Pictured above: Coleoptera Nitidulidae
Some macadamia processors are counting the cost of increasing incidences of sap beetle or dried fruit beetle Carpophilus spp. (Coleoptera: Nitidulidae) on nuts coming into their plants.
While little research exists on the unassuming sap beetle (Carpophilus), industry scientists suggest in the SAMAC (South African Macadamia Association) article that unexpectedly high rainfall and wet conditions during the past season could have played a significant role in rising numbers of the insects reported by some processors.
“The beetles have been observed on macadamia nuts for some time, but numbers and concomitant damage levels had been low. Things changed this season when several processors reported problems simultaneously,” the article says.
The insects are associated with varied cropping systems in wet environmental conditions, said the scientists, who theorised that the current high numbers were linked with the abnormally high rainfall this past season. “Prolonged wet conditions may have led to the nuts remaining on the ground for longer, resulting in decaying husk tissue that created perfect conditions for the beetle to thrive,” they said.
Walnut and almond impact
A 2019 research report in Campania, Italy, after an outbreak of the sap beetle C.truncatus on stored walnuts, delivered concerning findings.
Inspections in walnut warehousing uncovered numerous beetles (larvae and adults) on the stored nuts. They were identified as belonging to the genus Carpophilus Stephens (Coleoptera:Nitidulidae). Reports have also emerged of “unprecedented damage by Carpophilus on stored walnuts in Argentina and almonds in Australia.
“A Geographic Profiling approach has determined that the more virulent population was first introduced in Italy… climate conditions where C. truncatus is currently widespread and harmful indicate that the world’s entire walnut production is in jeopardy, as this species could adapt to any of the main walnut and almond production areas,” warned the scientists.
While online literature describes the beetles as a worldwide pest on fruits and grains, Wikipedia declares they are native to North America, Oceania and Europe.
Carpophilus hemipteris was first recorded in South Africa in 1979. It is presumed that due to an absence of natural predators, populations increased rapidly, with records of significant infestations in different seasons.
Further online research by The Macadamia revealed little in the way of information on natural predators.
Cactus pear damage
In a 2009 research paper titled “Bio-Ecology of Sap Beetles (Nitidulidae), a new double impact pest on Cactus Pear in South Africa”, authors S. Louw, J.V. Parau and J.C. Olevano describe the insect as a “known agricultural pest of numerous field and stored products”.
They say in the cactus pear, Carpophilus spp. (Coleoptera: Nitidulidae) is responsible for “wide-ranging direct (feeding) and indirect (disease transmission) health pressures on the crop”.
Further research by agronomists INCroP recorded three species (Carpophilus hemipterus, C. ligneus and Urophorus humeralis) on plants in the central Free State.
“The cosmopolitan C. hemipterus was quantitatively dominant throughout all the surveys. In this study, C. hemipterus bred prolifically in fermenting fruit, with the adults sheltering under the decaying, moist cladodes (fleshy stems or leaves) that had dropped from the plant. This species also transmits a wide range of diseases to the cactus pear plant,” the researchers said.
In the SAMAC article the beetles are described as small – about 3mm long – broad and flattened, with shortened wings that leave between one and three segments of the abdomen exposed.
“Although little is known about these beetles in South Africa, infestations are believed to originate in the field before they are transported to the (macadamia) processing facility, where damage becomes significant,” the articles states.
While there is no dedicated research in this field, Nelmak varieties were found to harbour large numbers of the beetles.
This is presumable because nuts of this cultivar tend to split open along the suture line when approaching maturity, SAMAC said.
The Sap beetle larvae are about 6mm long and cream-coloured. The head capsule and end of the abdomen are dark brown. The larvae have three pairs of true legs as well as horn-like structures on the anal end. Larvae can be found feeding inside the husk on decaying tissue: they enter the nut either through the hilum, sometimes even through the shell.
Damage to the macadamia shells includes partially constructed holes – in severe cases a shell may have several holes. “Once inside, the larvae consume the entire nut, turning it into a meal-like consistency,” the article reported.
