The escape response of pea aphids to foliar‐foraging predators: factors affecting dropping behaviour

Abstract

1. The effects of predator species, aphid density, aphid age, diel period, and habitat complexity on the dropping behaviour of the pea aphid Acyrthosiphon pisum were assessed in a series of laboratory and field-cage experiments.2. The presence of foliar-foraging predators significantly increased the proportion of aphids that dropped from alfalfa plants. In the absence of predators, less than 7% of the aphids dropped. Dropping more than doubled (14%) when one of three hemipteran predators, N. americoferus, G. punctipes or O. insidiosus, was present. Nearly 60% of the aphids dropped when the ladybird beetle, Coccinella septempunctata, was present.3. Adult aphids showed a significantly higher propensity to drop than immature aphids, regardless of the presence or absence of predators. Aphid density had no effect on dropping behaviour. 4. Neither diel period nor habitat complexity had an effect on aphid dropping behaviour. Aphids were significantly more likely to drop in the presence of predators during either the day or night and from either early or late regrowth alfalfa. 5. A review of the factors affecting dropping behaviour, including those elucidated in this study, indicates that the propensity to drop from a plant is influenced by three factors: the risk of predation on the plant, the quality of the resource to be abandoned, and the risk of mortality in the new microhabitat.

Host Location by Apterous Aphids After Escape Dropping from the Plant

“…1), as found in other studies (Roitberg et al, 1979;Losey and Denno, 1998b). Nearly all M. artemisiae individuals that drop, return quickly and efficiently to the host, with the nymphs returning at the slowest pace (Fig.…”

Leucopis annulipes larvae (Diptera: Chamaemyiidae) use a furtive predation strategy within aphid colonies

“…Among the active-searching predators, different predator species induce different levels of aphid defensive behaviour (Losey & Denno, 1998b;Nelson & Rosenheim, 2006). For example, Nelson & Rosenheim (2006) recorded that the ratio of disturbed : consumed A. pisum on alfalfa Medicago sativa L. was 19 : 2 when the predator was Nabis sp.…”

“…Most aphidophagous predators, such as ladybirds and lacewing larvae, use an active-searching strategy that elicits aphid defensive behaviour (Dixon, 1958;Losey & Denno, 1998b;Lucas & Brodeur, 2001). One known exception is the furtive predation strategy used by larvae of Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae) (Lucas & Brodeur, 2001).…”

Predators Reduce Prey Population Growth by Inducing Changes in Prey Behavior

“…Pea aphids (Acyrthosiphon pisum) feed by inserting their mouthparts into alfalfa phloem tissue, and they reproduce parthenogenetically at rates of 4-10 offspring/d (Tamaki et al 1970, Campbell andMackauer 1977). Pea aphids are attacked by a suite of natural enemies that includes lady beetles, parasitoid wasps, and damsel bugs; they respond to the presence of foraging predators by interrupting their feeding and walking away or dropping off the plant (Losey and Denno [1998a] and references therein). The costs suffered by pea aphids as a consequence of their defensive behavior may include increased mortality (Losey and Denno 1998b) and reduced reproductive output (Tamaki et al 1970).…”