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.

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.

Banana Scab Moth – general information

Posted on by Sarah Williams

Banana scab moth Nacoleia octasema

General information

Occurrence

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. Bunches that emerge from December through to the end of May are most at risk of severe fruit damage. The cooler and drier winter months are relatively free of banana scab moth damage. However, damage can occur if unseasonal rain occurs at this time. Research has shown adult moths do not mate or produce eggs under low humidity and dry conditions.

Life cycle of banana scab moth. Arrow indicates part of plant affected (bunch).

Description and lifecycle

The tiny (1.2-1.5mm) transparent or yellow flattened eggs are laid in clusters (of up to 30 eggs) that resemble miniature overlapping fish scales. These egg clusters are very difficult to locate because of their small size and the fact that they are laid near the throat of the plant. The eggs are usually laid on the emerging bunch and the surrounding leaves, but eggs have occasionally been found on the pseudostem below the new bunch. Larvae (caterpillars) are pink to brown in colour and range in length from 1.5mm when first hatched to about 25mm when fully developed. If disturbed the larvae wiggle violently and drop on silken threads to avoid predation. When larvae are fully mature they generally pupate in the trash at the base of plants or beneath dry leaf sheaths.

The adult moths are difficult to find due to their small size (22mm wingspan), the fact they hide during the day and their dull brown/grey colouration. Adults are most active at dusk when mating and egg laying occurs. Adults do not appear to be attracted to lights, unlike other moth species. The total lifecycle from egg to mature adult takes around 25-32 days.

BSM lifestages

Damage

The banana scab moth is a severe pest of bananas and can cause up to 100% damage to the bunch if left uncontrolled.

Feeding by young larvae starts as soon as the first bracts lift and usually increases in severity as the larvae grow and move progressively down the bunch as subsequent bracts open. The feeding causes cracking and scarring to the fruit skin, while severe cases can cause disfigurement of fruit as the fingers enlarge. Damage is usually only superficial, where affected fruit is downgraded or deemed unsuitable for the market.

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.  

Banana scab moth damage affecting multiple hands, progressing with intensity down the bunch.
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.

Larvae of banana scab moth also consume foliage and can damage plants where a bunch is absent. This leaf damage is worse in varieties such as Lady Finger and Ducasse and is generally not a problem in Cavendish.

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.

Banana Weevil Borer mass trapping

Posted on by Sarah Williams

Banana weevil borer Mass trapping: A novel design, supporting long-lasting pheromone lures in NSW

Banana Weevil Borer (BWB) is one of the main issues for NSW banana growers. When BWB reach high numbers in the field, they significantly affect productivity by creating a network of tunnels in the corm. This tunnelling weakens the plant and increases the likelihood of blowdowns. BWB infestations affect nutrition uptake, contributing to slow growth, decreased bunch weights and overall poor plant health. NSW growers have successfully designed and implemented mass trapping approaches to deal with this issue, a technique proven to be effective in other countries. Mass trapping reduces pest numbers by luring them, with an attractant, in large numbers to a trap that either kills them or prevents their exit. In this article, we discuss NSW growers’ implementation of mass trapping systems and their successes. Growers who use mass trapping have found it an effective tool for monitoring and successful in reducing BWB pressure and plant damage.

BWB mass trapping, 5 Litre bucket traps
5 Litre bucket traps
5 Litre bucket traps with hundreds of BWB
5 Litre bucket traps with hundreds of BWB

Background

In Australia, typically pseudostem discs or small pitfall traps (less than 500mL volume) are used for monitoring and, to a lesser degree, management of BWB. These strategies are effective in allowing growers to understand their BWB populations and their distribution across their farms. By comparison, international research, and growers, have designed larger pitfall traps (larger than 500mL volumes), to increase rates of BWB capture. These larger pitfall trap designs are possible through the long-lasting pheromone lures which can and historically have also been used domestically in small-scale traps and which can attract both male and female BWB from over 20m away in dry weather. According to an international study (Alpizar et al, 2012), using these large volume mass trapping pitfall traps (with the pheromone lures), at a density of 4 traps per hectare, was 5 to 10 times more effective than traps without pheromone. In this study, corm damage was reduced by half to two thirds after several months of use (from 20-30% corm tunnelling to 10% or less). The resulting reduction of corm damage was shown to increase bunch weights of Dwarf Cavendish (Musa acuminata Colla) by approximately 20%. Trials in Australian growing regions and prominent varieties are yet to be conducted and caution is needed before assuming similar performance outcomes could be attained.