Prevention better than cure
Prevention methodologies include early harvesting, meticulous sanitation and short nut pick-up cycles, which are believed to reduce the food source for the beetles. “These insects have a very wide host range and the presence of any over-ripe or fermenting fruit in or near a macadamia orchard may lead to higher numbers of the beetles.”
Because they are attracted to mouldy or fermenting fruit, bucket traps can easily be made on-farm that will lure large numbers of the insects. Buckets filled with rotten fruit, some water and yeast are ideal if the buckets are deeper than they are wide, to make sure the beetles are unable to escape.
The Macadamia’s Lindi Botha poses questions to keynote speaker Dorran Bungay about his career and what he believes the future holds for efficient and sustainable nut processing.
When and how did your macadamia nut journey start?
My introduction was in 1981, when I installed an irrigation system for the first macadamia farm in Chipinge, Zimbabwe.
In 1983 I joined Eskom and soon thereafter, Agrelek (Eskom’s agricultural department) appointed me as the ‘behind the meter’ agricultural electrical engineer for the sub-tropical portfolio in Nelspruit. In those days Eskom had an abundance of electricity and my task was to design electrical solutions for agriculture. I was rapidly immersed in the engineering skills of thermodynamics and psychometrics that provided me with the heating, cooling and dehydration tools necessary for so many of South Africa’s’ national farming applications. I designed tobacco and fruit dehydration systems (mango, guava, pineapple), heating and cooling environments for crocodile and fish production farms, steam applications, such as soil pasteurisation, heating and cooling for greenhouses and nurseries, among others.
In 1989 my first macadamia farmer client, Ed van de Hoek, and my first processor client, SAD, found me. I quickly discovered that these nuts are easily destroyed by rough handling and indiscriminate preservation practices. This revelation fuelled my quest and passion to identify the loss factors and to promote the best practices to help growers preserve the quality and shelf-life of this highly nutritious and palatable nut. The time I had spent in an earlier abandoned career choice looking for pathogens under a microscope in a medical laboratory provided me with the proclivity for recognising the cause and extent of the biological deterioration that plagued macadamia kernels.
What fascinates you about macadamias?
The design of the fruit is unique and fascinating – the entire nut is a stunning recipe that delivers an amazing food source of awesome nutritional value. The resultant edible kernel has, unfortunately, the highest risk value of all tree nuts and is prone to a rapid shelf-life loss if mishandled. The combination of its high value nutrients and the many post-harvest perils that threaten the macadamia fruit demands skill and passionate detailed attention by management.
What are your top tips for preserving nut quality between orchard and factory?
Macadamias are, contrary to popular belief, highly perishable – a lettuce in a hard shell! There are therefore several aspects farmers need to keep in mind:
- Ensure orchard floor hygiene before abscission and harvesting.
- Gather (harvest) mature nuts rapidly within a week of abscission, sooner if there is rain and if the orchard floor is wet. Dehusking must be done on the same day as harvest.
- Do not harvest nut-in-husk into plastic bags or containers that have no ventilation.
- Handle nut-in-husk and nut-in-shell gently. Avoid bruising the kernel by dropping or other deformation, like squeezing in a dehusker.
- Macadamia nut-in-shell must be cured immediately after harvest at the correct temperature and relative humidity.
- The on-farm operation from abscission through to dispatch to the processor should be as fast as possible, ideally within two weeks.
The most important insight gained during your work with preserving quality?
Too few growers understand the need to sufficiently invest in the most efficient infrastructure vital to preserve the monetary value of post-harvest quality – which is no less difficult or important than managing the day-to-day operational field and phenology that produces macadamia nuts.
If there were one thing you wished farmers and processors would do to preserve quality, what would it be?
Farmers should buy into the value chain without abdicating their responsibility for their nuts after they have left the farm gate. Processors and growers alike should regularly consume samples of their own macadamia production to be familiar with and proud of the quality they are sending into the wider world.
