title: Omega-3 deficiency impairs honey bee learning.
abstract: Deficiency in essential omega-3 polyunsaturated fatty acids (PUFAs), particularly the long-chain form of docosahexaenoic acid (DHA), has been linked to health problems in mammals, including many mental disorders and reduced cognitive performance. Insects have very low long-chain PUFA concentrations, and the effect of omega-3 deficiency on cognition in insects has not been studied. We show a low omega-6:3 ratio of pollen collected by honey bee colonies in heterogenous landscapes and in many hand-collected pollens that we analyzed. We identified Eucalyptus as an important bee-forage plant particularly poor in omega-3 and high in the omega-6:3 ratio. We tested the effect of dietary omega-3 deficiency on olfactory and tactile associative learning of the economically highly valued honey bee. Bees fed either of two omega-3-poor diets, or Eucalyptus pollen, showed greatly reduced learning abilities in conditioned proboscis-extension assays compared with those fed omega-3-rich diets, or omega-3-rich pollen mixture. The effect on performance was not due to reduced sucrose sensitivity. Omega-3 deficiency also led to smaller hypopharyngeal glands. Bee brains contained high omega-3 concentrations, which were only slightly affected by diet, suggesting additional peripheral effects on learning. The shift from a low to high omega-6:3 ratio in the Western human diet is deemed a primary cause of many diseases and reduced mental health. A similar shift seems to be occurring in bee forage, possibly an important factor in colony declines. Our study shows the detrimental effect on cognitive performance of omega-3 deficiency in a nonmammal.
authors.affiliation: B. Triwaks Bee Research Center, Department of Entomology, Robert H. Smith Faculty of Agriculture, Food & Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel;
authors.forename: Yael
authors.initials: Y
authors.lastname: Arien
authors.affiliation: Gilat Research Center, Institute of Plant Sciences, Agricultural Research Organization, Mobile Post Negev 85280, Israel.
authors.forename: Arnon
authors.initials: A
authors.lastname: Dag
authors.affiliation: B. Triwaks Bee Research Center, Department of Entomology, Robert H. Smith Faculty of Agriculture, Food & Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel;
authors.forename: Shlomi
authors.initials: S
authors.lastname: Zarchin
authors.affiliation: B. Triwaks Bee Research Center, Department of Entomology, Robert H. Smith Faculty of Agriculture, Food & Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel;
authors.forename: Tania
authors.initials: T
authors.lastname: Masci
authors.affiliation: B. Triwaks Bee Research Center, Department of Entomology, Robert H. Smith Faculty of Agriculture, Food & Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel; sharoni.shafir@mail.huji.ac.il.
authors.forename: Sharoni
authors.identifier: http://orcid.org/0000-0002-9068-1078
authors.initials: S
authors.lastname: Shafir
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology*; D001923:Brain Chemistry; D003071:Cognition; D003214:Conditioning, Classical; D005227:Fatty Acids / Q000032:analysis; D015525:Fatty Acids, Omega-3 / Q000032:analysis / Q000502:physiology*; D043371:Fatty Acids, Omega-6 / Q000032:analysis; D007858:Learning; D011058:Pollen / Q000737:chemistry
chemical_list: D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6
keywords: Apis mellifera; alpha-linolenic acid; associative conditioning; fatty acids; proboscis extension response