Development of practical pheromone lures for Lygus hesperus and Lygus elisus (Heteroptera: Miridae)

Authors: HALL, DAVID - University Of Greenwich; Serrano, Jacqueline; YOKOTA, GLENN - University Of California Berkeley; NIETO, DIEGO - Driscoll'S; FARMAN, DUDLEY - University Of Greenwich; MC ELFRESH, JAMES - University Of California, Riverside; DEL-POZO, ALEJANDRO - Virginia Tech; MILLAR, JOCELYN G - University Of California, Riverside; DAANE, KENT - University Of California Berkeley

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2024
Publication Date: 11/22/2024
Citation: Hall, D.R., Serrano, J.M., Yokota, G.Y., Nieto, D.J., Farman, D.I., Mc Elfresh, J.S., Del-Pozo, A., Millar, J., Daane, K.M. 2024. Development of practical pheromone lures for Lygus hesperus and Lygus elisus (Heteroptera: Miridae). Journal of Economic Entomology. https://doi.org/10.1093/jee/toae266.
DOI: https://doi.org/10.1093/jee/toae266

Interpretive Summary: Lygus bugs are pests of many crops in the United States including fruits and vegetables. They are known to disperse between crop and non-crop hosts, making their monitoring and management difficult. Traps and attractant baits are available for many pest insect species however the use of attractant pheromones for Lygus bugs hJournal of Economic Entomology has been difficult, in part because the identification of pheromones for these insects is complicated by the large amounts of volatile defensive chemicals that are produced. An international team of researchers in the United States and the United Kingdom, reevaluated pheromones volatiles produced by female Lygus bugs and used that knowledge to develop a practical dispenser for the pheromone that could be used in traps for long-term monitoring. Field trials demonstrated the effectiveness of an attractive lure developed for one Lygus species. The field trials for another Lygus species performed better than control traps, however but trap catches do not appear to scale with population density. These results highlight the importance of carefully formulated lures that could be useful for detection of the onset of immigration of Lygus bugs into crops.

Technical Abstract: The mirid bugs Lygus hesperus (Knight) and L. elisus (van Duzee) are key pests of forage, fiber, and fruit crops. Our goals were to identify pheromone components produced by females of both species and to develop practical pheromone dispensers for use in monitoring these pests. Volatiles collected from virgin female L. elisus contained (E)-2-hexenyl butyrate (E2HB) as the major component with lesser amounts of hexyl butyrate (HB) and (E)-4-oxo-2-hexenal (E4OH) (ratio 117.2:100:17.1, respectively), whereas volatiles and solvent extracts from L. hesperus contained HB and E4OH as major components, with only small amounts of E2HB (100:23.6:3.4, respectively in volatiles). Dispensers fabricated from pipette tips released the components at ~10 µg/d in a ratio similar to the loading ratio. These lures were used to optimize the pheromone blends in field studies from 2012 to 2017. Blends of E2HB and E4OH attracted L. elisus, and a 100:60 blend was optimal. Blends of HB and E4OH attracted L. hesperus, and a 100:60 blend was adopted as a base blend. The additions of possible minor components such as (Z)-3-hexenyl butyrate, (E)-2-hexenal, or 1-hexanol did not improve the attraction of L. hesperus. In trials in alfalfa and strawberry, traps baited with blends of HB:E4OH (100:60) were equally or more effective for monitoring L. hesperus than sweep or vacuum samples, with pipette tip dispensers lasting 2–3 weeks under field conditions. The numbers of L. hesperus captured were lower than expected as compared with reports of pheromone trapping for other Lygus spp. Some possible reasons were investigated.