Clark, Katherine Elizabeth (2011) Linking aboveground and belowground insect herbivore interactions: a case study with the vine weevil (Otiorhynchus sulcatus). Doctoral thesis (DPhil), University of Sussex.

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Abstract

Interactions between insect herbivores and host plants are fundamental, shaping both
ecosystem functions and community structure. One aspect of insect-plant interactions that
has received considerable attention recently is the indirect linkages between aboveground
and belowground insect herbivores via a shared host plant. To date, the relationship
between a maternal insect aboveground and her soil dwelling offspring has been largely
overlooked. This study aimed to examine the interactions between the adult insect and soil
dwelling larvae of the vine weevil (Otiorhynchus sulcatus) with reference to the preference–
performance hypothesis, using an agronomically important host plant, red raspberry (Rubus
ideaus).

A meta–analysis of aboveground–belowground insect herbivore interactions highlighted
that belowground Coleopteran herbivores positively impacted aboveground Homoptera
and that general predictions from conceptual models in the literature regarding the
direction of interactions between insects were correct, but not statistically significant. In
addition it was found that aboveground insect herbivores negatively influenced the survival
of belowground herbivores. The preference–performance hypothesis was not supported in
the findings for the vine weevil on raspberry. Instead a conflict between larval
development and adult egg laying behaviour was observed, with a significant reduction in
larval mass recorded when maternal adults fed on the same host plant. Larval mass was
decreased by 19% after prior conspecific root feeding, but maternal weevils did not
distinguish between plants with and without larvae for oviposition. Significant differences
between larval performance (abundances and mass) on the raspberry cultivars Glen Rosa
and Glen Ample were not correlated with adult oviposition aboveground. Instead, in some
instances, maternal egg laying was correlated with foliar nitrogen content, suggesting that
this may be an influential factor in the oviposition behaviour of adult vine weevils.
Significant differences seen in larval performance in the laboratory were not reflected in the
field, with adult vine weevil populations on Glen Rosa and Glen Ample showing no
significant differences in terms of abundance.

The findings from this study suggest that mother–offspring relationships in an
aboveground–belowground context warrant further consideration. In particular, the
identification of potential conflict between mother and offspring highlights another factor
influencing aboveground–belowground relationships that could consequently influence
terrestrial ecosystems.

Item Type:	Thesis (Doctoral)
Schools and Departments:	School of Life Sciences > Biology and Environmental Science
Subjects:	Q Science > QH Natural history > QH0301 Biology Q Science > QK Botany > QK0710 Plant physiology
Depositing User:	Library Cataloguing
Date Deposited:	23 Feb 2011 07:40
Last Modified:	13 Aug 2015 14:34
URI:	http://sro.sussex.ac.uk/id/eprint/6317

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