By Rebecca A. Schmidt-Jeffris and Brian A. Nault
When used as foliar sprays, neonicotinoids have caused some concern among the general public because — like any pesticide — they can harm bees and other beneficial insects. However, using neonicotinoids as seed treatments minimizes these risks, and has become a commonly used tool for proactively protecting crops from insect damage. These seed treatments have benefits that include relatively low costs, low mammalian toxicity, and reduced worker handling of pesticides.
Within the processing vegetable industry, crops like snap bean are typically grown using neonicotinoid treated seeds to control seed and seedling pests, while pyrethroids are used later during the crop’s development to control foliar- and pod-feeding pests. Like neonicotinoids, pyrethroids can negatively impact non-target organisms and some insect pest populations can become resistant to them. Although both neonicotinoids and pyrethroids are typically cost-effective and reliable chemistries for reducing insect damage, we sought to determine if an alternative class of chemistry could be effectively used. If successful, farmers would have an additional tool for insect management, which could be especially important if neonicotinoids and/or pyrethroids lose their registrations.
Anthranilic diamides have the potential to replace neonicotinoids and pyrethroids in vegetable pest management. Chlorantraniliprole and cyantraniliprole are two active ingredients that are currently registered for use on many vegetable crops. The systematic activity and residual control provided by these products make them ideal candidates for delivery as either seed treatments or as foliar sprays to manage a variety of pests in many crops. Anthranilic diamides are also considered to be fairly selective, with low toxicity to many beneficial arthropods. However, only chlorantraniliprole is registered as a seed treatment on rice and corn in the U.S.
Registrations of new active ingredients on vegetables and other specialty crops typically occur after they are registered on row crops grown on large acreages. Such decisions, which are made by crop-protection companies, are financially based. The IR-4 Project, which is headquartered at Rutgers University in Princeton, NJ, was created to work with crop protection companies and specialty-crop industries to generate information that will lead to registrations of new crop-protection products on specialty crops. If anthranilic diamide seed treatments effectively manage vegetable pests, future registrations of these chemistries on specialty crops might be obtained through the IR-4 Project’s assistance.
We conducted a series of studies in western New York to determine if anthranilic diamides delivered via multiple approaches could successfully control two major pests of the processing snap bean industry — the seed corn maggot (Delia platura) and the European corn borer (Ostrinia nubilalis). The results are published in the Journal of Economic Entomology.
Currently, seed corn maggots are managed with a neonicotinoid seed treatment, and European corn borers are controlled with foliar-applied pyrethroids. Chlorantraniliprole and cyantraniliprole were tested in different formulations as seed treatments and in-furrow and foliar applications, and were then compared to the standard neonicotinoid seed treatment and pyrethroid foliar sprays.
Efforts were made to substantially elevate infestations of both seedcorn maggot and European corn borer in these field trials. The anthranilic diamides performed as well as the industry standards when applied in a similar manner (i.e., comparing seed treatments with seed treatments and foliar applications with foliar applications). Many anthranilic diamide seed treatments reduced seed corn maggot damage to levels equivalent to the industry standard. Foliar applications, regardless of active ingredient (anthranilic diamide or pyrethroid), were typically more successful at controlling European corn borer than seed treatments or in-furrow applications. However, one chlorantaniliprole seed treatment was equally effective as a pyrethroid foliar spray, and many of the seed treatments and in-furrow applications substantially reduced damage compared with damage levels in the untreated control. It is possible that under lower, more typical pest pressure, these seed treatments would have performed as well as the foliar applications.
Our results demonstrate that anthranilic diamides have the efficacy of replacing their industry standard counterparts when applied in the same manner. Anthranilic diamides could replace neonicotinoid seed treatments, and foliar-applied diamides, which are already commercially available, could replace pyrethroids. More importantly, our study demonstrated that a single seed treatment of chlorantraniliprole has the potential to manage both a seed/seedling-feeding and foliar-feeding pest simultaneously, providing protection throughout the growing season. This could reduce the risk of pesticide exposure to applicators and non-target organisms, while simultaneously decreasing application costs due to the reduction in labor, fuel, and water use from switching from multiple foliar sprays to a single seed treatment.
While anthranilic diamides have been effective pest control tools, they have not been a cost-effective option for some crops. Diamides are more expensive to produce than pyrethroids and neonicotinoids, resulting in higher prices for farmers who purchase them. Reduced prices of diamides or decreased availability or efficacy of older materials will likely be needed to change existing patterns of pesticide use. Nevertheless, we envision that anthranilic diamides will play a critical role in future vegetable pest management programs.
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Rebecca A. Schmidt-Jeffris is a postdoctoral research associate in the Department of Entomology at Cornell University. She studies the effects of landscape and management practices on arthropod pests and natural enemies in agroecosystems. Her research interests include landscape ecology, biological control, pesticide efficacy, and non-target effects. Follow her on Twitter at @Phytoseiid.
Brian A. Nault is a professor in the Department of Entomology at Cornell University’s New York State Agricultural Experiment Station in Geneva, NY. His research and extension program focuses on studying the key biological and ecological elements in the life histories of insects that attack vegetable crops, developing management programs for these pests, and then providing research-based solutions to stakeholders.