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Mean percentage (95% confidence interval) mortality of Planococcus ficus on grapevine leaves treated with Steinernema yirgalemense infective juveniles (IJs) after 48 h exposure in a glasshouse environment. IJs were applied to leaves with a handheld sprayer at a concentration of 3 000 IJs/ml (one-way ANOVA: F (3,120) = 241.52; p = < 0.01). Means of bars sharing a letter are not significantly different from one another.
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The vine mealybug (Planococcusficus) is regarded as a key mealybug pest of grapevines in South Africa, with entomopathogenic nematodes (EPNs) being touted as a potential alternative to chemical control, although their vulnerability to above-ground environmental conditions has limited their use. In this study, tests were conducted to assess the abil...
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Mortality of imported entomopathogenic nematodes, Heterorhabditis bacteriophora (HP88),H. indica, and Steinernema carpocapsae (All) compared with local EPNs isolates, H. bacteriophora (Ar-4), H. bacteriophora (Serag1), and H. bacteriophora (Ht) alone or combined with the recommended dose of abamectin and fenamiphos on juvenile mortality percentages...
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... Mixing nematode suspensions with adjuvants, or a combination of adjuvants, should facilitate the use of biological control agents in aboveground areas that have previously been considered inaccessible for nematode application (Platt et al., 2020). As the use of EPNs against the vine mealybug would be an aboveground application, Platt et al. (2019a) assessed the ability of adjuvants to increase the survival rate of S. yirgalemense on grapevine leaves. The combination of both Nu-Film-P ® (poly-1-p-menthene, spreader, sticker; Hydrotech, Pretoria, South Africa) and Zeba ® (starch-g-poly (2-propenamideco-2-propenoic acid) potassium salt; Tongaat Hulett Starch, Germiston, South Africa) resulted in significantly more IJs being deposited over a 4 cm 2 of grapevine leaf disk than before. ...
... The results of this study showed that adding these surfactants increased the survival rate of EPN larvae. Increasing the survival rate of IJs using adjuvants was also demonstrated in studies by Platt et al. [50]. In field studies [51] where Atpolan Bio 80 EC adjuvant was used with S. feltiae ZAG15 isolates, a relatively high effectiveness was achieved with foliar application. ...
The larvae of ermine moths from the Yponomeutidae family (Lepidoptera) feed on a range of species and varieties of fruit and ornamental trees. Some species of this family pose a serious threat to the environment, mainly because of the significant defoliation they cause but also due to the widespread use of insecticides used to control them. This study was designed to assess the sensitivity of Yponomeuta padella and Yponomeuta cagnagella larvae and pupae to a native strain of Steinernema feltiae ZAG15 nematodes under laboratory conditions and to test the biological activity of these nematodes against the larvae and pupae of these species in field studies. The following doses were used in the laboratory tests: 50 IJs/insect (Petri dish tests) and 100 IJs/insect (container tests). Petri dish and container tests were performed at 20 °C and 60% humidity. Mortality of two stages (larvae and pupae) was determined 3 days after treatment. In the field trials, the nematodes were applied at the following doses: 4000 IJs/web for the caterpillars of Y. padella and Y. cagnagella and 1000 IJs/web for the pupae of Y. padella and Y. cagnagella (this corresponded to approximately 200 IJs/insect). Nematodes were applied using a 1 L hand sprayer and a lance. The efficacy of the application was assessed after seven days. The results of our study showed that the larvae (81.7%) and pupae (88.3%) of Y. padella had a greater susceptibility to entomopathogenic nematodes (EPNs) than those of Y. cagnagella (50% and 33.3%, respectively). However, our promising laboratory results did not translate into results in field trials, where the application of EPNs proved to be ineffective.
... For a quick advance for their implementation in the field, the selection of adjuvants authorized for use in the vineyard to be combined with the EPN is a smart strategy (Campos-Herrera et al., 2021). The screening of their compatibility in laboratory and greenhouse approaches allows the selection of the best EPN-adjuvant mix (Platt et al., 2019a). In addition, investigating the differential ability of the EPN to kill the insect exposed to various plant organs, such as the fruit (grapes), the leaves, and the trunk, will provide critical information on the suitability of application. ...
