Successful completion and long-term maintenance of eradication of boll weevil (BW), Anthonomus grandis grandis Boheman, in Texas would be improved by the development of adult control technologies to eliminate BW reproduction in active eradication zones and help prevent dispersal into and reproduction in post-eradication zones. Spinosad (Tracer®) mixed with 10% sucrose in ppm active ingredient (wt: vol) was evaluated as a toxicant when ingested by field-captured adult BW with additional field assessments of spinosad/feeding stimulant mixtures or bait formulations with grandlure as an attractant. Ingested spinosad was highly toxic to BW adults with a lethal concentration to kill 90% (LC90) of 27.79 ppm after 24 hours. Ingestion of spinosad by BW at lethal concentrations ranging from 28 to 10,000 ppm was inhibitory compared to the sucrose solution alone, but the level of inhibition was not consistent relative to gender or concentrations. In field tests, bait formulations mixed with spinosad at 300 ppm and sprayed on individual yaupon shrubs baited with a pheromone lure killed BW in numbers similar to BW captured in individual traps baited with the pheromone lure alone. This study demonstrates that sugar-based adult control technologies with spinosad as a toxicant and grandlure as an attractant effectively attract and kill BW adults. This strategy may have potential to attract and kill BW in environmentally-sensitive non-cotton habitats, and may have application during the host free window to reduce populations and curtail movement of adults into eradicated zones, both goals of BW eradication programs.
