Optimizing <I>Helicoverpa zea</I> (Lepidoptera: Noctuidae) Insecticidal Efficacy in Minnesota Sweet Corn: A Logistic Regression to Assess Timing Parameters

Abstract

Late-season plantings of sweet corn in Minnesota result in an abundant supply of silking corn, Zea mays L., throughout August to early September that is highly attractive to the corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). During a 10-yr period, 1997-2006, insecticide efficacy trials were conducted in late-planted sweet corn in Minnesota for management of H. zea. These data were used to develop a logistic regression model to identify the variables and interactions that most influenced efficacy (proportion control) of late-instar H. zea. The pyrethroid lambdacyhalothrin (0.028 kg [AI]/ha) is a commonly used insecticide in sweet corn and was therefore chosen for use in parameter evaluation. Three variables were found to be significant (alpha = 0.05), the percentage of plants silking at the time of the first insecticide application, the interval between the first and second insecticide applications, and the interval between the last insecticide application and harvest. Odds ratio estimates indicated that as the percentage of plants silking at the time of first application increased, control of H. zea increased. As the interval between the first and second insecticide application increased, control of H. zea decreased. Finally, as the interval between the last insecticide application and harvest increased, control of H. zea increased. An additional timing trial was conducted in 2007 by using lambda-cyhalothrin, to evaluate the impact of the percentage of plants silking at the first application. The results indicated no significant differences in efficacy against late-instar H. zea at 0, 50, 90, and 100% of plants silking at the first application (regimes of five or more sprays). The implications of these effects are discussed within the context of current integrated pest management programs for late-planted sweet corn in the upper midwestern United States.

Novel Vip3A Bacillus thuringiensis (Bt) maize approaches high-dose efficacy against Helicoverpa zea (Lepidoptera: Noctuidae) under field conditions: Implications for resistance management

“…3,21 Compared to the single gene Bt11 event, this combination of Bt proteins significantly increases control efficacy against a broader spectrum of Lepidopteran pests for several reasons. First, the MIR162 event region, so regular monitoring of insects not affected by the expressed Cry1Ab or Vip3A proteins continues to be essential for successful IPM.…”

Continental-scale migration patterns and origin of Helicoverpa zea (Lepidoptera: Noctuidae) based on a biogeochemical marker

“…The first period, which starts around mid-June, is primarily comprised of moths migrating from the southern states. The second period, beginning in late July to early August, typically encompasses multiple flights and can contain migratory adult moths and F 1 individuals from the first flight period ( Hardwick 1965 , Westbrook 2008 , Burkness et al 2009 ). Therefore, the sample, which was collected in September and categorized as having a local origin, could potentially represent an F 1 individual from the first flight period.…”

Identification of compounds produced by male hairpencil glands of corn earworm, Helicoverpa zea and their role in male autodetection and female mate acceptance

“…Helicoverpa armigera , H. zea , Helicoverpa assulta (Guenée, 1852) (Lepidoptera: Noctuidae), Helicoverpa punctigera (Wallengren, 1860) (Lepidoptera: Noctuidae) and H. virescens are important pests on a range of food crops such as cotton, corn, sorghum, soybean, flax, tobacco and tomato (Hillier & Baker, 2016). Helicoverpa zea is a major polyphagous pest that has become one of the most constant insect pests of sweet corn, Zea mays (Burkness et al, 2009). Female moths of H. zea can lay over 2000 eggs within a 2‐week period, ovipositing primarily on newly emerging silk tissues of corn.…”

“…Female moths of H. zea can lay over 2000 eggs within a 2‐week period, ovipositing primarily on newly emerging silk tissues of corn. Once eggs hatch, emerging larvae then move down the silk to the ear tip, where they then start to feed on the corn kernels (Burkness et al, 2009).…”