No abstract

The aphids Macrosiphum euphorbiae (Thomas) and Myzus persicae (Sulzer) (Homoptera: Aphididae) are serious pests of potato ( Solanum tuberosum L.) (Solanaceae), notably in transmitting several plant viruses. Heterospecific interactions may occur between these two species as they are often seen at the same time on the same potato plant in the field. As aphid infestation is known to induce both local and systemic changes, we conducted experiments to determine the effect of previous infestation on probing behaviour and feeding-related parameters. We used the DC electrical penetration graph technique to characterize the influence of previous infestation by conspecific M. persicae or by heterospecific Ma. euphorbiae on M. persicae feeding behaviour at both local and systemic levels, i.e., on previously infested leaves and on non-previously infested leaves of infested plants, respectively. Conspecific and heterospecific infestation led to similar modification of M. persicae feeding activities. However, the effects of previous infestation occurring at the local level were opposite to those observed at the systemic level. Myzus persicae food acceptance was slightly enhanced on previously infested leaves, whereas it was inhibited on non-infested leaves of infested plants, which indicated an induced resistance mechanism. Our results advance the understanding of the mechanisms involved in aphid-host plant acceptance and colonization processes on potato plants in conspecific and heterospecific situations.

Herbivory induces numerous defence reactions in plants, which can in turn alter the plant quality for insects. The potato aphid, Macrosiphum euphorbiae (Thomas), and the green peach aphid, Myzus persicae (Sulzer) (both Hemiptera: Aphididae), are two important sympatric potato pests in northern France. The objective of this study was to evaluate the effect of a previous infestation of a potato plant, Solanum tuberosum L. (Solanaceae), by M. persicae or M. euphorbiae on the host attractiveness, feeding behaviour, and biological performance of M. euphorbiae subsequently colonising the plant. The preference of aphids was studied with a dual‐choice olfactometer and their feeding behaviour was monitored using the electrical penetration graph technique. Their biological performance was assessed by an in planta bioassay. Non‐infested plants were significantly more attractive to M. euphorbiae than plants pre‐infested by conspecific individuals. Aphids showed a strong reduction in the time spent ingesting phloem sap when feeding on pre‐infested plants. The biological performance of M. euphorbiae was not affected by previous conspecific infestation. Conversely, M. euphorbiae feeding behaviour was not affected on plants previously infested by M. persicae but aphids were more attracted to and had a faster population build‐up on those plants. Our results show that plant response and its effect on M. euphorbiae differed depending on the aphid species previously feeding on the potato plant. This variability in plant response could lead to competition or facilitation between aphids temporally and spatially separated, and promote dispersal under field conditions.

Plant induced responses are activated by multiple biotic and abiotic stresses, and may affect the interactions between a plant and phytophagous insects. The objective of this work was to evaluate the effects of different stresses inflicted to potato plants (Solanum tuberosum) on the potato aphid (Macrosiphum euphorbiae). Abiotic wounding, biotic wounding by Leptinotarsa decemlineata and treatment with volatile methyl jasmonate (MeJA) were evaluated with regard to the orientation behaviour, the feeding behaviour and the development of the potato aphids. Dual‐choice olfactometry showed that plants treated with MeJA lost their attractiveness for the potato aphids, while both abiotic and biotic wounding did not alter the orientation of aphids. Electropenetrography revealed that the feeding behaviour of aphids was only slightly disturbed by a previous L. decemlineata wounding, while it was highly disturbed by mechanical wounding and MeJA treatment. Aphid nymph survival was reduced on mechanically wounded plants, the pre‐reproductive period was lengthened and the fecundity reduced on plants treated with MeJA. Our results bring new information about the effects of various stresses inflicted to S. tuberosum on M. euphorbiae. We showed that wounding and MeJA treatment induced an antixenosis resistance in potato plants against M. euphorbiae, which may influence aphid colonization processes.