Rapid responses of winter aphid-parasitoid communities to climate warming

Abstract

Consequences of environmental fluctuations, including those associated with climate changes, can have a knock-on effect from individual to community scale. In particular, changes in species seasonal phenology can modify the structure and composition of communities, with potential consequences on their functioning and the provision of ecosystem services. In mild climate areas, aphids can be present in cereal fields throughout the winter, which allows aphid parasitoids to remain active. Using a nineyear dataset of aphid-parasitoid winter trophic webs in cereal fields of Western France, we report that the community structure and composition that prevailed before 2011 have recently shifted toward a more diversified community, with the presence of two new braconid parasitoid species (Aphidius ervi and Aphidius avenae), a few hyperparasitoid species and one aphid species (Metopolophium dirhodum). Increases in minimal winter temperatures and the frequency of frost events across the years partially explain observed community changes. Strong bottom-up effects from the relative abundances of aphid species also determine the relative abundance of parasitoid species each winter. Strong compartmentalization in parasitoid preference for host is reported. We suggest the recent modifications in parasitoid community composition to be linked to shifts in diapause expression (reduction or arrest of the use of winter diapause) and to host availability throughout the year. We highlight the implications for natural biological control in cereal fields. Perspectives are proposed to predict the composition of future host-parasitoid communities in the climate change context.

Ecology and Genetic Structure of the Parasitoid Phobocampe confusa (Hymenoptera: Ichneumonidae) in Relation to Its Hosts, Aglais Species (Lepidoptera: Nymphalidae)

“…Alternatively, at northern latitudes, the impact of climate change is modulated by the fact that most species are living at a much lower temperature than their physiological optima and, for those, warming is expected to enhance individual fitness [ 42 ]. Most importantly, climate warming may alter life history traits of both the parasitoids and their hosts [ 38 , 43 , 44 ], causing a rapid mismatch in the phenology of these interacting species [ 45 ], as shown in our data. Host use might also be affected by the warming.…”

Mechanisms structuring host–parasitoid networks in a global warming context: a review

“…Global warming could modify host and parasitoid population dynamics (Jeffs & Lewis, 2013) by altering life-history traits such as developmental time, life span and winter diapause, for both hosts and parasitoids (Hance, 2007;Schreven et al, 2017;Tougeron et al, 2018). As host-parasitoid trophic interactions are typically specialised, and hosts and parasitoids often respond differently, this could disrupt phenological synchrony between hosts and parasitoids (Visser & Both, 2005;Klapwijk et al, 2010;Dyer et al, 2013).…”

Simulated heatwave conditions associated with global warming affect development and competition between hyperparasitoids

“…Temperature-related differences in larval competitive interactions between the two species in northern Europe may therefore favor C. vestalis if the warming continues unabated. Warming-induced shifts in community structure have also been observed in other host-parasitoid systems (Tougeron et al 2018).…”