Effectiveness of hot-water immersion against Brevipalpus yothersi (Acari: Tenuipalpidae) as a postharvest treatment for lemons

Citrus leprosis is a destructive disease of Citrus caused by several viruses (CiLVs) that are quarantine pests in the United States. Brevipalpus yothersi Baker (Acari: Tenuipalpidae) vectors the most virulent strain of CiLV. This mite is present in the US and could facilitate the spread of the disease if CiLV reaches the country. Post-harvest treatments could mitigate B. yothersi on imported commodities from areas where CiLV exists. We explored the effectiveness of hot-water immersion as a post-harvest treatment against B. yothersi. Lemons were immersed in water at 21, 48, 53 or 63˚C for 5, 10, and 15 minutes. Immersions at 53 and 63˚C for all time schedules dislodged over 99 % of adult mites. Lemon fruit quality and B. yothersi egg viability after hot-water immersion were also evaluated. Fruit quality significantly decreased in lemons treated at 63˚C resulting in decay (grade 3, rejection), while at 53˚C there was a quality reduction (grade 2, minimum acceptable market level) compared to lemons immersed at 21˚C or non-treated controls (grade 1). None of the eggs hatched when the lemons were immersed in water at 63˚C and an average of 1.5% hatched at 53˚C for all time schedules. Immersion at 53˚C for five minutes dislodged 99.71%, 57.14% of adult and immature mites respectively, and resulted in 98.11% unhatched eggs without significant fruit quality reduction. Hot-water immersion could be a key component in a systems approach to control B. yothersi on imported citrus fruits from countries where citrus leprosis is present.