Leucopholis rorida

Systematic position: Leucopholis rorida is a beetle species belonging to the order Coleoptera and the family Scarabaeidae. These insects are significant members of the soil-dwelling pest complex, particularly known for their subterranean larvae that cause severe damage to the root systems of various economically important crops in tropical ecosystems.

Affected crops: This pest is polyphagous, meaning it feeds on a wide range of plants. It is particularly notorious for damaging industrial plantations, including rubber trees (Hevea brasiliensis) and oil palms. Furthermore, it poses a severe threat to sugarcane fields and horticultural nurseries, where high larval densities can result in the complete destruction of seedling roots.

Biology and lifecycle: The lifecycle of this beetle includes egg, three larval instars, pupa, and adult stages. Adult beetles are nocturnal and feed on foliage, whereas the larvae (white grubs) reside in the soil for several years. The larvae exhibit a C-shaped body and are highly mobile in the soil, actively searching for roots as their primary food source, with their distribution in the soil profile depending on moisture levels.

Nature of damage: The primary harm is caused by the larvae feeding on roots, which disrupts the plant's ability to absorb water and essential nutrients. Affected plants exhibit signs of stunted growth, yellowing foliage, and wilting. In mature plantations, root destruction can lead to increased vulnerability to secondary fungal diseases and susceptibility to being toppled by high winds due to compromised root anchoring.

Control measures: Managing Leucopholis rorida populations requires an integrated pest management (IPM) strategy:

• Deep plowing and soil cultivation to expose larvae to desiccation and natural predators like birds.
• Application of soil-incorporated insecticides during the peak feeding periods of the first and second larval instars.
• Utilization of biological control agents, such as entomopathogenic fungi (e.g., Beauveria or Metarhizium species).
• Implementation of light traps to monitor and reduce the population of adult beetles before they lay eggs.