM), intermediate on the OH population, and significantly lower on the WIN population. Moreover, development was prolonged and biomass was reduced on herbivore-induced plants. However, only the survival of parasitized hosts (and not that of healthy larvae) was affected by induction. Analysis of glucosinolates in leaves of the cabbages revealed higher levels in the wild populations than cultivars, with the highest concentrations in WIN plants. Multivariate statistics revealed a negative correlation between insect performance and total levels of glucosinolates (GS) and levels of 3-butenyl GS. However, GS chemistry could not explain the reduced performance on induced plants since only indole GS concentrations increased in response to herbivory, which did not affect insect performance based on multivariate statistics. This result suggests that, in addition to aliphatic GS, other non-GS chemicals are responsible for the decline in insect performance, and that these chemicals affect the parasitoid more strongly than the host. Remarkably, when developing on WIN plants, the survival of Mi. mediator to adult eclosion was much higher than in its host, M. brassicae. This may be due to the fact that hosts parasitized by Mi. mediator pass through fewer instars, and host growth is arrested when they are only a fraction of the size of healthy caterpillars. Certain aspects of the biology and life-history of the host and parasitoid may determine their response to chemical challenges imposed by the food plant.

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Glucosinolate (GS) concentrations measured in samples taken from cultivated (CYR or STH) or wild cabbage (Brassica oleracea) plants originating from England (KIM, OH, WIN population). Samples were taken from non-induced plants (Non) and from plants that had been exposed to Pieris rapae feeding for 7 d (Ind). Concentrations of the detected 11 GS compounds were pooled for the three different GS classes: aromatic, indole, and aliphatic GS. Aliphatic GS were further subdivided into sulfinyl, alkenyl and hydroxylated GS. Bars give the mean values (+SE) for total GS concentrations. The number of samples varied between 8 and 10 per plant line and treatment
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Fig3: Glucosinolate (GS) concentrations measured in samples taken from cultivated (CYR or STH) or wild cabbage (Brassica oleracea) plants originating from England (KIM, OH, WIN population). Samples were taken from non-induced plants (Non) and from plants that had been exposed to Pieris rapae feeding for 7 d (Ind). Concentrations of the detected 11 GS compounds were pooled for the three different GS classes: aromatic, indole, and aliphatic GS. Aliphatic GS were further subdivided into sulfinyl, alkenyl and hydroxylated GS. Bars give the mean values (+SE) for total GS concentrations. The number of samples varied between 8 and 10 per plant line and treatment

Mentions: Glucosinolate Analysis GS profiles differed profoundly for the different plant populations (Fig. 3). In CYR plants, the profile was dominated by sulfinyl GS (primarily 3-methylsulfinylpropyl GS), whereas in STH plants, it was dominated by alkenyl GS (primarily 2-propenyl GS). In the wild populations, there was both quantitative and qualitative variation in GS profiles. WIN plants produced high levels of alkenyl GS (especially 3-butenyl GS), and most plants of this population contained small amounts of the aromatic GS 2-phenylethyl GS, whereas in the other two wild populations, all aliphatic GS classes were represented. Feeding by P. rapae increased levels of the indole GS and total GS concentration (indole GS, F1,81 = 59.0, P < 0.001; total GS, F1,81 = 10.0, P = 0.001). For the indole GS, the degree of induction depended also on the population (population–induction interaction F4,81 = 9.96, P < 0.001). The increase of indole GS was significant only for the wild populations (all P-values <0.001, Tukey-Kramer).Fig. 3


Population-related variation in plant defense more strongly affects survival of an herbivore than its solitary parasitoid wasp.

