I found no effect on the reproductive success of O. bicornis in relation to weed abundance in cereal fields. Nevertheless, it was observed that organic fields exhibited higher levels of both weed and pollinator abundance and diversity, indicating potential variations in resource availability. However, these disparities did not seem to have an impact on the reproductive success of O. bicornis. One possibility is that the floral resources within the fields were insufficient to support successful reproduction, suggesting that a greater abundance of weeds may be required to enhance reproductive outcomes.
Additionally, heightened competition among pollinators for in-field weed resources could potentially impede the attainment of more cocoons from increased weed resources. Lastly, the influence of weeds on reproductive success may be influenced by the surrounding landscape and accessibility to other semi-natural habitats, such as forests and field margins.
Although O. bicornis is not known to forage extensively within closed forests, it is possible that the bees derive benefits from the microclimatic conditions provided by forests, such as reduced wind speed and air temperature. These conditions can be advantageous for the bees, particularly during hot and dry weather periods. This may help explain why weed abundance did not contribute significantly to the reproductive success of O. bicornis in this study.
It could also be that weeds are not an important determinant for reproductive success but rather act as an energy source. Although there is limited research on the specific effects of weeds on the energy requirements of bees, it is believed that the presence of weeds can aid bees in obtaining the necessary resources for nest establishment. In this study, weed diversity affected the nesting behaviour of O. bicornis. This suggests that weeds may provide the essential resources needed for successful nesting by O. bicornis. The presence of a diverse range of weeds can be advantageous as it helps maintain resource availability throughout multiple blooming seasons, which could contribute to the nesting success of O. bicornis.
Finally, this study found that fields with organic farming systems have more weeds and pollinators than fields with conventional farming systems and therefore, are contributing to the biodiversity in agricultural landscapes.