Biodiversité fonctionnelle en maraîchage biologique : mise en place de bandes florales pour favoriser les punaises prédatrices - compte-rendu d'essai 2012

Summary

Functional biodiversity can be enhanced by in settling, in the crops surroundings, specific vegetal species that will increase the occurrence of beneficial insects, by providing shelters, and alternative preys. This technique, also called biological control by habitat manipulation, was adapted in Southern France to control spider mites (Tetranychus urticae), and white flies (Trialeurodes vaporariorum and Bemisia tabaci) using two predatory mirid bugs Macrolophus pygmaeus and Dicyphus errans.
Trials started in 2007, with a first step consisting in selecting adapted host-plants for these two mirids. 22 species of host-plants have been sown in strips between greenhouses at the experimental station of GRAB (Avignon – Provence). Germination rate, competition with weeds have been evaluated. Exhaustive samples of insects on these host-plants have been realised. The ratio [number of predators / number of phytophagous] has been calculated, and the number of predatory mirid bugs evaluated.
Dittrichia viscosa and Calendula officinalis appeared to be the most promising species, considering their rusticity, their high ratio [predators/phytophagous] and their ability to shelter Macrolophus and Dicyphus.
Works focused since 2011 on the potential of Geraniacae as host-plants for Dicyphinae, and on the interest of establishing flower strips in the shelters.