Figure 1: Carpophilus beetle (Carpophilus davidsoni) (top) and carob moth (Ectomyelois ceratoniae) (bottom) causing almond damage (photos courtesy of David Madge, DEPI)

All About Almonds

Australian Almonds

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Carpophilus Beetle -

Another insect eating your profits?

Ben Brown, Almond Board of Australia

is often first on the scene preferring fruit that is in its early stages of ripening. C. hemipterus normally arrives on the scene once the fruit begins to rot and drops to the ground. Understanding the population dynamics in Australian almond orchards would go a long way

Introduction

The Australian almond industry plantings increased significantly during the 2000s with most of this acreage now bearing and near maturity. Whilst we commonly discuss this feature in a positive light it appears the large footprint we now have isn’t without its challenges.

For those who attended the Activated Almonds R&D Forum in June 2013 or downloaded the presentations from our website, you would remember for probably the first time being alerted to a potential new pest of almonds - Carpophilus beetle (Figure 1). This pest was detected by David Madge and the DEPI Victoria research team while undertaking the industry’s carob moth (Figure 1) R&D project.

This concern has grown through the 2013/14 season with the Almond Board of Australia (ABA) receiving contact from several concerned growers and processors that its presence and kernel damage has increased, to the extent it is sometimes more damaging than carob moth. What’s particularly worrying is the beetle doesn’t discriminate between almond varieties.

For those who have been involved in horticulture for a while you would have definitely heard about carpophilus beetle but only as a serious pest of stone fruit, where in Australia crop losses of up to 30% can occur. As an aside, carpophilus beetles are also a serious pest of stone fruit in New Zealand, Middle East and USA.

Biology and behaviour

At least 12 species of carpophilus beetle occur in Australia with C. davidsoni (Figure 2), C. hemipterus (Figure 2), and C. mutilates (Figure 2) causing the greatest economic damage in ripening stone fruit. C. davidsoni is native to Australia whereas the other two species are cosmopolitan. It’s worth highlighting C. davidsoni is the common species caught in Australian stone fruit orchards and

Figure 2: C. davidsoni (left), C. hemipterus (middle) and C. mutilates (right) Images courtesy: Pest and Diseases Image Library, Bugwood.org

season in both almonds and stone fruit.

The host range of carpophilus is also extensive and broadening, where in recent years they have become significant pests of new crops with substantial crop losses in cherries and strawberries.

Whilst it is not known why carpophilus has become attracted to almonds, it’s thought the volatiles from ripening or rotting fruit (and mummies) are likely to play a role, just as it does in stone fruit. It should be remembered almonds are from the same genus (i.e. Prunus) as peaches, apricots, cherries, etc.

Other than cause physical damage and rapid breakdown to stone fruit, carpophilus also can cause indirect damage by acting as a vector of brown rot inoculum (Monilinia spp.), which frequently develops at the sites of beetle entry.

In almonds, there have been no reports of a correlation between almond kernel damaged by carpophilus and infected almonds by Monilinia spp. or alternatively Aspergillus spp. (aflatoxin producing) fungal spores, but the physical damage has been quite severe. These relationships will need to be watched carefully.

What is concerning with the behaviour of carpophilus is they penetrate and burrow into the kernel and reside there for some time (Figure 3), and don’t just feed on the surface as carob moth tend to. This penetrating behaviour and visual presence later in the supply chain makes the product redundant and even with further processing can’t be salvaged. The only market left is oil and for those growers that aren’t aware this price is the lowest of the lows attracting less than $0.80/kg.

Management OptionsLike the management of most pests, success is achieved with an integrated approach.

Orchard hygiene

Unfortunately or fortunately, depending on how you look at it, successful management of carpophilus is likely to be associated with good orchard hygiene, aka reduction in mummy numbers. Unfortunately, mummy reduction is easier said than done as it is a major flaw of our most prominent variety Nonpareil. Fortunately, mummies are the source of many other problems (e.g. hull rot inoculum, Aspergillus inoculum, and carob moth), so every effort invested in reducing mummy numbers should pay dividends. It’s worth highlighting mummy reduction is just not a matter of reducing over wintering fruit by using effective harvesting or re-shaking practices, but to also engage a preventative approach of avoiding hull rot and “rotting fruit”. It cannot be stressed enough that mummy reduction and orchard hygiene is a non-negotiable in the successful management of an almond orchard.

Monitor

It will be important to identify high risk blocks from a past history of damage. This history is achieved two ways:

1. Active monitoring in-season. Establish a trapping grid, check traps weekly, identify species, record and plot results, and analyse trends. Monitoring can be undertaken very quickly and cheaply using green funnel traps hung at eye level inside the orchard, and an attractant supplied by Insect Management Services or manufactured using the following recipe:

• Dissolve 1g of dry yeast in 200ml of 100% apple juice.

• Absorb mixture into 10g of polyacrylamide granules (e.g. Yates

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towards understanding what’s driving their presence.

Carpophilus are highly active pests that have several generations per year with females laying an average of 1071 eggs, with eggs hatching in 1-4 days, and larval development taking 4-14 days. They are also strong fliers with distances greater than 4km achieved.

Carpophilus are very resilient pests and can hibernate as mature larvae, pupae and adults.

Like most pests, carpophilus is affected by environmental conditions with relative humidity less than 40% reducing larvae and egg laying; consequently, dry conditions in the previous autumn and winter reduce spring populations.

A quick review of the weather conditions over the last two seasons indicates the relative humidity for the 2013/14 season was higher than the 2012/13 season, particularly when comparing the spring period. This may explain why we have seen increased pest pressure this

Figure 3: Kernel damage caused by carpophilus beetle.

