The Khapra beetle is one of the world’s most destructive pests of grain and seed products. The beetle originated in India and was first discovered in Guinea corn in Nigeria in 1948. Smaller than a grain of rice, the beetle is very difficult to control, and can survive anywhere they are protected from the cold.
Their ability to go without food for up to three years, and their preference for dry conditions and low-moisture foods, coupled with their resistance to many insecticides, makes them extremely dangerous to the safety of a country’s food supply. Worse still, the beetle can also infest dried grocery products, including dog food, bread, and other plant or animal products.
The Khapra beetle exhibits a “dirty eating” behavior — a feeding habit where the beetle eats only a little of a single grain before moving on to others. Additionally, the beetle poses a contamination threat because of the hairs associated with the larvae and cast off skins, creating a potential allergen and respiratory hazard, especially to young children.
Khapra beetles have quarantine status in the U.S.
The Khapra beetle is so notorious, it is the only stored product pest with quarantine status in the U.S. The Khapra beetle is also the only pest that will automatically trigger a rejection of imported shipments based solely on the findings of non-living life stages, cast skins or other body parts of the insect.
The U.S. Department of Agriculture’s (USDA) current quarantine regulations recognizes 25 countries where the Khapra beetle is endemic. There is also a list of countries where the Khapra beetle has become established. including: Algeria, Austria, Cyprus, Egypt, Israel, Lebanon, Libya, Morocco, Spain, Switzerland, Syria, Tunisia, Turkey (southeastern), and the United Kingdom (protected environments only).
The Khapra beetle in the U.S.
The potential threat of Khapra beetles coming into the U.S. was brought home when in 1953, they were discovered in California. The finding resulted in a 13-year eradication effort costing $15 million. Since that time, the Khapra beetle has been detected in Arizona, New Mexico, and Texas, as well as Mexico. In all cases, the beetle was eradicated. The pest was also found in a residence in Connecticut in 2006 but was also eradicated.
The USDA’s Response Guidelines for the Khapra beetle was written in 2009. Since that time, drought and a warming climate could trigger a change in the number of regions in the U.S. considered to be at risk for an infestation of the beetle. Currently, Arizona, California, Kansas, New Mexico, Oklahoma, Texas, Utah, and Nevada are on the list.
With the considerable threat posed to U.S. agriculture, the USDA is working with scientists at the Edgewood Chemical Biological Center, along with the Department of Homeland Security’s Science and Technology Directorate and the U.S. Department of Agriculture’s Animal Plant Health Inspection Service’s Plant Protection Quarantine, to find an easier way to detect Khapra beetles in the nation’s bulk food supply.
Use of a Colorimetric Sensor array in detecting the Khapra beetle
In a project funded by the Department of Homeland Security’s Seedling Program, Edgewood researchers, in partnership with iSense LLC, are studying the use of colorimetric sensor arrays (CSA) in detecting invasive species in shipping containers.
The postage stamp-sized sensors, manufactured by iSense, are disposable and inexpensive. They are spotted with 73 dyes which change color in response to various vapors (or odors) coming in contact with the CSAs from the sample. A pest is not detected by any single spot of color change, but instead, a combination of color changes across many dots forms a “signature” or fingerprint that identifies compounds found in the sample.
So far, researchers have been able to distinguish between beetle-infested and non-beetle-infested grain based on the CSA’s response to volatile organic compounds, and that is a big step forward in protecting our food supply. “Our vision is to create remote interrogation of shipping containers that reduces the burden on the customs officials,” said Jeff Ballin, Ph.D, ECBC lead for this project.
