Physical and Chemical Interactions between Insects and Plants

A special issue of Insects (ISSN 2075-4450). This special issue belongs to the section "Insect Pest and Vector Management".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 26621

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Dipartimento di Scienze Agrarie, Alimentari e Ambientali, University of Perugia, Perugia, Italy
Interests: insect–plant mechanical and chemical interactions; indirect plant defences; constitutive or induced by herbivores; insect electrophysiology; behaviour and chemical ecology of egg-parasitoid; morpho-functional adaptations of insects

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Guest Editor
Dipartimento di Chimica, Biologia e Biotecnologie, University of Perugia, Perugia, Italy
Interests: functional morphology of insect attachment devices; insect-plant interactions; insect sensilla; functional morphology of aquatic insects

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Guest Editor
Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, 24118 Kiel, Germany
Interests: biological attachment; functional morphology; biomechanics; biotribology; biomimetics
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Special Issue Information

Dear Colleagues,

Plants and herbivorous insects, as well as their natural enemies, such as predatory and parasitoid insects, are united by intricate relationships. During the long period of co-evolution with insects, plants developed a wide diversity of features to defense against herbivores and to attract pollinators and herbivore natural enemies. The chemical basis of insect-plant interactions is established and many examples are studied, where feeding and oviposition site selection of phytophagous insects are dependent on plant secondary chemistry. Additionally, insect endosymbionts play an important role in the chemical perception, nutrition, metabolism, as well as reproduction of their host, which together determine its survival and fitness on the plant. 

However, often overlooked mechanical interactions between insects and plants can be rather crucial. In this context, the evolution of plant surfaces and insect adhesive pads is an interesting example of competition between insect attachment systems and plant anti-attachment surfaces. To achieve sufficient attachment to enable locomotion on widely diverse plant surfaces, insects evolved various types of leg attachment devices enabling them to overcome plant physical defence such as cuticular microfolds, various kinds of trichomes and cristalline wax covered surfaces. Also insect mouthpart mechanics is adapted to certain mechanical properties of the plant surface, which in combination may determine insect-plant interactions.

This Special Issue will focus on the chemical and physical interactions between insects and plants, in order to understand the functional significance of plant chemistry, plant surface structures and their relationships with broad range variety of ecological groups of insects, including pollinators, herbivores and parasitoids. Contributions to all aspects of direct insect–plant interactions and as a multilayered relationship with various micro- and macro-organisms associated either temporally or spatially are welcomed.

Prof. Gianandrea Salerno
Prof. Manuela Rebora
Prof. Stanislav Gorb
Guest Editors

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Published Papers (13 papers)

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Editorial

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3 pages, 168 KiB  
Editorial
Mechanoecology and Chemoecology: Physical and Chemical Interactions between Insects and Plants
by Gianandrea Salerno, Manuela Rebora and Stanislav Gorb
Insects 2023, 14(7), 657; https://doi.org/10.3390/insects14070657 - 23 Jul 2023
Cited by 2 | Viewed by 722
Abstract
Plants and herbivorous insects, as well as their natural enemies such as predatory and parasitoid insects, are united by intricate relationships [...] Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)

