ORCID Profile
0000-0001-5430-5748
Current Organisations
University of Illinois System
,
University of Nebraska-Lincoln
,
University of Melbourne
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Publisher: Oxford University Press (OUP)
Date: 12-09-2012
Publisher: Oxford University Press (OUP)
Date: 12-2006
Publisher: Proceedings of the National Academy of Sciences
Date: 12-02-2008
Publisher: Oxford University Press (OUP)
Date: 06-2012
DOI: 10.1603/EC11424
Abstract: Feedstock crops selected for bioenergy production to date are almost exclusively perennial grasses because of favorable physiological traits that enhance growth, water use, and nutrient assimilation efficiency. Grasses, however, tend to rely primarily on physical defenses, such as silica, to deter herbivores. Silica impedes processing of feedstocks and introduces a trade-off between managing for cost efficiency (i.e., yield) and plant defenses. To test how silica modulates herbivory in two of the most preferred feedstock crops for production across the central United States, miscanthus (Miscanthus x giganteus Greef and Deuter ex Hodkinson and Renvoize) and switchgrass (Panicum virgatum L.), we examined the performance of two immature generalist insect herbivores, fall armyworm (Spodoptera frugiperda (J.E. Smith) and the American grasshopper [Schistocerca americana (Drury)], on grasses grown under silica and nitrogen amendment. Both miscanthus and switchgrass assimilated nitrogen and silica when grown in amended soil that altered the consumption and conversion efficiency of herbivores consuming leaf tissue. The magnitude of nutrient assimilation, however, depended on intrinsic plant traits. Nitrogen increased conversion efficiency for both fall armyworm and American grasshopper but increased consumption rate only for fall armyworm. Silica reduced conversion efficiency and increased consumption rate only for the American grasshopper. Because of this variability, management strategies that reduce silica or increase nitrogen content in feedstock crops to enhance yields may directly influence the ability of bioenergy grasses to deter certain generalist herbivores.
Publisher: Coleopterists Society
Date: 03-2008
DOI: 10.1649/999.1
Publisher: Oxford University Press (OUP)
Date: 26-07-2008
DOI: 10.1093/AOB/MCN127
Publisher: Public Library of Science (PLoS)
Date: 30-10-2019
Publisher: Oxford University Press (OUP)
Date: 11-2006
Publisher: Proceedings of the National Academy of Sciences
Date: 25-09-2013
Abstract: Some herbivorous insects induce galls, abnormal structures, in their host plants, benefiting the gall-forming parasite by providing nutritive tissue. The gall-forming insect phylloxera induces stomata, openings through which plants regulate water and CO 2 , on the upper surface of grape leaves where they typically do not occur. Carbon uptake and transpiration by induced stomata facilitate nutrient acquisition by gall tissue and phylloxera. Moreover, gall formation reprograms the host-leaf transcriptome to increase transcripts associated with sucrose mobilization and glycolysis and decrease defense-related transcripts. Thus, stomata induction by phylloxera reconfigures leaves to increase carbon gain, to partially offset negative impacts of gall formation.
Publisher: Wiley
Date: 06-2018
DOI: 10.3732/AJB.1600111
Publisher: Frontiers Media SA
Date: 17-07-2020
Publisher: Oxford University Press (OUP)
Date: 03-2007
DOI: 10.1603/0022-2585(2007)44[351:LVIDOF]2.0.CO;2
Abstract: The use of the postmortem interval (PMI) in practical applications of forensic entomology is based upon developmental data of blow flies (Diptera: Calliphoridae) generated under controlled environmental conditions. Careful review of the published forensic entomology data sets showed that experimental (environmental) parameters differed between studies. Despite the differences in study design, there are no empirical data on the effect of photoperiod on blow fly development yet, photoperiod has been shown to alter some insect development and behavior among noncalliphorids. Consequently, will differences in photoperiod alter the developmental times of calliphorids, and thereby alter PMI estimates? To answer this question, we used a replicated design with precise temperature measurement to examine the effects of photoperiod on the forensically important blow fly Phormia regina (Meigen). We concluded that inaccurate temperature recordings by using set-chamber temperatures over rearing-container temperatures would have overshadowed any affect light had on development. Second, constant light increased variation in overall adult developmental time and significantly delayed development compared with cyclic light. Finally, not accounting for delayed development induced by photoperiod underestimated the initial empirical estimate of the PMI. These sources of variation need to be included in forensic estimates because this variation can compromise predictions of PMI based upon current data sets. Without pinpointing optimal photoperiods with which to test development, we must assume that potentially large sources of variability exist within current estimates of the PMI.
