Optimizing Torula Bait for Anastrepha suspensa (Diptera: Tephritidae) Trapping in the Dominican Republic

Abstract

Torula yeast is the most common bait used by growers and agriculture professionals for trapping of tephritid flies in the Dominican Republic. However, the efficiency of the bait is influenced by weather conditions, aging, and contamination with undesirable microorganisms. Thus, additives such as benzalkonium chloride, a quaternary ammonium compound, have been used together with torula yeast as a bait stabilizer. This study evaluated the effect of the addition of benzalkonium chloride to torula yeast bait, and time of renewal in guava orchards for trapping of Caribbean fruit flies (Anastrepha suspensa Loew; Diptera: Tephritidae). A field study was conducted in 2 consecutive 8-wk periods between Oct 2019 and Feb 2020. Six treatments were evaluated based on the type of bait (torula yeast or torula yeast + benzalkonium chloride) and renewal frequency (weekly, biweekly, or without renewal). Treatments were arranged in a randomized complete block design with 4 replications. Data indicated that torula yeast was attractive to 85.2% and 80.2% more males and females of Caribbean fruit flies compared to torula yeast + benzalkonium chloride, respectively. Similarly, traps without renewal attracted an average of 49.8% more females than traps renewed weekly or biweekly, regardless of the bait type. Analysis of both baits showed a rapid decrease in pH of the torula yeast. The addition of benzalkonium chloride may have affected the microbial activity in the solution, leading to reduced decomposition of torula yeast + benzalkonium chloride and, therefore, reduced captures.