Insect sanctuaries for beneficial predators and parasites

Posted on by Sarah Williams

Insect sanctuaries for beneficial predators and parasites in bananas

By Daniel Farrell

Beneficial insects are species that provide a positive effect or interaction in an ecosystem, such as pollinators, predators, or decomposers. Predators and parasites, known collectively as natural enemies, play a critical role as beneficial insects by suppressing and controlling pest insects in ecosystems.

Beneficial predators and parasites: hover fly, green lacewing, and orange caterpillar parasite (left to right)

In most agricultural ecosystems, including bananas, beneficial insects aren’t considered in management programs. Farming practices, for instance, pesticide usage, monocropping, tillage, and weed control along with the lack of suitable habitat can cause these ecosystems to be unhabitable for beneficial insects to remain, thrive and continue to provide biological control.

Insect sanctuaries are areas of non-harvested companion plants grown free from disturbances of farming practices and grown to encourage and attract beneficial insects to establish and remain in the ecosystem.  Insect sanctuaries may consist of flowering or herbaceous plants, native shrubs or trees, or areas of specific weeds and grasses.

Insect sanctuaries are important for creating an agricultural ecosystem that is sustainable and suitable for beneficial insects by providing them with alternative food sources including important proteins and carbohydrates. In addition, sanctuaries provide harbourage and shelter increasing insect longevity and reproduction. An ecosystem with high biodiversity is generally more resilient to changes and less likely to experience pest outbreaks as natural enemies are available.

Insect sanctuaries can be planted externally or internally in existing production systems, as interrow or guard row (strips), or as a border or hedgerow (see below). Multiple small insect sanctuaries are just as significant to beneficial insects as large-planted areas, as they provide greater cross-over throughout the crop to optimize pest control and safe areas.

Designs of how insect sanctuaries can be incorporated into a cropping system

This DAF innovation-funded project aimed to use a Conservation IPDM approach to alter the banana ecosystem to provide more favourable conditions to enhance the population of beneficial insects. Seven flowering plants were evaluated including dill, fennel, Salvia, lemon balm, Thai chilli, garlic chives, and Impatiens (pictured).

These treatments were compared to a bare-ground control to determine if the composition of the insect community could be altered by incorporating additional plant biodiversity. The abundance (how many individuals) and diversity (how many different species) of insects attracted to each treatment were monitored in March – September 2022 using sticky traps, pitfall traps, and physical observations at the South Johnstone research facility. Collected insects were identified to the species level and then sorted into groups based on their role in the system as beneficial (predators, parasites, decomposers, etc) or pest (sap-feeders, herbivores, omnivores, etc) insects.

Salvia – Red (Salvia splendens)
Impatiens –New Guinea white (Impatiens hawkeri)
Lemon balm (Mellissa officinalis)
Thai Chilli (Capsicum frutescens)
Dill (Anethum greveolens)
Fennel (Foeniculum vulgare)
Garlic Chives (Allium tuberosum)

In general, the results found that insect diversity and abundance significantly increased over the trial duration. This could be due to either a combined treatment effect where the addition of all insect sanctuaries increased diversity and abundance to the trial site, or a general increase in abundance and diversity over time (i.e. warmer weather). From data models, we were able to devise some general relationships between treatments and the attraction or suppression effect they had on the insect groups (see below). 

Suppression or attraction effect of each flowering insect sanctuary treatment for specific groups

From these trial findings, Salvia and Impatiens would likely be suitable plants for insect sanctuaries in bananas, due to their high attraction for natural enemies and suppression of some pests.  Dill would also seem suitable due to its good attraction to predators and suppression effect on pests; however, noting it was not a preferred host by parasites. Interestingly, Salvia, Thai chili, and Garlic chives were all suppressive to Thysanoptera (Thrips), further research could be useful to provide an alternative suppression option for banana rust thrips and banana flower thrips.