Research

Jump to: Editorial

11 pages, 5957 KiB  
Article
Petals Reduce Attachment of Insect Pollinators: A Case Study of the Plant Dahlia pinnata and the Fly Eristalis tenax
by Elena V. Gorb and Stanislav N. Gorb
Insects 2023, 14(3), 285; https://doi.org/10.3390/insects14030285 - 14 Mar 2023
Cited by 1 | Viewed by 1929
Abstract
In order to understand whether the petal surface in “cafeteria”-type flowers, which offer their nectar and pollen to insect pollinators in an open way, is adapted to a stronger attachment of insect pollinators, we selected the plant Dahlia pinnata and the hovering fly [...] Read more.
In order to understand whether the petal surface in “cafeteria”-type flowers, which offer their nectar and pollen to insect pollinators in an open way, is adapted to a stronger attachment of insect pollinators, we selected the plant Dahlia pinnata and the hovering fly Eristalis tenax, both being generalist species according to their pollinator’s spectrum and diet, respectively. We combined cryo scanning electron microscopy examination of leaves, petals, and flower stems with force measurements of fly attachment to surfaces of these plant organs. Our results clearly distinguished two groups among tested surfaces: (1) the smooth leaf and reference smooth glass ensured a rather high attachment force of the fly; (2) the flower stem and petal significantly reduced it. The attachment force reduction on flower stems and petals is caused by different structural effects. In the first case, it is a combination of ridged topography and three-dimensional wax projections, whereas the papillate petal surface is supplemented by cuticular folds. In our opinion, these “cafeteria”-type flowers have the petals, where the colour intensity is enhanced due to papillate epidermal cells covered by cuticular folds at the micro- and nanoscale, and exactly these latter structures mainly contribute to adhesion reduction in generalist insect pollinators. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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12 pages, 1971 KiB  
Article
Can Macrolophus pygmaeus (Hemiptera: Miridae) Mitigate the Damage Caused to Plants by Bemisia tabaci (Hemiptera: Aleyrodidae)?
by Alessia Farina, Giuseppe Eros Massimino Cocuzza, Pompeo Suma and Carmelo Rapisarda
Insects 2023, 14(2), 164; https://doi.org/10.3390/insects14020164 - 08 Feb 2023
Cited by 1 | Viewed by 1751
Abstract
Nowadays, in protected vegetable crops, pest management based mainly on biological control represents the most sustainable alternative to pesticide use. The cotton whitefly, Bemisia tabaci, is one of the key pests that negatively impact the yield and quality of such crops in [...] Read more.
Nowadays, in protected vegetable crops, pest management based mainly on biological control represents the most sustainable alternative to pesticide use. The cotton whitefly, Bemisia tabaci, is one of the key pests that negatively impact the yield and quality of such crops in many agricultural systems. The predatory bug Macrolophus pygmaeus is one of the main natural enemies of the whitefly and is widely used for its control. However, the mirid can sometimes behave as a pest itself, causing damage to crops. In this study, we investigated the impact of M. pygmaeus as a plant feeder, by analyzing the combined impact of the whitefly pest and the predator bug on the morphology and physiology of potted eggplants under laboratory conditions. Our results showed no statistical differences between the heights of plants infested by the whitefly or by both insects compared with noninfested control plants. However, indirect chlorophyll content, photosynthetic performance, leaf area, and shoot dry weight were all greatly reduced in plants infested only by B. tabaci, compared with those infested by both pest and predator or with noninfested control plants. Contrarily, root area and dry weight values were more reduced in plants exposed to both of the insect species, compared with those infested only by the whitefly or compared with noninfested control plants, where the latter showed the highest values. These results show how the predator can significantly reduce the negative effects of B. tabaci infestation, limiting the damage it causes to host plants, though the effect of the mirid bug on the underground parts of the eggplant remains unclear. This information might be useful for a better understanding of the role that M. pygmaeus plays in plant growth, as well as for the development of management strategies to successfully control infestations by B. tabaci in cropping environments. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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18 pages, 5040 KiB  
Article
Effect of Leaf Trichomes in Different Species of Cucurbitaceae on Attachment Ability of the Melon Ladybird Beetle Chnootriba elaterii