Publisher: Springer Science and Business Media LLC
Date: 14-07-2023
DOI: 10.1007/S10340-022-01529-W
Abstract: Cowpea ( Vigna unguiculata ) is one of the most important crops in semiarid areas of the world, where it thrives in hot, dry conditions. While cowpea is able to withstand abiotic stresses, it suffers serious losses from biotic antagonists, including infestation by the cowpea aphid ( Aphis craccivora ). Cowpea aphid infestations are highly destructive, especially on young plants. However, it is unclear whether cowpea aphid damage is the result of aphids having phytotoxic effects on their hosts, or simple density effects. To better understand cowpea aphid damage and the potential for resistance traits to mitigate aphid impacts, we evaluated phenotypic changes in cowpea in response to variable aphid densities and systemic versus local infestations. Low aphid densities induced leaf distortions and pseudogalling, suggesting that cowpea aphids are phytotoxic to cowpea. Resistance to the cowpea aphid has been previously identified in an African cowpea germplasm, and near isogenic lines (NILs) containing resistance quantitative trait loci (QTL) were generated in the California blackeye cultivar background. Using a series of performance assays, we determined that resistance conferred by the two QTL counteracts aphid phytotoxicity and severely limits aphid growth and fecundity. Using choice assays, a preference by cowpea aphids for the susceptible NIL was observed. Electrical penetration graph analysis revealed that the resistance phenotype includes weak surface level deterrence and strong phloem-based resistance that manifests during the sap ingestion phase. Our study provides evidence of phytotoxic traits in A. craccivora while identifying a viable means of counteracting aphid damage and reproductive potential through resistance.
Publisher: Springer Science and Business Media LLC
Date: 23-07-2020
DOI: 10.1186/S12915-020-00820-5
Abstract: Although native to North America, the invasion of the aphid-like grape phylloxera Daktulosphaira vitifoliae across the globe altered the course of grape cultivation. For the past 150 years, viticulture relied on grafting-resistant North American Vitis species as rootstocks, thereby limiting genetic stocks tolerant to other stressors such as pathogens and climate change. Limited understanding of the insect genetics resulted in successive outbreaks across the globe when rootstocks failed. Here we report the 294-Mb genome of D. vitifoliae as a basic tool to understand host plant manipulation, nutritional endosymbiosis, and enhance global viticulture. Using a combination of genome, RNA, and population resequencing, we found grape phylloxera showed high duplication rates since its common ancestor with aphids, but similarity in most metabolic genes, despite lacking obligate nutritional symbioses and feeding from parenchyma. Similarly, no enrichment occurred in development genes in relation to viviparity. However, phylloxera evolved 2700 unique genes that resemble putative effectors and are active during feeding. Population sequencing revealed the global invasion began from the upper Mississippi River in North America, spread to Europe and from there to the rest of the world. The grape phylloxera genome reveals genetic architecture relative to the evolution of nutritional endosymbiosis, viviparity, and herbivory. The extraordinary expansion in effector genes also suggests novel adaptations to plant feeding and how insects induce complex plant phenotypes, for instance galls. Finally, our understanding of the origin of this invasive species and its genome provide genetics resources to alleviate rootstock bottlenecks restricting the advancement of viticulture.
Publisher: Springer Science and Business Media LLC
Date: 11-09-2020
DOI: 10.1186/S12915-020-00864-7
Abstract: An amendment to this paper has been published and can be accessed via the original article.
Publisher: Wiley
Date: 06-04-2021
DOI: 10.1002/ECE3.7550
Abstract: Herbivory is a highly sophisticated feeding behavior that requires abilities of plant defense suppression, phytochemical detoxification, and plant macromolecule digestion. For plant‐sucking insects, salivary glands (SGs) play important roles in herbivory by secreting and injecting proteins into plant tissues to facilitate feeding. Little is known on how insects evolved secretory SG proteins for such specialized functions. Here, we investigated the composition and evolution of secretory SG proteins in the brown marmorated stink bug ( Halyomorpha halys ) and identified a group of secretory SG phospholipase C (PLC) genes with highest sequence similarity to the bacterial homologs. Further analyses demonstrated that they were most closely related to PLCs of Xenorhabdus , a genus of Gammaproteobacteria living in symbiosis with insect‐parasitizing nematodes. These suggested that H. halys might acquire these PLCs from Xenorhabdus through the mechanism of horizontal gene transfer (HGT), likely mediated by a nematode during its parasitizing an insect host. We also showed that the original HGT event was followed by gene duplication and expansion, leading to functional ersification of the bacterial‐origin PLC genes in H. halys . Thus, this study suggested that an herbivore might enhance adaptation through gaining genes from an endosymbiont of its parasite in the tripartite parasitic and symbiotic interactions.
