Impacts of Dietary Phytochemicals in the Presence and Absence of Pesticides on Longevity of Honey Bees (Apis mellifera).

Ling-Hsiu Liao,Wen-Yen Wu,May Berenbaum

doi:10.3390/insects8010022

Abstract

Because certain flavonols and phenolic acids are found in pollen and nectar of most angiosperms, they are routinely ingested by Apis mellifera, the western honey bee. The flavonol quercetin and the phenolic acid p-coumaric acid are known to upregulate detoxification enzymes in adult bees; their presence or absence in the diet may thus affect the toxicity of ingested pesticides. We conducted a series of longevity assays with one-day-old adult workers to test if dietary phytochemicals enhance longevity and pesticide tolerance. One-day-old bees were maintained on sugar syrup with or without casein (a phytochemical-free protein source) in the presence or absence of quercetin and p-coumaric acid as well as in the presence or absence of two pyrethroid insecticides, bifenthrin and β-cyfluthrin. Dietary quercetin (hazard ratio, HR = 0.82), p-coumaric acid (HR = 0.91) and casein (HR = 0.74) were associated with extended lifespan and the two pyrethroid insecticides, 4 ppm bifenthrin (HR = 9.17) and 0.5 ppm β-cyfluthrin (HR = 1.34), reduced lifespan. Dietary quercetin enhanced tolerance of both pyrethroids; p-coumaric acid had a similar effect trend, although of reduced magnitude. Casein in the diet appears to eliminate the life-prolonging effect of p-coumaric acid in the absence of quercetin. Collectively, these assays demonstrate that dietary phytochemicals influence honey bee longevity and pesticide stress; substituting sugar syrups for honey or yeast/soy flour patties may thus have hitherto unrecognized impacts on adult bee health.

Highlights

Nectar and pollen, both raw and in their processed forms as honey and beebread, have long been considered as the principal natural sources of carbohydrate and protein, respectively, for honey bees
When heterologously expressed in a baculovirus expression system, three members of the CYP9Q subfamily upregulated by quercetin, CYP9Q1, CYP9Q2, and CYP9Q3, metabolize quercetin as well as pyrethroid and organophosphate pesticides [5]
Insects 2017, 8, 22 a broad-spectrum pyrethroid acaricide. These findings strongly suggest that honey is more than a fuel source and that pollen is more than merely a protein source for the bees; the phytochemicals of honey and pollen appear to play an essential role in honey bee health, in the presence of pesticides

Summary

Introduction

Both raw and in their processed forms as honey and beebread, have long been considered as the principal natural sources of carbohydrate and protein, respectively, for honey bees. Contemporary beekeeping practices have led to the creation of substitutes or supplements for honey and pollen, notably sucrose or fructose for honey and soy flour diet for pollen [1]. Phytochemicals clearly serve important functions beyond carbohydrate and protein nutrition for honey bees [2,3,4] and their absence from dietary supplements or substitutes may have effects on honey bees that are as yet undetermined. Among the phytochemicals present in most pollens and in honey from a diversity of nectar sources, the phenolic acid p-coumaric acid and the flavonol quercetin upon ingestion upregulate expression of a diversity of xenobiotic-metabolizing cytochrome P450 genes, including those encoding. When heterologously expressed in a baculovirus expression system, three members of the CYP9Q subfamily upregulated by quercetin, CYP9Q1, CYP9Q2, and CYP9Q3, metabolize quercetin as well as pyrethroid and organophosphate pesticides [5].

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Conclusion