Finding the high attraction of beneficial insects to Salvia and Impatiens suggests that further studies in this area would be useful. Ideally, larger plantings with assessments for bunch pests on fruit should be conducted to explore pest-controlling relationships. Ultimately, a list of suitable plants for incorporation into insect sanctuaries associated with banana plantations considering seasonality and soil types could provide growers with options for dedicating an area on their farm for beneficial insect conservation.  

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
13 25 23 or email betterbananas@daf.qld.gov.au 

This project was funded by the Department of Agriculture and Fisheries through an Agri-Science Queensland innovation grant.

A growers’ guide to ant related problem and their management

Posted on by Sarah Williams

A growers' guide to ant related problems and their management

By Daniel Farrell, Richard Piper, David East and Kathy Grice

Ants are commonly found in commercial and backyard plantings of bananas across Australia. Ants find suitable sites to nest including in the ground, behind old leaf sheaths, inside decaying pseudostems or on weeds and leaf trash surrounding the plants. Depending on the species, ants play a different role on the farm and have a different effect on production.

Ants – Good and bad

Different species of ants can co-exist in bananas, however, depending on management practices and the surrounding environment, only one or two species typically dominate at any given time. Ants can be broadly split into two groups, based on their food preferences, either sugar feeders or protein feeders.

Protein feeders including green tree ants, Argentine ants, and coastal brown ants can be useful biological control agents as they prey on pest insects including banana scab moth, cluster caterpillar, banana weevil borer and thrips.

Sugar feeders on the other hand, can be detrimental as they aid the build-up of sap sucking insects such as aphids, scale insects and mealybugs, which they protect (‘farm’) in return for their sugary secretions. Many species are involved, and they are commonly referred to as sugar or tramp ants.

Exotic Electric ant species farming a mealybug in bananas. (Credit: Hawaii Ant Lab.)
Sugar ants farming a colony of banana aphids. (Photo courtesy of Australian Banana Growers Council)

Invasive ant species (Electric ants, fire ants and yellow crazy ants) are also be present in Queensland. Contact Biosecurity Queensland on 13 25 23 if you suspect you have exotic ants on your farm.

Ant problems

Ants generally aren’t considered a major pest for bananas, however, damage to fruit associated with abdominal spray secretions, secondary infections and pests, or nest construction in the bunch can be an issue.

Several species of ants spray formic acid from their abdomens when disturbed, which can damage the fruit. This damage appears as dark brown to black sunken trails or marks on the fruit skin.

Formic acid spray damage by ants on fruit.
Sooty mould growth on fruit associated with honeydew from sap sucking insects ‘farmed' by ants.

Ants protecting sap sucking insects in the bunches can lead to black fungal growth known as sooty mould developing on the fruit. Sooty mould is caused by a fungus growing on the honey dew produced by sap sucking insects, for example scale insects, mealybugs and aphids. This mould is superficial, but difficult to remove from fruit. If banana aphids are present, they may also transmit the virus that causes bunchy top disease.

 

During wet weather ants can build nests by carrying soil and debris up into the bunch. This contamination can result in marking of the fruit when it is harvested and transported to the shed.

Ants also pose an occupational health and safety hazard to workers, with risks of biting, stinging or injury from formic acid sprays. Ants can also cause indirect problems such as damaging and blocking irrigation lines.  

Ant management

Ants can be difficult to manage, however, they are generally suppressed with insecticide treatments used against other pests. Ground spray applications for banana weevil borer or banana rust thrips control will reduce populations and bunch protection applications will protect the fruit.

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
13 25 23 or email betterbananas@daf.qld.gov.au 

This information has been updated as part of the Banana Integrated Pest and Disease Management Program (BA21004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.

Daniel Farrell

Posted on by Sarah Williams

Daniel Farrell

Harnessing nature’s defenders: the work of an upcoming banana entomologist

Daniel has worked as a technical officer since mid-2019, working with Plant pathologist, David East and Entomologist, Richard Piper. Before that, he gained his introduction to bananas working as a field officer with the Banana Extension team.

