Unraveling grain vulnerability to the khapra beetle (Trogoderma granarium): Structure and mineral content

The pest-substrate relationship plays a crucial role in infestation dynamics, yet certain economically significant invasive pests, such as the khapra beetle ( Trogoderma granarium ), remain understudied. This study examines the susceptibility of different grain species and substrates to T. granarium infestation, focusing on the influence of grain physical properties and mineral composition. Laboratory trials assessing whole and processed grains revealed that structural integrity significantly affects pest colonization. Hard grains, such as rice, exhibited lower infestation rates, whereas softer grains, like wheat and maize, provided more favorable conditions for larval development . Processed forms, including cracked grains and flour, showed heightened vulnerability, likely due to increased surface area facilitating pest feeding and reproduction. Additionally, mineral composition emerged as a potential determinant of susceptibility, with higher magnesium content correlating with increased pest performance, suggesting a role for mineral availability in pest development. These findings highlight the multifactorial nature of grain susceptibility, where both physical barriers and chemical properties shape infestation dynamics. The study underscores the need for integrated pest management strategies that consider grain type, processing state, and nutritional composition. Future research should explore the biochemical mechanisms underlying insect-mineral interactions and assess potential breeding or storage interventions to mitigate pest impact. A deeper understanding of these complex relationships is critical for developing targeted strategies to preserve grain quality and reduce post-harvest losses, ensuring food security in global storage systems. • This study demonstrates that grain form (whole, cracked, flour) and grain species interact significantly to influence pest survival, reproduction, and development. • Hard grains like rice were significantly less susceptible to infestation, whereas processed and soft grains like cracked wheat and flour exhibited high vulnerability. • A strong correlation was found between magnesium and iron content and key biological parameters of the khapra beetle, highlighting a potential nutritional basis for pest preference. • The study introduces mineral and phenolic profiling as novel tools to assess grain vulnerability to insect pests—a relatively underexplored area in stored product entomology. • By integrating physical, chemical, and biological factors, the study presents a multifactorial approach to understanding pest dynamics, setting a new standard for research in the field of stored grain protection.