Project Detail

Project Number

EPN-9

Project Leader

A. P. Malan

Institution

Stellenbosch University

Team Members

M. F. Addison

Student(s)

D. Odendaal

Date Started

February, 2016

Date Completed

October, 2019

Incorporating entomopathogenic nematodes and fungi in an integrated pest management system for the control of codling moth

Objectives and Rationale

The codling moth, Cydia pomonella, is one of the most successful insect pests in the world, due to its extreme adaptability, and is a major pest in apple-growing areas around the globe. The main aim of this study is to build on previous research undertaken with codling moth (CM) and entomopathogenic nematodes (EPNs), and to provide insight into how to incorporate EPN and EPF individually, and in combination, into an integrated pest management (IPM) system directed towards the effective control of diapausing codling moth populations. The objectives of the study include the following: to identify indigenous EPF and EPN isolates from apple orchards in the Western Cape province, and test their pathogenicity towards diapausing codling moth larvae; to determine the compatibility of selected EPNs with adjuvants and their effect on the control of codling moth larvae and pupae under laboratory and field conditions; to determine the effect of the separate and combined application of EPF and EPN selected strains on diapausing codling moth larvae, under controlled and field conditions and; to compare the performance of in vivo and in vitro cultured nematodes, in both the laboratory and the field.

Methods

EPN and EPF have been isolated and their efficacy tested against various stages of the codling moth life cycle. EPN and EPF were evaluated in the laboratory and the most effective isolates tested in the field. EPN and EPF concentrations were calculated in the laboratory and then applied onto wire mesh cages, replicating an infested apple tree (20 codling moth larvae and apple tree bark), in the field with hand sprayers. After 24 h cages were removed from the field, larvae rinsed and placed in petri dishes on moist filter paper, and kept in a growth chamber at 25°C. From 2-7 days after treatment, trials were monitored, and results recorded.

Key Results

Of the isolated EPF, the most abundant species isolated were Metarhizium pinghaense (45%) and

Metarhizium robertsii (33%). The most effective EPF isolates were determined to be M. pinghaense DO8,

  1. robertsii DO3 and DO36, M. anisopliae DO4 and Beauveria bassiana DO40. The local EPN isolate, Steinernema jeffreyense, proved most effective and reliable. EPF mode of action takes longer than EPN, thus EPF must be applied before EPN. When EPF are applied 48 h to 72 h before EPN, it results in additive or synergistic control of codling moth larvae – resulting in higher codling moth mortality than if either entomopathogens was applied alone.

Key Conclusions of Discussion

Entomopathogens are been underestimated and thus underappreciated as pest control agents. These organisms will become the nucleus of an IPM strategy if utilized in a proper manner. A different strategy needs to be followed regarding their introduction to the pest control market, as they are live organisms whose biology needs to be understood at a fine scale – a skill which cannot be entrusted to non- nematologists. If this underdog is to become top-dog, companies specializing in these products, must be established and these companies must conduct the application of these entomopathogens in IPM programs.

For Final Report, please contact:

anita@hortgro.co.za