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Trogoderma granarium (Khapra Beetle) and Its Management

Introduction 

khapra beetle is also called a cabinet beetle belongs to Family Dermestidae and order Coleopteran and it is the most destructive stored grain pest. It is native to India and has been established in other countries Asia, Africa, the Mediterranean and the Middle East. In fact, it ranked as one of the 100 worst invasive alien species worldwide. It has posed a serious threat to global food security and safety. It is of quarantine concern due to its spread is through international trade. It is of high economic importance because of the continued occurrence of commodities imported from countries. Infestations are difficult to control because of the insect’s ability to survive for long periods. Larval stages of this insect are considered the most destructive stage that causes heavy economic losses to stored grain and other food commodities. Handling and consuming contaminated commodities can lead to serious health issues such as skin irritation and gastrointestinal diseases.

Biosystematics of Trogoderma granarium

Adults are oval – oblong in shape; about 1.6-3 mm long and 0.9-1.7 mm wide. Males are dark brown to black in colour and females are slightly larger with a lighter colour. Antennae are 11 segmented; the head is small and flexed. Immature larvae are up to 5 mm long and are covered in dense, reddish-brown hair. There are 5 to 6 instars of the larvae. A characteristic feature of larvae is the presence of simple and barbed hair. Larvae of T. granarium have been reported to survive for 6 months without food. The pupa is of excreting type male smaller than female, the average length being 3.5 mm and 5 mm respectively. Its cylindrical eggs with one end are more pointed than the other, 0.7 mm long and 0.25 mm broad. Eggs are initially white later pale yellowish. The incubation period is 3 to 14 days, depending upon the temperature. Complete development from egg to adult can occur from 26 to 20 days, depending upon the temperature. The optimum temperature for development is 25 C, if the temperature falls below 25, they may enter diapause. The Khapra Beetle is a synanthrope, living in close association with humans.

Economic importance of Trogodermagranarium

Its great economic importance is due to its ability to cause heavy losses in stored grain commodities through voracious feeding, ability to live on food with low moisture content and larval ability to withstand starvation up to the 3 Years.

T. granarium as a food security threat 

Storage losses are caused by the pests like Rhizopertha, Dominica, T. granarium, Sitophilusoryzae, S. ranaries and many others including rodents and birds. The Khapra Beetle is one of the most dreaded pests of whole-grain cereals, oilseeds and other foodstuffs. Its great importance is mainly due to huge loss in stored commodities through feeding and the capability of the larval stage to live up to 3 years without food. This pest is cold hardy and can tolerate both high temperature and low humidity. Estimates of storage losses of food grains due to insects have been recorded to 10-18 % in Pakistan.

Management strategies 

Chemical Control

Fumigation with methyl bromide is the most effective treatment for the eradication of this pest.

The addition of high levels of CO2 to phosphine also increased the mortality rate.

Surface treatments with IGRs (Integrated Growth Regulators) also proved beneficial for controlling its infestation.

Deltamethrin, cypermethrin, monocrotophos, spindosad had shown potential for eradication of this pest.

 A very effective strategy is the combination of fumigant with CO2.

Physical Control

Exposure of T. granarium to 60° C for 30 min is effective to kill 100 % of all stages.

Gamma and other types of radiation are considered as quarantine treatment against khapra Beetle.

A good Quarantine solution can be provided by vacuum treatment.

The heat combined with a CO2 based modified environment is considered effective for the control of this pest.

Plant extracts

The use of plant extracts essential oils, botanical powders considered beneficial for reducing its infestation

Use of neem essential oil as fumigant and ora seed powder seems to be an effective method against this pest.

Biological control

Many natural enemies, predators, parasitoids, nematodes, as control agents against Khapra Beetle.

Bacillus thuringiensis, the Laeliuspedatus, and Xylocorisflavipes predator has been found to parasitize or prey the T. granarium. 

Binish Munawar: BSc, Department of Entomology
Faculty of Agricultural Sciences, University of Punjab Lahore

Times Agriculture

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