Khapra beetle | |
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Adult Khapra beetle | |
Larvae of Trogoderma granarium | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Coleoptera |
Family: | Dermestidae |
Genus: | Trogoderma |
Species: | T. granarium |
Binomial name | |
Trogoderma granarium Everts, 1898 |
The Khapra beetle (Trogoderma granarium), also called cabinet beetle, which originated in South Asia, is one of the world’s most destructive pests of grain products and seeds. It is considered one of the 100 worst invasive species in the world. Infestations are difficult to control because of the insect's ability to survive without food for long periods, its preference for dry conditions and low-moisture food, and its resistance to many insecticides. There is a federal quarantine restricting the importation of rice into the U.S,. from countries with known infestations of the beetle. Khapra beetle infestation can spoil otherwise valuable trade goods and threaten significant economic losses if introduced to a new area. Handling or consuming contaminated grain and seed products can lead to health issues such as skin irritation and gastrointestinal distress.
Adult beetles are brownish and 1.6–3 mm long. Immature larvae are up to 5 millimeters long and are covered in dense, reddish-brown hair. The larval stage can last four to six weeks, but can be extended up to seven years. Males are dark brown or black, and females are slightly larger with lighter colors. The lifespan of adult Khapra beetle is usually between five and ten days. The beetle prefers hot, dry conditions and can be found in areas where grain and other potential food is stored, such as pantries, malt houses, grain and fodder processing plants, and stores of used grain sacks or crates. The species is native to India, with a native rage extending from Burma to Western Africa. The Khapra beetle is a synanthrope, predominantly living in close association with humans. Information regarding the beetle’s behavior in non-human environments is limited.
The eggs of the khapra beetle are cylindrical with one end more rounded and the other more pointed, about 0.7 mm long and 0.25 mm broad, weighing about 0.02 mg. The pointy end has a number of spine-like projections. The eggs are initially a milky white but over several hours turn a pale yellowish color.
The Khapra beetle’s physiology is significantly impacted by its diet. Borzoui et al. found that rye provides the most optimal environment for breeding and development of individuals. Conversely, walnut and rice diets reduced female fertility and adult weight of the individuals, while increasing the duration of the larval stage.
The Khapra beetle has become established in many Mediterranean, Middle Eastern, Asian and African countries. It has also been discovered in North America. United States customs agents have discovered it in isolated infestations on the East and West coast of the United States, but until this point have been successful in containing and eradicating the pest. US customs agents intercepted the beetle 100 times in 2011, “compared to three to six per year in 2005 and 2006, and averaging about 15 per year from 2007 to 2009.”