<i>Drosophila</i> spp. (Diptera: Drosophilidae) bait evaluation for monitoring in sweetpotato storage facilities

Drosophila hydei (Diptera: Drosophilidae) is an emerging pest within sweetpotato storage facilities in North Carolina because of their ability to mechanically transmit Ceratocystis fimbriata, a fungal pathogen of sweetpotato roots. Information about D. hydei population dynamics in sweetpotato storage facilities is limited. To address this knowledge gap, this study conducted laboratory and field behavioral choice experiments to assess the most attractive bait for pest monitoring. Laboratory reared flies were placed in arenas containing 2 liter plastic bottle traps each baited with a single treatment: (i) banana and yeast mixture, (ii) fermented sugar water with yeast, (iii) apple cider vinegar, and (iv) water control. Flies captured in each bait treatment were counted after 24 h. The most effective bait was the banana yeast mixture. Field bait assays included the same baits distributed across 20 10 × 15 m storage rooms at two different times spaced 7 d apart (N = 40 replications per treatment). Sticky cards were placed in each room to estimate Drosophila spp. abundance and total arthropod diversity. Field bait experiments showed that apple cider vinegar was a preferred bait for D. hydei and D. funebris, which were the two most common species in sweetpotato storage facilities. In contrast to a previous study of Drosophila spp. in sweetpotato storage, our study found that D. funebris was the most common species. Further research will be necessary to assess D. funebris and its impact on sweetpotatoes. Determining the optimal bait will enable synthesis of chemical baits for population monitoring in sweetpotato storage facilities.