Forum—The Never-Ending Insect Control Contest

Thousands of different insect species are serious threats to agricultural production in the United States, and hundreds of others represent potential threats that could decimate our natural, agricultural, and urban landscapes. Without the pest control measures that we have today, insects would be eating or otherwise putting to ruin about half of all the crops grown in the United States each year, causing significant damage to our livestock, and even inflicting harm to us and our capacity to live peacefully in our homes.

Luckily, scientific research has provided a large toolbox of measures and strategies to help farmers and ranchers, gardeners, homeowners, and the general public control many of these problem insects. These tools include chemical insecticides, biological control agents, lures and traps, insect-resistant crops, organic treatments and insecticides, decoy (trap) crops, areawide control programs, physical barriers, and many others. For livestock insect pests, there are dips, repellents, and insecticidal sprays and dusts, as well as novel management strategies, natural enemies, and more.

Many of the innovations for successful control have resulted from the work of Agricultural Research Service scientists, such as the discovery in 1936 that selenium is absorbed by plant roots and carried to foliage where it kills aphids, which became the first systemic insecticide; finding genetic resistance to corn earworm in a line of flour corn in 1941; and developing the sterile male insect release technique that led to the eradication of the screwworm from the United States in 1966, a method that is being used today to keep this and other pests like the Mediterranean fruit fly out of the country.

Unfortunately, we cannot rest on previous successes, even successes like those described above, because insects continue to evolve countermeasures. They find ways to bypass or overcome virtually every control method, which then calls for scientists to find even more novel approaches. Whether insecticide resistance will evolve is not among the leading questions asked by entomologists; the accepted consensus is that it will. Instead, the questions are when will the resistance evolve, what are the mechanisms underlying it, how can we slow the evolution of resistance, and are there new mechanisms remaining to be discovered? There is a continuing “arms race” between research to find new control measures and the countermeasures of the insects.

Beyond that, the expectations and requirements of end-users and policymakers, and even social attitudes, keep changing, which generally means the bar for what is expected from insect control measures keeps being raised. Today, we want insect control methods to be not only highly effective, but also narrowly focused, that is, effective against a target pest insect, but not harmful to nontarget species; less persistent in the environment; less harmful to human applicators as well as the general public; and have less of an impact on the environment in terms of the raw ingredients from which they are made. Finally, in addition to all of the above, new control methods have to be economical to develop and use.

To meet all of these high expectations, ARS scientists are continually seeking novel ways to control insects. For example, researchers at the ARS Imported Fire Ant and Household Insects Research Unit, in Gainesville, Florida, are testing a group of unique alkaloids from Central and South American poison frogs as potential compounds to control fire ants. See the story, "Fire Ants Are No Match for Poison Frogs," in this issue.

In Tifton, Georgia, an ARS entomologist is trying out low-tech, low-impact insect control measures, like plastic barriers between peanut and cotton fields, to see whether they will stop native stink bugs from moving between crops. See the story, "Controlling Native Stink Bugs in the Southeast," in this issue.

At the other end of the technology scale, ARS researchers are turning to our growing knowledge of genomics and biochemistry to explore novel ways to develop very targeted pest control measures. For example, they are combining genome sequencing with bioinformatics and molecular biology tools, such as high-throughput proteomics, microarrays, and RNA interference, in an effort to develop a vaccine against cattle ticks using information encoded in the cattle tick genome.

ARS scientists are also breeding new, very specific insect-resistance traits right into the crop itself. One such project is under way to develop soybeans resistant to soybean aphids, which arrived here from Asia around 2000. ARS researchers are conducting fine mapping, metabolomics, transcriptomics, and proteomics studies of several lines of soybeans that make a specific biochemical change when the aphids attack, a change that could lead to natural resistance to this pest.

A challenging goal of ARS research is to stay ahead of the insects, finding new ways to keep them from doing serious harm, because the insect pests will continue to adapt and evolve, sometimes quite rapidly. Fortunately, so will science and scientists.

DeWayne Shoemaker
Acting National Program Leader
Veterinary, Medical, and Urban Entomology
Beltsville, Maryland

"Forum" was published in the November/December 2014 issue of Agricultural Research magazine.