scholarly journals Aboveground Herbivory Influences Belowground Defense Responses in Maize

2021 ◽  
Vol 9 ◽  
Author(s):  
Lise Pingault ◽  
Saumik Basu ◽  
Prince Zogli ◽  
W. Paul Williams ◽  
Nathan Palmer ◽  
...  

The European corn borer (ECB; Ostrinia nubilalis) is an economically damaging insect pest of maize (Zea mays L.), an important cereal crop widely grown globally. Among inbred lines, the maize genotype Mp708 has shown resistance to diverse herbivorous insects, although several aspects of the defense mechanisms of Mp708 plants are yet to be explored. Here, the changes in root physiology arising from short-term feeding by ECB on the shoot tissues of Mp708 plants was evaluated directly using transcriptomics, and indirectly by monitoring changes in growth of western corn rootworm (WCR; Diabrotica virgifera virgifera) larvae. Mp708 defense responses negatively impacted both ECB and WCR larval weights, providing evidence for changes in root physiology in response to ECB feeding on shoot tissues. There was a significant downregulation of genes in the root tissues following short-term ECB feeding, including genes needed for direct defense (e.g., proteinase inhibitors and chitinases). Our transcriptomic analysis also revealed specific regulation of the genes involved in hormonal and metabolite pathways in the roots of Mp708 plants subjected to ECB herbivory. These data provide support for the long-distance signaling-mediated defense in Mp708 plants and suggest that altered metabolite profiles of roots in response to ECB feeding of shoots likely negatively impacted WCR growth.

2006 ◽  
Vol 73 (3) ◽  
pp. 956-961 ◽  
Author(s):  
Jun Fang ◽  
Xiaoli Xu ◽  
Ping Wang ◽  
Jian-Zhou Zhao ◽  
Anthony M. Shelton ◽  
...  

ABSTRACT Bacillus thuringiensis vegetative insecticidal proteins (Vip) are potential alternatives for B. thuringiensis endotoxins that are currently utilized in commercial transgenic insect-resistant crops. Screening a large number of B. thuringiensis isolates resulted in the cloning of vip3Ac1. Vip3Ac1 showed high insecticidal activity against the fall armyworm Spodoptera frugiperda and the cotton bollworm Helicoverpa zea but very low activity against the silkworm Bombyx mori. The host specificity of this Vip3 toxin was altered by sequence swapping with a previously identified toxin, Vip3Aa1. While both Vip3Aa1 and Vip3Ac1 showed no detectable toxicity against the European corn borer Ostrinia nubilalis, the chimeric protein Vip3AcAa, consisting of the N-terminal region of Vip3Ac1 and the C-terminal region of Vip3Aa1, became insecticidal to the European corn borer. In addition, the chimeric Vip3AcAa had increased toxicity to the fall armyworm. Furthermore, both Vip3Ac1 and Vip3AcAa are highly insecticidal to a strain of cabbage looper (Trichoplusia ni) that is highly resistant to the B. thuringiensis endotoxin Cry1Ac, thus experimentally showing for the first time the lack of cross-resistance between B. thuringiensis Cry1A proteins and Vip3A toxins. The results in this study demonstrated that vip3Ac1 and its chimeric vip3 genes can be excellent candidates for engineering a new generation of transgenic plants for insect pest control.


2019 ◽  
Vol 113 (1) ◽  
pp. 194-202
Author(s):  
Xiujing Shen ◽  
Xiaowei Fu ◽  
Yunxin Huang ◽  
Jianglong Guo ◽  
Qiulin Wu ◽  
...  

Abstract The Asian corn borer (ACB), Ostrinia furnacalis (Guenée), is a notorious polyphagous insect pest in China and other regions of East Asia. The long-distance flight behavior of the ACB moths, however, is not well understood, especially in the field conditions. In this study, nightly monitoring data for multiple years (2003–2017) on the long-distance flight of adults crossing the Bohai Strait in northern China, showed that a large number of the adults frequently flew across the Bohai Strait from May to September with the peak migrations usually occurred, followed in order by September, June, July, and May, and the number of southward migrants was larger than that of northward migrants. From May to September in 2010, 2011, and 2017, a subsample of trapped ACB females was dissected (879 individuals in 2010, 197 individuals in 2011, and 247 individuals in 2017), and the results showed that the sex ratio of the trapped ACB moths was unbiased each month from May to September. While the proportion of mated females in northward populations (May to July = 92.85 ± 4.86%) was significantly higher than that in southward population (August and September = 74.53 ± 8.55%) . The seasonal pattern in the proportion of sexually mature females was similar to the above proportion of mated females. We conclude that the ACBs have a strong propensity and ability for long-distance migration, although local dispersal is generally considered to be the primary movement of the ACB. These findings may be helpful to improve the forecasting systems and the pest management schemes for the ACBs.