Publisher: Springer Science and Business Media LLC
Date: 27-06-2017
Publisher: Elsevier BV
Date: 03-2021
Publisher: Springer Science and Business Media LLC
Date: 23-02-2012
DOI: 10.1007/S00442-012-2261-8
Abstract: Herbivory can influence ecosystem productivity, but recent evidence suggests that damage by herbivores modulates potential productivity specific to damage type. Because productivity is linked to photosynthesis at the leaf level, which in turn is influenced by atmospheric CO(2) concentrations, we investigated how different herbivore damage types alter component processes of photosynthesis under ambient and elevated atmospheric CO(2). We examined spatial patterns in chlorophyll fluorescence and the temperature of leaves damaged by leaf-chewing, gall-forming, and leaf-folding insects in aspen trees as well as by leaf-chewing insects in birch trees under ambient and elevated CO(2) at the aspen free-air CO(2) enrichment (FACE) site in Wisconsin. Both defoliation and gall damage suppressed the operating efficiency of photosystem II (ΦPSII) in remaining leaf tissue, and the distance that damage propagated into visibly undamaged tissue was marginally attenuated under elevated CO(2). Elevated CO(2) increased leaf temperatures, which reduced the cooling effect of gall formation and freshly chewed leaf tissue. These results provide mechanistic insight into how different damage types influence the remaining, visibly undamaged leaf tissue, and suggest that elevated CO(2) may reduce the effects of herbivory on the primary photochemistry controlling photosynthesis.
Publisher: FapUNIFESP (SciELO)
Date: 08-2009
DOI: 10.1590/S1516-89132009000400005
Abstract: The twospotted spider mite Tetranychus urticae Koch is a common pest on soybean plants. To clarify plant-arthropod interaction on mite-soybean system, leaf fluorescence, photosynthetic responses to variable carbon dioxide levels, and chlorophyll content were evaluated. Significant photosynthetic rate reduction was observed due to stomatal limitation. Stomatal closure was the major plant physiological response. As a consequence, there was reduction in photosynthetic rates. Surprisingly, plants did not show chlorophyll content reduction associated with photosynthetic impairment. No differences in fluorescence data indicate that T. urticae injury did not impair the function of light harvesting and photoelectron transport. These results showed that T. urticae could be a serious pest of soybean even on lower infestation, at least when photosynthesis was determinant to yield.
Publisher: Springer Science and Business Media LLC
Date: 12-2019
DOI: 10.1186/S12864-019-6313-X
Abstract: All eukaryotes share a conserved network of processes regulated by the proteasome and fundamental to growth, development, or perception of the environment, leading to complex but often predictable responses to stress. As a specialized component of the ubiquitin-proteasome system (UPS), the RING finger domain mediates protein-protein interactions and displays considerable versatility in regulating many physiological processes in plants. Many pathogenic organisms co-opt the UPS through RING-type E3 ligases, but little is known about how insects modify these integral networks to generate novel plant phenotypes. Using a combination of transcriptome sequencing and genome annotation of a grapevine galling species, Daktulosphaira vitifoliae , we identified 138 putatively secretory protein RING-type (SPRINGs) E3 ligases that showed structure and evolutionary signatures of genes under rapid evolution. Moreover, the majority of the SPRINGs were more expressed in the feeding stage than the non-feeding egg stage, in contrast to the non-secretory RING genes. Phylogenetic analyses indicated that the SPRINGs formed clusters, likely resulting from species-specific gene duplication and conforming to features of arthropod host-manipulating (effector) genes. To test the hypothesis that these SPRINGs evolved to manipulate cellular processes within the plant host, we examined SPRING interactions with grapevine proteins using the yeast two-hybrid assay. An insect SPRING interacted with two plant proteins, a cellulose synthase, CSLD5, and a ribosomal protein, RPS4B suggesting secretion reprograms host immune signaling, cell ision, and stress response in favor of the insect. Plant UPS gene expression during gall development linked numerous processes to novel organogenesis. Taken together, D. vitifoliae SPRINGs represent a novel gene expansion that evolved to interact with Vitis hosts. Thus, a pattern is emerging for gall forming insects to manipulate plant development through UPS targeting.
Publisher: Public Library of Science (PLoS)
Date: 11-10-2017
Publisher: Oxford University Press (OUP)
Date: 2013
DOI: 10.1093/JXB/ERS364
Publisher: Oxford University Press (OUP)
Date: 04-2011
DOI: 10.1603/EC10311
Abstract: Large-scale cultivation of plants used as biofuels is likely to alter the ecological interactions of current agricultural crops and their insect pests in a myriad of ways. Recent evidence suggests many contemporary maize pests will be able to use potential biofuel crops such as switchgrass, Panicum virgatum L., and miscanthus as hosts. To determine how suitable these biofuels are to the maize, Zea mays L., pest and generalist graminivore, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), we examined host plant preference and larval performance on foliage grown for commercial biofuel production. Larvae fed leaf tissue from both field- and greenhouse-grown switchgrass and miscanthus were monitored for survival, development, and food use relative to field-grown maize. Survivorship on biofuel crops was high on greenhouse-grown leaf tissue but severely reduced for field-grown switchgrass, and no larvae survived on field-grown miscanthus. Larvae fed field-grown tissue had larger head capsules yet achieved lower pupal weights because the increased toughness of the leaf tissue prevented the assimilation of nitrogen. Given that larvae overwhelmingly preferred maize to other biofuel crop species and that survival and performance were dramatically reduced on biofuel crop species, it is likely that biofuel crops, as grown for field cultivation, will suffer reduced damage from maize pests such as S. frugiperda because of reduced suitability.
