Assessing olfactory and visual cues in host selection behavior to improve pre-release host range prediction of Mogulones borraginis (Coleoptera: Curculionidae) for houndstongue, Cynoglussum officinale (Boraginaceae)

While much of pre-release host range testing focuses on differing test conditions to either assess the fundamental host range (no-choice) or the realized host range (choice and field tests), little research is directed at the underlying importance of host plant cues triggering or preventing a potential agent female’s host choice. This is true for the seed-feeding weevil, Mogulones borraginis, currently proposed as a biological control agent for houndstongue, C. officinale, because of its narrower host range. However, pre-release host range evaluation for M. borraginis is complicated by the fact that some native confamilials in North America are rare and/or cannot be grown under greenhouse conditions. Therefore, we assessed host location behavior of the weevil from houndstongue and two critical test plant species in a quarantine facility using a circular four-area olfactometer for olfactory cue and a Y-maze apparatus for visual cue. We assert that one of the major advantages of this approach is a possibility to exclude test plants that were previously oviposited by female or were difficult to grow in a quarantine facility because host selection behavior is a catenary process, involving finding the host plant via olfactory and visual cues, before examining and accepting it for feeding and oviposition.