|Smith, Julia - WCRL, PHOENIX, AZ|
|Rodriguez Saona, Cesar|
Submitted to: Entomological Society of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 6, 2000
Publication Date: N/A
Technical Abstract: Lygus hesperus populations increase on a variety of weeds, and then subsequent generations migrate to alfalfa and cotton, where they can cause severe damage to the growing terminals and reproductive structures. Development of a synthetic attractant for Lygus could play an important role in managing these insects. We investigated the response of naive and experienced 5th instar nymphs and adult L. hesperus to volatile cues associated with conspecifics and alfalfa. Bioassays were conducted in a 40-mm diam. x 36-cm long Y-tube olfactometer, where incoming air was filtered through activated charcoal and humidified by means of distilled water that was placed in a gas-washing bottle, then passed through each of 2 holding chambers; one control and the other held the test material. Tests were conducted at 24 +/- 2 deg C, 870 +/- 6 lux, with an airstream rate of 4.8 l/min. After the bioassays, 5th-instar nymphs were held until they matured and then gender was determined. Adult Lygus were more likely to progress upwind to flowering alfalfa than to vegetative alfalfa, and females were more likely than males to choose the side containing the plant. 5th instar nymphs exhibited less switching between Y-tube arms and were more likely to choose the odor source. Preconditioning to the host plant led to an increase in the percentage of individuals that progressed upwind, but did not increase their likelihood of selecting the odor source. Nymphs exhibited a stronger response to vegetative alfalfa, but nymphs destined to be females were more likely to choose the odor source.