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

Abstract

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.

Control potentials of some entomopathogenic nematodes against Asian chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu, 1951 (Hymenoptera: Cynipidae)

“…Although EPNs have the potential to infect aboveground pests, they are mostly used to control pests of soil borne insect pests (Wright et al, 2005;Şahin et al, 2018) because there are important factors such as temperature, ultraviolet radiation and humidity that mostly make the above-ground application unsuccessful (Georgis et al, 2006;Lacey & Georgis, 2012). Despite all these factors, many studies are underway to enable the use of EPNs for the control of aboveground insect pests and remarkable results have been achieved (Maketon et al, 2010;Beck et al, 2013;Şahin et al, 2018;Platt et al, 2019). Similar to our study, Cutler et al (2017) have achieved control of adults of some cockroach species [Blaptica dubia (Serville, 1838), Gromphadorhina portentosa Schaum, 1853) and Nauphoeta cinerea (Olivier, 1789)] using Heterorhabditis and Steinernema spp.…”

Potential of in vivo- and in vitro-cultured entomopathogenic nematodes to infect Lobesia vanillana (Lepidoptera: Tortricidae) under laboratory conditions

“…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 – 49 ], especially when used in an integrated pest management programme.…”

“…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 – 26 ] has shown.…”

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

“…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.…”