Inside IPM: stories and discussions

‘pIPMing’ Your Farm: It’s easier than you think!

By Dr Anthony Rice, Insect Ecologist and IPM Consultant

Insects are under threat globally, and without insects, ecosystems collapse and our food webs will no longer support us. Insecticides are recognised as key drivers for invertebrate decline all over the world and yet their industrial-scale over-use has become normalised in our conventional food production systems.

The relatively new (1990's) neonicotine insecticides are up to 10 000 more toxic to insects than anything we have made before, but the way we use them, and measure them, hasn't kept up with the challenges that brings. These insecticides are also highly persistent in the soil, highly mobile in water and are used globally every year in sufficient quantities to kill every terrestrial arthropod on Earth hundreds of times over. This is not a cost of doing business of growing enough food. The science is clear, we do not need them, especially as seed treatments which is what most are used for. Despite this, the global market for neonicotine insecticides is expected to grow by 5.4% annually, and by 2032 be worth over $8bn. Are we mad? Can IPM help save us?

Neonicotine insecticides (Group 4A): the greatest threat to our landscape functionality we have ever faced.

The fact that the neonicotine (Group 4A) insecticides have a relatively low mammalian toxicity, are effective at extremely low levels and are systemic means that they can be pitched as safe, highly targeted and to some extent, sustainable. Reading the promotional blurbs of commercial seed treatments, they appear to be a good thing, and you can see why on face value, they are popular.

Having meaningful conversations about the neonicotines is problematic because finding solid data is difficult. The two most common measures we use to talk about insecticides are their LD50 which measure their efficacy, and their half-life in the soil which measure their persistence. Imidacloprid is the world’s most popular insecticide by a significant margin and has been well studied, especially its effect on bees. However, like a lot of data around neonicotine insecticides, the reported LD50 for imidacloprid in bees varies greatly. Many studies report LD50’s in the microgram range, often reporting testing to ‘international standards’ (eg OECD test 213, OEPP/EPPO test 75) which may not continue the test long enough to see toxic results. Additionally, bees vary greatly in their susceptibility to imidacloprid, both between colonies and even within colonies. Some studies report sublethal effects at the nanogram and even picogram (10^-12) range, especially if testing continues beyond the standard testing protocol of 48 to 96 hours. If we assume that imidacloprid is toxic to bees at the 4 picogram level, there is sufficient imidacloprid in a single NST seed to kill 133 000 bees. Because work in other groups of insect pollinators indicates both greater and lesser susceptibility compared to honeybees, it is reasonable to assume that our native invertebrate fauna could be susceptible to imidacloprid, well below the levels being reported.

While neonicotines break down relatively quickly in the presence of sunlight, the most common use of these chemicals is seed treatments (NST) where they are protected from sunlight and applied directly into the soil. There is also great variation in reported soil half-lifes of neonicotines and in the case of clothianidin (another component of NST), range from several weeks to over three years. The US EPA report clothianidin half-life of up to 19 years and one test was abandoned because the chemical didn’t break down at all. It is not clear what the half-life would be in our ancient Australian soils but if we assume a half life of three and a half years, yearly applications of NST’s into any particular patch of soil would result in annual accumulation of these chemicals that wouldn’t plateau for 15 years.

The reported uptake of neonicotines in treated maize seeds is a little under two percent meaning that over 98% of the chemical remains in the soil after application. Because neonicotines are highly water soluble, a rain event or excessive irrigation can cause them to enter ground water and waterways through runoff. These chemicals are commonly found in runoff water from soils far from where they are applied.

The ecological value of remnant vegetation in agro-ecosystems is now widely recognised and the Australian Government has several schemes to reward landholders to maintain refuges to help preserve our threatened biodiversity. However, if NST’s are washed from the site of application they can end up in the very refuges we are being paid to preserve. We know that imidacloprid is taken up by eucalypts and it was used in forestry in the form of a soluble tablet against establishment pests. Consequently, the remnant vegetation we value so highly, could be a source of chronic low level exposure to any invertebrates that make contact with the pollen, nectar, leaves, shoots, stems or roots of the native vegetation to the most effective insecticides we have ever invented. Studies in the UK and US show that NST’s have caused declines in non-target butterflies, wild bees and other pollinators. Once NST leave the site of application, the situation becomes untenable because environmental fallout becomes likely, largely unmeasurable and a much broader societal issue.

You may think that the use of NST’s is just an unfortunate cost of doing business in an industry that is trying to feed the world. This is absolutely untrue. When we have looked, studies in EU, US and Canada show that in over 95% of cases there is no justification for their use. These are not insignificant studies; they covered dozens of trials over several years. Before the advent on NST’s, (1990’s) roughly 50% of corn in the US was treated with at least one insecticide, now it is 100% with no tangible increase in pest pressure. It has become a habit, and most farmers are not aware they are even using (and paying for) NST’s. Here in Australia, if you want to use untreated seed to plant a pasture, you have to actively look for suppliers to find a source and it is becoming increasingly difficult to find. We seem caught up in a perfect storm of industrial scale misuse of insecticide that we don’t need, and are largely unaware of.

