Les pucerons, des insectes passionnants et problématiques (1/2)

National audienc

Les pucerons, des insectes passionnants et problématiques (2/2)

National audienc

L’entomofaune des îles subantarctiques françaises

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Myzus ascalonicus, an Aphid Recently Introduced to Sub-Antarctic Islands, Prefers Native to Exotic Host-Plants

International audienceNewly introduced phytophagous insects can affect native and introduced plant species. If the native plant species evolved without undergoing selective pressure from these insects, insect-plant interactions may be different for native and introduced plant species. In particular, this difference may involve mechanisms of plant defense against herbivores. If native plants lack such mechanisms, they may be more palatable to insects than exotic plants. On isolated sub-Antarctic islands, native plant species have evolved in the absence of sap-feeding insects, subsequently introduced a few decades ago. In this study, performance of an introduced aphid species, Myzus ascalonicus Doncaster, was experimentally compared on three native [Pringlea antiscorbutica Hook.f., Acaena magellanica (Lam) Vah, and Leptinella plumosa Hook.f.] and three exotic plant species (Taraxacum officinale F. H. Wigg, Cerastium fontanum Baumg., and Senecio vulgaris L.) found on the Kerguelen Islands. Counts and weights of aphid colonies were 2-7 times higher on native plants than on exotic plants depending on experimental conditions. The results are discussed in light of the possibility of an absence or ineffective defense mechanisms in native plants

The Terrestrial Macroinvertebrates of the Sub-Antarctic Iles Kerguelen and Ile de la Possession

International audienceThe sub-Antarctic islands are remote and isolated environments with original flora and fauna composed of a few species that are highly adapted to cold oceanic conditions. Their peculiar naturalness makes these ecosystems intrinsically fragile.This book focuses on terrestrial ecosystems and, in particular, on invertebrates - earthworms, mollusks, spiders and insects - that inhabit the French sub-Antarctic islands of the South Indian Ocean. All native and introduced species are presented in the form of individual fact sheets, which include the main identification criteria, geographical distribution and principal ecological traits. Numerous summary tables, distribution maps of introduced species, and a discussion on the originality and vulnerability of this fauna are also included.The Terrestrial Macroinvertebrates of the Sub-Antarctic Iles Kerguelen and Ile de la Possession is based on an expansive literature base, as well as on observations and photographs taken as part of a research program funded by the French Polar Institute Paul-Emile Victor (IPEV). The book also gives an important part to the history of the discoveries of the different species, as well as current conservation issues

The Terrestrial Macroinvertebrates of the Sub-Antarctic Iles Kerguelen and Ile de la Possession

International audienceThe sub-Antarctic islands are remote and isolated environments with original flora and fauna composed of a few species that are highly adapted to cold oceanic conditions. Their peculiar naturalness makes these ecosystems intrinsically fragile.This book focuses on terrestrial ecosystems and, in particular, on invertebrates - earthworms, mollusks, spiders and insects - that inhabit the French sub-Antarctic islands of the South Indian Ocean. All native and introduced species are presented in the form of individual fact sheets, which include the main identification criteria, geographical distribution and principal ecological traits. Numerous summary tables, distribution maps of introduced species, and a discussion on the originality and vulnerability of this fauna are also included.The Terrestrial Macroinvertebrates of the Sub-Antarctic Iles Kerguelen and Ile de la Possession is based on an expansive literature base, as well as on observations and photographs taken as part of a research program funded by the French Polar Institute Paul-Emile Victor (IPEV). The book also gives an important part to the history of the discoveries of the different species, as well as current conservation issues

Monitoring and Forescasting

International audienceThis chapter covers the monitoring and forecasting of aphids: why, what, where, when and how? Attention to the first four questions is a prerequi­site for proper consideration of the fifth

Les arthropodes terrestres des iles Kerguelen : une histoire évolutive coupée du monde

National audienceL'isolement produit toujours d'étranges espèces. Dans ce domaine, les insectes et araignées autochtones des îles Kerguelen font figure de cas d'école. Si l'absence de prédateur et les basses températures ont facilité leur inaptitude au vol, leur histoire évolutive est plus complexe qu'il n'y parait

Global Warming Could Magnify Insect-Driven Apparent Competition Between Native and Introduced Host Plants in Sub-Antarctic Islands

International audienceAbstract Pristine sub-Antarctic islands terrestrial ecosystems, including many endemic species, are highly threatened by human-induced cosmopolitan plant invasion. We propose that native plant suppression could be further facilitated by the subsequent invasion by generalist pest species that could exacerbate their competitive exclusion through the process of apparent competition. By comparing the biological parameters of an invasive aphid species, Myzus ascalonicus, on one native (Acaena magellanica) and one invasive (Senecio vulgaris) plant species, we showed that survival and fecundity were higher and development time lower on the native plant species than on the invasive one. Moreover, comparing the effect of a temperature increase on the population dynamics of M. ascalonicus on the two plants, we showed that the relative profitability of the native species is further amplified by warming. Hence, while pest population doubling time is 28% higher on the invasive plant under current temperature, it would become 40% higher with an increase in temperature of 3°C. Consequently, our findings demonstrate that global warming could exacerbate competitive exclusion of native plants by invasive plants in sub-Antarctic islands by its indirect effect on the apparent competition mediated by generalist phytophagous pests

Biological invasions, risk assessment and risk management in the subantarctique and the Antarctic

International audienc