Defensive behaviour of the wheat aphid, Schizaphis graminum (Rondani) (Hemiptera: Aphididae), against Coccinellidae

Abstract

SYNOPSIS An account is given of the behaviour of the wheat aphid, Schizaphis graminum, in response to attacks by two coccinellid predators Scymnus morelleti and Exochomus concavus. Various responses are described and their influence on predator efficiency is investigated.

Dropping to escape: a review of an under‐appreciated antipredator defence

“…The type of predator may also determine the best defensive behaviour as, for instance, flight‐capable insects may still choose to drop where their chances of flying escape are limited by dangers from above (Ben‐Ari & Inbar, ). The predator: prey size ratio – often influenced by the instar stages of both sides – will also influence the effectiveness of running, kicking or dropping as defensive strategies (Dixon, ; Brown, ; Evans, ; Hoki, Losey & Ugine, ). More generally, different predators have been observed to elicit different dropping rates in the same insect prey species (Losey & Denno, ; Castellanos & Barbosa, ; Day et al, ; Castellanos et al, ).…”

“…So-called 'secondary defences' act once subjugation or contact has begun (stages 5 and 6). Unusually, dropping escape can be deployed either as a primary defence [see Barnett et al (2017), Brown (1974) and Clegg & Barlow (1982) for some examples of dropping pre-subjugation] or a secondary defence [see Cloudsley-Thompson (1995) for some examples of dropping post-contact], suggesting that the timing of this escape behaviour can be varied in an adaptive way. Generally, we might not expect prey to drop as soon as they perceive a predator as they will not definitely be at risk of attack unless the predator has already detected them, identified them as prey and begun their approach.…”

“…We define dropping as a voluntary antipredator defence whereby a prey individual uses gravity, wind or water currents to power escape from imminent threat. Dropping can either be passive, where an individual simply falls away or releases its hold on a substrate, or active, where the individual may jump away from a substrate, sometimes kicking or somersaulting in the process (Brown, ); as an example of this variability, Haemig () describes wood ants, Formica aquilonia , both falling and deliberately jumping from trees. Whether passive or active, key to dropping is that the behaviour must result in the individual escaping in a trajectory determined primarily by the external force (gravity or bulk fluid flow) only modified modestly, if at all, by the organism itself.…”

“…Unusually, dropping escape can be deployed either as a primary defence [see Barnett et al . (), Brown () and Clegg & Barlow () for some examples of dropping pre‐subjugation] or a secondary defence [see Castellanos et al . () and Cloudsley‐Thompson () for some examples of dropping post‐contact], suggesting that the timing of this escape behaviour can be varied in an adaptive way.…”

The Effect of Density and Temperature on the Swimming and Aggregating Behaviour of the Backswimmer, Anisops deanei (Heteroptera: Notonectidae) and Subsequent Encounter Rate with a Sit‐and‐Wait Predator

“…I have shown elsewhere (BAILEY 1985(BAILEY , 1986 b) that at different densities the number of A. deanei eaten by R. dispar is related to its multi-prey capturing ability and the rate of extraction of prey body contents. However, it has been shown by other workers that the prey's behaviour (in addition to the predator's) significantly influences the functional response (see for example DIXON 1959;WRATTEN 1973;BROWN 1974;GLEN 1975;THOMPSON 1975). Furthermore, it is to be expected that in a sit-and-wait predator/mobile prey interaction those particular behaviours of the prey, for example, speed, movement patterns, aggregating behaviour, will play a significant part in determining the rate of encounter with the predator, thus influencing the number that may be caught.…”