By Cornelius Oosthuizen: Marketing & Technical Manager,
Christiaan Pretorius: Technical Advisor
At Koppert, we know that many of the challenges we find on farms already have a solution hidden in nature – we just have to find it! During the past few seasons, the Koppert South Africa technical team, together with industry partners, were hard at work developing commercial protocols for the macadamia and avocado industry. We did this by using biological control agents such as predatory mites and parasitic wasps.
We are excited to share that we have seen some incredible breakthroughs and part of the success has been the first commercial release of a parasitic wasp to destroy stink- bug eggs. We can truly say that the results obtained stunned both friend and foe!
Test protocols were rolled out on commercial scale in all macadamia-growing regions of South Africa – Limpopo, Mpumalanga, and KwaZulu-Natal. The major pests tackled were thrips, MNB (macadamia nut borer) and stink- bug. To ensure a complete integrated pest management approach, our roll-out, and corresponding treatment approach, ensures that every stage of the macadamia’s development is effectively covered by biological control.
Control thrips during macadamia flower development
Swirski Ulti-Mite is the first line of defence and is used as a preventive method. Apply the product in orchards with a history of thrip damage once flowering starts at the end of July or August. Each sachet of Swirski Ulti- Mite, with a hook, contains a breeding colony of 250 predatory mites mixed with carrier mate- rial. Each sachet yielding will amount to more than 1000 predatory mites. The packaging is fully biodegradable and controls temperature fluctuation in the sachets for subtropical areas. It is also rain-proof to ensure that mites will not drown inside the sachet.
Best working conditions for Swirski Ulti-Mite
The predatory mite can be introduced during the wintertime. It is tolerant to high temperatures and a Swirskii population will start to develop when the temperatures during the day regularly exceed 20 – 22 °C. Adult predatory mites search for their prey or wait for it to pass by and subsequently feed on their prey.
MNB under control!
The macadamia nut borer (Thaumatotibia batrachopa) is native to Africa. Macadamia is the major host of this moth species, and it has not been linked to any other crop or indigenous host in South Africa. It is a quarantine pest and control procedures must be carried out to enable export.
Appearance and life cycle of MNB
MNB lay their eggs on the macadamias and normally move a couple of millimetres and penetrate the macadamias. Once the MNB is inside the macadamia no chemical can reach the worm, thus farmers need to effectively control the egg stage. In this life cycle phase, Koppert will introduce a well-known predatory wasp called Tripar-C (Trichogrammatoidea cryptophlebiae). Tripar-C is a very small, yellow parasitic wasp that seeks and parasitises various moth eggs. It is indigenous to Southern Africa and the only egg killer of MNB on the market. The adult Tripar-C wasps lay their eggs inside the False codling or MNB moth egg. The eggs are laid singly on young nuts and are flat and oval with a pitted surface. Females can lay between 170 to 300 eggs in their lifetime.
The eggs hatch between 7 – 12 days and the young larvae bore their way into the young nuts. The larvae are cream to grey in colour with dark spots on the body and the head capsule is brown. The pupa is dark brown and (if pupation takes place in the soil) encased in a cocoon of soil particles. There is no cocoon if pupation takes place in the nut. The moth is small and grey with indistinct darker and paler markings. It has a characteristic saddle-like structure behind the head.
Damage and symptoms
Damage before shell hardening is caused by the larvae which bore into the fruit. In small nuts, the entire kernel is eaten, whereas, in large fruit, part of the kernel may remain.
A larva can consume several small nuts by moving from one fruit to another. This type of damage is small, and trees can compensate for damage because of the large volume of flowers and small nuts produced by macadamia trees early in the season. Fruit with hardened shells cannot be penetrated, larvae then feed on the inside of the husk. Damaged nuts are shed by the tree.
Biological control of egg stage of macadamia nut borer
Many larva control products are on the market, but they do not work for the egg stage of the life cycle. So, to stop MNB in its tracks, farmers must use Tripar-C. Tripar-C releases start once nuts are susceptible to MNB damage. Nuts are susceptible from November till April. This allows for 6 releases of Tripar-C.
Advantages of using Tripar-C
- No tractor is needed, so no diesel is used.
- Tripar-C wasps leave no chemical residues and are therefore completely safe to apply in both conventional and organic agricultural systems.
- Easy to use and quick to distribute in affected areas.
- Environmentally friendly and cannot pollute the soil or water, as is often the case with conventional pesticides.
- Pests cannot develop resistance against their natural enemies; thus Tripar-C is an excellent tool to combat resistance.
- No repercussion problems can occur as Tripar-C is target specific and have no adverse effect on other beneficials.
- Effective in areas that are difficult to reach with spray equipment, for example very large and high macadamia trees.
Koppert offers a broad scope of biological control solutions to the macadamia industry.
We are excited about the broad scope of solutions Koppert has to offer the macadamia industry.
The newest addition to our biological control power pack is a parasitic wasp to control eggs laid by various stinkbug species, including the much-dreaded two-spotted stinkbug (Bathy- coelia natalicola). The first commercial trials in South Africa, using Green Shield® (Trissolcus basalis), gave phenomenal results and more than 90% of stinkbug eggs were destroyed.
This reinforces the effectiveness of biological control agents incorporated into a Koppert crop protection program and we look forward to working with you to become Partners with Nature.