Efficacy of alkaline hydrolyzed torula yeast for monitoring Anastrepha spp.

Anastrepha fruit flies (Diptera: Tephritidae) are important pests of several crops in the Americas. Alkaline hydrolysis of proteins represents a potential source of novel attractants. Previous studies revealed a higher response by Anastrepha obliqua (Macquart) to alkaline hydrolyzed torula yeast compared with other attractants. Under field conditions, captures of Anastrepha fraterculus (Wiedemann), Anastrepha ludens (Loew), and Anastrepha serpentina (Wiedemann) were significantly higher in traps baited with alkaline hydrolyzed torula yeast than in traps baited with acid hydrolyzed protein (Captor) + borax. Fly attraction to alkaline hydrolyzed torula yeast varied with species but was higher in the 1st week and decreased after 2 or 3 weeks of use in the field. The release of ammonia gas from alkaline hydrolyzed torula yeast and CeraTrap was reduced after 3 weeks, but CeraTrap remained effective in the capture of flies whereas alkaline hydrolyzed torula yeast did not. No improvement in fly captures was observed for aged alkaline hydrolyzed torula yeast when 1% ammonium acetate was added to traps. The addition of propylene glycol or benzalkonium chloride did not improve trap captures over time. Although CeraTrap has advantages in attractiveness and durability, the attraction, simplicity, and low cost make alkaline hydrolyzed torula yeast a promising attractant when compared with the standard Captor + borax in short-term monitoring programs targeted at Anastrepha pests.