Earlier research by NSW DPI investigated two types of long-lasting pheromone lures (effective for 90 days), to determine the most effective for the NSW region. While both lures are effective at attracting BWB, Cosmolure P160-lure 90 (C.sordidus) is preferred as it does not contain isoamyl acetate, which attracts native turkeys and domestic chickens that damage the traps. Growers who collaborated in the earlier pheromone investigation have continued trapping and over time have developing unique trapping systems using the longer-lasting pheromone.

Mass trapping pitfall design 1 (5L bucket trap)

One of the new innovative methods that growers have developed and implemented is the modified 5L bucket trap. NSW growers have modified a 5-litre bucket to make large volume, mass trapping pitfall traps. To make these traps firstly, several 10-millimetre holes are drilled into the side of the bucket. Next, the bucket is firmly established into the ground. It is important that the drilled holes are flush with ground level and soil ramps need to be made (simply pile soil up into a ramp so that BWBs would be able to walk into the hole and fall into the bucket). Once the trap is established in the hill side, the pheromone bait is set by hanging from the centre of the lid via a piece of wire.

5 litre bucket pitfall trap positioned into the side of the hill
The pheromone lure is attached to the lid where BWB are unable to get to.
The pitfall trap has holes on the side to allow the weevil to enter. Ensure that soil ramps are built up, and level with the hole, to allow BWB the ability to easily walk into the trap.
5 litre bucket pitfall trap is highly efficient with hundreds of dead weevils.

Mass trapping pitfall design 2 (PVC pipe trap)

PVC pitfall trap position on hill side.
100mm PVC pitfall trap position on hill side with soil ramps which allows BWB to easily walk up and into the trap.
100mm PVC pitfall trap inspection. An easily removable lid allows growers to easily inspect the trap to monitor and remove BWBs.
100mm PVC pitfall trap pheromone position. The pheromone lure is placed on the far side of the wall, providing an attractant while weevils fall into the trap below.

Another innovative design that NSW growers have adopted is a PVC pipe trap. This trap is made from PVC piping which creates a narrower but deeper trap, more stabilised into the hillside compared to the larger, shallower trap, shown in design 1. In this case, the dimensions are 100mm in diameter, and 500mm in length with the bottom of the trap made watertight with end caps and the top cap left loose to be able to take off.  Similar to the pitfall trap there are drilled several holes, 10mm in size, where the trap meets the soil line to allow for BWB to enter. A wire is fixed into the lid or on the side, used to hold the pheromone lure in place. The grower used an auger to install the PVC pipe approximately 300 millimetres in depth into the soil.

“I decided to increase the size of the trap purely because the original (smaller pitfall) traps were filling up in a couple of days! After increasing the size of the traps, I now only need to revisit the trap every month for soil ramp maintenance and emptying. I’m more clued in, knowing where hot spots of densely populated BWB zones were located on their farm, and using this knowledge to inform decisions around when to apply chemical management options. Something that I didn't foresee is the increased peace of mind. Now, having the traps in the ground, I see it as a second line of defence, not just relying on chemical application to control BWB, especially within the hotter and wetter periods of the year."
-Coffs Harbour grower comments on using the 5L BWB bucket trap design

Trap maintenance and upkeep

The enlarged pitfall traps require low maintenance and only need to be checked on average once per month or after severe weather events. Emptying of dead BWB will fluctuate as BWB numbers and movements vary throughout the year. According to growers, ensuring the trap stays in place, and maintaining the soil ramps up to the trap are some of the key considerations to keep an eye on and it’s suggested to check these features more regularly.

It has been a suggestion to add soapy water to the bottom of pitfall traps to terminate BWBs once they are in the trap. Furthermore, the soap makes the walls of the trap slippery, preventing them from exiting the trap. However, growers have found that this may not be necessary when the walls of the trap are smooth, as the weevils find it hard to get traction to climb out of the traps.

Cost

The P160-Lure90, Cosomolure (C. sordidus) is approximately $11 per bait (tablet) and lasts 90 days. The current advised density is 4 traps per hectare with one pheromone bait in each trap, totalling 16 pheromone baits per hectare per year. Therefore, currently in 2024, the approximate cost is $175 per hectare, per year. This does not include the material for pitfall traps or labour costs to install and maintain them which needs to be considered. Prices will vary over time. Ensure getting quotes from relevant suppliers before implementation. For some growers, this is a relatively low cost per hectare to substantially reduce BWB numbers throughout a block in NSW. The continued pursuit of trapping innovations reflects the proactive approach NSW growers are taking in BWB management, offering a promising avenue for control. If you are interested in more information about BWB mass trapping contact Steven Norman (NSW DPI Industry Development officer) for assistance.