by Valerio Saitta, Manuela Rebora, Silvana Piersanti, Elena Gorb, Stanislav Gorb and Gianandrea Salerno
Insects 2022, 13(12), 1123; https://doi.org/10.3390/insects13121123 - 05 Dec 2022
Cited by 7 | Viewed by 1810
Abstract
This study investigates the attachment ability of the oligophagous melon ladybird beetle Chnootriba elaterii to leaves of several Cucurbitaceae species. Using cryo-SEM, we described adult and larva tarsal attachment devices and leaf surface structures (glandular and non-glandular trichomes) in Citrullus lanatus, Cucumis [...] Read more.
This study investigates the attachment ability of the oligophagous melon ladybird beetle Chnootriba elaterii to leaves of several Cucurbitaceae species. Using cryo-SEM, we described adult and larva tarsal attachment devices and leaf surface structures (glandular and non-glandular trichomes) in Citrullus lanatus, Cucumis melo, Cucumis sativus, Cucurbita moschata, Cucurbita pepo, Ecballium elaterium, Lagenaria siceraria and Luffa aegyptiaca. Using traction force experiments and centrifugal force tests, we measured the friction force exerted by females and larvae on plant leaves. We observed that Cucurbitaceae glandular trichomes do not affect insect attachment ability at both developmental stages, suggesting some adaptation of C. elaterii to its host plants, while non-glandular trichomes, when they are dense, short and flexible, heavily reduce the attachment ability of both insect stages. When trichomes are dense but stiff, only the larval force is reduced, probably because the larva has a single claw, in contrast to the adult having paired bifid dentate claws. The data on the mechanical interaction of C. elaterii at different developmental stages with different Cucurbitaceae species, combined with data on the chemical cues involved in the host plant selection, can help to unravel the complex factors driving the coevolution between an oligophagous insect and its host plant species. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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20 pages, 76787 KiB  
Article
Attachment Performance of Stick Insects (Phasmatodea) on Plant Leaves with Different Surface Characteristics
by Judith Burack, Stanislav N. Gorb and Thies H. Büscher
Insects 2022, 13(10), 952; https://doi.org/10.3390/insects13100952 - 19 Oct 2022
Cited by 9 | Viewed by 2405
Abstract
Herbivorous insects and plants exemplify a longstanding antagonistic coevolution, resulting in the development of a variety of adaptations on both sides. Some plant surfaces evolved features that negatively influence the performance of the attachment systems of insects, which adapted accordingly as a response. [...] Read more.
Herbivorous insects and plants exemplify a longstanding antagonistic coevolution, resulting in the development of a variety of adaptations on both sides. Some plant surfaces evolved features that negatively influence the performance of the attachment systems of insects, which adapted accordingly as a response. Stick insects (Phasmatodea) have a well-adapted attachment system with paired claws, pretarsal arolium and tarsal euplantulae. We measured the attachment ability of Medauroidea extradentata with smooth surface on the euplantulae and Sungaya inexpectata with nubby microstructures of the euplantulae on different plant substrates, and their pull-off and traction forces were determined. These species represent the two most common euplantulae microstructures, which are also the main difference between their respective attachment systems. The measurements were performed on selected plant leaves with different properties (smooth, trichome-covered, hydrophilic and covered with crystalline waxes) representing different types among the high diversity of plant surfaces. Wax-crystal-covered substrates with fine roughness revealed the lowest, whereas strongly structured substrates showed the highest attachment ability of the Phasmatodea species studied. Removal of the claws caused lower attachment due to loss of mechanical interlocking. Interestingly, the two species showed significant differences without claws on wax-crystal-covered leaves, where the individuals with nubby euplantulae revealed stronger attachment. Long-lasting effects of the leaves on the attachment ability were briefly investigated, but not confirmed. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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18 pages, 8224 KiB  
Article
Floral Volatile Organic Compounds and a List of Pollinators of Fallopia baldschuanica (Polygonaceae)
by Anna Jakubska-Busse, Mariusz Dziadas, Iwona Gruss and Michał J. Kobyłka
Insects 2022, 13(10), 904; https://doi.org/10.3390/insects13100904 - 05 Oct 2022
Cited by 3 | Viewed by 2278
Abstract
