*Article* **Hydroxymethylfurfural A** ff**ects Caged Honey Bees (***Apis mellifera carnica)*

#### **Aleš Gregorc 1,\*, Snežana Juriši´c 1 and Blair Sampson 2**


Received: 28 November 2019; Accepted: 28 December 2019; Published: 31 December 2019

**Abstract:** A high concentration of hydroxymethylfurfural (HMF) (e.g., 15 mg HMF per kg honey) indicates quality deterioration for a wide range of foods. In honey bee colonies, HMF in stored honey can negatively a ffect bee health and survival. Therefore, in the laboratory, we experimentally determined the e ffects of HMF on the longevity and midgut integrity of worker *Apis mellifera carnica* by feeding bees standard diets containing five concentrations of HMF (100, 500, 1000, and 1500 ppm). Simultaneously, we also examined HMF's e ffect on *Nosema ceranae* spore counts within infected honey bees. We performed an immunohistochemical analysis of the honey bee midgut to determine possible changes at the cellular level. No correlation was established between HMF concentration and *N. ceranae* spore counts. Negative e ffects of HMF on bees were not observed in the first 15 days of exposure. However, after 15 to 30 days of exposure, HMF caused midgut cells to die and an increased mortality of honey bee workers across treatment groups.

**Keywords:** hydroxymethylfurfural; honey bee; cell death; immunohistochemistry; *Nosema ceranae*