‘Working under the plant pathologist and entomologist really gives me the best of both the banana pest and disease worlds,’ Daniel said. ‘I love drawing connections between the two and developing my skills in integrated pest and disease management.  Every day there is always something new to learn from my mentors and that’s always exciting to me.  I’m also extremely looking forward to conducting more project work with beneficial insects (predators and parasites) in banana production systems’.

Daniel Farrell Researcher profile

Daniel Farrell
Technical officer
Department of Agriculture and Fisheries
Centre for Wet Tropics Agriculture
South Johnstone

Daniel was born and raised just northwest of Hobart, Tasmania, in the mountains of Collinsvale. He grew up helping in his parents’ vineyard and mostly looking after sheep and horses. His family spent a few transition years on the Gold Coast at Mt Tamborine, looking after a macadamia farm, before moving further north to Cairns in 2015.  

Daniel studied a Bachelor of Science majoring in Zoology and Ecology at James Cook University, at the Cairns campus. He started his Masters of Philosophy with James Cook University (JCU, Cairns Campus) in May of 2023. His thesis focuses on the mite predator ladybird, Stethorus fenestralis, looking to develop a methodology to mass-produce ladybirds for biological control and to explore the influences of pesticides on Stethorus populations.

On the weekend, you can normally find Daniel playing tabletop games with his friends or hunting down a new house plant and treats at the markets.

‘I’m also have a strong passion for my visual arts projects and like using my spare time as a creative outlet,’ Daniel said.

Daniel loves some banana bread fresh out of the oven with vanilla ice-cream topped with honey! But they are also a great snack on their own.

Banana Roadshows 2024

Posted on by Sarah Williams

Recent Banana Roadshows apeel to participants!

The recent banana roadshows were well attended by over 120 growers, agronomists, ag resellers and industry stakeholders. The four roadshow events were held during August and September in Carnarvon, Western Australia, along with Tully, Innisfail, and Mareeba in FNQ. This year marks 10 years since the first banana roadshow events commenced!

The events were delivered as part of the National Banana Development and Extension Program and provided the opportunity for attendees to hear updates on an array of different research and development topics. The series highlighted recent findings on research including biological bunch pest control, yellow Sigatoka, Sooty blotch, nematodes, soil health, nitrogen rate trials, and an update on variety development. Also included was an update on the Australian banana marketing program and benchmarking.

This year also featured a “walk and talk” session, which included interactive displays to spark further conversation between researchers and participants.

Kathy Grice (DAF) and David East (DAF)
Grant Leahy and Sarah Strutt (Hort Innovation)
Gavin Mackay and Stewart Lindsay (DAF)
Naomi Brownrigg and Louis Lardi
Paul Lardi and Tegan Cavallaro (DAF)
Ben Barton, Kieren Borgna and Sarah Williams (DAF)
Richard Piper (DAF) and Cameron Flegler
Tully Roadshow
Eleanor Sibree (ABGC) and Will Darveniza
Innisfail Roadshow
Andrés Morera (DAF), Tony Pattison (DAF) and Geoff Wilson (ABGC)
Thi Dieu Hien Nguyen (Sophia), Koichiro Otsubo (Koshie), Daniel Farrell (DAF) and Trang Thu Nguyen
David Ruiz, Kathy Grice (DAF) and Nandita Pathania (DAF)
Mareeba Roadshow
Sharan Muthukumar (DAF) and Daniel Farrell (DAF)
Jeff Daniells (DAF) and Ben Gu
Carnarvon roadshow
Graeme Sinclair, Valerie Shrubb (WA DPIRD)
Sarah Strutt (Hort Innovation) and Luke Posma

The roadshows were well received with 92% of FNQ participants who provided feedback saying that they learnt something new that would assist their business as a result of attending. Participants had positive feedback on the half-day events.        

One participant said ‘The short direct presentations worked well and conveyed a good amount of info.’

Another participant said ‘Loved the quick & sharp presentations. The layout was great, especially being time poor with the option to stay back to chat… Great researchers and crew.’  

