Immersion in hot water as a phytosanitary treatment for Thaumatotibia leucotreta (Lepidoptera: Tortricidae) in bell pepper (Capsicum annuum L.)
2022
Mwando, Nelson L. | Ndlela, Shepard | Meyhöfer, Rainer | Subramanian, Sevgan | Mohamed, Samira A.
The False codling moth (FCM), Thaumatotibia leucotreta is a major quarantine pest that hampers Capsicum production and trade in sub-Saharan Africa (SSA) and may need a postharvest treatment to meet quarantine standards of lucrative overseas markets. In this study, we evaluated the efficacy of hot water treatment (HWT) as a potential nonchemical quarantine control option against T. leucotreta in bell pepper and its effect on the quality parameters of the peppers. Infested bell pepper harboring different immature stages of T. leucotreta were subjected to a hot water treatment of 50 ± 0.2 °C for eight different time-points to determine heat susceptibility of immature stages of T. leucotreta. The third-instar was the least heat susceptible, followed by second-and first-instar larva and the egg stage, respectively. The immersion time of 44.23 min (95% CL 43.22 – 45.24) was estimated to be the minimum time required to attain 99.9968% control level. In the large scale confirmatory experiment, there were no survivors from the 20,325 third instar individuals treated in bell pepper (180 – 220 g). Additionally, none of the 25,384 third instars exposed to 50 ± 0.2 °C for 32 min survived. The impact of the HWT schedule on bell pepper fruit quality parameters was assessed and there were no significant effects on weight loss, moisture content, total soluble solids, titratable acidity, dry matter and pH post treatment. These results provide strong evidence that the HWT schedule is an effective phytosanitary treatment for control of T. leucotreta, and may be adopted to facilitate access to overcome the phytosanitary barriers imposed by importing countries to capsicum from SSA.
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