Title of Oral/Poster Presentation

Interactions between neonicotinoids and water stress lead to Banks grass mite outbreaks in corn

Class

Article

Department

Biology

Faculty Mentor

Ricardo Ramirez

Presentation Type

Oral Presentation

Abstract

Drought conditions are prevalent in the Intermountain West and are predicted to persist, while neonicotinoids are one of the most widely used insecticides as seed treatment in corn. Spider mites, a very common pest, are thought to proliferate with elevated temperature and prolonged dry conditions and with applications of neonicotinoids. On one hand drought is thought to increase the plant nutrient availability and make it more susceptible to herbivory; on the other hand neonicotinoids appear to modify plant physiological pathways leading to enhanced spider mite reproductive rate. What it is not clear is how these two factors interact and what the outcomes are for spider mites. In the summer of 2013 and 2014 we conducted a field study to examine the effect of drought stress (+,-) and neonicotinoid corn seed treatments (+,-) on the resident population of Banks grass mites on field corn plants receiving 100%, 50% (moderate water stress) and 25% (heavy water stress) of the total water lost by evapotranspiration. Mites were recorded weekly throughout the season. Our results show that drought stress increases the abundance of mites and, interestingly, the effect of drought is exacerbated by the use of neonicotinoid insecticides only when combined with heavy water stress. Growers can expect higher mite outbreaks under dry conditions, therefore irrigation and insecticide use should be managed more cautiously.

Start Date

4-9-2015 1:00 PM

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Apr 9th, 1:00 PM

Interactions between neonicotinoids and water stress lead to Banks grass mite outbreaks in corn

Drought conditions are prevalent in the Intermountain West and are predicted to persist, while neonicotinoids are one of the most widely used insecticides as seed treatment in corn. Spider mites, a very common pest, are thought to proliferate with elevated temperature and prolonged dry conditions and with applications of neonicotinoids. On one hand drought is thought to increase the plant nutrient availability and make it more susceptible to herbivory; on the other hand neonicotinoids appear to modify plant physiological pathways leading to enhanced spider mite reproductive rate. What it is not clear is how these two factors interact and what the outcomes are for spider mites. In the summer of 2013 and 2014 we conducted a field study to examine the effect of drought stress (+,-) and neonicotinoid corn seed treatments (+,-) on the resident population of Banks grass mites on field corn plants receiving 100%, 50% (moderate water stress) and 25% (heavy water stress) of the total water lost by evapotranspiration. Mites were recorded weekly throughout the season. Our results show that drought stress increases the abundance of mites and, interestingly, the effect of drought is exacerbated by the use of neonicotinoid insecticides only when combined with heavy water stress. Growers can expect higher mite outbreaks under dry conditions, therefore irrigation and insecticide use should be managed more cautiously.