Quantitative Assessment of Biotic Mortality Factors of the European Corn Borer (Lepidoptera: Crambidae) in Field Corn

Abstract

Five treatments were used to exclude naturally occurring predators and parasitoids, based on body size and flight ability, to assess their effect on Ostrinia nubilalis (Hübner) populations on corn plaits. Two initial O. nubilalis egg densities (one egg mass and three egg masses per plant) were assigned to each treatment. Egg predation was higher in uncaged treatments than in caged treatments. Flying insect predators, primarily Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae), reduced egg densities by 50%. Thirty-five to 84% of O. nubilalis larvae were infected with Nosema pyrausta (Paillot) (Microspora: Nosematidae). The incidence of Beauveria bassiana (Balsamo) Vuillemin (Deuteromycotina: Hyphomycetes), ranged from 0 to 21%, whereas larval parasitism, mainly by Macrocentrus cingulum Reinhard (Hymenoptera: Braconidae) ranged from 0 to 31%. In contrast to previous studies, this 3-yr field study documents that egg predation and larval infections of O. nubilalis were significant and consistent biotic mortality factors.

Seeds of Change: Corn Seed Mixtures for Resistance Management and Integrated Pest Management

“…Biological control by endemic and introduced natural enemies is a cornerstone of IPM, and seed mixtures may affect the ability of these natural enemies to persist in cropland and their contributions to pest management (Wilhoit 1991). Predators, parasitoids, and pathogens are a frequent and free source of biotic mortality for all pests in cropland (Brust et al 1986;Lewis and Bing 1991;Andow 1992;Jackson and Hesler 1996;Cottrell and Yeargen 1998;Phoopholo et al 2001;Pfannenstiel and Yeargen 2002;Toepfer et al 2008;Lundgren et al 2009a,b;Toepfer et al 2009), and our farm management decisions should encourage their conservation and contributions to pest management whenever possible. Currently, there are no consistently documented toxicological effects of Cry toxins expressed in commercial Bt corn against predators or parasitoids (Marvier et al 2007, Wolfenbarger et al 2008, Duan et al 2010), but Bt corn certainly changes the corn environment relative to non-Bt habitats, and these changes could have important implications for biological control (Dean andDe Moraes 2006, Lundgren et al 2009a).…”

Conidia production by Beauveria bassiana (for the biocontrol of a diamondback moth) during solid-state fermentation in a packed-bed bioreactor

“…The genus Beauveria, which is known as an imperfect state of Cordyceps, has potential in herbal medicines as well as biocontrol agents against insect pests. B. bassiana is one of the most commonly occurring entomopathogenic fungal species, and shows strong pathogenicity to Lepidoptera, Hymenopterta, Coleoptera, and Leptinotarsa (Harris et al 2000, Fernandez et al 2001, Mannion et al 2001, Phoofolo et al 2001.…”

Effects of combining Beauveria bassiana and Nosema pyrausta on the mortality of Ostrinia nubilalis

“…3,[6][7][8][9]. Generally, control agents fall into two categories: i) fast-acting pathogens that cause acute diseases of their hosts, suitable for use as microbial insecticides in inundative biocontrol strategies, and ii) low virulence agents that produce chronic debilitating infections, better suited for classical biocontrol.…”

“…This fungus, which is regularly observed in natural populations of ECB [e.g. 7,9,12,16,17], can be effective against larvae when applied to plant foliage [e.g. 16,18,19].…”

“…9,[20][21][22][23]. Nosema pyrausta Paillot (Microsporida, Nosematidae) is a common and widespread obligate intracellular parasite of ECB and plays an important role in suppressing its population levels [e.g.…”