Attraction, arrestment, and preference by immature Trogoderma variabile and Trogoderma granarium to food and pheromonal stimuli

The invasive khapra beetle, Trogoderma granarium, is an economically destructive species and the only stored product insect pest that is quarantined in the USA. In the past several decades, there have been an increasing number of interceptions of T. granarium at ports in the USA. The established trap and lure used for surveillance of T. granarium in high risk areas was developed 30 years ago, but since then new lures containing food and/or pheromonal stimuli have become available. In the USA, researchers must work with it in an approved quarantine facility, which slows research and development into mitigation strategies for the species. However, there are closely related dermestids already in the USA but not under quarantine, such as Trogoderma variabile, which may be able to act as a surrogate species for the behavioral responses of T. granarium. Thus, we evaluated the attraction to, arrestment by, and preference between different semiochemical stimuli for immature life stages of both these species and determined whether T. variabile could serve as a surrogate species for T. granarium. While all lures showed some positive response in each of the assays, lures with food cues and pheromones together exhibited the most consistent positive response by larval T. granarium. However, the behavioral response of T. variabile was not consistently correlated with that of T. granarium. Our study contributes updated data that can be used by biosecurity experts in developing surveillance programs for T. granarium.