Fallopia baldschuanica (Polygonaceae) is an Asian plant growing wild in parts of Europe and North and Central America as an introduced taxon, in many countries it is considered a potentially invasive species. This article presents the list of 18 volatile organic compounds (VOCs) [...] Read more.
Fallopia baldschuanica (Polygonaceae) is an Asian plant growing wild in parts of Europe and North and Central America as an introduced taxon, in many countries it is considered a potentially invasive species. This article presents the list of 18 volatile organic compounds (VOCs) emitted by the flowers of F. baldchuanica and identified by headspace gas chromatography/mass spectrometry (HS-GC/MS) analyzes, and a list of flower-visiting and pollinating insects that have been observed in the city center of Wrocław (SW Poland). β-ocimene, heptanal, nonanal, α-pinene, 3-thujene, and limonene, were detected as the floral scent’s most important aroma compounds. F. baldschuanica also produces the aphid alarm pheromones, i.e., β-farnesene and limonene, that repels aphids. Additionally, the pollinators of F. baldschuanica were indicated, based on two years of observations in five sites in the urban area. It was found, that the pollinators of this plant with the highest species stability are: Diptera from families Syrphidae (Chrysotoxum bicinctum, Eristalis pertinax, Eupeodes corollae, Episyrphus balteatus, Eristalis tenax, Syrphus ribesii, Eristalis intricaria), Muscidae (Musca domestica), Sarcophagidae (Sarcophaga spp.), Calliphoridae (Lucilia sericata, Lucilia caesar), Hymenoptera from families Vespidae (Vespula vulgaris), and Apidae (Apis sp., Bombus sp.). The key role of VOCs in adaptation to plant expansion is discussed. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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20 pages, 2633 KiB  
Article
Physicochemical Properties of Sugarcane Cultivars Affected Life History and Population Growth Parameters of Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae)
by Seyedeh Atefeh Mortazavi Malekshah, Bahram Naseri, Hossein Ranjbar Aghdam, Jabraeil Razmjou, Seyed Ali Asghar Fathi, Asgar Ebadollahi and Tanasak Changbunjong
Insects 2022, 13(10), 901; https://doi.org/10.3390/insects13100901 - 03 Oct 2022
Cited by 1 | Viewed by 1444
Abstract
The use of resistant cultivars is an efficient management strategy against S. nonagrioides. The effects of different sugarcane cultivars, CP48-103, CP57-614, CP69-1062, CP73-21, SP70-1143, and IRC99-02 were evaluated on the oviposition preference (free-choice assay), life history, and life table parameters of S. [...] Read more.
The use of resistant cultivars is an efficient management strategy against S. nonagrioides. The effects of different sugarcane cultivars, CP48-103, CP57-614, CP69-1062, CP73-21, SP70-1143, and IRC99-02 were evaluated on the oviposition preference (free-choice assay), life history, and life table parameters of S. nonagrioides at 27 ± 1 °C, 60 ± 5% RH and a photoperiod of 16: 8 (L: D) h. The longest and shortest developmental times were on cultivars SP70-1143 and CP48-103, respectively. The oviposition preference of S. nonagrioides was the highest on cultivars CP48-103 and CP69-1062, and negatively correlated with the shoot trichome density and shoot rind hardness of the cultivars. The highest intrinsic rate of increase of S. nonagrioides was on cultivar CP48-103 and the lowest was on cultivar SP70-1143. The shortest mean generation time was on CP48-103 and the longest was on SP70-1143. The results indicate that cultivars CP48-103 and CP69-1062 were susceptible, and cultivar SP70-1143 was partially resistant against S. nonagrioides. This information could be useful for developing integrated management programs of S. nonagrioides, such as the use of resistant cultivars to reduce the damage caused by this pest in sugarcane fields. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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13 pages, 18721 KiB  
Article
Quantifying the Influence of Pollen Aging on the Adhesive Properties of Hypochaeris radicata Pollen
by Steven Huth, Lisa-Maricia Schwarz and Stanislav N. Gorb
Insects 2022, 13(9), 811; https://doi.org/10.3390/insects13090811 - 06 Sep 2022
Cited by 2 | Viewed by 1446
Abstract
Although pollination is one of the most crucial biological processes that ensures plant reproduction, its mechanisms are poorly understood. Especially in insect-mediated pollination, a pollen undergoes several attachment and detachment cycles when being transferred from anther to insect and from insect to stigma. [...] Read more.
