Use of macro and trace elements as biological markers in the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

The relationship between the occurrence and movements of Rhyzopertha dominica (F.), a serious pest of stored cereal grains, in distinctly different habitats is poorly known. Understanding the feeding ecology and dispersal patterns of R. dominica may likely help predict the abundance or movement of this pest in various habitats. Natal sites and movement of insects are studied using intrinsic methods involving elemental analyses. In this study, to understand the dietary history of R. dominica, trace and macro elements were used as potential markers. Insects reared on selected diets under laboratory conditions and adult beetles collected from the periphery of granaries or inside forested woodlands were used to determine 10 different elements in their body tissues. Quantities of 10 elements were also determined in respective laboratory hosts. The main discriminant elements for laboratory-reared R. dominica were Na, S and Zn, while significantly different elements were distinctive among field-collected beetles and included P, Ca, K, Zn, and Cu. The amount of Zn quantified in acorn-fed lab reared beetles was significantly lower than wheat- or corn-fed insects. Similarly, beetles captured in woodlands had significantly lower Zn in their body signatures, suggesting acorn seeds may have served as an alternate host in Quercus spp. dominated woodlands. Our studies showed that elemental profiles may potentially be used as biological markers for delineating food sources of R. dominica to mainly discriminate whether beetles originated in agricultural vs. wooded habitats.

► Elemental profiling is used as a method to track the dietary history of Rhyzopertha dominica. ► Adult R. dominica were collected from woodlands and commercial granaries. ► Field insects were compared for their elemental profiles with lab-reared insects. ► Results showed that Zn may be a useful elemental marker to distinguish insect origins.