... In the first screening, for each of the four EPN species/populations, we investigated the following treatments: Control (water), Multi-Us, Maximix, Dash-HC, NuFilm 17, and Adrex. In a second study, based on the results and the approach by Platt et al. (2019a), we selected the species S. feltiae 107 and S. carpocapsae All for the evaluation of the treatments: Control (water), Multi-Us, Maximix, and the combination of Multi-Us + Maximix. Overall, for the viability studies, the experimental unit was a 30 mm. diam. ...
... Each stem was vertically placed in a container with sterile pot soil (autoclaved for 2 h and oven dried for 3 day at 70 • C). Each of the EPN species/population suspensions was prepared to the concentration of 2000 IJs/ml (Platt et al., 2019a). The concentration of each adjuvant was prepared following the description above. ...
... Recent advances in specific formulations, adjuvants (e.g., antidesiccants, brighteners), and field application systems have begun targeting EPNs against aerial pests (Shapiro-Ilan and Dolinski, 2015; Nxitywa and Malan, 2021). The number of certified adjuvants in grapevines is limited today, but laboratory and greenhouse experiments have shown the great potential of this technology (Platt et al., 2019). Moreover, natural products produced by Xenorhabdus spp. ...
Entomopathogenic nematodes (EPNs) are biological control agents that often occur naturally in crop soils. The conventional agricultural practices of regular tillage and agrochemical applications predispose to soil biodiversity losses, compromising soil health and disrupting the natural balance of abiotic and biotic factors that might modulate EPN abundance and activity. The vineyard, which supports a relevant socio-economic sector worldwide, is one of the most intensively managed cropping systems. Therefore, approaches rather than reliance on mechanization and agrochemicals are needed to achieve more sustainable viticulture. We hypothesized that alternative strategies to tillage for soil management and the release of agrochemicals for pests, diseases, and weed management, such as cover cropping, mulching, and organic farming, would favor the native EPN community in vineyard soils. Therefore, our objective was to evaluate the impact of differentiated viticulture practices on native EPNs and other targeted organisms associated with their soil food web and how their assemblage might signal soil health in vineyards.
We implemented traditional and innovative methodologies to isolate and identify mesofauna to achieve this aim. Firstly, we estimated different soil activities, including those associated with EPNs, by baiting the soil samples with Galleria mellonella larvae. Besides, we used species-specific primers/probe qPCR sets to screen and quantify the occurrence and abundance of 10 EPN species and 12 organisms linked to their soil food web: four free-living nematodes (FLNs), six nematophagous fungi (NF), and two ectoparasitic bacteria (EcPB). Lastly, a third soil subsample set was employed to estimate the soil properties. Following this procedure, we performed three independent studies to evaluate the impact of different management practices on the EPN community and associated soils organisms in The Appellation of Origin (DOCa) Rioja vineyards (Northern Spain): (i) diverse cover crops (seeded with Bromus catharticus, flower-driven, and spontaneous) compared to regular tillage in an experimental vineyard, (ii) cover cropping and organic viticulture compared to regular tillage and Integrated Pest Management (IPM) in a survey comprising 80 vineyards, and (iii) various organic mulches (based on grape pruning debris, straw, and spent mushroom compost) compared to regular tillage and herbicide applications in an organic and IPM experimental vineyards.
We found seven EPN species and all the other screened species except the NF Arthrobotrys musiformis and the EcPB Paenibacillus nematophilus. The only EPNs reported in the three studies were Heterorhabditis bacteriophora, Steinernema feltiae, and the new EPN species S. riojaense, identified and isolated during the progress of this Thesis. Overall, EPN abundance and activity were higher for cover cropping and mulching than conventional soil management practices in both studies performed in experimental vineyards. However, the results obtained in the DOCa Rioja survey did not support this trend. It is possible that differential effects of diverse alternative strategies to regular tillage also affected the soil properties and, therefore, the EPN soil food web differentially. Indeed, we found lower numbers of potential enemies of EPNs, particularly NF, for spontaneous cover cropping and mulching based on spent mushroom compost, the treatments for which higher EPN activity rates and abundance were recorded.
On the other hand, in agreement with our hypothesis, organic viticulture enhanced the activity of native EPNs and the abundance and activity of the predominant EPN species, S. feltiae, in the DOCa Rioja survey. In addition, we obtained similar results for the organic vineyard in the mulching study. Organic viticulture also supported a higher FLN abundance and richness of the overall nematode species screened since the EPN species Steinernema affine, S. carpocapsae, and S. kraussei, as well as the FLN species Oscheius onirici, only occurred in organic vineyards.