The extension team would like to thank all growers and industry stakeholders who attended, as well as banana researchers Jeff Daniells, Daniel Farrell, Richard Piper, Kathy Grice, David East, Alex Lindsay, Andrés Morera, Tony Pattison (DAF) for their contribution along with Belinda Van Schaik (Hort Innovation), Andrew Burns (ABGC), Geoff Wilson (ABGC) and Eric Schluter (Aglytica). The team would also like to thank ABGC’s communication team and Valerie Shrubb and Mel Ford (WA DPIRD) for their support.

Keep an eye out in industry communications for info about NSW Roadshow activities later in the year.

Extension events are funded as part of the National Banana Development and Extension Program (BA19004). This project is funded by Hort Innovation, using the Hort Innovation banana research and development levy, co-investment from the Queensland Department of Agriculture and Fisheries and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.

Agronomic evaluation Lady Finger-like varieties

Posted on by Sarah Williams

Agronomic evaluation of Lady Finger-like varieties (December 2022)

Lady Finger-like varieties from Brazil under trial at South Johnstone

By Jeff Daniells, Katie Robertson, Sharan Muthukumar and Carole Wright (August 2024)

Latest update...

Several Fusarium wilt Race 1 resistant Lady Finger-like varieties are being assessed for agronomic performance at the South Johnstone Research Facility. The plant crop data and a summary of the results is available below. 

The first ratoon harvest is already underway with harvest commencing in May 2024. The trial will be completed after the first ratoon harvest. Local taste panel results for varieties will be available then. Results from Panama disease Race 1 screening available next year will help guide any future on-farm studies.

Those who attended the September 2023 field walk had an opportunity to see plant crop bunches of these Lady Finger-like varieties. A video field walk through the block, prepared for the 2023 Industry Roadshows in NSW at about that time, is available.

Background

According to the ‘Australian Horticulture Statistics Handbook 2022/23’ the annual production of Lady Finger banana in that year was 11,228 t compared to 363,023 t of Cavendish, so Lady Fingers represent only about 3% of overall banana production. However, the farmgate value of Lady Finger production can be estimated as worth about $30 million, which because of the higher price paid for Lady Finger per kg of fruit, represents about 5% of the overall banana industry. But whatever way you want to look at it, the Lady Finger industry is an important industry in its own right.  In New South Wales the Lady Finger industry is proportionally much more important than it is overall for Australia.

In the April 2024 edition of Australian Bananas (see here pp 26-27) we drew attention to the constraint that Fusarium wilt Race 1 has placed on Lady Finger production in Australia. Varieties with resistance have been sought and evaluated over time, but while many have been identified with resistance, none have so far measured up as replacements for the Race 1 susceptible Lady Finger in the marketplace. So where possible, affected growers have sought new ground not infested with the pathogen.

In 2019/20 some new Lady Finger selections, Lady Finger hybrids and Sugar hybrids were imported from banana breeding programs in Brazil to evaluate in Australia. As described in the April article in Australian Bananas, some of these are being screened against Race 1 on the Atherton Tablelands. Here in this article, we present results from the plant crop of their agronomic evaluation at South Johnstone. This evaluation is part of the project BA21002 – ‘New varieties for Australian banana growers’.

Trial results in plant crop

Tissue cultured plants of 3 Lady Finger selections, 4 Lady Finger hybrids and 2 Sugar (Silk) hybrids were field planted in December 2022 at South Johnstone DAF. Pacovan, SCS451 and the hybrids all came from Brazil. The 6 hybrids from the program of EMBRAPA are all reported to be resistant to both Panama disease Race 1 and yellow Sigatoka. Japira and Pacoua are also reported to be resistant to black Sigatoka. SCS451 is from the program of EPAGRI and was purported to have tolerance to Panama disease Race 1. Bunch emergence commenced in May 2023, and harvest was completed in December 2023.

