The banded fruit weevil (BFW) is a sporadic pest in wine grape vineyards. In this study, local entomopathogenic fungi (EPF) and an entomopathogenic nematode (EPN) were evaluated for their potential to serve as biological control against the different stages of the BFW (larvae, pupae and adults). The study was conducted as a laboratory trial.
- Three commercially available fungal formulations (Bb1, Bb2 and Ma1) as well as one local isolate (MaEA2) of EPF were used;
- S. yirgalemense was the only EPN used in the study;
- BFW were collected from vineyards in the Western Cape and reared at the SU insectary and larvae cultured;
- Each EPF and the EPN were tested individually for its efficacy against BFW larvae and adults;
- The four EPF strains were then also evaluated individually in combination with S. Yirgalemense in the following treatments:
- EPF + EPN applied simultaneously;
- EPF applied, then EPN applied 7 days later;
- EPF applied, then EPN applied 14 days later;
- BFW mortality was determined three weeks after the treatments were applied.
- Combined applications of EPF + EPN increased mortality of BFW compared to the control;
- When the EPN was applied 7 or 14 days after the EPF Bb1 or Bb2, 100% mortality for both BFV larvae and adults were achieved;
- Results indicated that where an EPF and the EPN were applied simultaneously, there was an additive effect whereas a synergistic effect was achieved when the EPN was applied 7 or 14 days after the EPF application;
- This study proved that a combination of an EPF and an EPN show promising results for use as a biocontrol agent against the BFW in laboratory conditions.
SIGNIFICANCE OF THE STUDY
As pressure against the use of chemical insecticides increases, developing biological control options against pathogens in vineyards becomes more critical. In this study, the combination of an EPF and EPN against the BFW showed promising results under laboratory conditions. However further research is required to determine whether the same results will be achieved under field conditions. Furthermore, the application of the biocontrol agents will also need to be practical and cost-effective.
Bonginkhosi E. Dlamini , Antoinette P. Malan & Pia Addison (2020): Combined effect of entomopathogenic fungi and Steinernema yirgalemense against the banded fruit weevil, Phlyctinuscallosus (Coleoptera: Curculionidae), Biocontrol Science and Technology, https://www.tandfonline.com/doi/abs/10.1080/09583157.2020.1797633
Image source: Biocontrol – https://microdok.com/entomopathogens/