Our results showed that organic viticulture and specific soil management practices that restrict or avoid regular tillage might support native EPNs in the vineyard, contributing to the maintenance of the ecosystem service these soil organisms offer as biological control agents. Moreover, these studies have illustrated how evaluating the EPN soil food web can signal soil health and the suitability of some viticulture practices over others. Applying innovative molecular tools and statistical analyses will improve understanding of the factors that determine the occurrence and distribution of EPNs in crop soils.
... Local research evaluated above-ground applications of certain local EPN isolates against the adults of the banded fruit weevil, Phlyctinus callosus (Schönherr) (Coleoptera: Curculionidae) Dlamini et al., 2019), the vine mealybug, Planococcus ficus (Signoret) (Le Vieux & Malan, 2013Platt et al., 2018Platt et al., , 2019a, the citrus mealybug, Planococcus citri (Risso) (Van Niekerk & Malan, 2012) and codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae) (De Waal et al., 2011Odendaal et al., 2016a, b). The diapausing larval population of codling moth overwinters in cryptic habitats, for example in old pruning wounds and cracks in the bark of apple trees, which offer an opportunity to use nematodes as a biological control agent prior to their emergence during the next growing season. ...
... Steinernema jeffreyense was previously evaluated against codling moth and false codling moth in both laboratory and field environments (De Waal et al., 2011Odendaal et al., 2016a;Steyn et al., 2019), as well as against the vine mealybug (Platt et al., 2018(Platt et al., , 2019a. Methods for mass culturing this nematode species have been demonstrated by Dunn & Malan (2019). ...
Plangia graminea, locally known as a katydids or “krompokkels”, is a minor pest of vineyards in the Western Cape province of South Africa. Is feed on leaves, and sporadically on the skin of grapevine berries. Under natural conditions, katydids are not of much agricultural importance, but pest outbreaks during favourable conditions can result in significant foliar damage. Observations indicate an increase in katydid abundance and damage intensity in recent years. Currently, no agrochemicals are registered for the control of this species, and its present natural enemies are unlikely to provide sufficient control without augmentation. In this study, 12 entomopathogenic nematode (EPN) species were evaluated against the nymphs of Plangia graminea in laboratory bioassays, and mortality by infection was investigated. Seven locally occurring nematode species achieved significant mortality, with H. zealandica, H. indica, S. jeffreyense and S. yirgalemense being found to perform the best (> 90% mortality).
... For example, in the IJs application, coformulation with adjuvants (antidesiccants, brighteners, etc.) will be required to enhance their survival in the aerial part (Shapiro-Ilan & Dolinski, 2015). To date, the evaluation of certified adjuvants to be released in vineyards is limited but has shown good potential and margin to improvement in laboratory and greenhouse approaches 9 (Platt et al., 2019). Similarly, the temperature can modulate the activity of the EPNs, in particular, if applied for targeting overwintering stages. ...
Vineyards face several biotic threats that compromise the grape quality and quantity. Among those that cause relevant economic impact and have worldwide distribution are the oomycete Plasmopara vitícola, the fungi Erysiphe necator and Botrytis cinerea, and the arthropods Lobesia botrana, Tetranychus urticae, and Phylaenus spumarius (principal vector of the bacterial disease Xylella fastidiosa in Europe). Their management relies primarily on agrochemicals with short persistence; widespread use of these chemicals causes environmental and human health problems. The challenge of sustainable viticulture is to provide ecologically sound alternatives. In this regard, the application of entomopathogenic nematodes (EPNs) and natural products derived from their symbionts can be an alternative. EPNs are well-known biocontrol agents for soil-dwelling insects. However, current research demonstrates the great potential of both EPN and their derivates as direct bio-tools against some of the key fungal and arthropods pests present aboveground. In addition, recent evidence shows that detecting EPN presence and activity and their relation with other soil organisms associated with them can help us to understand the impact of different agricultural practices on vineyard management. Altogether, this review illustrates the great potential of EPN to enhance pest and disease management in the next generation of viticulture.
