Sustainable Soybean Production—Part V

Insects can and do cause economic losses in Midsouthern soybeans. The below points outline the current tools that can/may be used to reduce or prevent these losses and enhance the sustainability of Mississippi soybean farming, along with potential new technologies that may become available in the future.

Integrated Pest Management (IPM) has been promoted and used for insect management in Mississippi soybean farming, and has resulted in significant cost savings and limited environmental impact. Some IPM components for soybean insect control include:

• Scouting fields for insect pests to determine if/when curative measures are needed based on thresholds that have been established for individual insect species;


• Relying on and protecting native insect predators and pathogens to allow them to play a key role in regulating some insect pests;


• Adjusting planting date to avoid damaging infestations of late-season defoliators and pod feeders; and


• Applying insecticides when damaging insect outbreaks occur.


 

Three factors contribute to soybean insects being managed differently than other pests.

1. Host-plant resistance in soybeans is available and has been for many years, but high-yielding varieties with resistance to insects that are problematic in the Midsouth have not been developed.


2. Transgenic insecticidal soybeans based on Bacillus thuringiensis (Bt) endotoxins are efficacious against defoliating insects. However, varieties with these traits have not been marketed in the US; the demand for them will determine their future development and availability.


3. Because of the above two factors, control of damaging populations of soybean insects relies mainly on the timely application of insecticides.


 

There are documented cases of evolving soybean insect resistance to various pesticides. The same insecticides being applied to most crops in the Midsouth may contribute to this selection for resistance. This resistance to insecticides can decrease sustainability of soybean production by reducing or eliminating options for insect control.

To ensure that current soybean insect management strategies remain effective for soybean insect control and that future insect management is sustainable for Mississippi soybean farming, the following points should receive attention.

• Thresholds used to trigger insecticide applications to control soybean insects should be verified for the various soybean production systems used in Mississippi soybean farming.


• The effectiveness and economics of using insect-resistant and/or transgenic soybeans as part of the management strategy for soybean insects in the Midsouth should be evaluated to determine if their use will affect economic yield and/or reduce dependence on management with insecticides.


 

larryheatherly@bellsouth.net