What inventions are still on your wish list?
There are three that are needed to improve efficiency and quality throughput: a dehusker that efficiently and quietly (noise means damage) removes husks without breaking or deforming the shell (which bruises the kernel); a cracking machine that is quieter, uses low energy, and produces a high percentage of wholes, with minimum milling dust; and a softer, more accurate styling method than the very damaging shaker tables.
Dorran Bungay headlines SA-hosted International Macadamia Symposium
Where will the industry be in 10 years and what will be the biggest drivers for success?
Macadamias have a great future. This high value crop is a relatively small component in the global nut trade, making up less than 2% of the world nut basket. The increasing importance of healthy eating habits has escalated the popularity and demand for plant-based protein and healthy fat snacks, so the present global macadamia production is simply too small to exploit the potential global market demand.
Agriculture is cyclical in nature and this industry is no exception. Many commodities and niche markets (like the macadamia) are, at times, subject to painful price fluctuations due to international politics, financial stress and market corrections. The current low price of macadamias is an opportunity for the industry to address all risky production aspects to improve and preserve quality and shelf-life. Consumers in the established markets have become progressively more sophisticated and will not easily accept the quality statement that is punted thus: “If it’s edible, it’s quality”.
The best driver of success will be achieved by those striving for “quality macadamias have zero defects”.
South Africa’s commercial agriculture representative body Agri SA has submitted comprehensive comments on the government’s proposed water use licence regulations, saying aspects of the draft regulations are unconstitutional and contradict existing law.
Earlier this year, the government’s Department of Water and Sanitation (DWS) called for public comment – by July 21 – on its proposed changes to the procedural requirements for water use licence applications and amendments.
Responding to emailed questions spokesman, Mavasa Wisane said the department had received 12 346 comments by July 19. She said further consultations would get under way with “key stakeholders” regarding the issues raised in these. “Thereafter the draft regulations will be revised where necessary before being published for implementation,” she said.
The initial draft regulations were published in the Government Gazette (48630) on May 19.
Before submitting their response, AgriSA had met the department’s Director-General, Dr Sean Phillips, and Water Allocation Director Sipho Skosana, among other officials, on June 15, to clarify some of the proposed amendments.
A media report released by the department on that same day explained that the changes applied only to applications for licences in relation to 1.5% of the water resources in the country not already allocated, and were not applicable for the renewal of existing water use licences or for applications which would arise out of compulsory licencing.
In other words, any water use licencing approved before the National Water Act 36 of 1998 was exempted from the proposed new regulations.
Department of Water and Sanitation Director General: Dr Sean Phillips.
In its official submissions, AgriSA’s Legal and Policy Executive Janse Rabie highlighted major concerns in Chapter 5 (regulations 12-14) of the draft regulations.
This aspect requires preference be given to black people, and then women, when allocating future water use licences relating to 1.5% of the water resources available for allocation.
Additionally, all future applications must allocate shareholdings to black people proportionally as follows:
Percentage shares allocated to blacks:
|Up to 250 000m³
||Up to 100ha
|250 000 to 500 000m³
||100 to 500ha
|500 000 to 1 000 000m³
||500 to 1 000ha
|More than 1 000 000m³
||More than 1 000ha
AgriSA contends that for Chapter 5 to have any hope of validity, it must be consistent with the relevant provisions of the National Water Act, specifically sections 26(1)(k) and 27(1), and with section 9(2) of the Constitution and sections 7,13 and 14 of the Promotion of Equality and Prevention of Unfair Discrimination Act 4 of 2000.
If the proposed changes went ahead in their current form, Rabie said the matter would be subject to a court challenge.
Food security under threat
While AgriSA was well aware of and supported the “importance of creating a more inclusive agricultural sector”, Rabie said this could not be achieved at the expense of food security or production.
Further, the rigid regulation as stipulated in the above table, he said, did not allow for discretion, was impractical at an operational level, and was “substantially indistinguishable from a quota”.
