Eradication of khapra beetle can be difficult due to its habit of hiding in cracks and crevices, and ability to enter an inactive state which reduces its susceptibility to some control methods. Control methods designed to eradicate existing or new infestations must be able to penetrate the infested material throughout the facilities. In cases of low level of infestation, detection by inspection is not reliable.
In storage facilities pheromone trapping and larval traps have proved to be useful surveillance tools. Inspectors should be aware of the potential for inadequately cleaned shipping containers to harbour an infestation, especially in the sub-floor area. Because larvae can survive for years without food infestations can be found in containers transporting non-food products.
Khapra beetle is of great quarantine concern. Its spread is mainly through international trade. Inspection at ports and entry points provides an effective way to restrict entry of this pest. The Diagnostic Protocol for the regulated pest Trogoderma granarium prepared by the European and Mediterranean Plant Protection Organization (EPPO), in English and French recommends means of positive identification and detection of the insect pest.
The protocol also includes description, impacts, host range, geographical distribution. The Pest Risk Assessment of khapra beetle conducted by the United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine (USDA, APHIS, PPQ), addresses the likelihood of the beetle becoming established in the United States, the economic consequences, and available information regarding pathways, probability of detection, and marketing/export consequences of infestation in the US.
Growers should also take preventative measures on farm by keeping an eye out for 'hitchhiker’ pests, such as khapra beetle, to ensure early detection and prevent spread. When opening imported cargo, pallets or packages, follow the below guidelines:
- Vehicles, machinery etc delivered on pallets should be opened on concrete, and in a contained environment, if possible.
- DO NOT open in the paddock or close to crops or storage.
- Check packaging/goods carefully.
- If you find something close the container/package or create a barrier (such as a blanket or tarpaulin), and isolate.
- Take photos, recording the location and collect a specimen if safe to do so. Use a knockdown spray as a last resort. Don’t use a knockdown spray if it will cause the insects to disperse.
Look for small beetles, larvae or cast skins found in cracks and wall linings of storage containers. Report any findings IMMEDIATELY.
In India, the use of deoiled neem (Azadirachta indica) seed powder and diatomaceous earth powder mixed into wheat seemed to be an effective and cheap method to control the pest in stored wheat, though these are not accepted for eradication or quarantine treatment.
Heat treatment has proved very effective. The treatment involves a 30 minute exposure at 60°C which has given a 100% kill of all stages of the beetle. Mortality of larvae begins at 42.5°C. Complete mortality however required eight days exposure at that temperature.
Inactive larvae are more resistant to high temperatures than non-diapausing ones. When heat treatment is used it is imperative that the centre of the stored product should be maintained at the desired temperature for at least half an hour.
Treatment with fast electrons, using a linear accelerator, could provide an efficient method of controlling khapra beetle in store grain.
The most effective and only reliable treatment is methyl bromide fumigation. Control requires a higher than usual concentration of methyl bromide because different developmental stages and physiological states (diapause) show different sensitivity.
Replacement of methyl bromide with phosphine, carbon dioxide, carbonyl sulphide, sulfuryl fluoride and other fumigants is being investigated. Similarly there are many very promising trials using controlled atmosphere where the oxygen content is kept very low and/or replaced by nitrogen or carbon dioxide. However, these methods have either low penetration or need prolonged exposure which is difficult to achieve.
Surface treatment is not reliable because of the unique ability of larvae to spend longer periods of time hiding in cracks and crevices in inactive state. Khapra beetle is known to show signs of tolerance or resistance to phosphine and malathion.
Facilities that cannot be fumigated may be sanitised and treated with a surface application of insecticide, but these are not reliable and not acceptable for eradication. Malathion applied repeatedly is currently approved for control of khapra beetle infestations in structures and surrounding surface areas.
Report any pests you suspect to be khapra beetle IMMEDIATELY.
- For pest reports related to imported goods, make a report to the Federal Department of Agriculture, Water and the Environment, or call the national See. Secure. Report hotline on 1800 798 636.
- For all other pest reports, submit report/photos to the Department of Primary Industries and Regional Development through one of the following:
Andras (Andy) Szito, Curator/Entomologist, Department of Primary Industries and Regional Development (entomology).
PaDIL (Pests and Diseases Image Library).