... Insects without a soil stage may be more susceptible to EPNs, as they may not have had the opportunity to evolve the resistance necessary to protect themselves from nematode infections. This weakness of above-ground pest defence mechanisms against microbiological pathogens can thus be exploited to provide biological control, for example, as with previous research on mealybugs, and the addition of adjuvants to nematode suspensions [18,[22][23][24][25][26] has shown. ...
... More nematode species, especially H. zealandica and other native species that show effective control against lepidopteran pests, can be evaluated in future research to establish a nematode susceptibly profile for L. vanillana. In addition, the application of nematode formulations to the canopy and soil of orchards may have the ability to control multiple pests simultaneously, which include in the case of table grapes: mealybugs, different weevil species, other lepidopteran insects, fruit fly and thrips [22,25,26,[47][48][49], especially when used in an integrated pest management programme. This is the first study on the use of EPNs to control L. vanillana by comparing in vivo-and in vitro-produced nematodes, without any loss of pathogenicity during the culture process, which is highly promising for the future commercial production of these biocontrol agents. ...
Entomopathogenic nematodes (EPNs) have been successfully applied as biological control agents against above ground and soil stages of insect pests. However, for commercial application, it is crucial to mass culture these nematodes using in vitro liquid culture technology, as it is not attainable when using susceptible insects as hosts. Lobesia vanillana (Lepidoptera: Tortricidae) is regarded a sporadic pest of wine grapes in South Africa. The in vivo- and in vitro-cultured South African EPNs, Steinernema yirgalemense and Steinernema jeffreyense (Rhabditida: Steinernematidae), were evaluated against larvae and pupae of L. vanillana in laboratory bioassays. For larvae, high mortality was observed for all treatments: In vitro-cultured S. yirgalemense (98%) performed better than S. jeffreyense (73%), while within in vivo cultures, there was no difference between nematode species (both 83%). No significant difference was detected between in vivo- and in vitro cultures of the same nematode species. The LD50 of the in vitro-cultured S. yirgalemense, was 7.33 nematodes per larva. Mortality by infection was established by dissecting L. vanillana cadavers and confirming the presence of nematodes, which was > 90% for all treatments. Within in vitro cultures, both S. yirgalemense and S. jeffreyense were able to produce a new cohort of infective juveniles from L. vanillana larvae. Pupae, however, were found to be considerably less susceptible to EPN infection. This is the first study on the use of EPNs to control L. vanillana. The relative success of in vitro-cultured EPN species in laboratory assays, without any loss in pathogenicity, is encouraging for further research and development of this technology.
... Studies have also shown the adjuvants to improve the efficacy of EPNs. For example, when S. yirgalemense suspensions were mixed with adjuvants (Zeba ® and Nu-Film ® ) and applied against Planococcus ficus (vine mealybug), the extent of control achieved was found to be greater than when no adjuvants were added, with a mortality rate of 84% under laboratory conditions and 88% in glasshouse trials, while the mortality rate obtained by the control (water only) was 28% and 30%, respectively (Platt et al., 2018). ...
Entomopathogenic nematodes (EPNs) are insect parasites that are used successfully as biological controlagents against key pest insects of grapevine. To achieve low chemical residues and the sustainableproduction of grapes, it is important that biological control agents such as entomopathogenic nematodesfor the control of grapevine insect pests be incorporated in an integrated pest management system forgrape production. However, the commercialisation and large-scale use of EPNs is limited by their shortshelf life in formulations and in storage, thus leading to poor quality and reduced efficacy against insectsin the field. In South Africa, interest in the use of EPNs within an integrated pest management system hasgrown over the past two decades, therefore developing a formulation technique with an acceptable storagesurvival period, while maintaining infectivity, is essential. Moreover, the successful control of insects usingEPNs is only achievable when the formulated product reaches the end user in good condition. This reviewis focused on the different types of formulations required for storage and ease of transport, together withthe application formulation for above-ground pests and the factors affecting them. The quality assessment,storage and handling of formulated EPNs are also discussed.
... Our results with Barricade® support prior findings that protective formulations can reduce desiccation and increase survival of arthropods. Adjuvants, including Barricade® have been used to reduce desiccation of EPNs to increase efficacy against flea beetles attacking canola and mealybugs pests in vineyards (Antwi & Reddy 2016, Platt et al., 2019. This study is particularly novel because, to our knowledge, it is the first to investigate benefits of a protective formulation or adjuvant when EPN are applied on animal hide. ...