Rabie said the regulations prescribed in the table would, in fact, restrict empowerment as follows:
- the narrow focus on the applicant companies’ percentages of black shareholding
- not properly designed to protect or advance the category of persons disadvantaged by unfair discrimination
- focusing solely on black ownership excludes granting consumptive water licences to those who have significant black representation in their management, a high percentage of other black employees and meaningful and progressive black employee skills development programmes, black enterprise-development programmes, black supplier-development programmes and socio-economic development programmes and
- by focusing solely on black ownership, the government precludes the granting of consumptive water use licences to applicants who have significant shareholders who are women, or a representation of women in management or a high number of employees who are women or are engaged in meaningful and progressive employee skills-development, supplier, socio-economic or enterprise development programmes for women.
In its submission AgriSA suggests Chapter 5 should read as: “Procedural Requirements for applications for licences to use water which has not been allocated before and for financial assistance for making such applications”.
And applicants should include their application relevant forms and supporting technical information such as:
- B-BBEE generic scorecard and status;
- the amended AgriBEE Scorecard and black economic empowerment status for the agri-sector codes of good practice;
- the particulars, numbers and percentages of black people who have ownership interests, are in management and among non-managerial staff;
- proof of compliance with the Employment Equity Act; and
- black and female skills development, enterprise-development, supplier development and socio-economic development programmes.
Added to that, applicants must submit an explanation not exceeding 2 000 words on why they believed granting them a licence would redress the results of past racial and gender discrimination.
Similarly, in the application for financial assistance, documentation should include particulars as defined in the Broad-Based Black Economic Empowerment Act, and the financial position of the applicant, to be substantiated by the most recent audited financial statements.
If a licence is granted, the applicant should be registered on the government’s central supplier database before any payment of any funding.
AgriSA’s Legal and Policy Executive Janse Rabie.
AgriSA said the proposals were so complex in their processes and procedures that applicants would have to appoint specialists at “substantial additional cost” to administer the submissions.
In many instances such a cost could not be justified, particularly in the case of applicants who were irrigation farmers. “This will increase the cost of food production and discourage new investments in agriculture,” Rabie said.
AgriSA urged the government to streamline its processes, particularly in irrigation-related applications, and for those applying for relatively minor water uses.
Alarmingly, the proposed amendments require applicants to have “lawful access to property”.
This means if an applicant wishes to take water from a water resource on a property owned by someone else, to lead water across that property and other properties owned by third parties, they would be prevented by this regulation from applying for those water uses.
Rabie says this is inconsistent with the National Water Act, which separates water use rights from riparian land ownership.
Regarding groundwater, section 24 of the National Water Act provides that a licence may be granted to use “water found underground on land not owned by the applicant if the owner of the land consents, or if there is good reason to do so”.
Further, an approved water use licence shall lapse if the holder fails to act on the approved authorised activities within three years of the issue of the licence.
Again, AgriSA contends this is not workable, as according to the National Water Act, the termination of a licence is considered at the time of issue and in consideration of the possible existence of mitigating factors. “The lapsing of a licence should be determined on a case-by-case basis and take into consideration the scale of a project to which the water use relates,” Rabie said.
It goes without saying that a large percentage of future water use licence applications would also require alignment and approval via the Mineral and Petroleum Resources Development Act (MPRDA) or the National Environmental Management Act (NEMA), or both. And while the regulation amendments stress that such authorisations “must be submitted and processed in an integrated manner”, Rabie said if such integration were to be effective it should be done in accordance with a set-down process agreed to by all three ministers.
“The draft of such an agreement should be published for comment – with drafts of all applicable regulations to be made by the ministers – because implementation will have a material bearing on applications that require authorisation under any environmental law. Then the integrated process will appear from the draft regulations and the draft process agreement,” he said.
