Flowers visited by bombus on flowers strips : complementatrity of direct observations and corbicular loads composition

Agri-Environment Schemes (AES) are increasingly implemented in European farmlands. Their contribution to biodiversity conservation remains poorly studied. In Belgium, two specific flower-strips AES are devoted to birds (fauna-strips) and to insects (pollinator-strips). We studied abundances and diversity of pollinating insects and flower resources (pollen and nectar) provided by both AES strips during four years. In particular, we aimed to check whether the strips provide floral resources to the main efficient pollinators in Belgium, bumblebees. We analyzed both the bumblebee-flower interactions and the fidelity of bumblebee individuals. The observations of direct flower-bumblebee interactions showed that only a few plant species, mainly belonging to Asteraceae, were visited. Centaurea jacea was the most visited plant species on insect-strips (75% of the visited flowers) and Trifolium incarnatum was the most visited on bird-strips (38%).Fidelity was determined by corbicular pollen load analyses. Trifolium repens was the most collected pollen on insect-strips (40% of corbicular pollen) whereas Phacelia tanacetifolia and Raphanus sativus were the most collected pollen on bird-strips (43% and 45% respectively of collected pollen). The combined approaches of direct flower-insect interactions and corbicular pollen load content revealed a sufficient complementarity in resources from the different plant species present in the strips

Balance between pollination and parthenocarpy in the pear (Pyrus communis) variety Conference

Pear is the second fruit growing in Belgium and the variety Conference represents 90% of the Belgian production. Pear tree (Pyrus communis) is a self-incompatible species and requires inter-variety cross-pollination to develop fruits. Hives are often settled in the orchards to facilitate pollination and allow a better fruit size production. However honeybees seem not really attracted by pear flowers and no accurate study of pear tree pollination by insects has been conducted. Moreover, pear tree blooming occurs early in the spring and could be subjected to frost events. Parthenocarpy induction by spraying plant hormones, mainly gibberellins, is a common practice in orchards and allows achieving sufficient yield even under climatically unfavorable spring conditions. No precise study has been carried on to determine the most efficient hormones (gibberellins, cytokinins,…), the moment of their application and the required amounts to apply. Our work aims to better highlight the pear tree reproduction and focuses on the pollination and parthenocarpy processes in the Conference variety