(Beyond Pesticides, November 13, 2012) There’s a new tool in the fight against aphids. Research published in the journal Horticultural Science discovered that reducing the amount of ultra-violet (UV) light in an environment can shrink the population of an aphid infestation. This study is encouraging as it has the ability to dramatically reduce pesticide applications.
Scientists carried out their study in two “tunnel type” greenhouses over three separate lettuce growing seasons. The crops in one greenhouse were covered with standard mesh netting, while crops in the other greenhouse were covered with netting that filtered radiation in the UV spectrum (the product ‘Bionet’ was used in the study). Researchers then artificially introduced aphid pests into the environment, and tracked their dispersal patterns and overall population weekly through a statistical analysis. Although the aphid population grew exponentially in both environments, it was significantly lower in the greenhouse where the aphids were covered by the UV-absorbing material. This has important implications for greenhouse-grown greens. Using this technique, farmers can reduce the costs associated with pesticide use, concurrently protecting the health of the surrounding environment and consumers purchasing their crops.
The researchers note that UV radiation acts as an important visual cue not only for aphids, but also other insect pests such as whiteflies, moths, and thrips. The study explains, “In fact, UV radiation is important in the visual cues of most insects, modifying their flying and alighting behavior, thus, governing its dispersal activity.” Modifying an insect pest’s dispersal pattern can help to cue farmers in on problem areas and prevent widespread infestations, making it easier to deal with the pests through non-toxic means.
It’s important to note that UV absorbing nets are not a perfect solution, but instead represent an effective strategy within a properly developed Integrated Pest Management (IPM) system. IPM is a program of prevention, monitoring, and control that eliminates or drastically reduces the use of pesticides. This is accomplished by utilizing a variety of methods and techniques, including cultural, biological, and structural strategies. It also stipulates the use of least-toxic chemical options only as the last resort. UV absorbing covers fit very well into an integrated pest management (IPM) program as they represent a method which minimizes waste material and avoids damage to the surrounding environment.
Aphids are harmful to both indoor and outdoor crops, and can cause substantial losses if not managed. The small pests, typically discovered eating the backside of a plant’s leaves, have the ability to transmit dozens of plant viruses and diseases. However there are a variety of ways to control an aphid infestation without resorting to harmful pesticides.
Mechanical methods of controlling aphids can be quite effective. This includes spraying aphids off of infected plants with a blast of water early in the day, or pruning or pinching heavily infested areas of the plant. However, pruning and pinching may only delay an aphid infestation and biological controls may need to be employed. When attempting to control aphids through biological means, the surrounding environment becomes very important. If predator species do not have an area to breed, natural pest control services are diminished. By introducing habitat for beneficial species, such as ladybugs, lacewings, or parasitic wasps, biological controls begin to put a check on aphid populations. As the beneficial insects feed, their population numbers go up while aphid numbers go down, eventually reaching a satisfactory medium where the remaining population can be dealt with through mechanical techniques. The fungus Beauvaria bassinana is also known to be an effective biological control for aphids, and it is commercially available under the product names Naturalis-O and Botanigard. Another noteworthy prevention technique is to avoid quick-release fertilizers, as aphid populations can explode as a result of high nitrogen levels in plants.
Embracing IPM in this sense means embracing an ecological approach to pest management. Mechanical controls, such as UV absorbing netting are effective tools, but in order to completely handle pest problems, they must be supported by an ecological strategy that increases the resiliency of the surrounding environment. By embracing biological diversity, no species breeds to the point where it becomes a pest problem, as the surrounding environment puts a natural “check” on its growth.
Learn more about controlling pest problems through non-toxic or least-toxic means by viewing our Organic Food program page. Organic systems embrace this approach, and are prohibited from employing any harmful synthetic pesticides. Learn more about controlling aphids indoors by viewing our “How to Manage Houseplant Pests” factsheet.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.