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Rhyzopertha dominica is a key pest of stored grain. Understanding the movement of this beetle on broad geographic scales is crucial, particularly when developing strategies to prevent the spread of phosphine resistance. We assessed population genetic structuring in this pest across Turkey, using a combination of mitochondrial (cytochrome oxidase I) and microsatellite markers. In addition, we screened samples for Wolbachia, as this endosymbiont has previously been suggested to be associated with low mitochondrial genetic diversity in this beetle. Mitochondrial genetic diversity was low, with only six haplotypes identified. The genetic diversity was, however, substantially higher than that previously found in Australia or India, suggesting that R. dominica may have originated in the Middle East. Wolbachia were detected only at a single site, indicating they are not impacting the mitochondrial genetic diversity of R. dominica across Turkey. Microsatellite markers indicated there is significant geographic genetic structuring across Turkey, even among sites less than 100 km apart, suggesting there is little movement of beetles across regions within the country. This contrasts with the significantly higher levels of gene-flow found in Australia and the United States. We suggest that the limited movement of beetles across Turkey may be due to a combination of the historically localised agricultural practices (which limits anthropogenic movement among regions), and the mountainous landscape (which limits active flight among regions). Our results demonstrate that the movement of stored product pests may differ significantly across studies conducted in different countries. As a consequence, phosphine resistance management strategies must incorporate region specific information on the extent of beetle movement.

The flight behaviour of Tribolium castaneum was studied in the laboratory by characterising the physiological factors related to flight initiation in these small but long-lived beetles. We investigated the flight propensity of T. castaneum at two different ages at the same time: old beetles (∼12 weeks post-emergence) and young ones (∼2 weeks post-emergence). A mixture of old and young individuals was used as an independent test of whether flying beetles had the same characteristics as young beetles and residents the same ones as old. First generation laboratory cultures of field-collected beetles were used to avoid the known effects of protracted laboratory culturing. Beetles that initiated flight were captured individually in the laboratory using a customized trap, and their age, sex, weight, size, fat content, fecundity, and lipofuscin intensity (as a potential correlation of age) were determined. Beetles that had not flown in the test were simultaneously collected to represent residents (non-flyers) in each treatment. The assays indicated that flight propensity declined significantly with age (more young beetles flew than old ones), was not related to sex or weight, but was associated with size (larger beetles flew more). Lipofuscin intensity of old beetles was similar to that of young beetles, so is not a good indicator of age, but it was significantly higher in young flying females than young resident ones, so may be related to metabolic status. Fecundity assessments on a subset of the captured beetles indicate that total fecundity was not related to age or flight propensity. Based on these results we predict that most of the flying T. castaneum in the field will be relatively young beetles of high fat content. These individuals are likely to live longer than older beetles although the fecundity of females will not be higher. © 2018 Elsevier Ltd