Almond Board of Australia Inc.9 William Street, PO Box 2246 l Berri South Australia 5343

P + 61 8 8582 2055 l F + 61 8 8582 3503E admin@australianalmonds.com.au l W www.australianalmonds.com.au

Almond Board of Australia Inc.9 William Street, PO Box 2246 l Berri South Australia 5343

P + 61 8 8582 2055 l F + 61 8 8582 3503E admin@australianalmonds.com.au l W www.australianalmonds.com.au

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Water Crystals).

• Wait an hour to allow juice to be absorbed fully.

• Place resultant gel in a 300ml plastic container and cover with a fine mosquito mesh secured with a rubber band to keep beetles out of the gel container.

• Place the gel container in the bottom of funnel trap.

• Place a 1cm2 piece of a household insecticide strip (i.e. dichlorvos) inside but near the top of the trap.

The attractant is to be replaced approximately every two weeks, and to measure the beetle population use a 50ml measuring cylinder (beetle no. = 200 x (vol (ml) – 0.18). Please contact state government chemical use laws regarding the use of this system.

2. Feedback from your processor/marketer. This precise trace back ability is not a strong point in many almond orchards as we bulk store on-farm by variety and don’t segregate by block like most soft fruit industries. As the old adage says, “If you can’t measure it, you can’t manage it”. This trace back ability needs to become a feature of the industry going forward and will be strongly promoted when we roll out our OrchardNet® project next season. Please contact Brett Rosenzweig, Industry Development Officer to learn more about this project.

Attract and kill

DEPI Victoria has researched and developed an attract and kill (A&K) system that has recently become commercialised for the stone fruit industry. The system uses a large funnel trap hung on a star picket outside of the block and relies upon a synergy between an aggregation pheromone, a synthetic food-volatile based co-attractant, and a toxicant in the funnel trap to kill the entering beetles (Figure 4). The system is designed to draw beetles out of the block, not to monitor the population. The A&K stations in stone fruit orchards are placed upwind on the outside of the block being protected and deployed approximately 6 weeks prior to the fruit ripening at stocking rates of approximately 2-3 traps per hectare and left in the block for

an additional 2 weeks after harvest. The traps are deployed before fruit ripens, to avoid competition with the volatiles from the ripening fruit. The aggregation pheromone and co-attractant are to be placed every 2 weeks and ensure the aggregation pheromone and co-attractant are not disposed in the block.

Warning: It is not recommended to monitor populations with the attract and kill option as it includes an aggregation pheromone that could see populations drawn into the monitored block or property thereby increasing the pest pressure. Research has not been completed to ascertain the attractive radius of the pheromone.

The deployment of this system in almond orchards has not been researched and registered for use, and despite it not being a treatment applied to the tree or crop it still requires APVMA permission for use in almonds. The only exception are Victorian growers who could still use it due to their off-label chemical use laws, but its precise use pattern in almonds is not known. Victorian growers are to contact the DEPI Chemical Standards Officer for clarification around off-label use.

The ABA is currently applying for a Minor Use Permit (MUP) with APVMA to allow the use of the A&K by all states in the 2014/15 season. Results of this will be known in the next few months.

It is worth highlighting the research trials showed the A&K system gave better control of damage and beetle numbers than insecticide treatments.

Chemical control

Chemical control of carpophilus beetle in stone fruit is often undertaken using bifenthrin, a pyrethroid, but it’s not registered for use in almonds. Despite it being available for use by Victorian almond growers due to their off-label use laws, it is not recommended. Bifenthrin commonly results in suppression but not control of beetle numbers as it only relies on contact and ingestion. The burrowing behaviour within a kernel protected by a husk and shell, and new incoming beetle flights will be difficult if not impossible to treat. In addition, bifenthrin is also a broad spectrum insecticide that is very detrimental to many beneficial insecticides and results in two-spot mite flare-ups that require further chemical control that is also very expensive. If uncontrolled, two-spot mites will cause in-season defoliation and many flow-on effects as a result. The flow-on effects of in-season defoliation should be fresh in everyone’s mind

Figure 4: Attract and kill system (photos courtesy of Insect Management Services)

For further information contact Ben Brown, Industry Development ManagerPublished by Almond Board of Australia, PO Box 2246, Berri, South Australia 5343

Telephone (08) 8582 2055 Facsimile (08) 8582 3503 Email admin@australianalmonds.com.au

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ACKNOWLEDGEMENTS

This project has been facilitated by HAL in partnership with the Almond Board of Australia and has been funded by the Research & Developement levy. The Australian Government provides matched funding for all HAL’s R&D activities.

©Almond Board of AustraliaAll rights reserved. No part of this publication can be reproduced or copied without the prior written consent of the Almond Board of Australia unless permitted under the Copyright Act 1968 (Cwlth).

DISCLAIMER

Almond Board of Australia and its employees do not guarantee the use, or results of the use, of the information contained herein as to its correctness, accuracy, reliability, currency or otherwise. The information supplied in the Fact Sheet was the best available at the time of publication. However, the understanding and management of almonds is constantly evolving and recommendations regularly change. As such, the reader should seek professional advice before acting upon any information in this Fact Sheet and should always comply with the relevant processing factory requirements, food safety legislation and the information listed on chemical labels.

ReferencesHossain, M.S. et al. 2009. Investigation of an area wide approach to control carpophilus beetle in stone fruit. HAL Project SF05006/SF05022.

Williams D.G. 2013. Carpophilus beetles, PowerPoint presentation, Department of Environment and Primary Industries, Victoria.