Here we show that a bacterial endosymbiont, Regiella insecticola, protects pea aphids (Acyrthosiphon pisum) from the aphid-specific fungal entomopathogen Zoophthora occidentalis but not from the generalist insect fungal pathogen Beauveria bassiana. This finding highlights the complex influence of fungi on the dynamics of this economically important agricultural pest.

The genome sequence of an alphabaculovirus isolated from Lambdina fiscellaria indicated that it is a novel member of a group II lineage. A putative transposable element was identified that contained two genes, including a transposase ortholog. These genes were most closely related to genes of the pea aphid, Acyrthosiphon pisum.

In Japan, pea aphids Acyrthosiphon pisum mainly feed on vetch and clover, and many aphid clones produce more progeny on vetch than on clover. In this context, particular genotypes of the facultative symbiont Regiella insecticola enhance reproduction of infected pea aphids specifically on clover, thereby broadening the suitable food plant range of the insect. A species that is sympatric to A. pi...

Symbiosis, the close association of unrelated organisms, has been pivotal in biological diversification. In the obligate symbioses found in many insect hosts, organisms that were once independent are permanently and intimately associated, resulting in expanded ecological capabilities. The primary model for this kind of symbiosis is the association between the bacterium Buchnera and the pea aphi...

Background. Many aphid species, including the pea aphid Acyrthosiphon pisum, exhibit a behaviour where they drop or fall from their host plant, a commonly used strategy to avoid predation, parasitism or physical disturbance. We hypothesised that there was a physiological non-consumptive cost due to such dropping behaviour because aphids would expend energy re-establishing themselves on a host p...

Changes in host plant quality, including foliar amino acid concentrations, resulting from global climate change and attack from multiple herbivores, have the potential to modify the pest status of insect herbivores. This study investigated how mechanically simulated root herbivory of lucerne (Medicago sativa) before and after aphid infestation affected the pea aphid (Acyrthosiphon pisum) under ...

Aphids are a major family of plant insect pests. Medicago truncatula and Acyrthosiphon pisum (pea aphid, PA) are model species with a suite of resources available to help dissect the mechanism underlying plant-aphid interactions. A previous study focused on monogenic and relatively strong resistance in M. truncatula to PA and other aphid species. In this study a moderate resistance to PA was ch...

Adaptation to different resources has the potential to cause rapid species diversification, but few studies have been able to quantify the time scale of recent adaptive radiations. The pea aphid, Acyrthosiphon pisum, a model of speciation for host-specialized parasites, consists of several biotypes (races or species) living on distinct legume hosts. To document this radiation, we used rapidly e...

The pea aphid Acyrthosiphon pisum : Harris (Hemiptera: Aphididae) is a phloem-feeding insect whose antipredator defenses include kicking, walking away, and dropping from the plant. Aphid dropping, a risky and energetically costly antipredator behavior, can be increased by the release of aphid alarm pheromone; there is also evidence that insect density and plant health can affect the likelihood ...