Pacovan Ken
Pacovan Ken were more pendulous than Lady Finger
Plantina lady finger hyrbid
Platina is shorter in stature than the other Lady Finger hybrids
Pacovan
Bunches of Pacovan were more pendulous than Lady Finger

Unfortunately, all except one of the Lady Finger (Improved) control plants were tissue culture offtypes. Thus, there are serious limitations when wishing to compare the new selections with the industry standard, Lady Finger. Nevertheless, reliable comparisons can be made amongst the new varieties. The agronomic and yield results from the plant crop are presented in the table below. Relative comparisons from previous studies suggest that for the Lady Finger data included in the table, the pseudostem height is indicative, but the duration from planting to harvest would usually be a little slower resulting in bunch weight/12 months being more in line with that obtained for SCS451.

Table: Selected yield and plant characteristics of varieties in the plant crop

Summary of results

A summary of the results and observations made are as follows:

  • The highest yielding varieties (per unit of time) were Pacovan, Pacovan Ken and SCS451, which were all significantly higher yielding than Tropical, Princesa and Japira. 

  • The tallest variety was Japira and the shortest in stature was SCS451. Several aspects of crop management are more difficult with the taller varieties.

  •  Japira, Pacovan Ken and Pacovan had significantly longer fruit on the 3rd hand, while fruit of Tropical and Princesa was significantly shorter.

Where to from here?

The first ratoon harvest is already underway with harvest commencing in May 2024. The trial will be completed after the first ratoon harvest. Local taste panel results for varieties will be available then. Results from Panama disease Race 1 screening available next year will help guide any future on-farm studies.

More information will be made available as the trial progresses.

This research has been funded as part of the project New varieties for Australian banana growers (BA21002), which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.

Panama disease Race 1 variety screening trial Atherton Tablelands, FNQ (2023)

Posted on by Sarah Williams

Variety trials seeking resistance to Fusarium wilt Race 1 commence on the Atherton Tablelands

By Jeff Daniells, Kathy Grice, Katie Robertson, Kaylene Bransgrove and Sharan Muthukumar (April 2024)

Latest update...

Eight new Lady Finger-like bananas – some from Brazil and some from Queensland DAF’s mutagenesis efforts have been field planted on cooperating grower’s properties at Mareeba. They will be assessed for resistance to Fusarium wilt Race 1 over two crop cycles. 

Background

Fusarium wilt of banana, also known as Panama disease, has plagued production of Lady Finger (AAB, Pome) in the subtropics of northern NSW and southern Queensland since early in the 20th century. That widespread distribution of Fusarium wilt in southern production areas, combined with improved transportation and ease of mechanisation in the north, has contributed to major development of the Lady Finger industry on the Atherton Tablelands in the past 30 years or so. Currently about 280 ha are grown there – an industry worth about $15 million/year (Figure 1). It wasn’t too long though, before Fusarium wilt found its way onto a commercial Lady Finger farm on the Tablelands, with the first detection confirmed in 2008. Since then, several more farms have become affected, but damage on the Tablelands is typically not as severe as that in the south, because of the milder winters experienced.

Lady finger production
Figure 1 Lady Finger production near Walkamin and Mareeba has grown substantially since the 1990s.

Fusarium wilt is caused by the fungal pathogen Fusarium oxysporum f. sp. cubense. The relevant races described in Australia are Race 1, Race 2, Subtropical Race 4 (SR4) and Tropical Race 4 (TR4) which have to do with their banana variety host range. Lady Finger is susceptible to Race 1, SR4 and TR4. Within the races there is another division known as Vegetative Compatibility Groups (VCGs) which is particularly helpful for correct identification purposes. The VCG present on the trial farms is identified as VCG 0124/5 which is grouped in Race 1. This is the same as in previous trial sites in NSW and the north Queensland wet coast and is the most prevalent VCG recovered from diseased Lady Finger in Australia.

