Helicoverpa Zea (Lepidoptera: Noctuidae) Dynamics and Parasitism in Maryland Soybeans

Tipping, Philip W.; Holko, Carol; Bean, Richard

doi:10.1653/0015-4040(2005)088[0055:hzlnda]2.0.co;2

Cited by 17 publications

(10 citation statements)

References 12 publications

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“…In nature, a large percentage of H. zea caterpillars may be parasitized ( 35 ), indicating that PDVs may be important and ubiquitous mediators of the interactions of H. zea with its host plants. Remarkably, Mc BV is able to manipulate phenotypes across multiple trophic levels including the phenotypes of a parasitoid, herbivore, and host plant.…”

Section: Resultsmentioning

confidence: 99%

Symbiotic polydnavirus of a parasite manipulates caterpillar and plant immunity

Tan

Peiffer

Hoover

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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SignificanceThe role of herbivore-associated microbes in mediating plant–herbivore interactions has gained recent attention. We show that a parasitoid associated with its caterpillar host not only suppresses the immune system of the caterpillar but also suppresses the induced defenses of the caterpillar’s host plant. Parasitoids inject eggs into their hosts but also inject polydnaviruses that suppress the caterpillar’s immunity. Immunosuppression enables eggs to hatch and develop as larvae within caterpillars. Additionally, the polydnavirus reduces salivary glucose oxidase, the primary elicitor found in the caterpillar’s oral secretions. Caterpillars injected with polydnavirus induce lower plant defenses than untreated caterpillars. Our results reveal a dimension to the complexity of plant–herbivore interactions indicating that polydnaviruses mediate the phenotypes of the parasitoid, herbivore, and plant.

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Section: Resultsmentioning

confidence: 99%

Symbiotic polydnavirus of a parasite manipulates caterpillar and plant immunity

Tan

Peiffer

Hoover

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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“…3 Annual migrations of populations from subtropical regions of North America and progeny of overwintering insects in more northern locations create continent-wide progressive infestations that follow northward patterns of host plant availability and maturity through the growing season. [5][6][7] The insect has a long history as a pest of cotton, although corn is the preferred agricultural host. 8 Almost all agricultural crops are fed on by bollworm, and effective management requires an understanding of sequence and distribution of hosts that are utilized *Correspondence to: Randall G. Luttrell Helicoverpa zea (Boddie), the bollworm or corn earworm, is the most important lepidopteran pest of Bt cotton in the United States.…”

Section: Introductionmentioning

confidence: 99%

Helicoverpa zea and Bt Cotton in the United States

Luttrell

Jackson

2012

GM Crops & Food

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Helicoverpa zea (Boddie), the bollworm or corn earworm, is the most important lepidopteran pest of Bt cotton in the United States. Corn is the preferred host, but the insect feeds on most flowering crops and wild host plants. As a cotton pest, bollworm has been closely linked to the insecticide-resistance prone Heliothis virescens (F.), tobacco budworm. Immature stages of the two species are difficult to separate in field environments. Tobacco budworm is very susceptible to most Bt toxins, and Bt cotton is considered to be "high dose." Bollworm is less susceptible to Bt toxins, and Bt cotton is not "high dose" for this pest. Bt cotton is routinely sprayed with traditional insecticides for bollworm control. Assays of bollworm field populations for susceptibility to Bt toxins expressed in Bt cotton have produced variable results since pre-deployment of Bt cottons in 1988 and 1992. Analyses of assay response trends have been used by others to suggest that field resistance has evolved to Bt toxins in bollworm, but disagreement exists on definitions of field resistance and confidence of variable assay results to project changes in susceptibility of field populations. Given historical variability in bollworm response to Bt toxins, erratic field control requiring supplemental insecticides since early field testing of Bt cottons, and dramatic increases in corn acreage in cotton growing areas of the Southern US, continued vigilance and concern for resistance evolution are warranted.

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“…In natural populations, a large fraction of the larvae of insect herbivores can be parasitized by parasitoids. For example, parasitism rates of fall armyworm Spodoptera frugiperda on maize can exceed 70% (Ashley, 1986;Ashley, Barfield, Waddill, & Mitchell, 1983) and corn earworm Helicoverpa zea parasitization rates ranged from 50% to over 80% depending upon location and host plants (King & Coleman, 1989;Tipping, Holko, & Bean, 2005;Young & Price, 1975).…”

Section: Discussionmentioning

confidence: 99%

Top‐down effects from parasitoids may mediate plant defence and plant fitness

et al. 2020

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Plants face many environmental stresses that can impact their survival, development and fitness. Insects are the most diverse, abundant and threatening herbivores in nature. As a consequence, plants produce direct chemical and physical defences to reduce herbivory. They also release volatiles to recruit natural enemies that indirectly protect them from herbivory. The recruitment of parasitic wasps can benefit plant fitness because they ultimately kill their insect hosts. Recently, studies showed that parasitoids can indirectly mediate plant defences by modulating herbivore oral secretions. In addition to the direct benefits of parasitoids in terms of reducing herbivore survival, we tested if the reduction in induced defences by parasitized caterpillars compared to non‐parasitized caterpillars may reduce the costs associated with defence expression. We provide evidence that tomato plants treated with saliva from parasitized caterpillars have significantly higher fitness parameters including increased flower numbers (16.3%) and heavier fruit weight (13.5%), compared to plants treated with saliva from non‐parasitized caterpillars. Since plants were grown without actual herbivores, the higher values for these fitness parameters were due to lower costs of induced defences and not due to reduced herbivory by parasitized caterpillars. Furthermore, the resulting seed germination time was shorter and the germination rate was higher when the maternal plants were previously exposed to parasitized herbivore treatment compared to control (non‐treated) plants. Overall, application of saliva did not result in transgenerational priming of offspring defence responses. However, offspring of parents exposed to caterpillar saliva had lower constitutive levels and higher induced levels of trypsin inhibitor than offspring from unexposed parents. This study shows that the saliva of parasitized caterpillars can modulate plant defences and further demonstrates that the lower induction of plant defences is associated with elevated plant fitness in the absence of herbivore feeding, suggesting that induced plant defences are costly. A free Plain Language Summary can be found within the Supporting Information of this article.

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Helicoverpa Zea (Lepidoptera: Noctuidae) Dynamics and Parasitism in Maryland Soybeans

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 17 publications

References 12 publications

Symbiotic polydnavirus of a parasite manipulates caterpillar and plant immunity

Symbiotic polydnavirus of a parasite manipulates caterpillar and plant immunity

Helicoverpa zea and Bt Cotton in the United States

Top‐down effects from parasitoids may mediate plant defence and plant fitness

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