Globally, we pump millions of tons of insecticide into the very food bowl that supports us. We cannot overestimate the importance of invertebrates to every aspect of our ecosphere. We owe them everything and yet show them little tolerance, and have got very, very good at killing them. Unlike most existential threats we are bombarded with daily, this is a relatively easy fix, we just need the collective will to fix it.

What is IPM and how can it help?

Integrated Pest Management (IPM) has a long history and has collected many definitions. There are calls for an updated holistic definition but that seems a bit distractive from the general understanding that it represents a management system that relies on a suit of solutions rather than the conventional reliance on chemical interventions. The two most important aspects of a good IPM program are that it accepts a sub-economic level of pests in the crop and is based on comprehensive data on both pests and beneficial insects.

It has been demonstrated repeatedly that IPM works. I have seen it myself and am in no doubt that we need IPM more now than ever before. So why isn’t everyone doing it?

IPM has been made overly complicated, and while we still need to aspire to the model it represents, the first steps can appear to be prohibitively difficult. The standard paradigm looks like this: cultural pest management techniques; biological control; biopesticides and then chemical pesticides as a last resort. Consultants (me included) talk about reimagining your agricultural landscape, including flowers in your crop, releasing natural enemies, and avoiding harmful fungicides and insecticides. While this is still where we must eventually go, it’s a massive ask for a farmer who, today, mostly relies on chemical salesmen for management advice.

However, there are eight practical easy steps that we can take without ever having to embrace the full IPM model if you don’t want to, and you can reduce your chemical footprint overnight. You can manage risks, real or perceived, before you begin. You could do them in a morning, they cost almost nothing, and they will get your first foot on the IPM journey. These eight steps rely on harnessing the benefits of the ubiquitous army of beneficial insects, the natural enemies that are present in our crops, gardens and landscapes and exert a unheralded level of control that we only become aware of once we start spraying broad-spectrum insecticides and disrupt their efficacy and essentially realise that “we just made things worse”.

The Fateful Eight

Step 1. Stop using NST’s

Not only do NST’s have potentially devastating environmental impacts, they also contradict the IPM paradigm in several ways. Firstly, NST’s are used universally for a pest problem that does not exist. The pest problem may come to pass or it may not. Seed treatments are used as insurance against the possibility that there may be a pest problem and this is an attractive idea, especially to risk-averse corporate managers answerable to boards and stakeholders, and essentially amounts to misuse of insecticides at industrial scales. Secondly, there is very little data available on the impact of natural enemies feeding on pests that have ingested NST’s at low chronic levels and how it impacts their efficacy. Thirdly, if you subscribe to the ‘clean’ crop philosophy where you have no pests in your crop, there is nothing to attract you natural enemies and harness their benefits.

Acknowledging the potential environmental fallout from NST’s and the bewildering lack of evidence to support their use, it starts to look strangely like we are caught up in an addictive relationship that we are unable to justify.

Step 2. Rearrange your chemical shed.

It may still be dark, but once you have the first cup of blend 43 under your belt and your still feeling motivated towards change, go out to your chemical shed on rearrange your insecticides by Resistance Management Group number (on the front of every commercial container of insecticide) from highest to lowest. This is probably the strangest but also the most important changes you can make. If you then conceptually superimpose the lifecycle of your crop over the order of insecticides, you end up with the highest numbers at the earliest stages of you crop cycle. These are broad brush strokes, but generally, the higher the number, the newer the insecticide, and the more likely it is to be softer on natural enemies. Chemical companies have invested significant resources into producing IPM-friendly insecticides and there are some very good products available that will allow you to control your pests and leave natural enemies intact to carry on their good work. This is essential to reducing our chemical input to food production because if you use broad-spectrum insecticides early in your crop cycle, you kill your natural enemies, and there is nothing left to control the next inevitable outbreak. More information on the impacts of insecticides on beneficials can be found in the document “A guide to pesticide effect on beneficials” (use a search engine)– it’s a great resource and impressive piece of work.

Step 3. Talk to Your Pest scout

A pest scout is someone who comes in to check your pest status and recommend control. There are good reasons that every grower should have a pest scout that is independent to their on-farm production systems. Many growers have a pest scout who is employed by chemical re-sellers and provide a free service as long as you buy your insecticides from them. This may seem to be an unhealthy relationship but its important to note that this army of professional specialists could be the instrument of change on a national scale. If you have the conversation and explain that you want to go down the IPM pathway and ask them for help. Can they provide you with comprehensive data on your pest levels and natural enemy numbers, ask if they can show them to you, ask how their recommendations for control are IPM-friendly. Ask for scout results and recommendations in writing which doesn’t always happen routinely but it can help you monitor pest levels over time and add accountability.

