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American Society for Testing and Materials

Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Citation classic - optimal foraging - a selective review of theory and tests

Bees are subject to numerous pressures in the modern world. The abundance and diversity of flowers has declined, bees are chronically exposed to cocktails of agrochemicals, and they are simultaneously exposed to novel parasites accidentally spread by humans. Climate change is likely to exacerbate these problems in the future. Stressors do not act in isolation; for example pesticide exposure can impair both detoxification mechanisms and immune responses, rendering bees more susceptible to parasites. It seems certain that chronic exposure to multiple, interacting stressors is driving honey bee colony losses and declines of wild pollinators, but such interactions are not addressed by current regulatory procedures and studying these interactions experimentally poses a major challenge. In the meantime, taking steps to reduce stress on bees would seem prudent; incorporating flower-rich habitat into farmland, reducing pesticide use through adopting more sustainable farming methods, and enforcing effective quarantine measures on bee movements are all practical measures that should be adopted. Effective monitoring of wild pollinator populations is urgently needed to inform management strategies into the future.

https://science.sciencemag.org/content/sci/early/2015/02/25/science.1255957.full.pdf

Bee declines driven by combined stress from parasites, pesticides, and lack of flowers

1. Introductory remarks 2. Convolvulacaea 2. Scrophulariaceae, Gesneriaceae, Labiatae, etc. 4. Cruciferae, Papaveraceae, Resedaceae, etc. 5. Geraniaceae, Leguminosae, Onagraceae, etc. 6. Solanaceae, Primulaceae, Polygoneae, etc. 7. Summary of the heights and weights of the crossed and self-fertilised plants 8. Difference between crossed and self-fertilised plants in constitutional vigour and in other respects 9. The effects of cross-fertilisation and self-fertilisation on the production of seeds 10. Means of fertilisation 11. The habits of insects in relation to the fertilisation of flowers 12. General results Index.

The Effects of Cross and Self Fertilisation in the Vegetable Kingdom: CONVOLVULACEÆ

Systemic insecticides are applied to plants using a wide variety of methods, ranging from foliar sprays to seed treatments and soil drenches. Neonicotinoids and fipronil are among the most widely used pesticides in the world. Their popularity is largely due to their high toxicity to invertebrates, the ease and flexibility with which they can be applied, their long persistence, and their systemic nature, which ensures that they spread to all parts of the target crop. However, these properties also increase the probability of environmental contamination and exposure of nontarget organisms. Environmental contamination occurs via a number of routes including dust generated during drilling of dressed seeds, contamination and accumulation in arable soils and soil water, runoff into waterways, and uptake of pesticides by nontarget plants via their roots or dust deposition on leaves. Persistence in soils, waterways, and nontarget plants is variable but can be prolonged; for example, the half-lives of neonicotinoids in soils can exceed 1,000 days, so they can accumulate when used repeatedly. Similarly, they can persist in woody plants for periods exceeding 1 year. Breakdown results in toxic metabolites, though concentrations of these in the environment are rarely measured. Overall, there is strong evidence that soils, waterways, and plants in agricultural environments and neighboring areas are contaminated with variable levels of neonicotinoids or fipronil mixtures and their metabolites (soil, parts per billion (ppb)-parts per million (ppm) range; water, parts per trillion (ppt)-ppb range; and plants, ppb-ppm range). This provides multiple routes for chronic (and acute in some cases) exposure of nontarget animals. For example, pollinators are exposed through direct contact with dust during drilling; consumption of pollen, nectar, or guttation drops from seed-treated crops, water, and consumption of contaminated pollen and nectar from wild flowers and trees growing near-treated crops. Studies of food stores in honeybee colonies from across the globe demonstrate that colonies are routinely and chronically exposed to neonicotinoids, fipronil, and their metabolites (generally in the 1–100 ppb range), mixed with other pesticides some of which are known to act synergistically with neonicotinoids. Other nontarget organisms, particularly those inhabiting soils, aquatic habitats, or herbivorous insects feeding on noncrop plants in farmland, will also inevitably receive exposure, although data are generally lacking for these groups. We summarize the current state of knowledge regarding the environmental fate of these compounds by outlining what is known about the chemical properties of these compounds, and placing these properties in the context of modern agricultural practices.

