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J Insect Physiol. 2016 Oct - Nov;93-94:56-63. doi: 10.1016/j.jinsphys.2016.08.010. Epub 2016 Aug 25.

Effects of a neonicotinoid pesticide on thermoregulation of African honey bees (Apis mellifera scutellata).

Author information

1
Department of Agricultural Sciences, Alma Mater Studiorum University of Bologna, viale Giuseppe Fanin 42, 40127 Bologna, Italy; Honey Bee and Silkworm Research Unit, Council for Agricultural Research and Economics (CREA-API), via di Saliceto 80, 40128 Bologna, Italy; Division of Biological Sciences, Section of Ecology, Behavior, and Evolution, University of California, San Diego, 9500 Gilman Drive, MC0116, La Jolla, CA 92093-0116, United States.
2
Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria, South Africa.
3
Honey Bee and Silkworm Research Unit, Council for Agricultural Research and Economics (CREA-API), via di Saliceto 80, 40128 Bologna, Italy.
4
Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria, South Africa. Electronic address: hhuman@zoology.up.ac.za.

Abstract

Thiamethoxam is a widely used neonicotinoid pesticide that, as agonist of the nicotinic acetylcholine receptors, has been shown to elicit a variety of sublethal effects in honey bees. However, information concerning neonicotinoid effects on honey bee thermoregulation is lacking. Thermoregulation is an essential ability for the honey bee that guarantees the success of foraging and many in-hive tasks, especially brood rearing. We tested the effects of acute exposure to thiamethoxam (0.2, 1, 2ng/bee) on the thorax temperatures of foragers exposed to low (22°C) and high (33°C) temperature environments. Thiamethoxam significantly altered honey bee thorax temperature at all doses tested; the effects elicited varied depending on the environmental temperature and pesticide dose to which individuals were exposed. When bees were exposed to the high temperature environment, the high dose of thiamethoxam increased their thorax temperature 1-2h after exposure. When bees were exposed to the low temperature, the higher doses of the neonicotinoid reduced bee thorax temperatures 60-90min after treatment. In both experiments, the neonicotinoid decreased the temperature of bees the day following the exposure. After a cold shock (5min at 4°C), the two higher doses elicited a decrease of the thorax temperature, while the lower dose caused an increase, compared to the control. These alterations in thermoregulation caused by thiamethoxam may affect bee foraging activity and a variety of in-hive tasks, likely leading to negative consequences at the colony level. Our results shed light on sublethal effect of pesticides which our bees have to deal with.

KEYWORDS:

Hypothermia; Nicotinic acetylcholine receptors; Sublethal effects; Thermogenesis; Thiamethoxam; Thorax temperature

PMID:
27568395
DOI:
10.1016/j.jinsphys.2016.08.010
[Indexed for MEDLINE]

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