Because semiochemical signals often influence insect behavior, synthetically replicating these scents equips growers with a powerful tool to manage agricultural insect pests. This strategy works most effectively if the chemical composition of the natural odor is identified and isolated, and if the behavior it elicits is fully understood. The invasive brown marmorated stink bug (BMSB) (Halyomorpha halys) and the harlequin bug (Murgantia histrionica) (Figure 1) both respond to traps baited with pheromone lures which can be used in order to monitor levels of these pests to determine whether or not to take action against them with insecticides (Figure 2).
Yet another piece to this complicated smell puzzle stems from cross-species attraction, meaning that the deployment of a pheromone by one stink bug species can attract another stink bug species. Scientists can monitor BMSB by using MDT, the aggregation pheromone of a completely different stink bug species (the Asian brown-winged green bug, Plautia stali). However, because the pheromone is most attractive to BMSB in the fall, which is after most crop harvests have finished or already starting, so this is not very helpful for most growers1.
To produce better attractants for BMSB, researchers successfully identified the specific aggregation pheromone produced by BMSB adult males. The pheromone (commonly called murgantiol) is comprised of two different isomers, or molecular conformations, with a specific ratio. This ratio is important to know because there can be variation between species, and even between individual bugs, for what ratio is most attractive. Dr. Weber and colleagues determined which isomer ratio of murgantiol was most attractive separately to BMSB, and then combined this pheromone with MDT to see if a blend of the two was attractive to the bugs. The two pheromones together were much more attractive than either alone – with an added advantage of this blend being attractive to the bugs all season long, unlike MDT by itself. These pheromones also do not need to be extremely pure, which is good news for keeping the cost of lure production low.
While Dr. Weber and his colleagues uncovered a lot of information about stink bug pheromones, there is still room to further our understanding. Now that researchers have evidence for which pheromone blends work most effectively for the two species, there is a lot of fine-tuning to be done about how exactly to use them in traps, and the most economical way to produce them. Dr. Weber and his colleagues also have plans in the works to investigate using pheromones for other pest-combating purposes, such as attracting insect predators of pest species like stink bugs, and genetically engineering plants to produce insect pheromones and act as trap crops. Overall pheromones offer an exciting approach to manage not only stink bugs, but many different pest insects, to better protect our agriculture.
To learn more about Dr. Weber’s research or contact him, visit his USDA homepage. For more information on BMSB or Harlequin bugs, you can visit the University of Maryland Extension pages on BMSB and Harlequin bugs.
Authors: Elizabeth Brandt, Aditi Dubey, Morgan Thompson
- Sugie et. al. 1996 "Identification of the Aggregation PHeromone of hte Brown-Winged Green Bug, Plautia stali Scott (Heteroptera: Pentatomidae)" Applied Entomology and Zoology 31:427-431
- Funayama 2008, "Seasonal fluctuations and physiological status of Halyomorpha halys (Stal)(Heteroptera: Pentatomidae) adults captured in traps baited with synthetic aggregation pheromone of Plautia crossota stali Scott (Heteroptera: Pentatomidae)," Japanese Journal of Applied Entomology and Zoology, 52:69-75.
- Weber et al. 2014 "Synergy of Aggregation Pheromone With Methyl (E,E,Z)-2,4,6-Decatrienoate in Attraction of Halyomorpha halys (Hemiptera: Pentatomidae)" J. Econ. Entomol. 107:1061-1068.
- Leskey et al. 2015. "Behavioral Responses of the Invasive Halyomorpha halys (Stal) to Traps Baited with Stereoisomeric Mixtures of 10,11-Epoxy-1-bisabolen-3-OL" J. Chem. Ecol. 41: 418-429.
- Zahn et al 2008. "Identification, Synthesis, and Bioassay of a Male-Specific Aggregation Pheromone from the Harlequin Bug, Murgantia histrionica" J Chem Ecol (2008) 34: 238-251.
- Fahey et al. 2001 "The chemical diversity and distribution of flucosinolates and isothiocyanates among plants." PHytochemistry 56:5-51.
- Weber et. al., unpublished data.