The Khapra beetle has been nominated as one of the top 100 worse invasive species in the world. In 1953, it was discovered in California, this lead to an eradication program that cost the government $15 million and lasted 13 years. The beetle can live without food for extended periods of time and survive on low moisture containing foods. It crawls into small cracks and stays there and is very resistant to insecticides. All the aforementioned characteristics of this beetle make it difficult to get rid of. The best control is to keep it from being introduced to pest-free environments. At this time, there are no infestations in the U.S.
Origin and Environmental Needs
The Khapra beetle originates in Burma to west Africa. It is difficult to be sure what countries have the beetle, because if they admit to having them the country may have trade restrictions imposed upon it. Commerce has spread this beetle to countries with like climatic conditions. It is estimated that 67% of the US would have the correct conditions for the Khapra beetle.
The Khapra beetle develops best in environments of 35 degrees Celsius. If the temperature drops or their larvae become overcrowded, they go into diapause. They can survive to minus 8 degrees Celsius in this condition of diapause, where the larvae molt but are otherwise inactive, and stay viable many years this way. They can survive low humidity as low as 2%, but high relative humidity is not well tolerated by them. Their adaptability is further aided by the large variety of stored, dry foods the larvae will eat. They also reproduce so rapidly that large numbers of them can be found on the surface of stored grain bins.
The Khapra beetle, in both the adult and larvae stage, are identified best microscopically. The USDA-APHIS inspect warehouses and cargo ships containing shipments from beetle-infested areas. Just before dusk, when the larvae are most active, they check cracks, crevices, behind paneled walls, etc. High concentrations of fumigants, kept high for the whole process, is necessary to penetrate all the beetles hiding places. Surface sprays have to be used, as well. Keeping the area clean and inspection of incoming cargo is needed to avoid infestations.
All this information helps us to see why the Khapra beetle has been in the news so much lately. When an inspection of some rice from India at an Indianapolis Federal Express center, turned up the feared pest, officials jumped into action. U.S. Customs and Border agents found the beetle in a bag of barley seeds from India. If the Khapra beetle is eaten, it will cause diarrhea and vomiting. These agents call this beetle “one of the world’s most tenacious and destructive stored-produce pests because of its ability to damage grain.”
“If a Khapra Beetle is hiding in a huge container full of grain coming from an infested overseas warehouse or within a small personal parcel, we’ll find it,” said Carl Ambroson, Acting CBP Director of Field Operations in Chicago. “Every day our CBP agriculture specialists sweep container floors, probe shipments and examine samples using every microscopic tool available. We guard against agro terrorism and bioterrorism while safeguarding agricultural resources from destructive pests and diseases.”
US grain Safe – So Far
These beetles have been intercepted 100 times this year. In 2005 and 2006 only 3 to 6 interceptions were made, and an average of 15 per year from 2007 to 2009. Unlike any other species, grain shipments do not require even a live beetle for the whole thing to be rejected. Fortunately, despite all the interceptions, the Khapra beetle has not made it into US grain supplies.