A Guide to Effective Resistance Management with Certis’ Virus Portfolio

By Scott Ockey, Senior Field Development Manager, PNW, and Richard Kelly, Senior Regional Manager, PNW

When it comes to pest control, resistance management is key for long-term control. Repeated use of a single product can lead to resistance in pest populations. This is where a well-designed rotation strategy becomes essential for sustained control and prolonged efficacy of products.

1. Understanding Our Virus Portfolio

Certis offers three highly effective bioinsecticides designed to combat codling moth larvae:

Madex® HP (Cydia pomonella granulovirus isolate V22)

• Target Pests: Oriental fruit moth and codling moth
• Usage: Conventional, soft, and organically managed orchards
• Benefits: Preserves beneficial species, 4-hour REI, 0-day PHI, exempt from residue tolerances. Tank-mix compatible with most fungicides, foliar nutrients, and insecticides

Madex® XLV (Cydia pomonella granulovirus isolate GV-0017)

• Target Pests: Oriental fruit moth and codling moth
• Usage: Conventional, soft, and organically managed orchards
• Benefits: Preserves beneficial species, 4-hour REI, 0-day PHI, exempt from residue tolerances. Tank-mix compatible with most fungicides, foliar nutrients, and insecticides

Cyd-X®HP (Cydia pomonella granulovirus isolate GpGV)

• Target Pests: Codling moth
• Usage: Conventional, soft, and organically managed orchards
• Benefits: Preserves beneficial species, 4-hour REI, 0-day PHI, exempt from residue tolerances. Tank-mix compatible with most fungicides, foliar nutrients, and insecticides

WHY ROTATION MATTERS:  A diverse portfolio is crucial for combating codling moth infestations. Cyd-X®HP, Madex® XLV, and Madex® HP each have distinct genotypes that target codling moth larvae uniquely. This diversity reduces resistance incidence and ensures long-term effectiveness.

2. The Issue of Codling Moth Pressure

Codling moth pressure has been high in recent years, raising concerns about resistance development. Resistance can emerge naturally, with higher populations increasing the likelihood of mutations harboring resistance. Continuous use of the same product allows resistant individuals to survive and proliferate.

Pests have a general mutation rate, where mutations might typically occur in about 1 out of every million individuals. If a mutation appears that favors resistance, larger populations increase the likelihood of this type of mutation occurring. When you treat with our products, even if only a few of these resistant pests are present, they will be effectively targeted and eliminated. Mutations favoring CpGv resistance are much less common; however, when these mutations do occur, viruses must be rotated to target these individual moth larvae.

3. The Importance of Resistance Management

Pesticide resistance is a critical concern in modern agriculture, having been a recognized issue since the 1950s due to the widespread development of insect resistance to organochlorides, due to the repeated use of organochloride insecticides. (Dennehy & Dunley, 1993).

The U.S. National Academy of Sciences report, Pesticide Resistance: Strategies and Tactics for Management, defines resistance as "any heritable decrease in sensitivity to a chemical within a pest population" (Entomological Society of America [ESA], 2020)

The aim of insect resistance management (IRM) is to postpone the development of resistance by implementing effective strategies that prevent the rise in the number of resistant individuals within susceptible insect populations. Essentially, IRM aims to minimize the selection pressure on targeted pest populations caused by the repeated use of compounds with the same mode of action (ESA, 2020)

Long-term consequences of resistance include reduced efficacy of treatments and increased costs. This is why being proactive is key. By maintaining the effectiveness of our products, you ensure consistent pest control and significant cost savings.

4. Embracing the Rotation Strategy
   

We recommend rotating virus strains between generations to maintain efficacy and manage resistance. Independent laboratory testing has shown that Madex® XLV is the only virus strain that can control known CpGV-resistant codling moth in the US.

The Madex^® family, which includes Madex® XLV and Madex® HP, targets both oriental fruit moth (OFM) and codling moth (CM), while Cyd-X®HP specifically targets codling moth (CM). It is important to select the appropriate product depending on the pest pressure in your orchard.

Start by applying Madex® XLV during the first generation. For the second generation, switch to either Cyd-X®HP or Madex® HP based on your specific pest profile. This rotation should continue in subsequent cycles to ensure consistent control.

Best use practices:

• Avoid using highly alkaline spray solutions, as they will reduce the effectiveness of the viruses.
• Employ mating disruption techniques targeting your specific pest complex to enhance overall pest management.
• Use the Madex^® family of viruses when dealing with both Oriental fruit moth and codling moth.
• Maintain good bin management and monitor bin movement. Bins harbor overwintering larvae and should ideally be sanitized after each use.

Additional best practices for improved pest control include implementing inputs like kairomones, mass trapping, and removing infested apples.

While the continuous use of one product is simple and may seem sufficient, implementing a rotation strategy reduces the need for additional treatments and preserves product efficacy.

Using a rotation strategy is essential for effective resistance management and long-term pest control. For further support and resources, contact us.

Always read and follow label instructions.

_______________________________

Citations and Links

Entomological Society of America. (2020). Insect resistance management position statement. Retrieved from https://www.entsoc.org/sites/default/files/files/Science-Policy/2020/ESA_IRM_Position_Statement_2020.pdf

Dennehy, T. J., & Dunley, J. (1993). Resistance Management. Washington State University Tree Fruit Research & Extension Center. Retrieved July 26, 2024, from https://treefruit.wsu.edu/crop-protection/opm/resistance/#:~:text=It%20involves%20reducing%20overall%20chemical,only%20limited%20areas%20in%20orchard