The polyvalent sequestration ability of an economically important beetle.

Many specialized herbivorous insects sequester single classes of toxic secondary metabolites from their host plants as protection against natural enemies. If and how herbivores can use multiple classes of plant toxins across the large chemical diversity of plants for self-protection is unknown. We show that the polyphagous adults of the beetle Diabrotica virgifera are capable of selectively accumulating benzoxazinoids, cucurbitacins, and glucosinolates but not cyanogenic glycosides.

Bacterial bioluminescence is an important regulator of multitrophic interactions in the soil.

Enormous efforts have been made to understand the functions of bioluminescence; however, its relevance in soil ecosystems has barely been investigated. In addition, our understanding of the biological relevance of bioluminescence is hampered by the scarcity of tools to genetically manipulate this trait. Using the symbionts of entomopathogenic nematodes, Photorhabdus bacteria, we show that bioluminescence plays important regulatory roles in multitrophic interactions in the soil.

Cultivar-Specific Defense Responses in Wild and Cultivated Squash Induced by Belowground and Aboveground Herbivory.

Plant domestication often alters plant traits, including chemical and physical defenses against herbivores. In squash, domestication leads to reduced levels of cucurbitacins and leaf trichomes, influencing interactions with insects. However, the impact of domestication on inducible defenses in squash remains poorly understood.

Sequestration of cucurbitacins from cucumber plants by larvae provides little protection against biological control agents.

Unlabelled: Cucurbitaceae plants produce cucurbitacins, bitter triterpenoids, to protect themselves against various insects and pathogens. Adult banded cucumber beetles (), a common pest of maize and cucurbits, sequester cucurbitacins, presumably as a defensive mechanism against their natural enemies, which might reduce the efficacy of biological control agents. Whether the larvae also sequester and are protected by cucurbitacins is unclear.

The effect of squash domestication on a belowground tritrophic interaction.

The domestication of plants has commonly resulted in the loss of plant defense metabolites, with important consequences for the plants' interactions with herbivores and their natural enemies. Squash domestication started 10'000 years ago and has led to the loss of cucurbitacins, which are highly toxic triterpenes. The banded cucumber beetle (), a generalist herbivore, is adapted to feed on plants from the Cucurbitaceae and is known to sequester cucurbitacins, supposedly for its own defense.

Caterpillar-Induced Volatile Emissions in Cotton: The Relative Importance of Damage and Insect-Derived Factors.

In response to herbivore attack, plants release large amounts of volatiles that can serve as attractants for the natural enemies of the attacking herbivores. Such responses are typically triggered by damage- and insect-associated factors. Cotton plants are somewhat peculiar because they release specific blends of volatiles in two waves in response to caterpillar attack.

Plant-associated CO mediates long-distance host location and foraging behaviour of a root herbivore.

Insect herbivores use different cues to locate host plants. The importance of CO in this context is not well understood. We manipulated CO perception in western corn rootworm (WCR) larvae through RNAi and studied how CO perception impacts their interaction with their host plant.

Entomopathogenic nematodes from Mexico that can overcome the resistance mechanisms of the western corn rootworm.

Natural enemies of herbivores are expected to adapt to the defence strategies of their preys or hosts. Such adaptations may also include their capacity to cope with plant metabolites that herbivores sequester as a defence. In this study, we evaluated the ability of Mexican entomopathogenic nematodes (EPN) to resist benzoxazinoids that are sequestered from maize roots by the western corn rootworm (WCR, Diabrotica virgifera virgifera; Coleoptera: Chrysomelidae), an important maize pest in America and Europe.

Publisher Correction: Engineering bacterial symbionts of nematodes improves their biocontrol potential to counter the western corn rootworm.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Engineering bacterial symbionts of nematodes improves their biocontrol potential to counter the western corn rootworm.

The western corn rootworm (WCR) decimates maize crops worldwide. One potential way to control this pest is treatment with entomopathogenic nematodes (EPNs) that harbor bacterial symbionts that are pathogenic to insects. However, WCR larvae sequester benzoxazinoid secondary metabolites that are produced by maize and use them to increase their resistance to the nematodes and their symbionts.

Plant defense resistance in natural enemies of a specialist insect herbivore.

Plants defend themselves against herbivores through the production of toxic and deterrent metabolites. Adapted herbivores can tolerate and sometimes sequester these metabolites, allowing them to feed on defended plants and become toxic to their own enemies. Can herbivore natural enemies overcome sequestered plant defense metabolites to prey on adapted herbivores? To address this question, we studied how entomopathogenic nematodes cope with benzoxazinoid defense metabolites that are produced by grasses and sequestered by a specialist maize herbivore, the western corn rootworm.

Entomopathogenic nematodes increase predation success by inducing cadaver volatiles that attract healthy herbivores.

Herbivore natural enemies protect plants by regulating herbivore populations. Whether they can alter the behavior of their prey to increase predation success is unknown. We investigate if and how infection by the entomopathogenic nematode changes the behavior of healthy larvae of the western corn rootworm (), a major pest of maize.

Photorhabdus khanii subsp. guanajuatensis subsp. nov., isolated from Heterorhabditis atacamensis, and Photorhabdus luminescens subsp. mexicana subsp. nov., isolated from Heterorhabditis mexicana entomopathogenic nematodes.

