After some fits and starts, biocontrols have gained broad acceptance thanks to new techniques and technologies
Those who have been in the business for several decades will likely remember the early days of biocontrols. One of those who does is Dr. Lance Osborne, Professor of Entomology at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS). He has dedicated his career to finding beneficial insects that work against greenhouse pests, and says things have changed dramatically as far as the tools growers have available now.
“When I was getting my Ph.D in California in 1979, people were just starting to get interested in biocontrols,” Osborne says. “Richard Linquist at Ohio State was getting growers to use them quite a bit in Ohio, and in Florida there was some work going on, but it didn’t get going really well because we just didn’t have all the tools. Back then about the only tool we had was persimilis [Phytoseiulus persimilis], a mite that fed on two-spotted spider mites. The problem was, if you used persimilis and stopped spraying for mites, broad mite would eat your lunch, because the persimilis didn’t kill broad mites. We also only had a couple of chemicals that were somewhat safe on the beneficials, so there were problems.”
Dr. Juang-Horng (J.C.) Chong, Associate Professor in the Entomology, Soils, and Plant Sciences Department at Clemson University, says grower acceptance has happened gradually, but in the last ten years he has seen a lot of growth.
“Just looking at attendance at biocontrol conferences and the numbers of articles and reports on the adoption of biocontrols by some high-profile growers gives me some idea of where the field is going,” Chong says. “I think that has a lot to do with several important issues we are facing in our industry. To name a few: poor efficacy of insecticides against some pests, such as thrips; emergence of resistance pests such as the Q- or Mediterranean-biotype of sweet potato whitefly; and more recently the decision by some growers to reduce or eliminate use of neonicotinoids from their pest management toolbox. Another very important factor is consumer demand for more sustainably grown plants.”
The Importance of Scouting Remains the Same
While the tools and technologies have changed through the last few decades, one thing remains steadfastly the same — the importance of scouting. Osborne says the importance of scouting was apparent from the beginning and remains vital to a successful biocontrol program now. The scout training he began at the University of Florida in 1981 is still in place and has expanded.
“One of the first things we had to do before we ould ever implement alternative, or even just IPM [integrated pest management] programs, was to train scouts,” Osborne says. “The requirement for being accepted into the scout training program was the employer had to agree to let them scout the crops on a regular basis for at least two hours per day. They couldn’t be pulled off to water plants, or pack, or other chores. Often when you do have someone scouting, the first thing that happens is there is an order that needs to go out, so the scout gets pulled off the job. So that is our stipulation.”
Both Osborne and Chong say the development of softer chemistries that can be integrated with biocontrol agents is an important development, and research is continuing in that area to better understand the effects on desirable insects.
Chong says while information on the acute, or lethal, effects of insecticides on beneficial insects is readily available, there is much less information on the sublethal effects.
“One hot issue is to better understand the sublethal effect, and how it may reduce the efficacy and persistence of biocontrol agents,” Chong says. “The insecticide residue may not be enough to kill the biocontrol agents outright, but it can still have an effect on how well they can find their prey or host, how many of these they can eat, how many eggs the biocontrol agents can produce, and how well the offspring of these biocontrol agents can survive. Most insecticides have some kind of sublethal effect on the biological controls. More research is being done in this area, because most scientists are realizing this is one area we don’t talk about much at all.”
Chong says identifying “hot spots” where pests are concentrated is another area of new research. Biocontrols work well when the pest level is fairly low, so the infestations need to be found before the pests spread.
“We need to improve our method and technology of releasing the biocontrol agent, as well as finding the hot spots,” Chong says. “Intense scouting is really the way to do it, but labor is one of the roadblocks. People are starting to think about automated ways to scout. The American Floral Endowment (AFE) recently announced funding for a research project to develop drones to do pest scouting. When pests have damaged leaves, they reflect light differently. The camera on the drone can detect that and identify areas of concern. Automation is really where we are going — even for delivery of the biocontrols, eventually.”
Just Being Alive Isn’t Enough
Osborne has many research projects on biocontrols underway in his lab in Florida. One area of focus is quality control. Growers need a way to evaluate whether the biological control agents they receive are going to be able to eat the pests and reproduce. If they can’t, they won’t be effective. Because they are living organisms and often subject to less-than-optimal conditions in shipping, sometimes the biocontrol agents are alive but past their prime.
“Sometimes it is the producers of the product who aren’t sending out the best quality, and sometimes the producer sends out excellent quality product, but can’t control what UPS or FedEx do,” Osborne says. “Sometimes growers are not handling it properly. Most of the biologicals should be treated like milk. It has to be stored correctly and used by the expiration date. You can’t just leave it on the dashboard of your car and expect to drink it next week. At the end of the day, you need to be able to evaluate the health of the biocontrol product before you waste time and money putting it in your greenhouse. If you stop spraying for mites, for example, and rely on predatory mites that look healthy but are past their prime, you have put your crop at risk.”
Osborne has been working on developing quality assays that allow growers to evaluate the quality of beneficial insects as soon as they arrive at the greenhouse. One of them involves putting two-spotted mites on five-day-old bean seedlings and then a week later adding the predatory mites. Since the beans have never been sprayed, there’s no chemical residue, which is sometimes why populations don’t thrive. If the predatory mites start feeding and reproducing on the bean seedlings, the grower knows they have arrived healthy.
Banker plant systems are another way to evaluate quality, and the type varies by insect species. Osborne cites as an example a grower who kept four-inch pots of corn that were infested with spider mites on hand in
isolation. Whenever a shipment of predatory mites came in, they would be placed on the corn and observed for feeding and reproduction behaviors.
Both Osborne and Chong credit organizations such as the Horticultural Research Institute, The Floriculture and Nursery Research Initiative (FNRI), the American Floral Endowment, and the Society of American Florists for providing grant money for much of the research taking place on biocontrols.
“They are making sure funding is reaching people who are answering some of the important questions in this area,” Osborne says. “I don’t think we would be where we are today without them. These organizations have really helped the industry move from just straight chemical control to true IPM programs.”
Osborne says the future holds a lot of promise for the biocontrols industry.
“We’ve got a lot of new, young scientists coming along, which is one of the main things. And lots of new tools. I have six ladybugs in culture right now: three new predators for whiteflies, two for aphids, and two for mealybugs. We’ve got so many new tools, I’ll probably have to retire before we get a lot of these products out there,” he says.
One roadblock is finding manufacturers to produce, package, and market the new beneficials, Osborne says. Many of the big companies produce for more northern states, and what works there doesn’t necessarily work in Florida.
Chong agrees. “Biocontrol agent suppliers introduce a new biocontrol agent every few years. The pace of introduction is usually slow and extremely expensive. But I do think there are more biocontrol agents coming, both in terms of availability and new species for different pests,” he says.