25 February 2021, USA: Organic production is tough enough without insect and disease pests to contend with. When they do show up, any increased resistance, development of insensitivity or tolerance to crop protection tactics among insect pests can make the selection of the proper control methods even harder and more important. Resistant or increased tolerant pest populations can migrate in to “organic” production acres from adjacent or nearby fields, be blown in from storms or come in on transplants from other areas. This imminent threat makes early detection of the pest(s) critical with properly selected and timed control measures.
How Insects Develop Resistance
Insects such as caterpillars or worms (lepidopterous larvae), can be predisposed to developing resistance to insecticides when one class of insecticide is used exclusively and repeatedly. Surviving insects (resistant or insensitive) can be left behind on the crop. Those surviving individuals, depending on the type of resistance/insensitivity/tolerance that they are carrying, can reproduce and pass those traits to the offspring/next generation. Over the course of multiple generations and applications, the insect populations can move from predominately susceptible to predominately resistant.
Prevention is Critical
Insecticide resistance costs growers in both yield and increased control costs – the Insecticide Resistance Action Committee (IRAC) notes that, “in some years [these costs are] more than $1 billion in cotton for the budworm/bollworm complex alone.”2 The IRAC recommends several resistance management strategies that a grower can incorporate into their crop management program to help prevent or delay resistance from developing2.
IRAC resistance management strategies include2:
Scout fields to determine pest and beneficial insect populations
Use insecticides when target pests meet economic thresholds based on scouting
Adopt an Integrated Pest Management (IPM) approach
Protect beneficial insect populations, particularly early in the season
Rotate insecticide classes/groups
Use trap crops
Breaking the Insecticide Resistance Cycle
A rotation program that includes efficacious active ingredients belonging to different insecticidal modes of action (MOA) is strongly encouraged by the IRAC1. Adding DiPel® DF Biological Insecticide Dry Flowable to your worm and caterpillar (lepidopterous larvae) control program can help break the resistance cycle, while also providing excellent control with the additional benefit of having a zero day pre-harvest interval. DiPel DF is an OMRI listed, organic insecticide derived from a soil bacterium that selectively targets destructive caterpillars and worms (lepidopterous larvae) across a wide variety of crops
By adding DiPel DF to your caterpillar/worm control program, the cycle is broken which can help delay the selection process for resistance traits already present among insect populations. Adding a unique mode of action such as group 11 A that Dipel DF is part of, can prolong the life of other classes/groups of insecticides that the grower relies on every growing season.
Group 28 chemistries like Coragen® are effective but should be rotated with other modes of action such as DiPel DF to delay the development of resistance to specific insecticide groups. Rotating multiple effective MOAs promotes good resistance management practices that helps ensure other currently used MOAs continue to work efficiently.
Why should you consider using DiPel DF?
DiPel DF is an excellent choice for caterpillar and worm control because it delivers effective and economical control on more than 30 pest species, including tent caterpillar, several armyworm species, loopers, tobacco budworms, cutworms and fruitworms. And, it has no harvest residue or MRL concerns because it is exempt from tolerances. DiPel DF is a great rotational or tank mix partner to reduce the potential of worms developing resistance to insecticides with other MOAs.