Two Gram-negative, rod-shaped, non-spore-forming bacteria, MEX20-17 and MEX47-22, were isolated from the digestive system of Heterorhabditis atacamensis and Heterorhabditis mexicana entomopathogenic nematodes, respectively. Their 16S rRNA gene sequences suggest that strains MEX20-17 and MEX47-22 belong to the γ-Proteobacteria and to the genus Photorhabdus. Deeper analyses using housekeeping-gene-based and whole-genome-based phylogenetic reconstruction suggest that MEX20-17 is closely related to Photorhabdus khanii and that MEX47-22 is closely related to Photorhabdus luminescens.

Whole-genome-based revisit of Photorhabdus phylogeny: proposal for the elevation of most Photorhabdus subspecies to the species level and description of one novel species Photorhabdus bodei sp. nov., and one novel subspecies Photorhabdus laumondii subsp. clarkei subsp. nov.

Bacterial symbionts are crucial for the infectivity and success of entomopathogenic nematodes as biological control agents. The current understanding of the symbiotic relationships is limited by taxonomic uncertainties. Here, we used whole-genome sequencing and traditional techniques to reconstruct the phylogenetic relationships between all described Photorhabdus species and subspecies as well as 11 newly isolated symbiotic bacteria of Heterorhabditis nematodes, including the unreported bacterial partner of H.

Aboveground herbivory induced jasmonates disproportionately reduce plant reproductive potential by facilitating root nematode infestation.

Different plant feeders, including insects and parasitic nematodes, can influence each other by triggering systemic changes in their shared host plants. In most cases, however, the underlying mechanisms are unclear, and the consequences for plant fitness are not well understood. We studied the interaction between leaf feeding Manduca sexta caterpillars and root parasitic nematodes in Nicotiana attenuata.

Localized micronutrient patches induce lateral root foraging and chemotropism in Nicotiana attenuata.

Nutrients are distributed unevenly in the soil. Phenotypic plasticity in root growth and proliferation may enable plants to cope with this variation and effectively forage for essential nutrients. However, how micronutrients shape root architecture of plants in their natural environments is poorly understood.

Species-specific regulation of herbivory-induced defoliation tolerance is associated with jasmonate inducibility.

Induced changes in root carbohydrate pools are commonly assumed to determine plant defoliation tolerance to herbivores. However, the regulation and species specificity of these two traits are not well understood. We determined herbivory-induced changes in root carbohydrates and defoliation tolerance in seven different solanaceous plant species and correlated the induced changes in root carbohydrates and defoliation tolerance with jasmonate inducibility.

A Herbivore Tag-and-Trace System Reveals Contact- and Density-Dependent Repellence of a Root Toxin.

Foraging behavior of root feeding organisms strongly affects plant-environment-interactions and ecosystem processes. However, the impact of plant chemistry on root herbivore movement in the soil is poorly understood. Here, we apply a simple technique to trace the movement of soil-dwelling insects in their habitats without disturbing or restricting their interactions with host plants.

Nematode Root Herbivory in Tomato Increases Leaf Defenses and Reduces Leaf Miner Oviposition and Performance.

The outcome of plant-mediated interactions among herbivores from several feeding guilds has been studied intensively. However, our understanding on the effects of nematode root herbivory on leaf miner oviposition behavior and performance remain limited. In this study, we evaluated whether Meloidogyne incognita root herbivory affects Tuta absoluta oviposition preference on Solanum lycopersicum plants and the development of the resulting offspring.

Auxin Is Rapidly Induced by Herbivore Attack and Regulates a Subset of Systemic, Jasmonate-Dependent Defenses.

Plant responses to herbivore attack are regulated by phytohormonal networks. To date, the role of the auxin indole-3-acetic acid (IAA) in this context is not well understood. We quantified and manipulated the spatiotemporal patterns of IAA accumulation in herbivore-attacked Nicotiana attenuata plants to unravel its role in the regulation of plant secondary metabolism.

A Nicotiana attenuata cell wall invertase inhibitor (NaCWII) reduces growth and increases secondary metabolite biosynthesis in herbivore-attacked plants.

Plant invertases are sucrolytic enzymes that are essential for the regulation of carbohydrate metabolism and source-sink relationships. While their activity has been well documented during abiotic and biotic stresses, the role of proteinaceous invertase inhibitors in regulating these changes is unknown. Here, we identify a putative Nicotiana attenuata cell wall invertase inhibitor (NaCWII) which is strongly up-regulated in a jasmonate (JA)-dependent manner following simulated attack by the specialist herbivore Manduca sexta.

Jasmonate-dependent depletion of soluble sugars compromises plant resistance to Manduca sexta.

Jasmonates regulate plant secondary metabolism and herbivore resistance. How they influence primary metabolites and how this may affect herbivore growth and performance are not well understood. We profiled sugars and starch of jasmonate biosynthesis-deficient and jasmonate-insensitive Nicotiana attenuata plants and manipulated leaf carbohydrates through genetic engineering and in vitro complementation to assess how jasmonate-dependent sugar accumulation affects the growth of Manduca sexta caterpillars.

Induced carbon reallocation and compensatory growth as root herbivore tolerance mechanisms.

Upon attack by leaf herbivores, many plants reallocate photoassimilates below ground. However, little is known about how plants respond when the roots themselves come under attack. We investigated induced resource allocation in maize plants that are infested by the larvae Western corn rootworm Diabrotica virgifera virgifera.