The electron microscopic examination of fungal distortions in the adult red flour beetle, Tribolium castaneum H. (Coleoptera: Tenebrionidae)

The red flour beetle (Tribolium castaneum) is one of the main pests infecting cereals and causes damage to stored grains. Many pests, including beetles, are susceptible to infection by naturally occurring insect-pathogenic fungi (entomopathogenic fungi). In the present study, wheat flour collected from the local markets in the Jazan region of Saudi Arabia and dead bodies of T. castaneum adults were separated. The fungi associated with these insect dead bodies were identified. The result concluded that the most dominant fungi were Beauveria bassiana (61.67%) and Verticillium lecanii (38.33%). Fungi showed different stages of infection, such as adhesion, spore germination and mycelium colonization in the insect cadavers, as illustrated by scanning electron microscopy (SEM). The deformations, mycelium extortion and colonization, decomposition and erosion of the cuticle occurring in the different parts of the insects' cadavers were recorded by SEM. The results showed the presence of entomopathogenic fungi B. bassiana or V. lecanii on T. castaneum, as well as the susceptibility of T. castaneum adults to these fungi. Key words: Stored wheat flour; Tribolium castaneum, Beauveria bassiana, Verticillium lecanii; scanning electron microscopy (SEM).