Toth Lab

Photograph of Dr. TothDr. Toth studies nutrition, behavior, genetics, and health of honey bees and other pollinators such as paper wasps and wild bees. Research focuses on how nutritional stress in bees relates to other bee health issues. Zooming out, the research addresses the effects of the landscape (in particular plant diversity) on bee nutrition and health. Zooming in, the research addresses how nutritional stress can interact with other health challenges such as diseases and pesticides. The following are results and on-going experiments being conducted by her lab.

Relevant Activities:

• Survey of viruses and nutritional state of managed honey bees from apiaries in different types of landscapes across Iowa.

• Track the incidence of honey bee viruses in other pollinators such as wasps and wild bees, including whether or not these viruses pose health risks to these insects.

• Determine the effect of landscape on the nutritional health of honey bees and wild bees, such as bumble bees.

• Understand the effect of good vs poor diet on bees’ ability to withstand diseases, including viruses.

• Document how bees respond, on both the level of behavior and on the level of individual physiology, to pollen that is contaminated with pesticides.


• Nearly all managed honey bee colonies sampled from Iowa carry multiple viruses of concern to honey bee health.

• Many wild bee species and even wasps are carriers of honey bee viruses, and some appear to be able to be infected with the viruses.

• Grassland management strategies that affect the abundance and diversity of flowering plants have the potential to affect the nutritional health of honey bees and bumble bees.

• Pollen that has high, but sub-lethal, levels of pesticides is often collected by bees and consumed at low levels. Bees behaviorally reject contaminated pollen, but this can also lead to increases in mortality in the long term.

• Bees that are fed on a poor diet (from a single pollen source instead of diverse pollen) are more susceptible to diseases including several viruses of concern to bee health

Take home messages:

• The incidence of honey bee hive mortality and virus levels in Iowa are moderate to high.

• Honey bees that have a diverse diet are healthier and better able to withstand diseases.

• How we use the land, especially whether or not land is managed in a way that promotes plant diversity, can potentially have large effects on bee nutrition and thus health.

• Pesticides are a concern to bee health because sublethal doses can lead to measurable long-term effects on bee health.