Foliar Application of Steinernema yirgalemense to Control Planococcus ficus: Assessing Adjuvants to Improve Efficacy

Platt, T.; Stokwe, Nomakholwa Faith; Malan, Antoinette P.

doi:10.21548/40-1-2920

Cited by 13 publications

(15 citation statements)

References 25 publications

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“…Applying S. yirgalemense in combination with both adjuvants on P. ficus infested leaf discs in a growth chamber, resulted in 84% mortality. Similar results were observed in a glasshouse trial, with 88% control of P. ficus on leaf discs hung on potted vines (Platt et al, 2018b). These studies demonstrated the potential of a combination of S. yirgalemense and adjuvants to give significant control of P. ficus on grapevine foliage in semi-natural conditions on vine leaves.…”

Section: Introductionsupporting

confidence: 82%

“…The different treatments applied include, Zeba ® only, Zeba ® + Nu-Film-P ® and nematodes without adjuvants, with a control of water only (without adjuvants). In a previous study, Platt et al (2018b) showed that Nu-Film-P ® alone did not significantly improve the deposition of IJ on grapevine leaves, over the applications of Zeba alone and therefore was not included as a separate treatment. Treatments were applied to the Petri dishes via a calibrated handheld sprayer, after which the leaves were removed and left for 3 min to eliminate excess runoff.…”

Section: Adjuvant Field Trialmentioning

confidence: 99%

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Grapevine Leaf Application of Steinernema yirgalemense to Control Planococcus ficus in Semi-field Conditions

Platt

Stokwe

Malan

2018

SAJEV

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The vine mealybug, Planococcus ficus Signoret (Hemiptera: Pseudococcidae), is a key insect pest of South African grapevine. The ability of mealybugs to avoid or resist the action of chemical pesticides has led to the investigation of alternative control methods, such as the application of entomopathogenic nematodes (EPNs). However, EPN application faces challenges, due to the maladaptation of EPN species to aboveground conditions. In this study, the ability of adjuvants to improve the control of P. ficus in grapevine using an indigenous nematode species, Steinernema yirgalemense, was investigated. A trial was performed to assess EPN survival on grapevine foliage, when applied in the morning (high humidity / low temperature) compared with in the afternoon (high temperature / low humidity). In a semi-field trial, the combination of adjuvants Zeba ® and Nu-Film-P ® resulted in 66% control of P. ficus after 48 h, compared to the use of Zeba ® alone (43%), and EPNs alone (28%). Additionally, lower concentrations of EPNs showed predictably lower mortality rates of P. ficus. Significantly, higher EPN survival was recorded at each time interval in the morning, compared with the corresponding interval in the afternoon. This study demonstrates the ability of S. yirgalemense, when applied with adjuvants and at an appropriate time of day, to control P. ficus on grapevine, under semi-field conditions.

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Section: Introductionsupporting

confidence: 82%

Section: Adjuvant Field Trialmentioning

confidence: 99%

Grapevine Leaf Application of Steinernema yirgalemense to Control Planococcus ficus in Semi-field Conditions

Platt

Stokwe

Malan

2018

SAJEV

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“…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 [22,25,26,44–46], especially when used in an integrated pest management programme.…”

Section: Discussionmentioning

confidence: 99%

“…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…”

Section: Introductionmentioning

confidence: 99%

Potential ofin vivo- andin vitro-cultured entomopathogenic nematodes to infectLobesia vanillana(Lepidoptera: Tortricidae) under laboratory conditions

Preez

Malan

Addison³

2020

Preprint

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The in vivo- and in vitro-cultured South African entomopathogenic nematodes (EPNs), Steinernema yirgalemense and Steinernema jeffreyense (Rhabditida: Steinernematidae), were evaluated against larvae and pupae of Lobesia 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, the best performing species, was 7.33 nematodes per larva. Mortality by infection was established by dissecting 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. The relative success of local in vivo- and in vitro-cultured EPN species against a tortricid species in laboratory assays is encouraging for further research and development of this technology.

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“…However, infectivity of S. yirgalemense was deeply affected by temperature and, above all, relative humidity, as mortality rates decreased from 70 to 40% when RH decreased from 100 to 60% (Platt et al 2018). Therefore, laboratory and glasshouse experiments were carried out with the aim to increase the nematode survival and infectivity in foliar applications by adding adjuvants, such as polysaccharide starch and spreader (Platt et al 2019). Addition of adjuvants concurred to increase mortality of P. ficus females by S. yirgalemense to 88% compared with nematode application with water alone.…”

Section: Nematodesmentioning

confidence: 99%

Sustainable management of the vine mealybug in organic vineyards

et al. 2020

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The vine mealybug (VMB), Planococcus ficus, is a major grapevine pest worldwide, whose chemical control is often unsatisfactory due to its cryptic behavior, insecticide resistance and high fecundity rate. Recently, increasing restrictions have been applied to insecticides used for managing VMB. This review discusses sustainable VMB management strategies in organic viticulture. Pheromone-mediated mating disruption has been proved to be effective in both organic wine and table-grape vineyards. Biocontrol projects carried out through the release of parasitoids and/or predators have often provided inconclusive results, ranging from effective reduction of mealybug infestation to a marginal impact of parasitoids on VMB density. The latter outcome is likely due to constraints affecting the parasitoid activity, such as the disrupting activity of mealybug-tending ants and broad-spectrum insecticides, or untimely release of parasitoids. Ant suppression should be associated with the release of beneficial organisms, as mealybug-tending ants can severely affect the parasitoid activity. Cultural and physical control and the employment of entomopathogens and natural products mitigate the buildup of VMB populations, but they are not widely applied. VMB control in organic viticulture requires the integration of different strategies, as application of single control tools as a stand-alone treatment may not be effective, especially for high pest infestation. Future research to determine the density action threshold below which sustainable methods are effective and calibrate efforts in relation with pest infestation is needed. A multi-disciplinary approach is required to define the most appropriate sustainable control protocols in different environmental conditions and promote a further spread of organic viticulture.

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Foliar Application of Steinernema yirgalemense to Control Planococcus ficus: Assessing Adjuvants to Improve Efficacy

Cited by 13 publications

References 25 publications

Grapevine Leaf Application of Steinernema yirgalemense to Control Planococcus ficus in Semi-field Conditions

Grapevine Leaf Application of Steinernema yirgalemense to Control Planococcus ficus in Semi-field Conditions

Potential ofin vivo- andin vitro-cultured entomopathogenic nematodes to infectLobesia vanillana(Lepidoptera: Tortricidae) under laboratory conditions

Sustainable management of the vine mealybug in organic vineyards

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