With tightening regulations and customer requirements around conventional crop-protection products, the market for biological alternatives is continuing to grow at a striking rate.
Independent biocontrols consultant Dr Roma Gwynn, who last year put growth in the sector at 15%, now says: "The biopesticide market has fulfilled the forecast and the growth rate is now forecast higher at 20%."
A report published by analysts at Research & Markets last November estimated the bacterial biopesticides market alone will more than double from a global value of $1.4bn in 2015 to $3.3bn by 2021.
Koppert UK general manager David Foster says: "Koppert is now 50 years old but sales of our oldest product, Spidex [with the predatory mite Phytoseiulus persimilis] is still growing and in fact was up 40% last year. More and more growers are looking to use these kinds of products as the chemical toolbox gets more restricted. We are pushing at an open door."
Partly this is because any side-effects of such products are more likely to be positive, he explains.
"Strawberry plants treated with Phytoseiulus against spider mites have been found not to get thrips either. Nature can help."
Koppert’s more recently introduced Aphiscout for soft-fruit growers contains five species of parasitic wasps. "Pests are becoming resistant to chemicals and these are being banned anyway because of residues," says Foster. "But growers struggle to identify different aphid species so this gives them the range of predators to treat the ones they are likely to encounter."
Trapping and monitoring
Successful pest control with natural predators often requires trapping and monitoring to indicate the right time for deployment.
But PG Horticulture business development manager James Avery says: "Growers often put up traps but then take no notice of them."
PG supplies Oecos products "for all things sticky trapping", he adds. "Our customers report that the specific yellow and blue used for Oecos traps outperforms the shades used by other manufacturers."
Drystick traps are coated with a hot melt glue that becomes tackier the hotter the conditions, so are ideal as an insect trap for glasshouse growers, he explains. Supplied with four silicone release papers, one section can be taken off each week, allowing growers to compare insect catches week by week on the trap for up to four weeks. Available in yellow, blue or white, drystick traps can be used for monitoring and catching a range of insect pests including thrips, whitefly and sciarid fly.
Oecos Rollertraps "are treated with an anti-UV agent to slow down their breakdown in bright conditions and prevent them going brittle", says Avery. "Their shades of colour are constantly reviewed to ensure they are the most effective at attracting insects onto them."
Supplied in widths of 15 or 30cm with a 100m length, "they are ideal for the mass catching of small insect flying pests, as they present a long, wide surface of coloured plastic for catching high numbers of insect pests such as whitefly, sciarid and thrips", he adds.
Another chemical-free control is the use of so-called semiochemicals that mimic chemical signals used by pests during mating. Launched by Fargro in the UK in January, Isonet T is a mating disruptor to control South American tomato moth Tuta absoluta, which has affected some UK tomato nurseries for the past few years as well as devastating some crops in southern Europe.
"Control in the UK has relied on preseason insecticides and establishment of biological controls but has been problematic owing to insecticide resistance issues, the difficulty of balancing pest and predator numbers and the potential of damage to beneficial insects if insecticides are used," says Fargro, pointing out that as a leaf miner, the larva can be difficult to target with chemical pesticides.
Thought to be the first approved mating disruption product for glasshouse use, Isonet T slowly releases a synthetic version of what female moths use to attract males for mating. With this ever-present in the glasshouse, male moths are unable to locate females, so disrupting mating and greatly reducing the number of eggs laid.
Spider mites: advanced cameras being developed to detect and quantify damage
Mode of action
With products such as biofungicides, understanding the mode of action is key to successful deployment, according to Lallemand Plant Care UK & Ireland area manager Andrew Gough. "That’s why it’s crucial to seek products offering the right beneficial fungal strain, isolated for specific plant disease-controlling properties," he says.
"This will determine how aggressively the roots, foliage, flowers and fruit are colonised to inhibit pathogen penetration.
The number of viable beneficial microbes is critical to success and is reflected in the colony forming units (CFU) per gram within the product."
With such "fungus-on-fungus" products "you need to be achieving a beneficial micro-organism population that is significantly greater than the concentration of the pathogen threatening your crop".
So, for example, the biofungicide Prestop contains a high concentration of Gliocladium catenulatum J1446, with at least 200 million CFU per gram of product — overwhelmingly greater than the concentration of Botrytis cinerea on a highly invaded crop when applied at the correct rate. "This biofungicide is highly aggressive, surviving around roots and on aerial plant parts for several weeks, attacking and suppressing pathogens."
The mycelium filaments, or hyphae, of strain J1446 are hyper-parasitic, secreting enzymes that dissolve cell walls of pathogenic fungi. Prestop treatments to soil, growing media and substrates provide protection against damping-off and root or base rots caused by a range of potential pathogens — Phytophthora, Pythium, Rhizoctonia and Fusarium — while aerial treatments protect against grey mould and cankers caused by Botrytis spp.
"If soil wetness and soil plus air temperatures are conducive to disease development, then they are equally suited to assisting control with a treatment such as Prestop," says Gough. Lallemand’s trials of strain J1446 have found it thrives in air and soil temperatures of 15-25°C, while aerial growth of Botrytis cinerea (grey mould) is optimised at 18-22°C. Soil pathogens causing damping-off and root rot prefer 15-20°C pre-emergence and 22-27°C post-emergence.
Gliocladium catenulatum strain J1446 was one of the main biocontrols showing an increase in use between 2013 and 2015, along with the bacterial controls Bacillus subtilis, used on a wide variety of crops but principally strawberry, and B. thuringiensis var. kurstaki, which has wide crop approval, according to the most recent Defra figures. These show the area of UK protected horticulture treated with biopesticides increased by 65% over the period.
Meanwhile, a new €530,000 project under the EU’s Co-ordinated Integrated Pest Management in Europe (C-IPM) programme aims to develop a more efficient ecological monitoring and decision support system for glasshouse growers.
Dr Rob Moerkens of the Hoogstraten vzw research centre in northern Belgium is the co-ordinator of the two-year PeMaTo-EuroPep project. "Proper pest monitoring is the basis of good biological control but an efficient and standardised system that covers all present pests is lacking," he maintains.
"The focus should shift from classical pest-monitoring systems towards the development of ecological monitoring systems, whereby you can determine the ratio of pest and beneficial insects."
Knowing this ratio is essential for determining a control strategy, but this can vary in the absence or presence of other organisms, with the varying distribution of insects in the glasshouse a further complication, he explains.
Intended to be applicable to any European production glasshouse, the ecological monitoring system being developed is based on an automated identification of insects with the aid of sticky traps. Advanced cameras will detect and quantify damage from spider mites, for example, while a decision support system will be developed based on population models.
Aphids: pests can be infected by fungus - image: Jason Baker
Alternative controls: potential new environmentally friendly pesticides
Researchers investigating the fungus Beauveria bassiana, and particularly the viruses that infect it, say this work could lead to a new generation of environmentally friendly pesticides.
B. bassiana is known to lethally infect pests such as whiteflies and aphids with its spores, and is already used in commercial myco-insecticides including Naturalis L and BotaniGard. But molecular virologists Dr Robert Coutts from the University of Hertfordshire and Dr Ioly Kotta-Loizou from Imperial College London have found that mycoviruses within the fungus cause hyper-virulence and so increase the myco-insecticidal effect.
"This discovery is potentially transformational for the sector," says Coutts. "By using viruses as enhancers we will create a new generation of improved mycoinsecticides, increasing the quality of global food production and reducing environmental impact."
Published in the journal PloS Pathogens, the work also has implications for controlling and potentially eliminating viruses including human ones such as polio and the common cold, the researchers add.