Arthropod-Plant Interactions (2008) 2, 197-207

Lynda E. Perkins, Bronwen W. Cribb, Jim Hanan, Ezekiel Glaze, Christine Beveridge and Myron P. Zalucki (2008)
Where to from here? The mechanisms enabling the movement of first instar caterpillars on whole plants using Helicoverpa armigera (Hübner)
Arthropod-Plant Interactions 2 (4), 197-207
Abstract: Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is an economically-important, polyphagous herbivore in Old World countries. The distribution of larvae within various host plants has been described, but few studies have tried to determine the behavioural mechanisms by which the given distributions arose. Our aim was to determine the mechanisms which enable larval movement on pea plants, starting with first instars. Observations and bioassays determined larval movement in response to light and angled surfaces, as well as the effect of feeding and plant volatiles on these responses. The majority (68-72%) of 1st instars were positively phototactic towards blue, green and white light and 42% towards UV light. In the dark, larvae showed negative geotaxis. The angle of their substrate also had a kinetic effect on larvae; the steeper the angle from horizontal the more larvae moved under all conditions. Phenylacetaldehyde (a flower volatile) suppressed larval movement except at 90°. (Z)-3-Hexenyl acetate (a green leaf volatile) reversed the direction of movement at the flattest angle. Feeding lessened the probability of moving. We suggest that phototaxis and geotaxis are behaviours common to larval lepidopterans (caterpillars), and that these basic behaviours are modulated by environmental, larval, and plant factors to give observed distributions. Using a multinomial model approach, we created a flow chart to qualitatively and quantitatively represent the decision-making process of first instar H. armigera in response to the factors influencing movement.
(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): Lynda E. Perkins, Myron P. Zalucki

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Helicoverpa armigera