Active dispersal of natural populations of Triatoma infestans (Hemiptera: Reduviidae) in rural northwestern Argentina.

An empirical model of flight initiation coupled with data from a longitudinal study predicted that the flight dispersal of Triatoma infestans from peridomestic sites was more likely to occur in late summer. To partially test this prediction, we operated 11-12 black light traps from 1945 to 2200 hours in March 2003 in two villages in northern Argentina. All peridomestic sites around the light traps were later inspected to assess the relative abundance and nutritional status of T. infestans at each site. Traps were located 19-94 m from the nearest infested site. A total of 2 female, 10 male, and 3 fifth-instar nymphs of T. infestans; 4 adult Triatoma garciabesi; and 1 Triatoma guasayana fifth-instar nymph were collected in 64 trap nights. Nearly two-thirds of the bugs arrived to the traps during the first hour after sunset, when ambient temperatures were 22-28 degrees C; 80% of adults were unfed. The number of T. infestans that flew to the traps was significantly and negatively associated with wind speed, and the number of males positively associated with the abundance of adult T. infestans in peridomestic sites within 200 m around each light trap. This is the first successful application of light traps for collecting dispersing nymphal and adult T. infestans on a village-wide scale. We attribute this success to the placement of traps with consideration to spatial infestation patterns and seasonal variation in nutritional status of peridomestic triatomine populations.