AgriSA disagrees with the proposal in the amendments that public participation across all three ministries be carried out jointly. “The minister cannot unilaterally bind the other two ministers responsible for the administration of the MPRDA and NEMA by asking that the public participation processes under those Acts are carried out jointly with the process of the National Water Act. Without coordinated draft regulations by all of the ministers and an agreed process, regulations cannot validly be made,” Rabie said.
Further detailed amendments include the alignment of jurisdictions during the processing, and that if a water use licence spans two water management areas, it should not be necessary to apply for separate licences in each jurisdiction.
And, if a licence is required for more than one water use for the same undertaking or project within one catchment area, then AgriSA suggests a single application would suffice, rather than two separate applications.
An important provision in the amended regulation pertains to financial provision in mining-related applications.
AgriSA contends there are two difficulties relating to this aspect: one of the cited corresponding regulations is not in the public domain and cannot be attached as an annexure as required, while others are either incomplete or inapplicable.
Related to the transfer of a water use licence transfer from one user to another, AgriSA believes a two-year restriction previously imposed on such cases was “never complied with or enforced”.
This, it said, was because the transfer of a water use licence may well incur significant expense, for example, to store water in a dam or divert the flow of water from a water course or to install irrigation systems.
“This capital outlay could never be justified for only two years when you consider a water licence may span 40 years,” Rabie said, adding that provision of a temporary transfer period should be determined on a case-by-case basis and the definition of ‘temporary transfer’ deleted from the proposed regulations altogether.
In the event of the proposed amendments linked to notice of applications for water use licences on properties under land claims, AgriSA said this should only apply to individuals or parcels of land where claims have been gazetted. Any comments by the regional land claims commissioner or representative of a gazetted land claim should be submitted by the specified date and must indicate whether they object to the granting of a licence, and why.
AgriSA called for clarity on the required submission of technical reports, saying a blanket approach was unworkable. It proposed the delineation of what technical report would be required for each specific area of application, for example, a new wastewater treatment plant technical requirement versus an irrigation installation would differ significantly.
Rabie said interaction and discussions between the department and AgriSA on the amendments were to be welcomed and that as the process moved ahead, he believed further discussions and meetings would be held accordingly.
Pictured Above: Hearne showed Miller how macadamias are sorted at Danroc before being sent to the processor.
United States agriculture advocate Michelle Miller, aka The Farm Babe, labelled South Africa’s macadamia farmers as “cool” and was impressed with our “boer maak ’n plan” (a farmer makes a plan) ethic in the face of adversity.
SAMAC research extension manager Schalk Schoeman gave the Farm Babe an overview of the macadamia industry.
On her recent visit to South Africa, the Farm Babe – or Michelle Miller – was suitably impressed with the country’s farmers, food systems and the value provided to consumers.
Consumer-agriculture advocates are now touted as a necessary element in bridging the gap between consumers and farmers to create a better understanding of how food is produced. Recognising this gap, Miller, who lives in Florida, has achieved global fame as a speaker, writer and columnist, online influencer and overall champion for global agriculture, with her social media advocacy platform Farm Babe.
Online agriculture star, Michelle Miller better known as the Farm Babe
With 300 000 followers and an average online reach of 4 million per month, she has made a name for herself as someone who busts food industry myths.
Earlier this year, Miller visited South Africa, touring farms from Limpopo to Mpumalanga and Gauteng to better understand agricultural production in the country.
Although familiar with Hawaiian macadamia nut production and that region’s penchant for chocolate covered macadamias, how macadamias were grown in South Africa was of interest to her as the country is the largest exporter of the crop worldwide.
The third-generation family farm operation Danroc Farm hosted the star for an afternoon. She was accompanied by the industry body SAMAC’s research extension manager, Schalk Schoeman.
This was Miller’s first visit to a macadamia farm, and her response to the lush orchards, sweet smelling flowers and clusters of nuts was a gushing: “This is crazy, cool, amazing!”
