Ash weevil

The Ash weevil (Myllocerus undecimpustulatus) is a significant coleopteran pest belonging to the Curculionidae family. Known for its wide host range and adaptability, this insect poses a persistent threat to various agricultural and horticultural sectors worldwide. Understanding its biological traits is essential for developing effective management programs.

This pest affects a diverse array of crops, including cotton, citrus, legumes, vegetable crops, and several ornamental tree species. The intensity of infestation often peaks during the early growth stages of plants, making it a critical threat to nurseries and newly established fields where even minor damage can lead to substantial loss of biomass.

The biological cycle consists of eggs, larvae, pupae, and adults. Eggs are typically laid in the moist soil near the root zone of the host plants. Larvae, which are soil-dwelling, feed predominantly on roots and organic matter. The adult stage completes its cycle by moving above ground to consume the foliage, creating a dual-threat environment for the host plant.

Damage is characterized by distinct notch patterns along the leaf margins caused by adults, which serves as a primary diagnostic sign. Larval feeding on root hairs and primary roots is more insidious, often resulting in stunted growth, yellowing (chlorosis), and reduced plant vigor, which can eventually lead to the collapse of the plant under water stress.

Management strategies require an Integrated Pest Management (IPM) approach. Cultural control methods, such as deep plowing to expose larvae to sunlight and predators, are highly effective. For chemical control, systemic insecticides are applied when adult populations reach the economic injury level. Biological control options, involving soil-applied entomopathogenic fungi, are becoming increasingly popular for long-term suppression of larval populations.