2020 ◽  
Author(s):  
Rebecca A Schmidt-Jeffris ◽  
Erica A Moretti ◽  
Kyle Wickings ◽  
Michael S Wolfin ◽  
Tobin D Northfield ◽  
...  

Abstract Slow and consistent nutrient release by organic fertilizers can improve plant nutrient balance and defenses, leading to herbivore avoidance of organically managed crops in favor of conventional crops with weaker defenses. We propose that this relative attraction to conventional plants, coupled with the use of genetically modified, insecticidal crops (Bt), has created an unintentional attract-and-kill system. We sought to determine whether Bt and non-Bt corn Zea mays L. plants grown in soil collected from five paired organic and conventional fields differed in attractiveness to European corn borer [Ostrinia nubilalis (Hübner)] moths, by conducting ovipositional choice and flight tunnel assays. We then examined the mechanisms driving the observed differences in attraction by comparing soil nutrient profiles, soil microbial activity, plant nutrition, and plant volatile profiles. Finally, we assessed whether European corn borer abundance near corn fields differed based on soil management. European corn borer preferred plants grown in conventional soil but did not discriminate between Bt and non-Bt corn. Organic management and more alkaline soil were associated with an increased soil magnesium:potassium ratio, which increased plant magnesium, and were linked to reduced European corn borer oviposition. There was an inconsistent trend for higher European corn borer moth activity near conventional fields. Our results extend the mineral balance hypothesis describing conventional plant preference by showing that it can also improve attraction to plants with genetically inserted toxins. Unintentional attract (to conventional) and (Bt) kill is a plausible scenario for pest declines in response to Bt corn adoption, but this effect may be obscured by variation in other management practices and landscape characteristics.


2015 ◽  
Vol 84 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Vladimír Ostrý ◽  
František Malíř ◽  
Annie Pfohl-Leszkowicz

Transgenic Bt maize is a potentially important tool against insect pest in the EU and other countries. Bt maize (e.g. MON 810, Bt 11) which carries the Bt gene is highly resistant to larval feeding of European corn borer, stalk borer, and Southwestern corn borer, depending on Bt toxin (δ toxin) production. Effective measures used to fight pests may often have positive side-effects in that they may also contribute to reducing mycotoxin concentrations. A systematic review has been used for the purposes of evaluating the studies on the reduction of aflatoxins in Bt maize. According to five studies, Bt maize has significantly lower concentrations of aflatoxins than non-Bt maize hybrids, only one study has shown no significant effect of Bt maize. Other studies have shown mixed results (four studies). The results of these studies were influenced by the year of sampling or by using maize breeding lines selected for resistance to aflatoxin accumulation.


2019 ◽  
Vol 35 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Pascal Gauthier ◽  
Mohamed Khelifi ◽  
Ariane Dionne ◽  
Silvia Todorova

Abstract. The European corn borer, (Hübner), is the major insect pest of sweet corn in the province of Quebec, Canada, and around the world. The presence of this pest results in substantial yield decreases and profit losses for farmers. Currently, chemical insecticides are the main method used to control this insect pest. Nevertheless, there are some interesting alternatives to chemicals for controlling the European corn borer, in particular the use of predator insects. Many research studies demonstrated the effectiveness of using wasps to successfully control the corn borer. However, this biocontrol method is more expensive and complex than chemical insecticides. The main objective of this research study was to investigate the technical feasibility of spraying pupae to facilitate the implementation of this method and reduce operating costs. For this purpose, many experimental trials using were carried out in the laboratory, with the objective of finding a suitable aqueous solution that both disperses the pupae in the sprayer tank and causes them to adhere to corn leaves once sprayed. A laboratory-scale spraying system was also designed and built to check the viability of T pupae after immersion in the spray solution and spraying. The viability of pupae was investigated further using a field prototype boom sprayer. The results showed that it is possible to spray pupae while preserving their physical integrity. In addition, a mixture of guar gum and xanthan gum was found to be the most suitable for the adhesion of pupae to corn leaves. The system overall decreased the emergence rate of Trichogramma by 10% to 15% which is considered acceptable by the authors. The success of this spraying technique for controlling the European corn borer in corn crops is highly valuable and could be generalized to other predator insects. Keywords: Biocontrol, Emergence rate, European corn borer, Spraying system, Sweet corn, Trichogramma ostriniae.