In previous banana plant protection projects, Fusarium wilt Race 1 screening has occurred at a field site in the subtropics of NSW. But due to budgetary constraints in the current Hort Innovation project – ‘New varieties for Australian banana growers’ (BA21002), the feasibility of conducting such trials on cooperating grower’s properties is now being examined on the Atherton Tablelands. So, two potential cooperating growers, that had sufficient Fusarium wilt disease present in their Lady Finger plantations, were identified at Mareeba in April last year.  Tissue culture plants of the required varieties had been multiplied, were grown on in the glasshouse at South Johnstone and field planting occurred in October/November (Figure 2).

Figure 2 Field establishment of tissue cultured plants being completed last November. Fusarium wilt affected Lady Finger in neighbouring row in the background (yellow circle).

About the trial

Varieties

  • SCS451 ‘Catarina’ reported to have tolerance to Race 1 in the Brazilian subtropics has been planted. It is certainly the one to watch. In our agronomic trial at South Johnstone it has performed well with bunches of SCS451 throwing well clear of the throat, not choking like what often occurs with Santa Catarina Prata, which we have had in Australia since the late 80s (see Figure 3).
  • The four best tasting Goldfinger variants from the mutagenesis program have been included to confirm that they have retained resistance to Fusarium wilt Race 1.
  • Three Lady Finger and Silk hybrids from the EMBRAPA program in Brazil are also being evaluated.
  • As with other Fusarium wilt screening trials in the past we have included a few reference varieties with a range of known levels of disease reaction. They are the key to correct interpretation of results. It is not so much the absolute level of severity of disease present in the new varieties being tested, but rather how their level of disease severity compares with that of the reference varieties. Here we have included Dwarf Ducasse (very susceptible), Lady Finger (susceptible), High Noon (intermediate) and Goldfinger (resistant).
Figure 3 The new import from Brazil, SCS451 (right) which is reported to be tolerant to Fusarium wilt Race 1, has bunches more pendulous than Santa Catarina Prata (left).
Santa Catarina Prata variety
SCS451 - The new import from Brazil.
Princesa variety

Disease inoculum

  • The trials were established in locations on the farms where Fusarium wilt was fairly widespread. Additionally, diseased pseudostem disks (about 5 cm thick) obtained from nearby blocks on the farm were placed in the bottom of each planting hole (Figure 4). This was to help enhance the uniformity of distribution of the pathogen and ensure that the roots of each plant in the trial were in close proximity.
  • The previous crop of Lady Finger on the sites was ‘knocked down’ in early/mid 2023 to allow for plant breakdown and cultivation of the rows prior to planting.
  • When any variety becomes diseased, the plan is to confirm by laboratory testing that the symptoms are due to VCG 0124/5.
Figure 4 A diseased pseudostem disk was placed in the bottom of each planting hole.

Trial progress

  • Disease ratings will get underway as soon as disease symptoms become evident which is expected in the next few months.

  • Disease development will be assessed in a plant and ratoon crop. 

  • Hopefully, we will get good indications from the Tableland trials of the disease response of the varieties. Selected varieties could then be considered for inclusion later, in pre-commercialisation sites in NSW and elsewhere. 

More information will be made available as the trial progresses.

This research has been funded as part of the project New varieties for Australian banana growers (BA21002), which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.

Banana scab moth Nacoleia octasema

Posted on by Sarah Williams

Scab moth

The banana scab moth (Nacoleia octasema) is a significant threat to banana crops, with the potential to cause up to 100% damage to fruit if left uncontrolled. The larvae of this moth feed on emerging banana bunches, leading to cracking, scarring, and disfigurement of the fruit. Damage is usually confined to the outer curve of the fingers (the area nearest to the bunch stalk) but, in more severe cases, damage can extend to the stalk, areas between touching fingers, or even extend to cover the whole fruit surface.  While the damage is usually superficial, severe cases can render the fruit unsuitable for the market.

BSM adult moth
Adult banana scab moth. Adults are approximately 22mm in width or wingspan.
Banana scab moth damage evident on back of hands close to bunch stalk.
Banana scab moth damage. Scarring on fruit makes it unsellable to market.
Severe damage close to the bunch stalk.

Banana scab moth is present throughout the year but is favoured by moist and warm conditions, hence the greatest potential for damage is during the wet season.