Step 4. Work with Pest Thresholds

In a system not dominated by chemical interventions, a few pests in a crop is a good thing. Working out the exact level that is relevant to your production system is challenging and subject to changing demands of consumers. However, the concept is essential to acknowledging that there is stability to be gained from having an acceptable level of pests in a crop – discuss with your pest scout.

Step 5. Coverage is King! (The ‘C’ word)

This discussion may seem counter to reducing your spraying footprint but if you want to spray less, when you do spray, spray well - spray smarter. The IPM philosophy acknowledges that some insecticides will need to be applied in commercial crops. Insecticide labels often state “the recommended rate will control 95 to 98% of a pest population”. This assumes a coverage of 100%, where every insect gets a recommended dose of said insecticide. If your coverage is any less that 100%, the level of control drops accordingly but if your coverage is good the insecticide does exactly what it was expected to do, and re-sprays are not required. Where coverage is less, and in most situations is about 60-70%, there is a latent pest population left, but no natural enemies to control them, and re-sprays are usually required.

Coverage can be improved by planting layout, pruning and equipment upgrades and you can seek professional help to get spraying better.

Step 6. Identify your top (3-4) pests

Consultants and proponents of IPM often say “correct identification is essential to an IPM program”. While they may have a point, asking anyone to identify the bewildering diversity of insects in a crop is prohibitive and can be an impediment to IPM adoption. Most primary producer will know and recognise their main pests and to simplify the process, can identify their top three to four main pests and develop a IPM program for them as a place to start. Your pest scout will help with the rest.

Step 7. Farm Biosecurity

We have all seen the signs at farm gates and now generally recognise the importance of not getting a pest in the first place. A good example of this is the common garden weevil pest of vineyards in Southwest WA. The pest is widespread and difficult to control but because it is flightless, good farm biosecurity could ensure that you don’t get it in the first place. Within-farm biosecurity can also be important. For pests like mites in field and tree crops that can be spread on workers clothing, if you work your youngest blocks first, they are less likely to be infested and act as a source to spread to the rest of your farm. In orchards, air-blast sprayers essentially air-blast pests such as mites into the air and are essentially mite spreaders. Most farms have pest hot-spots, and again, by spraying your un-infested blocks first, you can avoid unintentional spread of pests.

Step 8. Value your inter-rows

Acknowledging that most natural enemies can survive quite well on pollen and nectar from grasses and flowers of broad-leaf weeds can be an important step to getting natural enemies working for you, and your inter-rows instantly become a valuable resource.

Of Hedonism, Eggplants and The Insect Apocalypse

By Dr Anthony Rice, Insect Ecologist and IPM Consultant

If we wanted to be brutally hard on ourselves, we could argue that we are waging war on the most astoundingly diverse group of animals on the planet for a fleeting, hedonistic bliss. Okay, it’s a big leap but the connection is there and once you see it, the fruit and vegie aisle will never be the same.

Psychologists have written a lot about our decision-making process when it comes to food choice and, like any animal, it’s probably one of the most important functions our brains perform. Interestingly, much of it happens subconsciously. When we look at a piece of fruit, our brain performs a seemingly miraculous set of computations in nano-seconds. Firstly, we search our memory for previous experiences with said fruit, comparing it against a set of criteria, in particular, looking for experiences of pleasure. If we find those feelings, we begin to refine the process but if we see a blemish, the anticipated pleasure is reduced. If we find enough detracting features, we reject it. Right there, at that precise moment, we set off a chain of events that are both globally catastrophic and largely unnecessary.

Firstly, the supermarket will throw out the un-sold fruit. Ignoring the potent greenhouse emissions the anaerobically decaying fruit will produce in landfill, the other negative flow-on effect is that the supermarket will pass on our apparent demands for unblemished fruit to the grower. More insecticides go on, and more fruit never even gets picked.

Globally, nearly four million tonnes of pesticides are pumped into our food bowl every year and yet up to half the food we grow still gets dumped. Our favourite and largest selling insecticide, the neonicotines, are systemic, highly soluble in water, and end up in us, our food, our children and almost every other part of our planet’s food web. The science is out there and evidence is growing that the war we are waging on insects is slowly beating them down.

Unfortunately, with less than one percent of insects considered pests, this lost biodiversity is mostly collateral damage and the flow-on effect is scary. Rachel Carlson nailed it and sixty years on, Silent Spring is coming to pass.

Don’t get me wrong, as a pest management consultant I accept the fact that careful use of insecticides is an unavoidable part of feeding so many of us, for now at least. But the ubiquitous, systemic, institutionalised misuse of insecticides is hard to watch. The blame game is very human but who is to blame? Farmers or supermarkets or big chemical companies? We may feel angry and powerless but no, the culprit is much closer to home. As consumers, this is undeniably our fault. We have allowed this to happen. Let’s own it.

This isn’t something we can fix overnight but the single most important message we can broadcast, is that we want imperfect fruit. Next time you’re in the fruit and vegie aisle have a think about how you choose your next meal and what that choice means.