practices, plant growth and natural regulation, but their control in orchards most frequently relies on
regular treatments aiming to avoid direct damage and virus transmission. This study aimed first at
characterising farmers’ management strategies towards aphids and, secondly evaluating them in terms of
efficiency and impact on aphid natural enemies. Protection methods were first identified through semiopen
interviews and peach orchard pesticide records from 19 organic and conventional fruit farms in
south-eastern France. It appeared that in addition to the regular use of direct control, farmers also used
cultural and/or alternative methods and various decision-making indicators to optimise their orchard
crop protection. Comprehensive variables based on the technical guidelines of the IOBC (International
Organisation for Biological and Integrated Control) for crop protection made it possible to differentiate
four strategies: intensive, optimised, input-substitution and integrated. Visual monitoring of aphid
infestations and of beneficial populations was performed at the plot level. Brachycaudus schwartzi and
Myzus varians were the most frequently encountered aphid species but the structures of the communities
were affected by protection strategies: the more integrated the strategy, the more diverse and
abundant the aphids. The two most effective strategies were dominated by chemical treatments, whereas
the other two, less detrimental to aphid antagonists, were mostly carried out by organic farmers. Variations
in aphid communities were related to: (i) the use of toxic products, correlated with low-infestations
and low-abundance and diversity of antagonists; (ii) alternative and cultural methods (such as
mowed ground cover and manual pruning of infested branches, respectively) that promoted high populations
of both guilds. Unexpectedly, the structures of these communities were not related to the
number of treatments, management of tree vigour or of the surrounding environment. The four strategies
identified can be further interpreted as steps towards a redesign of orchard protection where
integrated organic farming would be the most advanced stage. However, the paradox between effective
protection strategy and biodiversity conservation still remains, casting doubts on the agroecological
concept of sustainability.
practices, plant growth and natural regulation, but their control in orchards most frequently relies on
regular treatments aiming to avoid direct damage and virus transmission. This study aimed first at
characterising farmers’ management strategies towards aphids and, secondly evaluating them in terms of
efficiency and impact on aphid natural enemies. Protection methods were first identified through semiopen
interviews and peach orchard pesticide records from 19 organic and conventional fruit farms in
south-eastern France. It appeared that in addition to the regular use of direct control, farmers also used
cultural and/or alternative methods and various decision-making indicators to optimise their orchard
crop protection. Comprehensive variables based on the technical guidelines of the IOBC (International
Organisation for Biological and Integrated Control) for crop protection made it possible to differentiate
four strategies: intensive, optimised, input-substitution and integrated. Visual monitoring of aphid
infestations and of beneficial populations was performed at the plot level. Brachycaudus schwartzi and
Myzus varians were the most frequently encountered aphid species but the structures of the communities
were affected by protection strategies: the more integrated the strategy, the more diverse and
abundant the aphids. The two most effective strategies were dominated by chemical treatments, whereas
the other two, less detrimental to aphid antagonists, were mostly carried out by organic farmers. Variations
in aphid communities were related to: (i) the use of toxic products, correlated with low-infestations
and low-abundance and diversity of antagonists; (ii) alternative and cultural methods (such as
mowed ground cover and manual pruning of infested branches, respectively) that promoted high populations
of both guilds. Unexpectedly, the structures of these communities were not related to the
number of treatments, management of tree vigour or of the surrounding environment. The four strategies
identified can be further interpreted as steps towards a redesign of orchard protection where
integrated organic farming would be the most advanced stage. However, the paradox between effective
protection strategy and biodiversity conservation still remains, casting doubts on the agroecological
concept of sustainability.
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