Hot Water Treatment for Post-Harvest Disinfestation of Bactrocera dorsalis (Diptera: Tephritidae) and Its Effect on cv. Tommy Atkins Mango

Abstract

Mango production and trade in sub-Saharan Africa is hampered by direct damage and the high quarantine status of B. dorsalis and the paucity of effective post-harvest phytosanitary treatments. The current study reports the development of a quarantine treatment protocol using hot water to disinfest B. dorsalis and assess its effect on cv. Tommy Atkins mango quality. We first determined the development of the eggs and all larval stages of B. dorsalis in cv. Tommy Atkins mango and used the information to establish a time–mortality relationship of the immature stages after subjecting infested fruits to a regimen of eight, time instances of hot water at 46.1 °C. Using probit analysis, we estimated the minimum time required to achieve 99.9968% mortality of each stage. Our results indicate that the egg was the least heat tolerant, followed by the first, second, and third instar. The time required to achieve 99.9968% control of the third instar in cv. Tommy Atkins mango (400–600 g) was determined to be 72.63 min (95% Cl: 70.32–74.95). In the confirmatory trials, the hot water treatment schedule of 46.1 °C/72.63 min was validated, and none of the 59,120 most heat-tolerant individuals treated survived. Further, there were no significant differences between hot water-treated and untreated mangoes recorded in weight loss, fruit firmness, pH, total soluble solids, moisture content, and titratable acidity eleven days post-treatment. These findings demonstrate an effectively optimum post-harvest disinfestation treatment against B. dorsalis in cv. Tommy Atkins mango that should be adopted commercially to facilitate access to profitable but strict export markets globally.

Efficacy of hot water treatment for postharvest control of western flower thrips, Frankliniella occidentalis, in French beans

“…An equal number of infested pods were set aside as control for use as an estimation of the number of eggs in the treated pods. The timing of the HWT commenced when all the pods in a treatment batch were completely submerged in the hot water treatment tank 39 containing water already at 45 ± 0.2 °C. The choice of the water temperature was based on pilot experiments conducted to determine the temperature that does not result in the scalding of pods post‐treatment.…”

“…The tank was connected to a Grant Squirrel data logger (SQ2020‐2F8) with 16 thermocouple probes (Tempcon Instrumentation Ltd, Arundel, UK) to give temperature recordings throughout the treatment (Fig. 1) as described by Mwando et al 39 …”

“…Compared to these techniques, the hot water treatment (HWT) technique offers the best non‐chemical alternative since it is reliable, efficient, viable and environmentally friendly 32,33 . The postharvest HWT technique is a suitable treatment for the control of other pests of quarantine importance such as codling moths and fruit flies in fresh produce 34–39 . Similarly, HWT was recently considered as a potential phytosanitary treatment for postharvest control of F. occidentalis in French beans 40…”

“…32,33 The postharvest HWT technique is a suitable treatment for the control of other pests of quarantine importance such as codling moths and fruit flies in fresh produce. [34][35][36][37][38][39] Similarly, HWT was recently considered as a potential phytosanitary treatment for postharvest control of F. occidentalis in French beans. 40 The International Standards for Phytosanitary Measures (ISPM) require that postharvest treatments are effective and the level of efficacy quantified statistically.…”

Important alien and potential native invasive insect pests of key fruit trees in Sub-Saharan Africa: advances in sustainable pre- and post-harvest management approaches

“…Hot water treatment experiments were also conducted independently of the West Africa studies and a temperature of 46.1 °C for 68 min was considered adequate to give 100% assurance that Apple mangoes were free from B. dorsalis (Ndlela et al 2017). Further studies have been conducted on Tommy Atkins mango variety and a temperature of 46.1 °C for 72-100 min was deemed adequate to disinfect the mangoes (Mwando et al 2021;Ocitti et al 2021). The protocol by Ndlela et al (2017) has since been shared with the EU through the Kenya Plant Health Inspectorate Service (KEPHIS), the regulatory body in Kenya.…”