Insects are small air-breathing arthropods (such as ants, beetles, butterflies, bees) with a three-part body (head, thorax and abdomen), three pairs of jointed legs, typically one or two pairs of wings, compound eyes and two antennae.
Insects are the most diverse group of animals; they include more than a million described species and represent more than half of all known living organisms and over 90% of the animal life forms on Earth. Insects are found in nearly all land environments, but only a few species reside in the oceans. Insects perform a vital role in supporting other life forms and ecosystems; pollination, soil aeration, processing of nutrients and as part of the overall food chain.
Entomology is the study of insects and their relationship to humans, the environment, and other organisms. Entomologists contribute to such diverse fields as agriculture, chemistry, biology, human/animal health, molecular science, and even criminology and forensics.
Nematodes, also known as roundworms and eelworms, are one of the most diverse and abundant groups of animals on earth. They are found on every continent and in almost every habitat known to man. Nematodes in the soil are microscopic organisms and can very rarely be seen with the naked eye. There are many different kinds of nematodes and they are divided into groups based on what they eat. Herbivorous nematodes (plant-parasitic nematodes), feed on all different parts of a plant. These nematodes are sometimes referred to as the bad nematodes because they can cause damage to agricultural crops and they make it difficult to grow the food we eat.
But there are also beneficial nematodes, the so called good guys, which can be beneficial to humans because they are essential for soil health. These nematodes are also divided into different groups. Bacterivores (nematodes that eat bacteria), fungivores (nematodes that eat fungi), predators (nematodes that eat other microscopic animals including other nematodes) and omnivores (nematodes that eat plants and animals). These nematodes play an essential role in the soil food web because not only do they eat the other organisms in the soil, but they are also food for many of the other animals also found in the soil. Nematodes are also important in nutrient cycling in the soil, enabling plants to take up nutrients and ensuring plant growth. In the soil environment there are millions of nematodes from all the different feeding groups.
Plants form one of the six big groups or kingdoms of living things. They have complex cells, make their own food and, usually, they cannot move (except for growing). Plants include familiar types such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The ornate members are called flowers. The scientific study of plants is called botany and has identified about 350,000 species of plants. Fungi and non-green algae are not classified as plants.
How plants grow
Most plants have stems that grow into the air and roots that grow in the ground. Some float on water. The root part absorbs water and nutrients which the plant needs to live and grow. The water and nutrients are transported from the roots through the stem to the leaves. The evaporation of water from pores in the leaves pulls water through the plant. This is called transpiration.
A plant needs sunlight, carbon dioxide, minerals and water to make food by a process called photosynthesis. A green substance in plants called chlorophyll, found mostly in leaves, traps the energy from the sun needed to make food. The leaf can be thought of as a food factory. Leaves of plants vary in shape and size, but they are always the plant organ best suited to capture solar energy. Food made in the leaf of the plant is transported to the other parts such as stems and roots.
Crops are plant or plant products that are grown deliberately. Food crops, such as fruit and vegetables, are harvested for human consumption. Grains, such as corn, wheat, and rice, are the world’s most popular food crops. Examples are wheat, maize and rice, all vegetables and fruit, flowers and even special grasses. Food crops were the first crops to be harvested through agriculture. Agricultural development and the growth of civilizations led to the diversity of other types of crops. Climate, topography and soil types will significantly influence what can grow where. Crops are easily identified as they are usually laid out in neat patterns to maximise utilisation of the land, to facilitate irrigation (where required) and harvesting, especially where machinery is involved.
Crops can be sold ‘fresh’ as harvested or sent on for further processing e.g. wheat for flour, fruit juices. Local micro-climates to protect and enhance crops can be created using large expanses of shade netting and controlled irrigation.
Irrigation is the application of controlled amounts of water to land for the purpose of agricultural production. Adequate irrigation will influence the entire growth process from seedbed preparation, germination, root growth, transport and utilisation of nutrients, plant growth, crop yield and quality. Irrigation systems provide water to crops during periods of low rainfall.
An irrigation system comprises a water source (river, reservoir, tank, underground aquifer) with or without a pump, and a distribution system comprising pipes, valves and nozzles. Optimum results require equal distribution. A farmer/producer can control how much water to supply and when to apply it, but the irrigation system determines the uniformity of distribution.
Deciding which irrigation systems are best for your operation requires knowledge of equipment, system design, plant species, growth stage, root structure, soil composition, and land formation. Irrigation systems should encourage plant growth while minimising salt imbalances, leaf burn, soil erosion, and water loss. Losses of water will occur due to evaporation, wind drift, run-off and water (with its nutrients) sinking below the root zone.
Proper irrigation management takes careful consideration and vigilant observation.
A sac spider, Cheiracanthium species, that can be found on different crops. Photograph by Peter Webb.