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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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Fitness correlates (development time and mass) of the herbivore Mamestra brassicae (a, b) and its parasitoid Microplitis mediator (c, d) when they were reared on cultivated (CYR or STH) or wild (KIM, OH, WIN) cabbage (Brassica oleracea). Hosts (healthy or parasitized) were reared in Petri dishes and provided with leaf tissues collected from non-induced plants (open bars) or from plants that had been exposed to Pieris rapae feeding for 7 d (hatched bars). Leaf tissues were replaced every other day. Parasitoids data are given for males (grey or hatched grey bars) and females (white or hatched white bars) separately. Bars are the mean values (+SE) based on pooled data per dish
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Fig1: Fitness correlates (development time and mass) of the herbivore Mamestra brassicae (a, b) and its parasitoid Microplitis mediator (c, d) when they were reared on cultivated (CYR or STH) or wild (KIM, OH, WIN) cabbage (Brassica oleracea). Hosts (healthy or parasitized) were reared in Petri dishes and provided with leaf tissues collected from non-induced plants (open bars) or from plants that had been exposed to Pieris rapae feeding for 7 d (hatched bars). Leaf tissues were replaced every other day. Parasitoids data are given for males (grey or hatched grey bars) and females (white or hatched white bars) separately. Bars are the mean values (+SE) based on pooled data per dish

Mentions: Development of Mamestra brassicae and Microplitis mediator on Induced and Non-induced Brassica oleracea Leaves Both development time (F4, 73.7 = 270, P < 0.001) and pupal mass (F4, 92.3 = 100, P < 0.001) of the herbivore M. brassicae were affected by the plant population on which the caterpillars had been feeding previously (Fig. 1a and b). Development time (F1, 64.4 = 158, P < 0.001) was longer and pupal mass (F1, 75.3 = 52.1, P < 0.001) was lower on induced compared to non-induced plants (Fig. 1a and b). Induction differentially affected development time and pupal mass depending on the population on which the caterpillars had previously been feeding (population–induction interaction for development time F3, 64.4 = 5.68, P = 0.002, and for pupal mass F3, 75.3 = 5.12, P = 0.003). The effect of induction was strongest for WIN plants, as none of the larvae developed into pupae when they had been feeding on induced WIN plant tissues. Larval survival to pupation was high; more than 90% of the larvae successfully developed into pupae on all plant populations with the exception of the WIN population (Fig. 2a). Survival curves of larvae feeding on induced and non-induced leaf tissues were significantly different for the WIN population only (log-rank test, P < 0.001).Fig. 1


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)

Fitness correlates (development time and mass) of the herbivore Mamestra brassicae (a, b) and its parasitoid Microplitis mediator (c, d) when they were reared on cultivated (CYR or STH) or wild (KIM, OH, WIN) cabbage (Brassica oleracea). Hosts (healthy or parasitized) were reared in Petri dishes and provided with leaf tissues collected from non-induced plants (open bars) or from plants that had been exposed to Pieris rapae feeding for 7 d (hatched bars). Leaf tissues were replaced every other day. Parasitoids data are given for males (grey or hatched grey bars) and females (white or hatched white bars) separately. Bars are the mean values (+SE) based on pooled data per dish
© Copyright Policy
Related In: Results  -  Collection

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

Fig1: Fitness correlates (development time and mass) of the herbivore Mamestra brassicae (a, b) and its parasitoid Microplitis mediator (c, d) when they were reared on cultivated (CYR or STH) or wild (KIM, OH, WIN) cabbage (Brassica oleracea). Hosts (healthy or parasitized) were reared in Petri dishes and provided with leaf tissues collected from non-induced plants (open bars) or from plants that had been exposed to Pieris rapae feeding for 7 d (hatched bars). Leaf tissues were replaced every other day. Parasitoids data are given for males (grey or hatched grey bars) and females (white or hatched white bars) separately. Bars are the mean values (+SE) based on pooled data per dish
Mentions: Development of Mamestra brassicae and Microplitis mediator on Induced and Non-induced Brassica oleracea Leaves Both development time (F4, 73.7 = 270, P < 0.001) and pupal mass (F4, 92.3 = 100, P < 0.001) of the herbivore M. brassicae were affected by the plant population on which the caterpillars had been feeding previously (Fig. 1a and b). Development time (F1, 64.4 = 158, P < 0.001) was longer and pupal mass (F1, 75.3 = 52.1, P < 0.001) was lower on induced compared to non-induced plants (Fig. 1a and b). Induction differentially affected development time and pupal mass depending on the population on which the caterpillars had previously been feeding (population–induction interaction for development time F3, 64.4 = 5.68, P = 0.002, and for pupal mass F3, 75.3 = 5.12, P = 0.003). The effect of induction was strongest for WIN plants, as none of the larvae developed into pupae when they had been feeding on induced WIN plant tissues. Larval survival to pupation was high; more than 90% of the larvae successfully developed into pupae on all plant populations with the exception of the WIN population (Fig. 2a). Survival curves of larvae feeding on induced and non-induced leaf tissues were significantly different for the WIN population only (log-rank test, P < 0.001).Fig. 1

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