Postharvest Disinfestation Treatments for False Codling Moth and Fruit Flies in Citrus from South Africa

Abstract

South Africa is the 13th largest producer and second largest exporter of citrus fruit globally. The false codling moth, Thaumatotibia leucotreta, and the fruit flies, Ceratitis capitata, C. rosa and Bactrocera dorsalis, can potentially infest citrus fruit and therefore pose a phytosanitary risk for export markets. Consequently, a wide range of postharvest phytosanitary treatments for disinfestation of citrus fruit from these pests have been investigated. These include cold treatments, irradiation, fumigation, heat treatments, and combinations of some of these. Due to the potential phytotoxic effects of all these treatments, the use of a systems approach that depends on two or more independent measures for acceptable phytosanitary risk mitigation is a preferable option. To date, the only postharvest disinfestation treatments used commercially for T. leucotreta and fruit flies for South African citrus, are stand-alone cold treatments and partial cold treatments, as a component in a multi-tiered systems approach. Research on development of novel and improvement of existing postharvest measures continues as a high priority. This includes postharvest detection technologies, in addition to treatment technologies.

Pest survey card on Thaumatotibia leucotreta

“…The adult of T. leucotreta is nocturnal and is attracted by light (CABI, 2019). Light traps will attract males and females of this species, as well as other Lepidoptera species (Mohr, 1973). Pheromone traps are more specific, as they target only T. leucotreta males.…”

Deliquescence‐induced release of ethyl formate and chlorine dioxide from their precursors‐loaded sachets for in‐package fumigation of spotted wing drosophila (Drosophila suzukii Matsumura)

“…Moreover, the zero tolerance regulations imposed by many countries for the presence of insect infestation in imported food commodities make the fumigation treatment a critical step to ensure that commodities are free of insect pests and their combined pathogenic microorganisms before shipping. 4,5 Methyl bromide (MB) has been used for many years as a broadspectrum fumigant for pre-plant soil fumigation to eliminate insects, pathogens, and weeds, as well as to control pests in buildings and commodities. 6 It is also very effective for post-harvest fumigation of fruits, vegetables, and grains.…”

“…Post‐harvest fumigation is a critical treatment to protect food commodities during storage and distribution. Moreover, the zero tolerance regulations imposed by many countries for the presence of insect infestation in imported food commodities make the fumigation treatment a critical step to ensure that commodities are free of insect pests and their combined pathogenic microorganisms before shipping 4,5 …”

“…4 | Mortality of SWD eggs, larvae, pupae, and adults exposed to ClO 2 gas larvae, and adults 26,27,29. However, SWD in the pupae stage is covered by a hard outer covering of cuticle that could provide some protection from ClO 2 exposure during the fumigation.…”

Improved statistical methods for estimating infestation rates in quarantine research when hosts are naturally infested

“…To provide that confidence, phytosanitary or quarantine treatments are often required, with trading partners often needing evidence of treatment efficacy through data generated according to internationally accepted research guidelines. Treatment schedules for fresh produce moving between jurisdictions, include cold storage, fumigation, irradiation, or heat treatments such as water, air, or vapor ( Follett and Neven 2006 , Dohino et al 2017 , Moore and Manrakhan 2022 ). When developing new schedules (dose, temperature, and duration) for these phytosanitary treatments where they do not already exist for a particular pest/commodity/country, testing on sufficient numbers of the target pest on or in the host is required to demonstrate an acceptable level of treatment efficacy.…”