The wheat aphid, Macrosiphum miscanthi, is a small, sap-sucking insect belonging to the Family Aphididae of the Order Hemiptera. Aphids come in many different species but have the same basic feeding behavior. They suck the juices from wheat plants’ stems, leaves, and flowers, reducing their growth and causing yellowing and wilting of the foliage.
They can reproduce quickly and often in high numbers, leading to large populations that can cause significant damage to wheat crops. In addition, aphids can act as vectors for plant diseases, transmitting them to other plants. To effectively manage this pest, it is important to understand its life cycle, its preferred habitats, and the best methods for controlling it. This article will provide an overview of aphids in wheat crops, including their symptoms, identification techniques, and control.
Wheat Aphids Management in Wheat
Life Cycle of Aphids in Wheat Crop
Generally, the life cycle of aphids in wheat crops is complex. They lay eggs in the spring, which hatch into nymphs. The nymphs molt several times before becoming adults. The adults reproduce in the summer. In the fall, the nymphs enter a dormant state and overwinter. The adults migrate to other wheat fields in the spring, potentially spreading the pest.
- Egg stage – The female aphid lays eggs in the spring, usually within the developing wheat crop. The eggs are typically laid in the crevices of the wheat leaves, the stem, or the seed heads.
- Nymph stage – After a few days, the eggs hatch into nymphs, and the nymphal phase ranges between 6-8 days with four instars. They feed on the sap of the wheat plants, causing damage to the crop. They molt several times before becoming adults.
- Adult stage – They feed on the sap of the wheat plant, which causes stunted growth and yellowing of the leaves. Adult aphids also reproduce, producing live young without mating.
- Reproductive stage – In the summer, the aphids can reproduce. The males and females mate, and the females lay eggs, which will hatch into nymphs in the fall.
- Overwintering stage – In the fall, the nymphs enter a dormant state, called diapause, and overwinter until the spring.
- Migration stage – In the spring, the adult aphids will migrate to other wheat fields for food. This can spread the pest quickly, leading to an infestation.
Occurrence of Aphids in Wheat Field
- Location of Wheat Aphid: Wheat aphid pest has been reported in wheat crops in many countries, including the USA, Canada, Australia, New Zealand, India, Pakistan, Russia, Turkey, South Africa, China, and the European Union.
- Host range: The pest can cause an infestation in wheat, barley, oats, and Cynodon dactylon (Doob grass).
Factors Favoring Population Increase of Aphids in Wheat Fields
- Temperature – Temperature ranges of 25-35°C allow for the rapid growth of aphids, resulting in more generations in a season. In addition, their bodies are more efficient at taking in nutrients in warmer temperatures, which can lead to larger populations.
- Food availability – Wheat plants provide ample food for the aphids, including sap and other plant matter. As the wheat plants grow, aphids can feed on the sap of the plant and reproduce quickly.
- Natural enemies – The presence of insects, such as ladybugs and predatory wasps, can influence the population of aphids.
- High reproductive rate – Aphids can reproduce quickly through parthenogenesis, by which female aphids produce offspring without fertilization. This can increase the aphids’ population in a very short amount of time.
- Overuse of pesticides – If they are overused, they can kill off the aphids’ natural predators, increasing the po