Wilma Mac Pherson
Technical Portfolio Manager

Andermatt Madumbi was proud to host Andermatt Product Managers, from Andermatt Biocontrol Suisse in Grossdietwil, Switzerland during July/August 2022. Heidi Widmer, (Dr. rer. nat.) and Anna Landwehr, (MSc ETH Agr), two of the four Andermatt Biocontrol Suisse baculovirus product managers enjoyed a long overdue (due to the Covid 19 pandemic) whirlwind country, customer and product tour.

Herewith a reminder as to why these quality biological solutions should form part of grower IPM programs this season.

1. Mode of action of baculoviruses

The image below portrays a simplified version of the mode of action of baculoviruses:

• Virus particles (occlusion body = OB) must be ingested by the larvae.
• The protein capsule of the occlusion bodies is dissolved by the high pH of the larvae’s midgut.
• The infective part of the virus is released (occlusion derived virus, ODV), enabling the primary infection of the midgut cells.

• Replication takes place in the nuclei of the midgut cells, followed by cell-to-cell infection of the entire larva.
• Towards the end of the infection cycle, larval host cells produce and release the occlusion bodies, which are infectious for other larvae.
• Protected by the occlusion body, the virus is able to survive outside of the host for a long time, ready to infect the next larvae.

2. The effects of baculoviruses explained

At Andermatt, different effects of baculoviruses are defined:

• Direct effect on larvae present in the field.  The larvae die after ingestion of treated plant material.
• Horizontal transmission: After larva death, the larva ruptures, and occlusion bodies are released in the field and may cause new infections.
• Vertical transmission affects the next generation (can occur when virus infection occurs late in the life cycle of the target pest, with late instars ingesting few virus particles leading to a sublethal dose rate):
  • Pupation rate decreases and fewer larvae become moths.
  • Eggs laid by moths that ingested sublethal dose rates have a decreased larval hatching rate, leading to fewer larvae in the field.

• Fitness effect:
  • Next-generation larvae may carry a viral infection which only causes an outbreak after activation through stress factors.
  • The population will be decreased during its lifecycle.
• Population reduction is a combination of the horizontal effect, vertical effect and fitness effect which spreads within the population.

3. Different dosages determine the time to death

Viruses do not have a typical dose-response, with different dosages (number of virus particles ingested) affecting time to death.

High dosage: Larva dies quickly, thus the larva causes little crop damage. The larva takes up a higher virus load, so it reaches a sufficient load to cause mortality quicker.

Low dosage: Larva dies slowly and therefore the larva causes more crop damage.

4. Good spray coverage is essential

There is no systemic or translaminar effect of baculovirus products. Application techniques are a key part of product efficacy in the field.
When considering which area of the plant should be sprayed for best efficacy, ask yourself these questions:

• Where does the pest occur on the plant?
• Where are the eggs laid?
• Where do the small larvae feed?

Key take out: The product needs to be ingested by the larvae to have an effect.

5. Application timing is important and is one of the factors that determines efficacy

Target eggs and first instar larvae.

• Some species feed on eggshells during hatching, as such the application on eggs can be useful in these cases.
• Mortality of young larvae is quicker and results in less crop damage (L1/L2 larvae die faster than L3-L6 larvae).
• Usually, bigger larvae incur quicker feeding damage on leaves and fruits.

Key take out: Ideally start to apply the product with the hatching of eggs and cover the whole egg-hatching period.

6. Andermatt’s baculovirus products are ready to use

UV protection is included in the formulation.

• No feeding stimulants, surfactant/wetting agents or other adjuvants are needed.
• Non-ionic or oil-based spreaders or stickers may be used on crops with waxy surfaces (e.g. Brassica).

Temperature, UV radiation and rain fastness

Temperature affects the development rate of the pest.

• UV radiation affects the viability of the baculovirus particles more quickly than high temperatures in the field.
• Product can be applied during the whole day, but spraying in the afternoon or evening is recommended.
• All virus products have good rain fastness due to the inherent properties of the formulation.

These products are registered by Andermatt Madumbi (Pty) Ltd, Postnet Suite 20, Private Bag X6011, Hilton, 3245.
Reg. No. 2009/020798/07. Bolldex® contains Helicoverpa armigera Nucleopolyhedrovirus (HearNPV). Reg. No. L8895,
Act No. 36 of 1947. Cryptex® contains Cryptophlebia / Thaumatotibia leucotreta Granulovirus (CrleGV). Reg. No. L8037,
Act No. 36 of 1947. Madex® contains Cydia pomonella Granulovirus (CpGV). Reg. No. L7950, Act No. 36 of 1947.

Andermatt Madumbi baculovirus’ solutions include Bolldex®, Cryptex® and Madex®.
Please contact your regional biospecialist for more information or visit www.andermatt.co.za.

Compatibility in a tank mix

Andermatt’s baculoviruses are compatible with most insecticides, fungicides and fertilisers as long as a pH level between 5 and 8.5 in the tank mix is respected. (Cryptex® compatibility
in the tank mix is extended to pH > 9.)

Always add the baculovirus product last to the tank and never mix with another concentrated agricultural product. Apply tank mix as soon as possible after mixing.

Baculoviruses are safe

• The baculoviruses in our products occur naturally, are not genetically modified and are highly host specific.
• Baculoviruses are safe for non-target species such as bees and beneficial insects.

Did you know?

Baculovirus general information

Production and quality control

• The production of baculovirus solutions is a highly specialised process.
• Andermatt continuously invests in in-house R&D ensuring constant improvements and new developments.
• Routine quality control bioassays are conducted to ensure consistent product performance.
• Andermatt Biocontrol is the global leader with more than 33 years’ experience in the development, production, formulation and application strategies with baculovirus products.