Wheat is a cereal grain belonging to the genus Triticum. It is recognized as one of the most widely cultivated food crops, providing a primary source of calories and vegetable protein for the human population. It was first cultivated in the Fertile Crescent region around 9600 BCE. Today, common wheat (Triticum aestivum) accounts for approximately 95% of the world’s production, making its presence ubiquitous across various agricultural ecosystems. This broad cultivation means the wheat plant, in its many stages, interacts with a wide array of animals, from field pests to domesticated livestock.
Wild Consumers of Growing Wheat
Wild animals frequently consume the wheat plant or its developing grain while it is still in the field, often resulting in economic damage before harvest. Mammals and birds are the primary consumers, each targeting different parts of the plant depending on the season. Early in the growth cycle, rodents like field mice, voles, and gophers may consume the fibrous roots or young stalks beneath the soil, hindering the plant’s establishment. Larger grazing mammals, such as deer, elk, and wild antelopes like the Nilgai (Boselaphus tragocamelus), browse on the tender, young wheat shoots during the vegetative stage.
As the wheat matures, the developing grain head attracts numerous granivorous bird species. House sparrows (Passer domesticus), starlings, and blackbirds are common culprits that feed directly on the ripening kernels, causing substantial losses when they gather in large flocks. In parts of Africa, the Red-billed Quelea (Quelea quelea) can cause millions of dollars in damage, as its flocks rapidly deplete entire grain fields. The damage is intense during the milky and dough stages of grain development, where the soft, nutrient-dense kernel is most appealing.
Beyond grazing and direct grain consumption, some larger animals destroy the crop by uprooting or trampling the plants. Wild pigs (Sus scrofa) are known crop-raiders, particularly in regions like the Himalayas, where they root through fields to consume underground parts and topple mature stalks. Elephants have also been documented to raid wheat fields, especially in areas bordering forests, where their sheer size can lead to the destruction of a large percentage of the crop area. Wild consumers pose a continuous challenge to farmers, requiring constant management to protect the investment from planting until harvest.
Invertebrate Pests of Stored Grain
Once harvested, wheat grain moves into enclosed storage environments like silos and warehouses, where it becomes vulnerable to invertebrate pests. These organisms, mainly insects and mites, are categorized based on whether they can infest an intact kernel. Primary pests are the most concerning because they can bore directly into the whole grain, with their larval stage developing unseen inside the kernel.
The Granary Weevil (Sitophilus granarius), Rice Weevil (Sitophilus oryzae), and the Lesser Grain Borer (Rhyzopertha dominica) are examples of primary internal feeders that cause significant losses worldwide. A female weevil chews a small hole in the grain, deposits an egg inside, and seals the opening, allowing the larva to consume the kernel’s interior before emerging as an adult. This internal feeding destroys the grain’s substance and reduces its germination viability and commercial value. The Angoumois Grain Moth (Sitotroga cerealella) functions similarly, with its larvae tunneling into the grain to feed and eventually emerging as small moths.
Secondary pests cannot typically penetrate an intact kernel and instead feed on grain dust, broken kernels, or flour created by primary pests or mechanical damage. This group includes species such as the Confused Flour Beetle (Tribolium confusum) and the Saw-toothed Grain Beetle (Oryzaephilus surinamensis). Their presence contaminates the product with body parts and excrement, often resulting in the grain being downgraded or rejected for human consumption. Controlling these pests requires careful sanitation and temperature management in storage facilities, as infestations can quickly multiply in warm, humid conditions.
Wheat as Feed for Domesticated Animals
The intentional use of wheat as a nutritional source for domesticated livestock represents the final major category of consumption, often utilizing grain that is surplus or does not meet quality standards for human food. Wheat grain is a highly digestible and palatable feedstuff, valued for its high starch content, which provides a dense source of energy for farm animals. For poultry, especially chickens and turkeys, whole or cracked wheat grain is a common ingredient, often comprising a large percentage of the diet due to its favorable energy and protein profile.
Swine diets commonly incorporate wheat as a primary energy source, where its gluten content is a secondary benefit that improves the quality and durability of pelleted feeds. However, using wheat in ruminant diets, such as those for cattle, requires specialized management due to its rapid fermentation rate in the rumen. The fast breakdown of wheat starch can lead to digestive issues like acidosis, so nutritionists limit the inclusion of whole wheat grain to a controlled percentage of the total ration.
Beyond the whole grain, the milling process for human flour generates several coproducts that are widely used in animal nutrition. Wheat bran, the outer layer of the kernel, and wheat middlings are rich in fiber and protein, making them beneficial additions to livestock diets. These byproducts offer a cost-effective way to supplement the energy and fiber needs of cattle, pigs, and poultry, ensuring that virtually all parts of the harvested wheat crop are utilized.