Entomopathogenic nematodes (EPNs), Steinernema riobrave and Heterorhabditis floridensis are under evaluation for eradication of the southern cattle fever tick, Rhipicephalus microplus infesting nilgai antelope, in South Texas. Cattle fever ticks are a significant threat to the U.S. livestock industry. Although they have been eradicated in the U.S. they frequently re-invade along the Texas-Mexico border. Remotely operated field sprayers have been developed to directly treat nilgai antelope with EPNs as they transit fence crossings and as they contact wetted foliage and soil from the surrounding area. EPNs are known to be susceptible to mortality from ultraviolet light (UV) and desiccation. A sprayable fire gel, Barricade®, has been reported to protect EPNs from UV and desiccation but has not been tested on animal hides. Barricade® at 1 and 2 percent rates was mixed with the water solution of S. riobrave and H. floridensis and applied to cowhides (to mimic direct treatment of nilgai) and filter paper and then these substrates were placed out of doors in 0, 30, 60 or 120 minutes of sunlight. Wax moth larvae, Galleria mellonella, were exposed to the cowhides and filter paper to determine efficacy of the EPNs. Efficacy of S. riobrave with 1 and 2% Barricade® gel applied to cowhides was significantly improved at 30 and 60 minutes as compared to the control. At 120 minutes mortality of the wax moth larvae was near zero for both the control and the treatments. Similar results were found with the filter paper test. In contrast, efficacy of H. floridensis with Barricade® applied to cowhides or filter paper was not significantly improved at 30, 60 or 120 minutes as compared to the water only control. Barricade® has the potential to improve the efficacy of S. riobrave and other EPNs by reducing mortality and desiccation, especially when used in the remotely operated sprayer developed for treatment of cattle fever tick infested nilgai.
... However, applying EPNs in agricultural production areas has become increasingly focused on controlling the soil-dwelling insect life stages, and less focused on their use against foliar, or aboveground, pests. This is due to the low tolerance of the EPNs to exposure to extreme temperature and desiccation risk in non-soil environments (Platt et al. 2019). Pseudococcus viburni is an above-ground pest of pome fruit and the ability of nematodes to complete their life cycle in the mealybug can have an added advantage in the pome fruit orchards, as the infected mealybug hosts may fall onto the moist and shaded orchard floor, which provides ideal conditions for the EPNs, where they can be recycled and potentially kill other soil-inhibiting pests within the orchard. ...
... Van Niekerk & Malan (2012) (2015) showed the potential of both S. yirgalemense and H. zealandica as effective biological control agents against P. ficus, 65 % and 96 % mortality, respectively, following assessment of the efficacy of two commercially available EPN isolates and six South African indigenous isolates. Platt et al. (2019) assessed the ability of S. yirgalemense in conjunction with two adjuvants, Nu-Film-P ® and Zeba ® , to control P. ficus on grapevine foliage. The study showed that the combined application of the nematode species with both the adjuvants resulted in heightened levels of mortality of the vine mealybug, with 84 % and 88 % mortality under laboratory and glasshouse conditions, respectively. ...
The obscure mealybug, Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae), is an important polyphagous, cosmopolitan insect pest of fruit crops, including apples, pears and grapes. The mealybug negatively affects fruit production both in South Africa and globally by feeding on phloem sap, excreting large amounts of sugar and water as a carbohydrate-rich sugary substance, known as honeydew, onto the leaves and fruit. Honeydew causes severe secondary damage, as it promotes the growth of sooty mould, which decreases the amount of photosynthesis, thus affecting the development of the host plant. Fruit consignments with fruits stained with sooty mould or suspected of containing live or dead mealybugs are rejected when exported, due to the strict phytosanitary standards. Managing mealybugs in agroecosystems is difficult, due to their small body size and cryptic nature. Currently, control relies on the use of chemicals and, to some extent, on biological control. However, using such methods has proven to be ineffective in the management of P. viburni. Entomopathogens, such as entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPNs), have been used across agricultural production areas to control a wide range of agricultural pest insects. The current review provides an overview of the biology and control of P. viburni, with special reference to biological control using EPF and EPNs in South African orchards, in an integrated pest management system.
