Bioactivity of Cereal- and Legume-Based Macaroni Pasta Volatiles to Adult Sitophilus granarius (L.)

SIMPLE SUMMARY: Pasta factories can be infested by insects. By following the odour of cereal-based pasta, insects can enter packages of commercial products. The aim of this work was to compare the bioactivity of volatiles produced by cereal- and legume-based macaroni pasta on adults of granary weevil, Sitophilus granarius, in multi-choice behavioural bioassays. Tests were performed with ten commercially available Italian macaroni pastas made from six different cereals or four different legumes. Granary weevil adults were more attracted to cereal-based pastas than legume-based pastas, but the differences in attractiveness were not always significant. Gas chromatography-mass spectrometry analysis of head-space solid-phase microextraction collections from the different pasta samples highlighted marked qualitative and quantitative differences, with aliphatic aldehydes and aliphatic alcohols being the most abundant volatile components of cereal- and legume-pastas, respectively. Moreover, the results of the two-choice behavioural bioassays suggested that the low level of attraction to legume pasta is mainly due to the lack of attractant stimuli other than emission of repellent compounds. ABSTRACT: The attractiveness of ten commercially available Italian macaroni pastas made from different cereals [Triticum durum; Triticum durum (whole wheat); Triticum dicoccum; mixture of five cereals; Triticum turgidum; Triticum turanicum] or legumes (Cicer arietinum; Lens culinaris; Pisum sativum; Vicia faba) to Sitophilus granarius, was compared. S. granarius adults were more attracted to cereal pastas than legume pastas, but the differences in attractiveness were not always significant. Consistent with the results of behavioural bioassays, the mortality of adults over 20 days exposed to pasta samples was 100% with the legume pasta samples and only 8% with the T. turanicum pasta. GC-MS analysis of HS-SPME extracts from the different pasta samples highlighted marked qualitative and quantitative differences, with aliphatic aldehydes and aliphatic alcohols being the most abundant volatile components of cereal- and legume-pastas, respectively. In two-choice behavioural bioassays, insect attraction to a 1:1 combination of T. turanicum and C. arietinum pastas (80%) was even higher than that observed in T. turanicum pasta alone (64%) and in C. arietinum pasta alone (20%). This strongly suggested that the low attractiveness of legume pasta is mainly due to the lack of attractant stimuli rather than emission of repellent compounds.