Gerrit Bezuidenhout, journalist for TV programme Landbouweekliks, accompanied the Farm Babe on her trip to South Africa’s macadamia producing region
She said she was “impressed” with South Africans and their warm, hospitable culture. Not to mention the farmers’ ability to “maak ’n plan” (make a plan) when it seemed everything was against them.
Danroc CEO Justin Hearne was in the spotlight during the Farm Babe’s recent visit to South Africa.
The landscape was also a highlight: “I’m so amazed by the topography and how quickly things can change from being flat to mountainous, and the crop diversity in a small space. It is mind-blowing to see the diversity of agriculture here,” she said.
In the dynamic capital equipment rentals and materials handling industry, new entrant Smith Power Equipment has emerged as a prominent player with its exciting offerings of top-quality machinery and services at more affordable rates.
National rental fleet manager for Smith Power Equipment, Craig Tutton, says his vision for the growing rental division is the relentless pursuit of client satisfaction. This requires highly tailored solutions to suit customers across a wide spectrum of industries while simultaneously enabling the company to become a turnkey provider of materials handling solutions for all equipment needs.
He adds that while the company has been involved in industrial and outdoor equipment such as tractors, turf maintenance and mobility solutions for many years, their primary focus has recently shifted to include material handling and related industrial vehicles. “We have a formidable offering to the material handling industry with top-notch brands like Ausa and Baoli (Kion Group) which makes the job of convincing clients much easier. The rental division will naturally also fan growth and sales of these brands for the company.”
Smith Power Equipment’s rental fleet of Baoli KB25 is a popular choice for rental
Try before you buy
“We have adopted a multifaceted approach to meet customers’ product and service requirements. This includes offering short-term and seasonal rentals that enable customers to effectively test the equipment firsthand before committing to a purchase. This innovative business model serves to generate short-term rental revenue while enticing potential customers to make long-term purchases once they experience the benefits of our top-quality equipment.
“Sales of this type of machinery has also taught us that uptime is crucial for customers in the material handling industry as it directly impacts their business and profitability and recognise that reliability is a critical requirement. Due to the industries demand SME have developed a fleet that covers all these demands from Agriculture, Brick yards, Construction, Retail, Cold Stores, Manufacturing, Logistics and Transport, Port Operations, Warehousing. The fleet currently includes both diesel, electric forklift, big trucks, and reach trucks.
“The rental fleet can also provide a rapid solution for companies with competitor machines facing equipment downtime due to faults or maintenance requirements and ensures their operations continue without disruption. It serves as a convenient option for customers who want to try out the equipment before making a long-term commitment and these are avenues we want to use to build trust and long-lasting relationships with our growing base of clientele,” says Craig.
The range of Ausa rough terrain forklifts provides customers with options where the concrete ends
He explains that Smith Power Equipment makes every effort to accommodate customers who can now choose to rent for specific durations in order to optimize their operating expenses, either through the duration of a project or adjust to diversify their fleet in line with their own changing market conditions. This is especially appealing for seasonal and project rentals, where the company aims to ensure that every customer finds a solution that aligns with their needs and budget.
Future plans may see even more industrial rental solutions being added to the range that may span the entire range of the company’s comprehensive product offerings including agricultural, turf, construction and other equipment. By doing so, Smith Power Equipment seeks to position itself as a comprehensive solutions provider for customers, enabling them to access a broad suite of equipment and services, ensuring convenience and reliability.
Baoli reach trucks provide efficient materials handling options
Craig concludes that the company is committed to shaping the future of equipment rentals and material handling solutions. The company is poised to become a trailblazer in the industry and ideal partner for its customers’ material handling requirements.
For more information, visit https://smithpower.co.za/
The macadamia industry is plagued by numerous insects and mites, with one of the biggest pest problems for farmers being the notorious stinkbug.
Infestation of the bugs results in young nuts dropping off the trees and older nuts developing lesions, which can add up to several millions of rands in annual crop losses.
This means most farmers have to spray large quantities of insecticides to keep the stinkbugs under control, and in a season of excessive rainfall, spraying is a challenge.
