Differences in defensive behaviour between host‐adapted races of the pea aphid

Abstract

Abstract. 1. Host races, i.e. host-adapted populations in partial reproductive isolation, have been reported in a growing number of insect herbivores including aphids. The pea aphid Acyrthosiphon pisum encompasses distinct races highly specialised on various Fabaceae plants. Races have been well documented at both the ecological and genetic level. However, little is known about possible behavioural differences between host races other than those involved in plant choice.2. The aim of this study was to determine whether pea aphid host races differ in the behavioural response to the aphid alarm pheromone that was used to simulate immediate predation risk. The behaviour of aphids towards a synthetic alarm pheromone applied in their vicinity was measured in several pea aphid clones originating from various legumes including Medicago sativa, Pisum sativum, Trifolium pratense, and Vicia faba. To control for the influence of plant traits, experiments were conducted on the preferred host plant and on the universal host plant Vicia faba.3. Host races differed in their defensive responses, with stronger behavioural responses in host races originating from M. sativa and T. pratense compared with those coming from P. sativum and V. faba. These differences in behaviour are inherent to the pea aphid host race but not dependent on the test plant.4. Our work shows that host-plant specialisation may involve behavioural traits in addition to host choice. Possible mechanisms of how different defensive behaviours might have evolved are discussed.

Personality variation in a clonal insect: The pea aphid,Acyrthosiphon pisum

“…Not all clones produced all phenotypes and clones differed in their dropping tendency (mean behavior). Similarly, Kunert, Belz, Simon, Weisser, and Outreman (2010) showed that clones that originated from different host plants species (i.e., host races, populations that are adapted to their host species) varied in their mean escape response when reared on the same host plant species. Our results suggest, that the escape behavior is not genetically fixed per se (in that case we would expect all individuals of one clone to show the same behavior) but that response rules are genetically determined (Houston & McNamara, 1999).…”

Predation Determines Different Selective Pressure on Pea Aphid Host Races in a Complex Agricultural Mosaic

“…This is because the high diversification of this group of animals may partly result from adaptive processes that reflect their specialization to different host plants (i.e., higher affinity to feed and reproduce on a particular plant) and associated assortative behavior among individuals within a group on one host plant-type potentially leads to reduced gene flow between groups feeding on different host plants [3]–[5]. In such cases, insect species form “host races” that are often a first step toward eventual sympatric speciation [3], [6]. These host races form, potentially leading to divergent selection via reproductive isolation [3], [7].…”

Strategies used by two apterous strains of the pea aphid Acyrthosiphon pisum for passive dispersal

“…Although wingless aphids mostly are sedentary and can only walk a relatively short distance, their dispersal behaviors are also important for aphids population (Braendle et al, 2006; Brisson, 2010; Irwin et al, 2007), and this has been confirmed by several studies (Phelan et al, 1976; Alyokhin and Sewell, 2003; Kunert et al, 2010; Ben-Ari et al, 2015). Comparing with fully developed winged aphids, wingless aphids have degenerations in some of their sense organs and lose locomotion abilities, resulting in different dispersal ranges (Braendle et al, 2006; Bromley et al, 1980; Kring, 1977; Moran, 1992; Park and Hardie, 2002).…”

“…Studies on apterae of Macrosiphum euphorbiae and Myzus persicae showed different dispersal behaviors and moment abilities (Alyokhin and Sewell, 2003). Many apterous aphids could increase their rate of locomotion and decrease their orientation to vertical image after being dislodged by an alarm pheromone (Phelan et al, 1976; Kunert et al, 2010). …”

“…It is believed that different plants could give different natural selection pressures or nutrition which could affect the behaviors of A. pisum (Phelan et al, 1976; Kunert et al, 2010) . Studies on another aphid, Nasonovia ribisnigri (Mosley 1841), showed that distribution patterns and dispositions of apterous were different in different seasons (Díaz et al, 2012).…”