Biological Control: A Major Component of the Pest Management Program for the Invasive Coconut Scale Insect,...

Area of Science:

• Agricultural Entomology
• Biological Control
• Pest Management

Background:

• The coconut scale insect (Aspidiotus rigidus) caused a significant outbreak in the Philippines between 2010 and 2015.
• Coconut plantations in the Southern Tagalog region were severely affected.

Purpose of the Study:

• To assess the role of the native encyrtid, Comperiella calauanica, in managing the Aspidiotus rigidus outbreak.
• To determine parasitization levels of C. calauanica on A. rigidus in field-collected samples.

Main Methods:

• Field sampling in three provinces across three periods to estimate parasitization levels.
• Correlation and regression analyses to assess host density-dependent parasitism.
• Comparison of findings with similar outbreaks managed by C. calauanica in the Zamboanga Peninsula.

Main Results:

• Comperiella calauanica consistently parasitized Aspidiotus rigidus where populations occurred.
• High parasitization levels were observed in the Southern Tagalog region (2014-2015) and Zamboanga Peninsula (2018-2020).
• A decrease in A. rigidus abundance correlated with increased parasitization and coconut tree recovery.

Conclusions:

• Host-specific parasitization by Comperiella calauanica provided effective biological control against the Aspidiotus rigidus outbreak.
• C. calauanica contributed to the management of the pest outbreak in both the Southern Tagalog and Zamboanga Peninsula regions.
• Inoculative releases of C. calauanica led to significant A. rigidus population reduction and subsequent coconut tree recovery.