Experimental and Applied Acarology (2000) 24, 427-440

B. Pels and M.W. Sabelis (2000)
Do herbivore-induced plant volatiles influence predator migration and local dynamics of herbivorous and predatory mites ?
Experimental and Applied Acarology 24 (5-6), 427-440
Abstract: If predators lack information on the prey' 's position, prey have more chance to escape predation and will therefore reach higher population densities. One of the many possible cues that predators may use to find their prey are herbivore-induced plant volatiles. Although their effects on the behaviour of foraging predators have been well studied, little is known about how these prey-related odours affect predator-prey dynamics on a plant. We hypothesise that herbivore-induced plant volatiles provide the major cue eliciting predator arrestment on prey-infested leaves and that the response to these volatiles ultimately leads to lower prey densities. To test this hypothesis experimentally, we created two types of odour-saturated environments: one with herbivore-induced plant volatiles (treatment), and one with green-leaf volatiles (control). An odour-free environment could not be tested because herbivores require plants for population growth. We measured the rate at which predatory mites (Phytoseiulus persimilis) immigrate, emigrate and exploit a single leaf infested by two-spotted spider mites (Tetranychus urticae). The experiments did not show a significant difference between treatment and control. At best, there was a somewhat higher rate of predator (and possibly also prey) emigration in the treatment. The lack of a pronounced difference between treatment and control indicates that at the spatial scale of the experiments random searching for prey was as effective as directional searching. Alternatively, predators were arrested in the prey patch by responding not merely to herbivore-induced plant volatiles, but also to other prey-related cues, such as web and faeces. Based on our current experience we advocate to increase the spatial scale of the experiment (>1 m²) and we provide other suggestions for improving the set-up.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Maurice W. Sabelis

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation
population dynamics/epizootiology

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Tetranychus urticae
Phytoseiulus persimilis (predator)	Tetranychus urticae