The Diamondback Moth: Pest Control Without Pesticide

Tony Shelton, Cornell professor of entomology, discusses how the Oxitec Diamondback Moth could provide an innovative solution to sustainable pest control-without the use of insecticide.
Video Produced by the Cornell Alliance for Science and the Science Media Production Center in International Programs / CALS of Cornell University
Camera - Hannah Walker
Video Editing - Jeremy Veverka, Chris Knight, Shailee Shah
Additional video and stills provided by Oxitec
To learn more, visit the Shelton Lab (shelton.entomol..., or see the coverage by The New York Times (www.nytimes.com..., BBC News (www.bbc.com/new..., and Cornell Chronicle (www.news.cornel....
Article for the Cornell Chronicle by Krishna Ramanujan
July 16, 2015
New moths suppress pests, delay Bt crop resistance
Diamondback moths are notorious pests of such vegetable crops as cabbages, broccoli, and mustards, costing farmers worldwide some $5 billion each year. They also can develop resistance to many insecticides. In the lab, diamondback moths have been shown to gain resistance to Bt (Bacillus thuringiensis), a common insecticide used by organic growers that has also been genetically engineered into several crops to make them resistant to insect attack.
A new study published in the July 16 issue of BMC Biology describes greenhouse trials of a genetically engineered (GE) diamondback moth that not only suppresses populations of pest diamondback moths (Plutella xylostella), but also reduces their resistance to Bt. Traditional insecticides and Bt crops kill pest insects, but steady exposure may lead to insects develop resistance to them.
The researchers used the diamondback moth and Bt broccoli as a model system to study a new approach to integrated pest management and how such insects evolve resistance. Though Bt broccoli is not commercially available, and there are no Bt crops on the market that diamondback moth larvae feed on, the study’s findings could apply to commercial Bt corn and Bt cotton to delay or prevent the evolution of resistance in pests that feed on those crops.
“We are at a crossroads right now with how we control pests, reduce pesticides and provide food for a growing world population in a changing climate,” said Anthony Shelton, professor of entomology at Cornell’s New York State Agricultural Experiment Station (NYSAES) in Geneva, New York, and co-author of the paper. “We need to put our heads together to solve these problems with new solutions.”
One such solution is a moth developed by the United Kingdom’s Oxitec Ltd. The moth carries a gene that prevents females from effectively reproducing. The paper describes greenhouse trials where high numbers of GE male moths were released into cages containing pest diamondback moths. Shelton and colleagues found that over just three to four generations, the engineered moths mated with the pest females, leading to a rapid decline of the pests.
In additional experiments, the researchers released low levels of the GE male moths in cages with Bt broccoli and pest moths. They discovered that the GE males kept pest populations in check and also delayed the build up of resistance to the Bt broccoli.
“Adding the two biotechnologies together - engineered insects and Bt plants - demonstrates that you could both suppress the pest population and also decrease the number of Bt-resistant individuals in the population. The way forward in farming is responsible integrated pest management (IPM) to improve available methods and to introduce new methods for safe and sustainable insect pest control,” Shelton said.
The research team is planning follow-up caged field trials to see how the moths fare outdoors, Shelton said.
The paper’s first author is Tim Harvey-Samuel at the University of Oxford and Oxitec; co-authors include Neil Morrison of Oxitec; and Luke Alphey at the Pirbright Institute in the U.K.
The study was supported by the Biotechnology and Biological Sciences Research Council in the U.K.