The plastic feeding ecology of wireworms: how can major crop pest behave as a predator?

International audienc

Une méthode simple pour élever des larves de taupins du genre Agriotes en conditions contrôlées

National audienc

Wireworm management in conservation agriculture

International audienceConservation Agriculture (CA), which combines three principles (1) limitation of soil disturbance, (2) its permanent cover and (3) crop diversification, is growing worldwide as a low-input system. By limiting soil disturbance, this farming system provides favourable conditions for the development of soil-dwelling organisms including insect pests. Despite potentially high wireworm densities in CA systems, economic damage to maize crop is rarely observed. In this study, we investigated the long-term influence of three tillage practices of decreasing intensity (mouldboard ploughing (MP), surface tillage (ST) and no-tillage (NT)) on wireworm density to confirm that reducing tillage intensity does increase wireworm density. In addition, we hypothesised that the presence of crop residues can limit damage caused by wireworms by diverting them from the main crop and altering their feeding behaviour. Accordingly, we examined whether covering the soil with a mulch at sowing date or leaving below-ground residues of a cover crop grown before maize sowing can limit wireworm damage on maize compared to leaving the soil bare. This study, using CA systems as a case study, improves our understanding of how cover crop management can help reducing wireworm damage for the following crop and illustrates the interest of manipulating pest feeding behaviour to design promising strategies of Integrated Pest Management (IPM)

Un outil moléculaire simple et abordable pour identifier les larves de taupins du genre Agriotes

National audienc

Alternative Strategies for Controlling Wireworms in Field Crops: A Review

International audienceWireworms, the soil-dwelling larvae of click beetles (Coleoptera: Elateridae), comprise major pests of several crops worldwide, including maize and potatoes. The current trend towards the reduction in pesticides use has resulted in strong demand for alternative methods to control wireworm populations. This review provides a state-of-the-art of current theory and practice in order to develop new agroecological strategies. The first step should be to conduct a risk assessment based on the production context (e.g., crop, climate, soil characteristics, and landscape) and on adult and/or larval population monitoring. When damage risk appears significant, prophylactic practices can be applied to reduce wireworm abundance (e.g., low risk rotations, tilling, and irrigation). Additionally, curative methods based on natural enemies and on naturally derived insecticides are, respectively, under development or in practice in some countries. Alternatively, practices may target a reduction in crop damage instead of pest abundance through the adoption of selected cultural practices (e.g., resistant varieties, planting and harvesting time) or through the manipulation of wireworm behavior (e.g., companion plants). Practices can be combined in a global Integrated Pest Management (IPM) framework to provide the desired level of crop protection

Stratégies alternatives pour la maîtrise de la nuisibilité des taupins sur culture de maïs

National audienc

Dynamic role of grasslands as sources of soil-dwelling insect pests: New insights from in silico experiments for pest management strategies

International audienceSustainable pest control strategies hinge on the knowledge of movement ecology within the agricultural landscape where contrasted habitat qualities intermingle, thereby influencing arthropod dispersal. Hence, habitat manipulation in space and time can be a lever for action to control pests with regard to landscape compositional constraints. In this study, we examined the role of grassland arrangements in field colonisation by soil-dwelling pests within a dynamic agricultural landscape, and discussed the implications for pest management with a focus on wireworms. For this purpose, we proposed a framework combining (i) a spatially explicit and mechanistic model describing the pest population dynamics in both aerial and soil compartments involved along its life cycle, and (ii) spatiotemporal representations of various landscape contexts. We addressed the role of grassland in plot history, in plot neighbourhood, or in both history and neighbourhood. Our results show that species with a short life cycle are more responsive to changes in land use, and that the neighbourhood effect strongly relies on dispersal mechanisms (random vs directed movements). We also highlight how the arrangement of grassy landscape elements in space and time can mitigate crop infestation by soil-dwelling pests, thereby emphasizing the relevance of managing grassland regimes. Once informed by critical pest life traits, our approach opens avenue for the exploration of the spatiotemporal land use manipulation meant for pest management. Future research consists in the exploration of suppressive patterns in simplified but realistic agricultural landscapes, generated under agronomic constraints at the farm or landscape scales

Temporal dynamics of grasslands as sources of soil-dwelling insect pests: implications for landscape-scale pest management strategies

International audienc

Foraging as the landscape grip for population dynamics—A mechanistic model applied to crop protection

Individual ability to survive and reproduce is driven by the foraging for various kinds of resources. In agricultural landscapes, accounting for the distributions of the resources foraged by a pest can help in assessing whether or not its population may damage crops. Such outcome results from landscape dependent processes occurring at several biological scales. We present a reaction-advection-diffusion population dynamics model accounting for the foraging process as a driver of an insect pest redistribution in space. It is based on three individual-scale components: resource perception, energy supply management, as well as their optimal interaction determining the optimal foraging strategies. These elements depend on the distribution of two competing resources (namely, feeding and laying sites) affecting (resp. positively or negatively) the energy supply of an insect pest. Here, resource distribution affects the population dynamics through (1) directed motions towards needed resources in response to their perception, and (2).a metabolic currency materialised by a limited laying ability and an additional death by starvation. Building on its multiscale and mechanistically enhanced sensitivity to landscape modifications, we applied this calibrated tool to a theoretical landscape planning problem. Eventually, the model appears as an efficient tool to achieve pest control, used to propose landscape arrangements more resilient to pest outbrea

A decision support system based on Bayesian modelling for pest management: Application to wireworm risk assessment in maize fields

International audienceProtecting crops against pests is a major issue in the current agricultural production system. In particular,assessing the risk to crops can promote integrated pest management (IPM) strategies that encourage naturalcontrol mechanisms and advocate the use of pesticides as a last resort. In this study, we focused on wireworms,major soil-dwelling insect pests inflicting severe economic damage on various crops (including maize, potatoesand cereals) across Europe and North America. We have developed an original hierarchical Bayesian model thatexplicitly accounts for biological knowledge and uncertainty in field observations, rather than relying solely onstatistical correlations, to predict the level of wireworm infestation. The model was calibrated and validatedusing a substantial dataset originating from an agro-environmental survey carried out over three consecutiveyears (2012–2014) in France, which provides the wireworm abundance in 419 maize fields, together with informationon the landscape context, field history, weather conditions, soil characteristics and farming practicesassociated to each field. Model outcomes show good agreement with current knowledge from literature and fieldexpertise in terms of the effects of variables on wireworm abundance, and provide fairly good predictive capacity.Subsequently, the model was encapsulated as a software (R shiny application) to predict the risk ofwireworm infestation in any field of interest, and can be used by farmers or agricultural advisors as a decisionsupport system for the implementation of IPM strategies. The conceptual framework that we implemented can beadapted to a wide range of similar situations involving other crops and pests