Acute oral toxicity, apoptosis, and immune response in nurse bees (Apis mellifera) induced by flupyradifurone

Abstract

The potential toxicity of flupyradifurone (FPF) to honey bees has been a subject of controversy in recent years. Understanding the effect of pesticides on nurse bees is important because the fitness of nurse bees is critical for in-hive activities, such as larval survival and performing hive maintenance. In order to evaluate the acute oral toxicity of flupyradifurone on nurse bees, flupyradifurone at five different concentrations was selected to feed both larvae and nurse bees. Our results showed that nurse bees were more sensitive to flupyradifurone than larvae (LD50 of the acute oral toxicity of flupyradifurone was 17.72 μg a.i./larva and 3.368 μg a.i./nurse bee). In addition, the apoptotic rates of neurons in mushroom bodies of nurse bees were significantly induced by flupyradifurone at sublethal concentrations (8 mg/L, 20 mg/L, and 50 mg/L) and the median lethal concentration LC50 (125 mg/L). The expression of immune-related genes (Hsp90, Toll-8/Tollo, and defensin) was significantly changed in exposed nurse bees at the field-realistic concentration of flupyradifurone. However, three detoxifying enzyme genes (CYP9Q1, -2, and -3) were not affected by pesticide exposure. Our data suggest that although flupyradifurone had a relatively lower acute oral toxicity than many other common pesticides, exposures to the field-realistic and other sublethal concentrations of flupyradifurone still have cytotoxicity and immune-responsive effects on nurse bees. Therefore, flupyradifurone should be considered for its application in crops.

Effects of pesticide-adjuvant combinations used in almond orchards on olfactory responses to social signals in honey bees (Apis mellifera)

“…The impaired olfactory responses may be attributed to toxic effects on the peripheral olfactory system of honey bees, central nervous system, or both. Sublethal doses of pesticides can induce neurotoxic effects in honey bees, including altered synaptic transmission, oxidative stress, and apoptosis 31 , 32 , 60 , 67 – 69 . Furthermore, Asian honey bees ( Apis cerana ) from areas with high pesticide use exhibit impaired olfaction, characterized by decreased proboscis extension response during olfactory learning, alterations in the expression of Calpain 1 (an important calcium-binding protein), and reduced calcium levels in their brains 29 .…”

Ultrastructural Changes in the Midgut of Brazilian Native Stingless Bee Melipona scutellaris Exposed to Fungicide Pyraclostrobin

“…The described characteristics are associated with programmed cell death (apoptosis) [ 60 ]. These responses can act as a defense mechanism against pyraclostrobin exposure, as observed with the other stressors [ 44 , 61 , 62 , 63 ]. However, even with the characteristics indicative of cytotoxicity, the cells maintained intact and probably active organelles (normal morphology), such as Golgi complexes, rough endoplasmic reticulums, and mitochondria.…”

Interaction of Flupyradifurone and Deltamethrin, Two Pesticides Commonly Used for Plant Pest Control, in Honeybees

“…The ten control (CTRL) groups were treated with sucrose solution only. The concentrations of DTM and FLU used were doses that caused acute intoxication and were chosen by referring to already-published studies [ 25 , 35 , 36 , 37 ]. Until administration, the prepared dilutions were kept between 6 and 2 °C and coated in aluminum foil to prevent light deterioration.…”