Analysis of components in male annihilation blocks used to manage Queensland fruit fly Bactrocera tryoni (Froggatt)

The male annihilation technique (MAT) is used throughout the world to assist in the management and eradication of fruit flies. In Australia, often MAT was deployed using particle board blocks (50 x 50 mm) and was used in southern New South Wales to manage Queensland fruit fly Bactrocera tryoni. We sampled 120 MAT blocks over two years which were newly manufactured, new and stored (for later use), exposed for a four or twelve months period and analysed them for the effects of environmental exposure on chemical contents and the weight of blocks. Chemicals present in the blocks were malathion (toxicant), cuelure (male lure) and raspberry ketone (male lure). Total weight of the blocks and the weight of the chemicals from the block's central core and edge components were recorded separately. We found that the storage of newly manufactured blocks did not prevent chemical degradation; cuelure and malathion contents were reduced by 25% and 16%, respectively, in a stored block when compared to a new block. Most changes in the chemical contents of the blocks occurred in the first four months of field deployment, with 56% and 35% reduction analysed in cuelure and malathion contents, respectively. Loss in chemical contents and weight of blocks continued with long-term exposure of blocks from four to twelve months. Edges were found to degrade more as compared to the central core of the used blocks. Managers need to be aware of chemical degradation patterns if particle board is to be used in future MAT programs.

Automated summary

The study found that storage of particle board blocks did not prevent chemical degradation, with reductions of 25% and 16% in cuelure and malathion contents, respectively, after a short period of use. The most significant changes in chemical contents occurred within the first four months, with reductions of 56% and 35% in cuelure and malathion contents, respectively. Chemical contents and weight of the blocks continued to decrease with long-term exposure, with the edges degrading more than the central core.