“It is not the many millimetres of rain that hampered spraying in the first quarter of this year, it was the frequency of the rain restricting access to orchards” said Green Farms Nut Company’s Technical Manager Barry Christie.
An adult stinkbug rests on a macadamia nut
Weather data showed that Nelspruit received 495mm of rain in February compared with 62mm in the same month in 2022. Levubu received 56mm in February 2022 and 241mm during February this year.
Christie said at their factory at Shaka’s Kraal on the KwaZulu-Natal North Coast, 207mm of rain was measured in February this year and 63mm during the same month last year.
But it was the fact that it rained almost every day in February in some regions that made it impossible for most farmers to get into the wet orchards with their sprayers, he added.
“Some farmers from the Nelspruit region reported having only four sunny days with favourable conditions for spraying in February. Wet soil kept us from entering the orchards, even on those precious warm days.”
Mieg Botha, who farms in the same region, said his inability to spray in the rainy weather did not have the same detrimental effect on his macadamia harvest as it did on some of the other farmers in the Nelspruit/White River region.
Botha is passionate about restoring the eco-balance in his orchards and only sprays chemicals when it is necessary.
Stinkbug eggs on a macadamia nut,
“The days of indiscriminately spraying all of the blocks multiple times a year are over. Such actions do not promote sustainability in the orchards and have a negative impact on a farmer’s profitability,” he said.
About two years ago, Botha decided to partner with nature by using parasitic wasps to control the stinkbugs thriving in his orchards. Green Shield (Trissolcus basalis), also known as Samurai wasps, are tiny insects – the size of a sesame seed – but very strong flyers, which distribute effectively throughout an orchard.
One female Samurai wasp can parasitise up to 300 stinkbug eggs and they are a hardy species, able to survive for up to two weeks without food. The Samurai feeds on pollen and nectar and uses the stinkbug eggs to reproduce.
Botha identified African Wild Basil as a preferred feeding ground shared by the bees and these tiny wasps, and planted it wherever he could.
When the time for reproduction comes, the parasitic wasp targets the eggs of various stinkbug species. The adults lay their eggs inside the stinkbug eggs, leaving larvae that eat the developing bugs before they pupate. The stinkbug eggs change from a cream colour to black after being parasitised. The newly hatched Samurai wasp will then emerge from the stinkbug egg, to soon parasitise more stinkbug eggs.
The parasitic Samurai wasp (Trissolcus basalis), which lays its eggs in stinkbug eggs.
Botha waits until the macadamias are in full bloom before releasing the wasps into his orchards. He gives the little Samurais the whole of September, October, and November to stabilise and parasitise stinkbug eggs. After the premature nut drop in November, he starts to scout intensively – 15 trees in a hectare.
The scouts will lay down shade nets beneath the trees, spray knock-down, and wait for 15 minutes before collecting the dead insects on the shade cloth to establish the severity of the stinkbug infestation in relation to the numbers of other harmless and beneficial insects.
Some of the insects found in the orchard during scouting for pests.
Only when the number of stinkbugs crosses Botha’s economical threshold will he revert to chemical spraying – and then only on the blocks identified by the scouts.
“I believe this was why the higher than usual rainfall in February and March did not affect me as much. I only needed to spray infested blocks, and the time that was available on those scarce sunny days was ample for me to get done what was needed,” he said.
He believes in an integrated pest control programme, where insect pathogens should form a bigger part of the crop protection set-up, and chemical control should be used only if pest levels warrant control determined by scouting, not as a form of insurance.
Alternative control measures that were investigated on the farm include trap crops, planting of pest resistant cultivars, manipulation of tree size to improve the effectiveness of chemical spraying, and other mechanical and physical practices, such as the collection and manual destruction of stinkbug eggs.
“It is highly unlikely macadamias will ever be produced in South Africa without pesticides, but farmers must make more effort to reduce chemical use. It is not only the right thing to do from an environmental perspective, but it would also result in healthier and better yielding orchards.,” Botha said.