Scientific Name: Trogoderma variabile Ballion

Common Names: Warehouse beetle, Grain dermestid

Synonyms

Trogoderma parabile, Trogoderma persica

Taxonomic Position

Class: Insecta

Order: Coleoptera

Family: Dermestidae

Genus: Trogoderma

Species: Trogoderma variabile

Geographical distribution

Asia - Afghanistan, China, Iran, Kazakhstan, Mongolia, Saudi Arabia, Tajikistan, Turkmenistan, Uzbekistan

Africa - South Africa

North America - Canada, Mexico, USA-Kansas

Europe - Czech Republic, Finland, Russian Federation, UK

Oceania- Australia -New South Wales

Host Range

Main hosts are cereal grains eg. Oats, barley, rice, maize and wheat

Pest Destructive Stage

Primary pest

Larva - The adult beetle does not bore into host material but young larvae feed on damaged seed and older larvae on whole grains. Damage can be severe with weight losses of between 5-30% and in extreme cases 70%.

Damage Symptoms

In grains, the first signs of infestation are masses of very hairy cast larval skins, the dead bodies of adults, and larvae crawling over the stored food

Identification Features - 

Larva

• Larvae are whitish yellow initially and darken with age.
• Larvae are typical dermestid larvae with tufts of dense hairs on the posterior segments.

Adult

• In shape and size, the adults resemble T. granarium but they have more distinct colour patterning on the elytra.
• The dorsal surface is moderately clothed in fine hairs.
• A median ocellus is present between the compound eyes.
• The number of antennal segments is usually 11 and there is a fairly distinct antennal club consisting of 6-7 segments in males and 4-5 segments in females.
• The antennae fit into ventral grooves in the prothorax.

Life Cycle

• T. variabile develops at temperatures of 17-38°C, but does not have the tolerance of hot, dry conditions.
  • The larvae can enter in diapause, which is induced by long photoperiod, scarcity of food, unfavourable temperatures or larval crowding.
  • Females mate 1-2 days after emergence and attract males using a sex pheromone.
  • When fed on wheat feed at 30°C and 60-70% RH the life cycle is completed in about 39 days, with males developing slightly more rapidly than females.

Detection Methods

Pheromone-baited sticky traps for adults are more effective.