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Biologicals: A stronger case for permanent status in the IPM program

| August 22, 2014

The rotation of different active ingredients with different modes of action is a paramount tactic to prevent insecticide resistance (Civolani et al. 2014). Integrated pest management (IPM) programs emphasize the use of multiple tactics (chemical, biological, mechanical, etc.) to control pest populations.

While combining these tactics can provide sustainable and efficacious pest suppression, many insecticides are detrimental to natural enemies, thereby preventing biological control methods to work properly (Roubos et al. 2014). Decimating natural enemies is not the only concern. Growth of insecticide resistance plays a more significant role, which varies across insect species. Furthermore, resistance can be more robust for particular chemical structures that present similar modes of action.

For example, Western flower thrips (WFT), Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), is a global polyphagous pest in vegetable, fruit, and ornamental crops. All insecticides used to control this pest other than spinosad (a nicotinic acetylcholine receptor (nAChR) allosteric modulator; IRAC 2013) are compromised by the same major mechanism of insecticide resistance, which limits the effectiveness of insecticide treatment programs (Kirk and Terry 2003, Guillen et al. 2014).

Combating insecticide resistance with a larger focus on the protection of beneficial insect pollinators and predators has begun to transform insecticide development and use patterns. It has recently been argued that the incorporation of biological insecticides into an insecticide rotation program has the potential to reduce insecticide resistance, conserve beneficial insects, and possibly result in greater pest insect suppression, all together providing improved management (Gentz et al. 2010).

From this transformation has emerged a greater focus on and increase in biological insecticide development and use. This includes incorporation of transgenic plants, fostering development of a more comprehensive practice. A case in point is the use of transgenic plants such as cotton varieties, to produce the Cry1Ac protein from Bacillus thuringiensis Berliner Bt. These transgenic plants have become a staple for integrated pest management, particularly of lepidoptera pests in the United States (Torres and Ruberson 2005).

Reduced-risk IPM programs incorporating these tactics have been shown to enhance the numbers of beneficial insects, and their predation and parasitization qualities (Roubos et al. 2014). With the use of such a comprehensive management practice, multistep programs can be developed to reduce the  use of synthetic insecticides, and to reinforce the more recent push to abolish nicotinic compounds.

In addition, the action of host selectivity, which is more robust in biological insecticides than in synthetics, helps suppress target pest populations by conserving beneficial insects and arthropods.

Healthy, stunted and dead Beet Army Worm (after treatment with Venerate)

Healthy, stunted and dead Beet Army Worm (after treatment with Venerate)

This is a preview of a full article published in International Pest Control – July/August 2014 issue.

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Author: Reid M. Ipser, Entomology Group Leader at Marrone Bio Innovations

 

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Category: Agriculture, Special features