Assessing the importance of flowers and their scents in the host selection of the seed-feeding weevil (Mogulones borraginis)

Current biological weed control testing procedures rely primarily on choice and no-choice feeding and developmental tests to assess the host range of potential agents. Few studies have been conducted to understand the role of visual and olfactory cues associated with the agents’ host selection behavior. Investigating these cues can, however, improve pre-release risk assessments because an insect first locates a host plant based on the presence of visual and olfactory cues. This approach also allows researchers to include previously untested, threatened or endangered plant species in host range assessments because visual and olfactory cues can often be collected in natural habitats with minimal disturbance to plants. We designed 1) a portable volatile collection system (PVCS) to collect headspace volatile organic compounds of plants in the field, and 2) a double stacked y-tube device (D-SYD) to assess the host selection behavior of female Mogulones borraginis, a seed-feeding weevil considered for the biological control of the rangeland weed houndstongue (Cynoglossum officinale). Our data demonstrate that female M. borraginis distinguish houndstongue from several previously untested native test plant species when visual, olfactory, or combined cues were offered to weevils in dual-choice bioassays. Data didn’t change, regardless of whether naïve weevils were kept on houndstongue or on respective test plant species. The results suggest that both, visual and olfactory cues play a significant role in the host selection of M. borraginis. Electrophysiological experiments, currently underway to identify specific wavelengths of light and compounds in headspace VOCs that the weevil is attracted, will be discussed.