2019 ◽  
Vol 112 (4) ◽  
pp. 2007-2011 ◽  
Author(s):  
Brad S Coates ◽  
Craig A Abel

AbstractThe European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), is a perennial insect pest of cultivated maize that was inadvertently introduced into North America in the early 1900s, but population densities have decreased since the widespread adoption of transgenic hybrids that express Bacillus thuringiensis (Bt) toxins. The native American lotus borer, Ostrinia penitalis (Lepidoptera: Crambidae), is among the most ancestral species described in the genus Ostrinia, and has a geographic range that coincides with that of O. nubilalis across major maize growing regions of North America. Due to the recent decrease in O. nubilalis populations, O. penitalis has become more pronounced in light trap samples intended to monitor O. nubilalis. A molecular tool based on variation in restriction endonuclease digestion pattern of a polymerase chain reaction amplified fragment of the mitochondrial cytochrome c oxidase subunit I (coxI) gene was developed and validated to differentiate these two species. This method was applied to light trap samples over a 2-yr period and achieved accurate quantification of species, and shows that O. penitalis can be prevalent in O. nubilalis first flight sampling. These methods are useful for contemporary O. nubilalis field research in North America.


2021 ◽  
Vol 22 (6) ◽  
pp. 3152
Author(s):  
Ralf Oelmüller

Adaptation and response to environmental changes require dynamic and fast information distribution within the plant body. If one part of a plant is exposed to stress, attacked by other organisms or exposed to any other kind of threat, the information travels to neighboring organs and even neighboring plants and activates appropriate responses. The information flow is mediated by fast-traveling small metabolites, hormones, proteins/peptides, RNAs or volatiles. Electric and hydraulic waves also participate in signal propagation. The signaling molecules move from one cell to the neighboring cell, via the plasmodesmata, through the apoplast, within the vascular tissue or—as volatiles—through the air. A threat-specific response in a systemic tissue probably requires a combination of different traveling compounds. The propagating signals must travel over long distances and multiple barriers, and the signal intensity declines with increasing distance. This requires permanent amplification processes, feedback loops and cross-talks among the different traveling molecules and probably a short-term memory, to refresh the propagation process. Recent studies show that volatiles activate defense responses in systemic tissues but also play important roles in the maintenance of the propagation of traveling signals within the plant. The distal organs can respond immediately to the systemic signals or memorize the threat information and respond faster and stronger when they are exposed again to the same or even another threat. Transmission and storage of information is accompanied by loss of specificity about the threat that activated the process. I summarize our knowledge about the proposed long-distance traveling compounds and discuss their possible connections.


2001 ◽  
Vol 81 (4) ◽  
pp. 783-787 ◽  
Author(s):  
E. Riga ◽  
J. Whistlecraft ◽  
J. Potter

A series of experiments was performed in the laboratory and in the greenhouse to assess the efficacy of the entomopathogenic nematodes, Steinernema glaseri or S. feltiae in decreasing the numbers of European corn borer, fall armyworm, western corn rootworm and the seedcorn maggot in corn. Both nematode species effectively controlled the four insect pest species. During greenhouse experiments, the number of plants protected with entomopathogenic nematodes against these insect pests was significantly higher than in the untreated controls. Similar results were obtained in a microplot study of corn infected with the European corn borer, the western corn rootworm and the seedcorn maggot. The application of a single nematode species against several insect pests has economic advantages. In addition, both S. glaseri and S. feltiae overwintered and survived in the field until the next growing season. Key words: Entomopathogenic nematodes, sweet corn, European corn borer, fall armyworm, seedcorn maggot, western corn rootworm


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