Embryoid induction and plantlet regeneration from leaf segments of sugarcane (Saccharum officinarum L.)

     Sugarcane (Saccharum officinarum L.) is an economically important crop in Sudan for domestic consumption and export. It is the first and essential source for production of high purity sugar. Tissue culture techniques can be used for in vitro conservation of sugarcane (Taylor and Dukic, 1993) and mass propagation of elite cultivars of crop species. Moreover, it was used for production of pathogen-free planting material from infected mother plants. Variability induced in vitro can furnish a base for improvement of vegetatively propagated crops including sugarcane. Different tissue culture techniques were applied successfully to sugarcane propagation and plant regeneration through organogenesis of shoot meristem (Nadar and Heinz, 1977; Ho and Vasil, 1983a), cell suspension cultures (Ho and Vasil, 1983b, Aftab et al., 1996) and protoplast cultures ( Liu, 1994). Cell suspen - Sion cultures were also used for cytological, pathological (Peros and Lombard, 1992), biochemical and physiological investigations of sugarcane (Heinz et al., 1977).      This study was initiated, during 1998-2000, to investigate the effect of 2,4-D on induction of embryogenic callus from leaf explants of sugarcane and regeneration of somatic embryos on different concen-trations of Murashige and Skoog (1962) medium (MS)

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

Background: The western flower thrips, Frankliniella occidentalis, is a quarantine pest of French beans that requires phytosanitary treatment to meet quarantine requirements for strict lucrative markets. In this study, the efficacy of hot water treatment against F. occidentalis eggs and its effects on the postharvest physicochemical quality parameters of French beans was evaluated. Results: The immersion time of 8.01 min (95% critical limits CL 7.77–8.24) was predicted by the probit model as the minimum time required to achieve a 99.9968% control level. Confirmatory tests with a large number of F. occidentalis eggs were performed to validate the estimated time to achieve probit-9 control level, and there were no survivors from the 50 103 eggs treated. Likewise, none of the 55 364 eggs exposed to 45 ± 0.2 °C for 7 min (observational time) survived. The effect of the treatment schedule on French beans quality parameters was assessed and there were no differences in weight loss, moisture content, total soluble solids, titratable acidity, pH, and reducing sugars between treated and untreated samples. Conclusion: Our results indicate that hot water treatment (at 45 ± 0.2 °C for a duration of 8.01 min is an effective phytosanitary treatment for the control of Frankliniella occidentalis on French beans, with no significant impact on pods quality. © 2022 Society of Chemical Industry

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

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

Advances in Postharvest Disinfestation of Fruits and Vegetables Using Hot Water Treatment Technology-Updates from Africa

Hot Water Treatment (HWT) provides adequate phytosanitary assurance that treated fruits and vegetables exported abroad are free from devastating quarantine pests. Two systems for HWT are currently available for commercial use namely the batch/jacuzzi and the continuous flow system depending on user requirements. Several protocols have been developed the world over and a few in Africa, but adoption has been lagging because of various factors chief among them lack of large scale validations of experiments to guide application at the commercial level. Mango, Bell pepper, avocado, and French beans play an important role in the livelihoods of people in Africa. However, their export is constrained by pests such as the invasive Oriental fruit fly, the false codling moth, and thrips. To circumvent this issue, disinfestation HWT protocols have been developed which seek to provide quarantine assurance to lucrative export markets. Hot Water Treatment technology has several advantages over other conventional phytosanitary treatments. It provides a triple function of cleaning, disinfesting, and disinfecting and is friendly to users, consumers of the treated commodities, and the environment. We discuss HWT in the context of its future and applicability in Africa. It is the future of postharvest treatments

Modeling the risk of invasion and spread of Tuta absoluta in Africa

Tuta absoluta is an invasive insect that originated from South America and has spread to Europe Africa and Asia. Since its detection in Spain in 2006, the pest is continuing to expand its geographical range, including the recent detection in several Sub-Saharan African countries. The present study proposed a model based on cellular automata to predict year-to-year the risk of the invasion and spread of T. absoluta across Africa. Using, land vegetation cover, temperature, relative humidity and yield of tomato production as key driving factors, we were able to mimic the spreading behavior of the pest, and to understand the role that each of these factors play in the process of propagation of invasion. Simulations by inferring the pest’s natural ability to fly long distance revealed that T. absoluta could reach South of Africa ten years after being detected in Spain (Europe). Findings also reveal that relative humidity and the presence of T. absoluta host plants are important factors for improving the accuracy of the prediction. The study aims to inform stakeholders in plant health, plant quarantine, and pest management on the risks that T. absoluta may cause at local, regional and event global scales. It is suggested that adequate measures should be put in place to stop, control and contain the process used by this pest to expand its range

Host-plant relationships and natural enemies of the invasive mealybug, Rastrococcus iceryoides Green in Kenya and Tanzania

The invasive mango mealybug, Rastrococcus iceryoides Green (Hemiptera: Pseudococcidae) believed to be native to Southern Asia has rapidly invaded Kenya and Tanzania. A survey was carried out from February 2008–July 2009 to study its geographical distribution, host plant relationships and associated parasitoids in both countries. Our results infer that R. iceryoides is widely distributed across the coastal belts of both countries. Rastrococcus iceryoides was recorded from 29 cultivated and wild host plants from 16 families. Twenty-one of these host plants are new records. Among the cultivated host plants, M. indica (8153.6±19.2/20 twigs and 6054.3±29.2/80 leaves in Kibaha, and 2979.3±33.8/5 fruits in Kinondoni) and Cajanus cajan (L.) Millspaugh (1452.2±44.7/80 leaves and 4672.3±54.7/twig in Morogoro) recorded the highest levels of infestation. Parkinsonia aculeata (7892.3±25.1/20 twigs, 11.6±1.25/80 leaves and 42.2±5.1/5 fruits in Kinango), Caesalpinia sepiaria Roxb (266.3±6.3/80 leaves and 3116.1±17.5/20 twigs in Kinondoni) and Deinbollia borbonica Scheff., (215.7±10.3/80 leaves and 2253±22.9/20 twigs in Kibaha) were found to be the most heavily infested wild host plants. Six parasitoid species were recovered and are reported here for the first time to parasitize R. iceryoides. Anagyrus pseudococci Girault was the most dominant species accounting for 21% parasitism on M. indica and 20% parasitism on P. aculeata in Tanzania and Kenya, respectively. Despite this, the ability of the parasitoid to regulate the population of R. iceryoides was inadequate. Therefore, there is a need for foreign exploration and introduction of efficient coevolved natural enemies from its aboriginal home of Southern Asia to minimize its impact on horticulture in Africa.This work was supported by the European Union (SANTE 2007 147–790). The Hlabisa HIV Treatment and Care Programme has received support through the United States Agency for International Development (USAID) and the President’s Emergency Plan (PEPFAR) under the terms of Award No. 674-A-00-08-00001-00.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-04182017-11-30hb2017Zoology and Entomolog