Influence of plant diversity, insecticide applications and landscape on arthropod species richness of two trophic levels in mango orchards : Présentation travaux

L'animation scientifique de L'UMR-PVBMT aura lieu ce jeudi 4 Mars 2015 à 11h salle 1 du Pole de Protection des Plantes au Cirad à Saint Pierre. Maxime Jacquot, doctorant de l'unité, présentera ses résultats en français mais ses diaporamas sont rédigés en anglais.

Sujet :

 Influence of plant diversity, insecticide applications and landscape on arthropod species richness of two trophic levels in mango orchards  a fait l'objet d'une présentation orale au British Ecological Society and Société Française d'Ecologie Annual Meeting 2014  (9 – 12 Décembre, Grand Palais, Lille) 

 Résumé

Conservation biological control implies an appropriate management of arthropod communities at several trophic levels. Plant addition in agroecosystems has effects on upper trophic levels by providing basal resources and new habitats. The abundance and species richness of phytophagous and predatory arthropods may therefore be modified with a potential impact on pest control. Landscape characteristics and pesticide applications are also well known to influence the different trophic levels of the agroecosystems. However, simultaneous influences of these factors on different trophic levels are still poorly reported.

In mango orchards in Reunion, we tested the hypothesis that species richness (SR) of two trophic levels (primary and secondary consumers), are determined by frequency of insecticides application (FIA), addition of cover plants and landscape features. To this end, we used mixed linear models on data on arthropods from extensive sampling (34738 individuals of 469 species in 20 mango orchards).

Our results showed that SR of primary consumers is significantly influenced by the abundance of plant detritus, SR of plants, FIA, proportion of semi-natural elements and the amount of ecotones (transition areas) in the landscape. Species richness of secondary consumers is significantly influenced by these same factors plus SR and abundance of primary consumers.

These results confirm that an integrative approach is essential to understand the factors influencing species richness at the different trophic levels. From an applied perspective, changes in SR of plants and frequency of pesticide use can be levers to design new cropping systems increasing biodiversity. Success or failure of such agroecological practices should also take into account the surrounding landscape.

Publiée : 02/03/2015