Item

Tri-trophic interactions between a plant, a herbivore and a predator: A dissertation submitted in partial fulfilment of the requirement for a degree of Bachelor of Horticultural Science with Honours at Lincoln University

Smith, Jason T.
Date
1994
Type
Dissertation
Fields of Research
ANZSRC::300804 Horticultural crop protection (incl. pests, diseases and weeds) , ANZSRC::410302 Biological control
Abstract
An experiment was conducted at Lincoln University, New Zealand, in the autumn of 1994. Four treatments consisting of four Spodoptera litura (Fabricius) larvae placed on unwounded and wounded tomato plants (Lycopersicon esculentum cv. Moneymaker (Miller)) in the presence or absence of a predatory carabid (Megadromus antarcticus (Chaudoir)) were established. Each treatment consisted of 20 replicates (i.e. plants) arranged in a randomised complete block design. The influence of wound induced chemical changes on the feeding behaviour of larvae and the extent of tri-trophic-level interactions were assessed after forty eight hours. Only approximately 50% of S. Jitura larvae survived the duration of the experiment in treatments containing predators. Wounding had no effect on the survival of caterpillars. The presence of a predator had no effect on the mean leaf area eaten, with 64.75% leaf area consumed in treatments without beetles compared with 45.95% in those with beetles. The mean leaf area eaten per meal by S. litura larvae was significantly influenced by wounding tomato plants. Larvae foraging on previously damaged tomato plants consumed smaller amounts of foliage more often than those on undamaged plants. Overall, more of the lower foliage of tomato plants was consumed by larvae in comparison with the upper tomato foliage, regardless of wounding or the presence or absence of a predator. The possible ecological consequences of this changed larval behaviour and the implications of tri-tropic level interactions are discussed.
Source DOI
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