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More information on Banana Weevil Borer:

References

Fu, B., Li, Q., Qiu, H., Tang, L., Zhang, X., & Liu, K. (2019). Evaluation of different trapping systems for the banana weevils Cosmopolites sordidus and Odoiporus longicollis. International Journal of Tropical Insect Science, 39, 35-43

Alpizar, D., Fallas, M., Oehlschlager, A. C., & Gonzalez, L. M. (2012). Management of Cosmopolites sordidus and Metamasius hemipterus in banana by pheromone-based mass trapping. Journal of chemical ecology, 38, 245-252.

This information has been produced as part of the National Banana Development and Extension Program (BA19004). This project has been funded by Hort Innovation, using the banana research and development levy with co-investment from the Queensland Department of Agriculture and Fisheries, New South Wales Department of Primary Industries and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.

Spider mites summary

Posted on by Sarah Williams

Spider mites

The banana spider mite (Tetranychus lambi) and the two-spotted mite (Tetranychus urticae) which are both commonly referred to as ‘spider mites’ or ‘red spider’, can cause significant damage to banana leaves and even fruit when present at high levels. They are a common pest of bananas, especially over the warmer spring and summer months. Mites feed mainly on the underside of plant leaves, consuming the contents of plant cells. This permanently damages the leaf and reduces its functionality. With moderate to severe mite damage, fruit development can be delayed and occasionally fruit can be marked with a reddish discolouration towards the cushion end. 

Adult spider mite with eggs
Adult spider mite with eggs

Early detection and the adoption of practices to help minimise spider mite populations will greatly assist in managing this pest. Click below for more information on management options.

More information

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.

Spider mites – life cycle and behaviour

Posted on by Better Bananas

Spider mites

Life cycle and behaviour

Both the banana spider mite (Tetranychus lambi) and the two-spotted mite (Tetranychus urticae) are often simply referred to as ‘spider mites’. Both are common pests of a broad range of crops and are widely distributed.

The life cycle and appearance of the banana spider mite and the two-spotted mite are similar. Both mites are typically found on the underside of leaves, only being present on the top side in very high infestations. The main distinguishing feature between the two types of mites is that high populations of the two-spotted mite are always associated with webbing (similar to spiders), while this is absent in infestations of the banana spider mite. Webbing occurs near mite colonies, typically on the underside of the midrib or in severe infestations, down the leaf veins. The two-spotted mite is more commonly found on bananas in South-East Queensland and northern NSW. By comparison, the banana spider mite predominantly is in Far North Queensland and is also identifiable as it is more straw coloured and lacks spots.

The life cycle of the mite (red arrows indicate parts of the plant affected)

The straw-coloured or greenish adult banana spider mites are usually less than 0.5mm in length and are best seen with the aid of a magnified (10X) hand lens. Under good light, the eight-legged adults have a spider-like appearance that can just be made out with the naked eye.

The very small transparent to yellow, spherical eggs are laid singly on the leaf surface and, upon hatching, pass through two nymphal stages before becoming adults. In hot conditions, the life cycle can be as short as seven to ten days.

Adult spider mite with eggs
Adult spider mite and its spherical eggs. Note the dark leaf tissue, an indication of dead leaf cells caused by mite feeding

By comparison, the adult female of the two-spotted mite (T. urticae) lives two to four weeks and can lay several hundred eggs during her life.1 Their quick life cycle and the ability of females to produce many eggs, can mean populations build rapidly if conditions are favourable.

Spider mites mainly use wind and small spun lines of web to migrate. The two-spotted mite is known to travel in winds as low as 8 km/h but prefers stronger winds.2 Mites also have the ability to move by walking on or short distances between plants2. Spider mites can migrate at any time, tending to move on when their populations become high, predators become abundant or the quality of food sources declines.

References

  1. Florida Department of Agriculture and Consumer Services, Division of Plant Industry 2009, University of Florida, viewed 17 January 2022, https://entnemdept.ufl.edu/creatures/orn/twospotted_mite.htm#top
  2. Seeman, O, Beard, J 2005, National Diagnostic Standards for Tetranychus Spider Mites, Plant Health Australia, Canberra

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For more information contact:

The Better Bananas team
Department of Agriculture and Fisheries
South Johnstone
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 
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.