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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.fatty acids | alpha-linolenic acid | Apis mellifera | associative conditioning | proboscis extension response

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BACKGROUND: Macronutrients play fundamental roles in processes affecting olive oil productivity and are expected to influence oil composition. A necessary step in optimal nutrient application management for olives is an understanding of the relationship between olive tree nutritional status and oil quality parameters. We studied the independent effects of N, P and K concentrations in irrigation solution on the oil quality of 'Barnea' olives by applying a wide range of macronutrient concentrations under highly controlled conditions.

SummaryIn this chapter we present a synthesis of recommendations for conducting field experiments with honey bees in the context of agricultural pollination. We begin with an overview of methods for determining the mating system requirements of plants and the efficacy of specific pollinators. We describe methods for evaluating the pollen-vectoring capacity of bees at the level of individuals or colonies and follow with methods for determining optimum colony field stocking densities. We include sections for determining post-harvest effects of pollination, the effects of colony management (including glasshouse enclosure) on bee pollination performance, and a brief section on considerations about pesticides and their impact on pollinator performance. A final section gives guidance on determining the economic valuation of honey bee colony inputs at the scale of the farm or region. Métodos estándar para el estudio de polinización con Apis mellifera ResumenEn este capítulo se presenta una síntesis de las recomendaciones para la realización de experimentos de campo con abejas melíferas en el contexto de la polinización agrícola. Comienza con una revisión de los métodos para la determinación de los requisitos del sistema de reproducción de las plantas y de la eficacia de los polinizadores específicos. Se describen métodos para evaluar la capacidad de las abejas como vectores de polen a los niveles de individuos o de colonias, y se continúa con los métodos para la determinación de las densidades óptimas de colonias en campo. Se incluyen secciones para la determinación de los efectos de la polinización en la cosecha, los efectos del manejo de las colonias (incluyendo el cercado en invernaderos) en el rendimiento de polinización de las abejas, y una breve sección sobre consideraciones acerca de los plaguicidas y su impacto en el rendimiento de los polinizadores. Una última sección ofrece una guía para la determinación del valor económico de los gastos de las colonias de abejas melíferas a escala de explotación o de región.

BackgroundPast clonal propagation of olive trees is intimately linked to grafting. However, evidence on grafting in ancient trees is scarce, and not much is known about the source of plant material used for rootstocks. Here, the Simple Sequence Repeat (SSR) marker technique was used to study genetic diversity of rootstocks and scions in ancient olive trees from the Levant and its implications for past cultivation of olives. Leaf samples were collected from tree canopies (scions) and shoots growing from the trunk base (suckers). A total of 310 trees were sampled in 32 groves and analyzed with 14 SSR markers.ResultsIn 82.7% of the trees in which both scion and suckers could be genotyped, these were genetically different, and thus suckers were interpreted to represent the rootstock of grafted trees. Genetic diversity values were much higher among suckers than among scions, and 194 and 87 multi-locus genotypes (MLGs) were found in the two sample groups, respectively. Only five private alleles were found among scions, but 125 among suckers. A frequency analysis revealed a bimodal distribution of genetic distance among MLGs, indicating the presence of somatic mutations within clones. When assuming that MLGs differing by one mutation are identical, scion and sucker MLGs were grouped in 20 and 147 multi-locus lineages (MLLs). The majority of scions (90.0%) belonged to a single common MLL, whereas 50.5% of the suckers were single-sample MLLs. However, one MLL was specific to suckers and found in 63 (22.6%) of the samples.ConclusionsOur results provide strong evidence that the majority of olive trees in the study are grafted, that the large majority of scions belong to a single ancient cultivar containing somatic mutations, and that the widespread occurrence of one sucker genotype may imply rootstock selection. For the majority of grafted trees it seems likely that saplings were used as rootstocks; their genetic diversity probably is best explained as the result of a long history of sexual reproduction involving cultivated, feral and wild genotypes.

BACKGROUND: Olive trees are generally grown under rain-fed conditions. Since yield response to application of water in the growing season may be considerable, irrigation is increasingly introduced to existing, mature orchards. An additional feature of modernization of olive cultivation is mechanical harvesting. To investigate the effect of irrigation level on the quality of virgin olive oil (VOO) produced from cv. Souri, six regimes, ranging from deficit to excess, were applied to trees in a mature, traditional orchard as it was converted to irrigation. Furthermore, in order to investigate the effect of damage incurred during harvest, oil quality of hand-picked fruit was compared to that of mechanically harvested olives.