Drugstore beetle

A notable characteristic of this species is the symbiotic relationship the beetles have with a yeast-like fungus which is transmitted from female to larvae through the oviduct.

[1] The drugstore beetle attacks a wide variety of food sources including pharmaceutical products and medicinal plants, earning its name.

The beetle eats bread, grain, coffee beans, powdered milk, sweets like cookies and chocolates, spices and herbs, dried fruit, seeds, and more.

Adults gnaw through packaging forming large holes in the material, leading to their deterioration, contamination, and loss of structural integrity.

The oldest known member of the genus is Stegobium raritanensis from the Late Cretaceous (Turonian ~94-90 million years ago) aged New Jersey amber.

Female drugstore beetles utilize stegobinone, a volatile compound, to elicit a pheromonal response that communicates their presence and availability to males.

[7] They produce copious amounts of sex pheromones, reaching as much as 50 to 200 ng, allowing the females to maintain the signal for greater distances.

The latter component involves the male detecting tactile cues by coming into contact with the female’s dorsal setae, which are sensory hairs located on her back.

[9] The tarsal claw slots are secondary sex features of males that play a major role in mating behavior, especially in species that don’t engage in parental care.

The male drugstore beetle uses the claw slots found at the end of their legs to trap the setae on the elytra or forewing of the female.

The larvae lack symbionts immediately after hatching until they take in the yeast cells orally, infecting the mycetocytes of the midgut mycetome organ.

Experiments discovered that when the yeast cells were eliminated, no larval growth occurred, indicating that the vitamins are essential for host survival.

[1] The oldest records of the modern drugstore beetle as a pest are known from the Bronze Age of Akrotiri, Santorini, Greece around 1500 BC where it was found associated with stored pulses.

That cons of insecticides, increasing resistance to compounds, and high costs were incentives that drove researchers to discover alternate means of pursuing pest control.

In the search for decent alternatives, scientists have found that carbon dioxide gas (CO2) and essential oils from plants could be used to safely regulate Drugstore Beetle numbers.

Studies were conducted to investigate the usefulness of an essential oil from Z. bungeanum Maxim on Drugstore Beetle larvae and adults.

The benefit of using essential oils is that they exhibit low mammalian toxicity which makes it a promising alternative to synthetic insecticides.

It has the capacity to prolong the time it takes for larvae to develop and can even keep adults from laying eggs successfully, effectively controlling pest numbers.

[16] A pest of many dried plant products, the drugstore beetle negatively impacts stored materials and leads to economic loss.

Sex pheromones play a significant role in mate selection which suggests that this beetle has a developed olfactory system, allowing semiochemical strategies to be used to provide a safe way to control this pest.

Chemicals released by Chinese medicinal plant materials (CMPMs) attracts large numbers of these beetles, leading to an infestation.

Their presence in stored products not only contaminates them with insect fragments, exoskeletons, and fecal matter but also renders them unfit for human consumption, leading to significant financial losses for businesses and households alike.

The damage inflicted by drugstore beetles often necessitates the disposal of affected goods, resulting in wasted inventory and revenue loss.

[18] Additionally, the presence of pests in food processing facilities, warehouses, and retail outlets can damage their reputation, delay the flow of goods, and attract attention from regulatory authorities, therefore worsening the economic impact.

Effective pest management strategies, including regular inspection, proper storage practices, and sanitation efforts, are essential to mitigate the economic impact of drugstore beetles.

By addressing infestations promptly and implementing proactive control measures, businesses and households can minimize financial losses and safeguard stored commodities from these persistent pests.

Drugstore beetle on human fingertip
Ventral side of drugstore beetle
Drugstore beetle life cycle
Drugstore beetle damage
Drugstore beetle as a household pest