A looming threat to our crops

The big worrying trend in Mauritius is the recent hog plum beetle invasion in our gardens. First detected in the Gentilly region in early 2025, this brightly colored leaf beetle (Podontia quatuordecimpunctata) aggressively targets the leaves of the Spondias dulcis (Ambarella or prunier de Cythère) trees. Both the larvae and adults feed on the soft tissue of the leaves, rapidly skeletonizing the foliage and severely weakening the tree.

Fortunately, there are proven ways to manage this pest. Prioritizing natural and biological methods is the safest approach for your garden, with chemical options available as a last resort for severe infestations.

Organic and Natural Remedies

Starting with non-toxic and organic methods will help protect your tree while keeping the surrounding ecosystem safe.

Manual Removal

For small or dwarf trees, carefully inspect the leaves. Hand-pick and crush egg clusters, larvae, and adult beetles. The larvae often cover themselves in their own excrement as a defense mechanism, so wearing thick gardening gloves is highly recommended.

Sanitation and Bagging

Prune badly infested branches and immediately stuff them into sealed plastic bags. Leave the bags sealed in the sun for about a week to ensure all pests are dead before composting or disposing of the plant matter.

Neem Oil Spray

Neem is a highly effective natural repellent and growth disruptor. Local agricultural guidelines recommend mixing 3 mL of neem oil per litre of water. Spray this mixture thoroughly over the foliage, ensuring you coat both the top and underside of the leaves.

Spinosad Treatments

Spinosad is a natural, organic substance made by a soil bacterium that is toxic to these beetles. It is often available at local agricultural cooperatives like MCAF. Spray this directly onto the leaves following the manufacturer dilution rates.

Biological Controls

Mauritian agricultural services are actively deploying the white muscardine fungus (Beauveria bassiana) and predatory stink bugs (Eocanthecona furcellata) to combat the beetles. You can check with local nurseries or agricultural extension offices for the availability of these specific biological agents for home garden use.

Targeted Chemical Options

If the infestation is severe and natural methods fail to halt the defoliation, targeted chemical interventions can be used. It is vital to target both the leaves (where adults and larvae feed) and the soil (where pupae hide) to break the reproductive cycle.

Foliar Spray for Leaves

Lambda-cyhalothrin is a targeted insecticide authorized for this pest in Mauritius. Mix at a rate of 0.5 mL per litre of water and spray directly on the leaves to eliminate active larvae and adults.

Soil Drench for Roots

To kill the pupae hiding in the ground, a systemic soil drench using Imidacloprid is highly effective. Mix 0.5 mL per litre of water and pour it directly onto the soil surrounding the trunk of the tree.

The Treatment Cycle

For the best results, local experts recommend a strict regimen. Spray the leaves on the first day, and drench the soil on the second day. Repeat this exact two-step process every 7 days for three complete cycles to ensure the beetles are eradicated at every life stage.

Tip: Always wear appropriate protective gear, such as masks and gloves, when handling and applying any chemical treatments in your garden.