Ancognatha scarabaeoides

Systematic position. This insect belongs to the order Coleoptera, family Scarabaeidae, and subfamily Dynastinae. The species Ancognatha scarabaeoides is a recognized agricultural pest, particularly prevalent in the Andean regions of South America, where it significantly impacts local vegetable production.

Affected crops. The primary host plant for this pest is the potato. However, it can also infest various other root and tuber-bearing crops. The larvae, commonly referred to as white grubs, live below the soil surface, where they target the underground structures of host plants, causing stunted growth and yield loss.

Biology and life cycle. The life cycle typically spans one year, though environmental conditions in higher altitudes can influence its duration. Adult beetles are nocturnal and often attracted to artificial light sources. Females oviposit into the soil near the root zone. Larvae pass through three instars, feeding voraciously on roots and tubers before pupating in earthen cells.

Damage and economic impact. Larval feeding causes direct mechanical damage, as grubs burrow into tubers, leaving large, hollowed-out cavities. These damaged areas not only ruin the commercial value of the crop but also act as entry points for pathogens, such as soft rot bacteria and fungi, which can lead to significant post-harvest losses in storage.

Protection measures. Effective control requires an integrated pest management (IPM) strategy due to the soil-dwelling nature of the larvae. Recommended practices include:

• Implementing crop rotation to disrupt the life cycle of the beetle.
• Deep plowing or mechanical soil cultivation before planting to expose larvae to environmental stress and predators.
• Application of targeted soil insecticides during peak infestation periods.
• Utilization of biological control agents, such as entomopathogenic fungi or nematodes, to manage population density.