/pdf/environmental-fate-and-exposure-neonicotinoids-and-fipronil-ln5a08bl9m.pdf

Environmental fate and exposure; neonicotinoids and fipronil

Pollination and seed setting in ficus sycomorus have been investigated in East Africa. Ficus sycomorus is monoecious, each fig bearing both male and female flowers. Inside the figs 6 sycophilous wasps develop: Ceratosolen arabicus, Ceratosolen galili and sycophaga sycomori (primary sycophiles), and Apocrypta sp., Eukoebelea sp. and Sycoryctes sp. (secondary sycophiles). The structure and behavior of these wasps and their bearing on pollination and seed productionare studied. Ceratosolen arabiacus is the legitimate pollinator of Ficus sycomorus. It oviposits chiefly into short—styled female flowers, thus ensuring seed setting in the long—styled ones. It is a mutualistic symbiont of the fig. Sycophaga sycomori oviposits into both short— and long—styled flowers, and does not cause seed setting. It is a competitor of Ceratosolen, but a parasite of the fig. Eukoebelea, Apocrypta and Sycoryctes are inquilines, making use of galls induced by the activity of the primary sycophiles. They do not interfere with seed production in pollinated flowers not occupied by Ceratosolen or Sycophaga.

On the Pollination Ecology of Ficus Sycomorus in East Africa

Summary
Flowering cycles in the ‘Balami’ variety of Ficus sycomorus, the sycomore, were studied in connection with the sycophilous wasps Sycophaga sycomori and Apocrypta longitarsus. In the coastal plain of Israel the syconia of Ficus sycomorus may follow either of two developmental courses: most of the syconia swell rapidly, when still at an early stage of anthesis, thus producing genuinely ‘vegetative parthenocarpic’ fruit; some of them, however, become inhabited by Svcophaga sycomori and then follow a full developmental course, ultimately producing ‘stimulative parthenocarpic’ fruit. The latter type of fruit is seedless, as is the former, and the stimulus for its development is provided by the wasps ovipositing in the flower ovaries and by the subsequent activity of the wasp larvae within. In order to ascertain the reason for the absence of seeds, controlled pollination experiments were conducted. These experiments, and also systematic observations on the sequence of flowering generations throughout the year, have yielded information on seed-setting and the interrelations between the sycomore and its wasps.

Flowering cycles and fruit types of ficus sycomorus in israel

Nectar and pollen within flowers are usually the primary attractants to floral visitors. Chemical analysis of almond nectar and pollen in this study revealed that they contain the secondary compound amygdalin. Floral display often reflects pollinator characters, and almond flowers are accordingly designated as ''bee flowers''. A previ- ous study in Israel showed that when almonds bloom early in the season they attract honeybees, but later in the season the bees shift toward other species that start blooming. In this study, we offered honeybees sugar solutions containing var- ious concentrations of amygdalin. These preference experiments revealed that in mid-summer bees were not selective, whereas early in the summer they were more discriminating, and consumed faster the sugar solutions with the lower amygdalin concen- trations. Possible roles of amygdalin in almond nectar and pollen are discussed.

Amygdalin in almond nectar and pollen – facts and possible roles

This paper reviews research on the role of electrostatic forces in pollination, both in natural and in agricultural systems. Researchers from various fields of biological studies have reported phenomena which they related to electrostatic forces. The theory of electrostatically mediated pollen transfer between insect pollinators and the flowers they visit is described, including recent studies which confirmed that the accumulated charges on airborne honey bees are sufficient for non-contact pollen detachment by electrostatic forces (i.e., electrostatic pollination). The most important morphological features in flower adaptiveness to electrostatic pollination were determined by means of two theoretical models of a flower exposed to an approaching charged cloud of pollen; they are style length and flower opening. Supplementary pollination by using electrostatic techniques is reported, and its possible importance in modern agriculture is discussed.

Dan Eisikowitch

Papers

On the Pollination Ecology of Ficus Sycomorus in East Africa

Flowering cycles and fruit types of ficus sycomorus in israel

Amygdalin in almond nectar and pollen – facts and possible roles

The role of electrostatic forces in pollination

Are electrostatic forces involved in pollen transfer