Effect of various heat treatments to target apple leafcurling midge (Dasineura mali) cocoons on apples
New Zealand apples infested with apple leafcurling midge (ALCM) cocoons are a quarantine issue for growers exporting to many markets. The presence of ALCM on apples in these markets requires fumigation with methyl bromide, which decreases fruit quality. The effectiveness of various forms of heat treatments on ALCM were evaluated as alternatives. Apples infested with ALCM cocoons were subjected to one of the following heat treatments: Controlled Atmosphere Temperature Treatment System (CATTS; 1% O2, 15% CO2, 46Â°C, 3 h), hot air (46Â°C, 3 h), hot water high pressure washing (hot-HPW; 55Â°C, 100 psi, 15—20 s), or hot water drench (HWD; 55Â°C, 40 psi, 15—20 s). ALCM removal and mortality were assessed 7-days post-treatment. The hot-air and CATTS treatments provided the greatest control, with 82.2 and 92.2% mortality respectively. More cocoons were removed with hot-HPW (46.6%) compared with ambient-HPW (27.1%). Neither HWD nor hot-HPW increased mortality of cocooned ALCM over that in untreated controls. ALCM cocoons are particularly difficult pests to remove/kill; further research should focus on incorporating multiple control measures into the current systems approach.