Susceptibility and attractiveness of ancient wheats to Sitophilus granarius and Rhyzopertha dominica

Abstract Ancient wheats are valuable genetic resources and could represent a source of income for farmers. Little is known on interactions between ancient grains and storage insect pests. In the present study, the susceptibility and attractiveness of one emmer (Padre Pio) and one spelt (Benedetto) variety toward Sitophilus granarius (L.) and Rhyzopertha dominica (F.) were evaluated. Samples of Padre Pio and Benedetto, with glumes or without, were infested with adults of S. granarius or R. dominica to test their susceptibility. A susceptibility index (SI) was calculated for each variety. Both Padre Pio and Benedetto were resistant to S. granarius if hulled and moderately resistant if de-hulled. For R. dominica, the same varieties were susceptible if hulled and highly susceptible if de-hulled. For S. granarius , the SI value was inversely correlated with protein content. The average development time of R. dominica was directly correlated with the kernel hardness. The volatile organic compound (VOC) profiles of hulled varieties tested were characterized by headspace solid-phase microextraction (HD-SPME) and gas chromatography coupled with mass spectrometry (GC–MS). The attractiveness toward S. granarius and R. dominica adults was evaluated in two-choice pitfall bioassays and Y-tube olfactometer, respectively. Both varieties were attractive to S. granarius adults, while odors from both varieties did not induce attraction in R. dominica adults. The GC–MS analysis highlighted the presence of a total of 50 VOCs. The possible reasons of differences in susceptibility and attractiveness are discussed.