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Pollen Identification

When many people hear the word "pollen," they often think of allergy season. However, pollen affects more than just humans. Pollen plays an integral role in insect and flower development, as it contains genetic material that unites with genetic material in flowers to create fruits and more flowers. Pollen identification is important because it tells scientists and farmers where the pollen came from, as well as how to prevent insect pests from ruining crops.

  1. Significance

    • Pollen is composed of sporopollenin, a very durable natural marker. This means that scientists can look at the pollen found on an insect and determine where the insect has been. This is imperative information when working with cash crops. For example, a study by the USDA determined that citrus pollen grains were found on crop-killing corn earworms in Oklahoma. The pollen indicated that the earworm pests had migrated from citrus-growing areas, such as Texas, Louisiana or Florida. By learning where the earworms came from, agriculturists were able to take steps to reduce their numbers and kill them before they could reach the corn and cotton region.

    History

    • Pfister first identified the geographic origins of pollen in 1895. He studied French, Swiss and other European honeys to show the scientific possibility of determining their geographical origins by identifying their internal pollen structures. In 1923, Parker studied the stomach contents of honeybees to identify the source of their nectar. Since then, many other types of insects and their markings of sporopollenin have been studied to identify where and what types of plants pollinated them.

    Characteristics

    • Pollen has many characteristics such as spines, pores, furrows and grains. Looking at the pollen characteristics can identify what plant it comes from. For example, ragweed pollen has short internal spines and contains both pores and furrows. Ash pollen has four furrows in a diamond shape, with the furrows at the points. The areas between the furrows are enlarged.

    Pollen Identification in Insects

    • Pollen may be identified in several ways by inspecting different parts of insects. Examining the internal digestive tracts or alimentary canals usually identifies the pollen found in insects such as boll weevils, hoverflies and lady beetles. Moths and butterflies are externally examined to determine what types of pollen they were exposed to. Pollen identification on honeybees is determined by examination of their external bodies, which typically brush up against the flower's anthers when they are foraging its nectar and pollen.

    Other Identification Methods

    • Many science class labs teach students how to identify the different types of pollen using simple tools. Open slides coated with silicon are left outdoors for the evening to collect pollen specimens. The slides are then stained with a mixture of glycerol, ethanol, distilled water and aqueous solution of fuchsin, a dye. The pollen is viewed under a microscope as pink cells. The pores, furrows and grains appear, and then the students can identify what type of pollen they have.

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