Within the constraints of the experiments conducted vine weevil were found to exhibit a
strategy of volume of indiscriminate oviposition rather than a strategy of definitives it eselection characteristic of a true oviposition behaviour.
A series of experiments was conducted to determine oviposition and host plant interactions
under conditions of choice and absence of choice of host plant. It was found that
oviposition was greatest for Yew, followed by polyanthus, fushcia, strawberry and (despite
the name) was found to be least on vine plants. Variation was attributed to a combination
mainly of ground cover and partially quality of host. Oviposition was found to be much
lower under conditions of absence of choice. Variation was attributed to the observation
that not all vine weevil oviposit all the time and that feeding and oviposition upon a plant
are independent.
A further experiment conducted using strawberry plants with variable leaf N reinforced the
interpretation that feeding and oviposition are independent functions. Under conditions of
choice of host plant it was found that feeding occurred upon plants that were not capable of
generating ova.
Passive transponders attached to individual vine weevil adults were Utilised in order to
relate oviposition and feeding to specific actions of individual vine weevil. If was found
that a greaterv olume of leaf matter was consumed from leaves of high N that was not
associated with an increase in plant visitation. It was also found that the presence of
surface refuge increases the volume of oviposition and feeding- possibly as a function of
increasing the number of vine weevil that remain in association with the host plant. Direct
measurement of leaf area consumed reinforced the observation that feeding and oviposition
are not correlated. Transponder signals that indicate that more than one weevil is present at
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an oviposition site suggests that vine weevil do not have the need to be alone when
ovipositing.
The distribution of oviposition is highly influenced by locomotion. Traditional arena based
studies suggested the high level of incidence of directional bias. In order to determine the
angle of rotation and the path length an item of apparatus was designed a nd created. The
AVOID apparatus enabled the measurement of path and angle without the detrimental
effect of an arena wall. The avoid apparatus was used to determine the variables related to
locomotion for a comparison of pre-oviposition weevil locomotion with post oviposition
locomotion, the effect of nutritional state upon locomotion and the effect of crowding.
Observations uggests that vine weevils that have oviposited have a greater tendency to
remain inactive than pre-oviposition vine weevils,which may result in an increased level
of dispersal of pre-oviposition vine weevils.
The contribution to dispersably larval stage0 . sulcatus was determined.It was found that
third instar vine weevil larvae are highly mobile. It is theorised that the artificial barrier
created by a plant pot prevent dispersal and,thus, exacerbate the larval status as a pest.
An attempt was made to develop a molecular biology technique to differentiate the ova
produced by multiple vine weevils at an oviposition site. It was determined that sufficient
DNA could be extracted from a single ovum to enable several PCR reactions. A
theoretical model of the inheritance of mtDNA molecules was created to test the feasibility
of mtDNA mutation as a differentiation method.
Date of Award | 2003 |
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Original language | English |
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Awarding Institution | |
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THE OVIPOSITION BEHAVIOUR OF THE BLACK VINE WEEVIL Otiorhynchus sulcatus (FABR)
Goodwin, T. J. (Author). 2003
Student thesis: PhD