Shallot aphid

The shallot aphid (Myzus ascalonicus) is a significant insect pest belonging to the order Hemiptera and the family Aphididae. It is widely recognized as a major threat to horticultural crops, particularly due to its ability to spread rapidly in cool environmental conditions both in greenhouses and open fields.

This pest is highly polyphagous, meaning it feeds on a vast range of plant species. While it is named after the shallot, it is notorious for causing damage to onions, garlic, leeks, strawberries, lettuce, and many ornamental bulbous plants such as tulips, which can be severely stunted by its feeding habits.

The biology of the shallot aphid is adapted to cool temperatures. It overwinters as nymphs or adults on perennial weeds or host plants. Throughout the spring, it reproduces parthenogenetically, creating dense colonies on the undersides of young leaves or inside the whorls of growing onions, where they are protected from environmental stress.

The damage caused by Myzus ascalonicus is twofold. Firstly, the direct removal of plant sap leads to curling, yellowing, and necrosis of leaves, resulting in reduced photosynthesis and stunted plant growth. Secondly, and more critically, it acts as a highly efficient vector for various plant viruses, causing widespread outbreaks of mosaic diseases.

Effective management requires an integrated approach. Farmers should prioritize early monitoring by using yellow sticky traps and inspecting crop centers. Recommended control measures include:

• removing potential weed hosts near fields;
• utilizing biological agents like ladybird beetles and lacewings;
• applying systemic insecticides during the early stages of infestation to prevent virus transmission.