MAHOGANY SHOOT BORER CONTROL IN MALAYSIA AND PROSPECTS FOR BIOCONTROL USING WEAVER ANTS

In Malaysia, cultivation of trees in the family Meliaceae, which include valuable tropical timber species such as Swietenia spp. (mahogany) and Khaya spp. (African mahogany), have been severely curtailed by attacks of the mahogany shoot borer (Hypsipyla robusta, Lepidoptera: Pyralidae). Mahogany shoot borers pose an international dilemma. Acknowledging dwindling natural stands and the high value and demand for mahoganies, various biological, chemical and silvicultural control approaches have been undertaken worldwide since the 1920s to address the shoot borer problem. These control approaches have not been successful in reducing shoot borer damage to acceptable levels. Thus, the area under mahoganies remains low in Malaysia. Two major factors combine to make this problem very challenging: (1) Hypsipyla spp. biology with their cryptic habit and overlapping generations, and (2) the biology of mahogany with production of multiple leaders following loss of apical dominance after shoot damage. Tolerance to damage is effectively zero. This paper describes characteristics of mahogany and its pest that are pertinent to its management in Malaysian mahogany plantations. Previous control approaches are summarized, the characteristics of a promising biological control agent, Oecophylla smaragdina (Hymenoptera: Formicidae) are described, and critical research areas are identified.