The Interplay of Olfaction and Vision in Host Plant Selection by Anthrenus verbasci

Anthrenus verbasci (Coleoptera: Dermestidae) is a notorious pest of museums, where the infamous larvae can destroy valuable collections and displays. In households they are a nuisance; carpets, fabrics, food-items, or any proteinaceous material can be damaged and even in agriculture their presence is an unwelcome one, as stored grains, spices, etc. can be contaminated by larvae. We know very little about the host preference of adults, they are frequently seen on plants of the Apiaceae and Asteraceae family, yet we do not know why they prefer these species. The main concept is that visual contrast of white flowers attract these insects primarily, yet we know little about how floral volatiles mediate host recognition. We observed a high abundance of A. verbasci adults on the umbels of ground elder ( Aegopodium podagraria ) and sought to determine whether this mass attraction is mediated by its floral volatiles. With gas chromatography coupled electroantennography (GC-EAD/FID), we have detected 8 antenally active compounds from the headspace volatilome of A. podagraria . Y-tube behavioral assays revealed that the odor of intact ground elder ( Aegopodium podagraria ) umbels attracted A. verbasci adults significantly; however, this attraction was reduced when damaged umbels were presented. In Petri dish experiments, germacrene-D induced an aversional effect from adults, highlighting a possible repellency. Beetles seemed to prefer discs baited with A. podagraria headspace volatiles at first, yet choice changed and shifted towards the visual stimulus of dried ground elder umbellets at the end of the experiments highlighting the importance of vision and olfaction. From our studies we have concluded that olfaction could play an important role in host recognition and could be implemented in integrated pest management of A. verbasci.