Being proactive and regularly checking bunches or getting feedback from baggers can help growers discover infestations before the fruit reaches the packing shed. Although damage can’t be undone, identifying, and addressing problems (re-training or integrating alternative control options) sooner can save other bunches from impact.

To manage infestations, year-round treatment is essential, most growers use chemical control through bell injection is recommended to prevent banana scab moth damage. Proactive monitoring and management are essential to minimize the impact of this pest on banana crops.

More information

This information has been prepared as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.

Banana scab moth – monitoring and control

Posted on by Sarah Williams

Banana scab moth – Nacoleia octasema

Monitoring and control options

Monitoring

Being proactive and regularly checking bunches or getting feedback from baggers can help growers discover infestations before the fruit reaches the packing shed. Although damage can’t be undone, identifying, and addressing problems (retraining or integrating alternative control options) sooner can save other bunches from impact. 

The method for monitoring for banana scab moth is to inspect freshly emerged bunches (bract fall) for the presence of damage and/or larvae. Pay attention to the underside of the fingers in each hand (closest to the bunch stalk) and the cushion area. In very young bunches, lifting the developing hand away from the bunch stalk may be necessary to reveal any larvae and/or fresh damage.

Banana scab moth larvae in feeding waste (frass and jelly).

Also, examine the base of the bunch stalk where the larvae enter the throat of the plant. Larvae can be detected by separating the base of the flag leaf and removing the bract that is attached to the stalk. Often a clear jelly-like substance or frass feeding waste, which appears to be associated only with banana scab moth feeding in bananas, is present at these sites. Monitoring known ‘hot spots’ such as rows adjacent to scrub or creek lines is also a good idea. Banana scab moth has been documented to use Pandanus spp. and Heliconia spp. as alternative host plants.

Managing banana scab moth

Treatment for banana scab moth should be performed year-round as damage results in immediate downgrading or rejection of fruit. Management of banana scab moth is particularly important if heavy bunching is anticipated and/or the forecast weather conditions are favourable (hot and wet).

Biological control

Banana scab moth can be controlled by application of Bacillus thuringiensis subsp. Kurstaki based biopesticides (also known as B.T.) that will not adversely affect other beneficial insects. Some insects (parasitic flies and wasps, ants, spiders and other predators) feed on banana scab moth caterpillars and provide some level of control.

BSM adult moth
Adult banana scab moth. Adults are approximately 22mm in width or wingspan.

Cultural control

Selecting followers of equal size which equates to synchronised bunch emergence over a block will ensure that the application of chemical control methods is more efficient.

Chemical control

Bell injection is the preferred method of insecticide application to prevent banana scab moth damage. Bell injection is a targeted application of insecticide into the newly emerged bunch and the technique is unlikely to impact beneficial insects on other parts of the plant. The correct site for injection is approximately one third of the way down from the top of the upright, vertically positioned bell. Bells which are injected later than this (i.e., when horizontal) have an increased risk of insect damage.

Initial trial work completed by the Department of Agriculture and Fisheries (DAF) has also indicated that the volume of insecticide applied in bell injection is an important consideration. As insecticides require larger volumes to ensure good coverage, initial trial work showed that using 40mL volume wasn’t sufficient to get appropriate control at times of high pest pressure. It is recommended that growers use a 60mL volume at the specified label (or permit) rate for bell injection to provide adequate coverage.

Always check the APVMA website for current chemical registrations before use. Below are insecticides currently registered (August 2024) and permitted for bell injection to control banana scab moth.

For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
13 25 23 or email betterbananas@daf.qld.gov.au 

This information is adapted from: Pinese, B., Piper. R 1994, Bananas insect and mite management, Department of Primary Industries, Queensland

Download this information as a fact sheet

This information has been updated as part of the National Banana Development and Extension Program (BA19004) which is funded by Hort Innovation, using the banana industry research and development levies and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. The Queensland Government has also co-funded the project through the Department of Agriculture and Fisheries.