Harvey JA, Gols R - J. Chem. Ecol. (2011)

Glucosinolate (GS) concentrations measured in samples taken from cultivated (CYR or STH) or wild cabbage (Brassica oleracea) plants originating from England (KIM, OH, WIN population). Samples were taken from non-induced plants (Non) and from plants that had been exposed to Pieris rapae feeding for 7 d (Ind). Concentrations of the detected 11 GS compounds were pooled for the three different GS classes: aromatic, indole, and aliphatic GS. Aliphatic GS were further subdivided into sulfinyl, alkenyl and hydroxylated GS. Bars give the mean values (+SE) for total GS concentrations. The number of samples varied between 8 and 10 per plant line and treatment
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3197929&req=5

Fig3: Glucosinolate (GS) concentrations measured in samples taken from cultivated (CYR or STH) or wild cabbage (Brassica oleracea) plants originating from England (KIM, OH, WIN population). Samples were taken from non-induced plants (Non) and from plants that had been exposed to Pieris rapae feeding for 7 d (Ind). Concentrations of the detected 11 GS compounds were pooled for the three different GS classes: aromatic, indole, and aliphatic GS. Aliphatic GS were further subdivided into sulfinyl, alkenyl and hydroxylated GS. Bars give the mean values (+SE) for total GS concentrations. The number of samples varied between 8 and 10 per plant line and treatment
Mentions: Glucosinolate Analysis GS profiles differed profoundly for the different plant populations (Fig. 3). In CYR plants, the profile was dominated by sulfinyl GS (primarily 3-methylsulfinylpropyl GS), whereas in STH plants, it was dominated by alkenyl GS (primarily 2-propenyl GS). In the wild populations, there was both quantitative and qualitative variation in GS profiles. WIN plants produced high levels of alkenyl GS (especially 3-butenyl GS), and most plants of this population contained small amounts of the aromatic GS 2-phenylethyl GS, whereas in the other two wild populations, all aliphatic GS classes were represented. Feeding by P. rapae increased levels of the indole GS and total GS concentration (indole GS, F1,81 = 59.0, P < 0.001; total GS, F1,81 = 10.0, P = 0.001). For the indole GS, the degree of induction depended also on the population (population–induction interaction F4,81 = 9.96, P < 0.001). The increase of indole GS was significant only for the wild populations (all P-values <0.001, Tukey-Kramer).Fig. 3

Bottom Line: Moreover, development was prolonged and biomass was reduced on herbivore-induced plants.However, GS chemistry could not explain the reduced performance on induced plants since only indole GS concentrations increased in response to herbivory, which did not affect insect performance based on multivariate statistics.This result suggests that, in addition to aliphatic GS, other non-GS chemicals are responsible for the decline in insect performance, and that these chemicals affect the parasitoid more strongly than the host.

View Article: PubMed Central - PubMed

Affiliation: Department of Terrestrial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands. j.harvey@nioo.knaw.nl

ABSTRACT
The performance of natural enemies, such as parasitoid wasps, is affected by differences in the quality of the host's diet, frequently mediated by species or population-related differences in plant allelochemistry. Here, we compared survival, development time, and body mass in a generalist herbivore, the cabbage moth, Mamestra brassicae, and its solitary endoparasitoid, Microplitis mediator, when reared on two cultivated (CYR and STH) and three wild (KIM, OH, and WIN) populations of cabbage, Brassica oleracea. Plants either were undamaged or induced by feeding of larvae of the cabbage butterfly, Pieris rapae. Development and biomass of M. brassicae and Mi. mediator were similar on both cultivated and one wild cabbage population (KIM), intermediate on the OH population, and significantly lower on the WIN population. Moreover, development was prolonged and biomass was reduced on herbivore-induced plants. However, only the survival of parasitized hosts (and not that of healthy larvae) was affected by induction. Analysis of glucosinolates in leaves of the cabbages revealed higher levels in the wild populations than cultivars, with the highest concentrations in WIN plants. Multivariate statistics revealed a negative correlation between insect performance and total levels of glucosinolates (GS) and levels of 3-butenyl GS. However, GS chemistry could not explain the reduced performance on induced plants since only indole GS concentrations increased in response to herbivory, which did not affect insect performance based on multivariate statistics. This result suggests that, in addition to aliphatic GS, other non-GS chemicals are responsible for the decline in insect performance, and that these chemicals affect the parasitoid more strongly than the host. Remarkably, when developing on WIN plants, the survival of Mi. mediator to adult eclosion was much higher than in its host, M. brassicae. This may be due to the fact that hosts parasitized by Mi. mediator pass through fewer instars, and host growth is arrested when they are only a fraction of the size of healthy caterpillars. Certain aspects of the biology and life-history of the host and parasitoid may determine their response to chemical challenges imposed by the food plant.

Show MeSH
Related in: MedlinePlus