Glyphosate, a widely used herbicide, has been shown to have a range of negative effects on bumblebees, including reduced brood care. Here are some of the ways in which glyphosate can affect brood care in bumblebees:

Reduced foraging activity: Glyphosate can reduce the foraging activity of bumblebees, which means they spend less time collecting pollen and nectar to feed their young. This can lead to a reduction in the amount of food available for the brood, which can stunt their growth and development.

Impaired learning and memory: Glyphosate can also impair learning and memory in bumblebees, which can make it difficult for them to remember the location of their nests and the flowers they need to visit for food. This can further reduce the amount of food available for the brood.

Increased susceptibility to disease: Glyphosate can also increase the susceptibility of bumblebees to disease, which can further reduce the survival of the brood.

Overall, glyphosate can have a range of negative effects on brood care in bumblebees, which can lead to reduced colony growth and survival.