Publisher: Cold Spring Harbor Laboratory
Date: 16-03-2023
DOI: 10.1101/2023.03.16.532987
Abstract: Herbivorous insects are exceptionally erse, accounting for a quarter of all known eukaryotic species, but the genetic basis of adaptations that enabled this dietary transition remains poorly understood. Many studies have suggested that expansions and contractions of chemosensory and detoxification gene families – genes directly mediating interactions with plant chemical defenses – underlie successful plant colonization. However, this hypothesis has been challenging to test because the origins of herbivory in many lineages are ancient ( million years ago [mya]), obscuring genomic evolutionary patterns. Here, we characterized chemosensory and detoxification gene family evolution across Scaptomyza, a genus nested within Drosophila that includes a recently derived ( mya) herbivore lineage of mustard (Brassicales) specialists and carnation (Caryophyllaceae) specialists, and several non-herbivorous species. Comparative genomic analyses revealed that herbivorous Scaptomyza have among the smallest chemosensory and detoxification gene repertoires across 12 drosophilid species surveyed. Rates of gene turnover averaged across the herbivore clade were significantly higher than background rates in over half of the surveyed gene families. However, gene turnover was more limited along the ancestral herbivore branch, with only gustatory receptors and odorant binding proteins experiencing strong losses. The genes most significantly impacted by gene loss, duplication, or changes in selective constraint were those involved in detecting compounds associated with feeding on plants (bitter or electrophilic phytotoxins) or their ancestral diet (yeast and fruit volatiles). These results provide insight into the molecular and evolutionary mechanisms of plant-feeding adaptations and highlight strong gene candidates that have also been linked to other dietary transitions in Drosophila .
Publisher: Annual Reviews
Date: 07-01-2013
DOI: 10.1146/ANNUREV-ENTO-120811-153544
Abstract: By changing the chemical composition of foliage, the increase in atmospheric CO 2 is fundamentally altering insect herbivory. The responses of folivorous insects to these changes is, however, highly variable. In this review we highlight emerging mechanisms by which increasing CO 2 alters the defense chemistry and signaling of plants. The response of allelochemicals affecting insect performance varies under elevated CO 2 , and results suggest this is driven by changes in plant hormones. Increasing CO 2 suppresses the production of jasmonates and ethylene and increases the production of salicylic acid, and these differential responses of plant hormones affect specific secondary chemical pathways. In addition to changes in secondary chemistry, elevated CO 2 decreases rates of water loss from leaves, increases temperature and feeding rates, and alters nutritional content. New insights into the mechanistic responses of secondary chemistry to elevated CO 2 increase our ability to predict the ecological and evolutionary responses of plants attacked by insects.
Publisher: Springer Science and Business Media LLC
Date: 06-05-2009
DOI: 10.1007/S00442-009-1360-7
Abstract: Elevated levels of CO(2), equivalent to those projected to occur under global climate change scenarios, increase the susceptibility of soybean foliage to herbivores by down-regulating the expression of genes related to the defense hormones jasmonic acid and ethylene these in turn decrease the gene expression and activity of cysteine proteinase inhibitors (CystPIs), the principal antiherbivore defenses in foliage. To examine the effects of elevated CO(2) on the preference of Japanese beetle (JB Popillia japonica) for leaves of different ages within the plant, soybeans were grown at the SoyFACE facility at the University of Illinois at Urbana-Ch aign. When given a choice, JB consistently inflicted greater levels of damage on older leaves than on younger leaves, and there was a trend for a greater preference for young leaves grown under elevated CO(2) compared to those grown under ambient CO(2). More heavily damaged older leaves and those grown under elevated CO(2) had reduced CystPI activity, and JB that consumed leaves with lower CystPI activity had correspondingly greater gut proteinase activity. Younger leaves with higher CystPI activity and photosynthetic rates may contribute disproportionately to plant fitness and are more protected against herbivore attack than older foliage. Cysteine proteinase inhibitors are potent defenses against JB, and the effectiveness of this defense is modulated by growth under elevated CO(2) as well as leaf position.
Publisher: Wiley
Date: 05-12-2016
Publisher: Springer Science and Business Media LLC
Date: 29-08-2012
Location: United States of America
No related grants have been discovered for Paul Nabity.