|Wallingford, Anna - Virginia Polytechnic Institution & State University|
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2018
Publication Date: 2/28/2018
Citation: Thrift, E., Herlihy, M.V., Wallingford, A.K., Weber, D.C. 2018. Fooling the harlequin bug (Hemiptera: Pentatomidae) using synthetic volatiles to alter host plant choice. Environmental Entomology. https://doi.org/10.1093/ee/nvy013.
Interpretive Summary: The harlequin bug is a serious stink bug pest of cruciferous vegetables. New tools are needed for vegetable growers to manage this pest with reduced or no pesticide inputs. We investigated attractants for harlequin bugs as part of a larger project to develop new traps or trap crops to manage this pest. Both sexes of the adults, as well as the nymphs (young) of the harlequin bug, are strongly attracted its male-produced pheromone, murgantiol. Potted plant hosts vary significantly in their attractiveness. They attract and accumulate many-fold more bugs when baited with the mixed pheromone preparation, than when the pheromone lure is absent. Plant volatiles unique to plants preferred by harlequin bug can also be attractive. These “mustard oils” can potentially increase attraction, and, along with the bug’s pheromone, can mislead the bug and attract it to non-host plants. However, the bugs don’t remain very long on non-host plants, so there remains a need to arrest or kill bugs that are attracted, in order to be useful in this pest’s suppression. This results of this research will be useful in developing traps or trap crops to manage this serious pest, and will be of interest to pest managers and researchers developing environmentally-friendly methods to manage vegetable pests.
Technical Abstract: Harlequin bug, Murgantia histrionica (Hahn) (Hemiptera: Pentatomidae), is a widespread invasive pest that feeds on a variety of brassicaceous crops and other plants. To understand olfactory cues which mediate host-finding, and possible utility in pest management, we deployed aggregation pheromone (mixed murgantiols = 10,11-epoxy-1-bisabolen-3-ols) and/or isothiocyanate host plant volatiles with potted host plants and non-host soybean, in field choice bioassays. Adults were strongly attracted (10-31x) to collard host plants baited with pheromone lures, compared to unbaited collards, as were nymphs (4.6x); adult sex did not influence response. Collard plants baited with lures containing allyl and/or benzyl isothiocyanate showed a 1.3x and 1.9x increase in attractiveness respectively, not differing by life-stage nor sex; multiple lures showed additive attraction. Non-host soybean, baited with pheromone lure, was 4.6-7.5x more attractive to adults than unbaited collard; conversely, baited collard was 124x more attractive than unbaited soybean. The number of bugs observed on and near poisoned plants was significantly greater than those on unpoisoned plants. The difference in observed effect (269x versus 3.8x) indicated that attraction was underestimated by circa-daily counts of unpoisoned plants, presumably because poisoned plants killed all attracted individuals,and that bugs were rapidly abandoning the baited non-host soybean plant, sometimes redistributing to the unbaited collard host. Results indicate that harlequin bugs can be misled to encounter and feed on non-hosts by their aggregation pheromone, but additional means may be needed to retain them. Attraction to hosts is increased both by the aggregation pheromone, and at least two host plant volatiles, allyl and benzyl isothiocyanate. This contributes to our knowledge of host finding in harlequin bug, and to possible trapping and trap cropping schemes for pest management.