Although pollination is one of the most crucial biological processes that ensures plant reproduction, its mechanisms are poorly understood. Especially in insect-mediated pollination, a pollen undergoes several attachment and detachment cycles when being transferred from anther to insect and from insect to stigma. The influence of the properties of pollen, insect and floral surfaces on the adhesion forces that mediate pollen transfer have been poorly studied. Here, we investigate the adhesive properties of Hypochaeris radicata pollen and their dependence on pollen aging by quantifying the pull-off forces from glass slides using centrifugation and atomic force microscopy. We found that the properties of the pollenkitt—the viscous, lipid liquid on the surface of most pollen grains—influences the forces necessary to detach a pollen from hydrophilic surfaces. Our results show that aged H. radicata pollen form weaker adhesions to hydrophilic glass than fresh ones. On the other hand, when a pollen grain ages in contact with glass, the adhesion between the two surfaces increases over time. This study shows for the first time the pollen aging effect on the pollination mechanism. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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18 pages, 2901 KiB  
Article
Full-Length Transcriptome Sequencing-Based Analysis of Pinus sylvestris var. mongolica in Response to Sirex noctilio Venom
by Chenglong Gao, Lili Ren, Ming Wang, Zhengtong Wang, Ningning Fu, Huiying Wang and Juan Shi
Insects 2022, 13(4), 338; https://doi.org/10.3390/insects13040338 - 30 Mar 2022
Cited by 2 | Viewed by 1911
Abstract
Sirex noctilio is a major international quarantine pest that recently emerged in northeast China to specifically invade conifers. During female oviposition, venom is injected into the host together with its symbiotic fungus to alter the normal Pinus physiology and weaken or even kill [...] Read more.
Sirex noctilio is a major international quarantine pest that recently emerged in northeast China to specifically invade conifers. During female oviposition, venom is injected into the host together with its symbiotic fungus to alter the normal Pinus physiology and weaken or even kill the tree. In China, the Mongolian pine (Pinus sylvestris var. mongolica), an important wind-proof and sand-fixing species, is the unique host of S. noctilio. To explore the interplay between S. noctilio venom and Mongolian pine, we performed a transcriptome comparative analysis of a 10-year-old Mongolian pine after wounding and inoculation with S. noctilio venom. The analysis was performed at 12 h, 24 h and 72 h. PacBio ISO-seq was used and integrated with RNA-seq to construct an accurate full-length transcriptomic database. We obtained 52,963 high-precision unigenes, consisting of 48,654 (91.86%) unigenes that were BLASTed to known sequences in the public database and 4309 unigenes without any annotation information, which were presumed to be new genes. The number of differentially expressed genes (DEGs) increased with the treatment time, and the DEGs were most abundant at 72 h. A total of 706 inoculation-specific DEGs (475 upregulated and 231 downregulated) and 387 wounding-specific DEGs (183 upregulated and 204 downregulated) were identified compared with the control. Under venom stress, we identified 6 DEGs associated with reactive oxygen species (ROS) and 20 resistance genes in Mongolian pine. Overall, 52 transcription factors (TFs) were found under venom stress, 45 of which belonged to the AP2/ERF TF family and were upregulated. A total of 13 genes related to the photosystem, 3 genes related photo-regulation, and 9 TFs were identified under wounding stress. In conclusion, several novel putative genes were found in Mongolian pine by PacBio ISO seq. Meanwhile, we also identified various genes that were resistant to S. noctilio venom, such as GAPDH, GPX, CAT, FL2, CERK1, and HSP83A, etc. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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13 pages, 1554 KiB  
Article
Herbivore-Induced Rice Volatiles Attract and Affect the Predation Ability of the Wolf Spiders, Pirata subpiraticus and Pardosa pseudoannulata
by Jing Liu, Liangyu Sun, Di Fu, Jiayun Zhu, Min Liu, Feng Xiao and Rong Xiao
Insects 2022, 13(1), 90; https://doi.org/10.3390/insects13010090 - 13 Jan 2022
Cited by 8 | Viewed by 1755
Abstract
Spiders are important natural enemies of rice pests. Studying the effects of herbivore-induced rice volatiles on spider attraction and predation ability may lead to safer methods for pest prevention and control. In this study, four-arm olfactometer, predation ability experiment, and field trapping experiment [...] Read more.
Spiders are important natural enemies of rice pests. Studying the effects of herbivore-induced rice volatiles on spider attraction and predation ability may lead to safer methods for pest prevention and control. In this study, four-arm olfactometer, predation ability experiment, and field trapping experiment were used to evaluate the effects of herbivore-induced rice volatiles on Pirata subpiraticus Bösenberg et Strand (Araneae: Lycosidae) and Pardosa pseudoannulata Bösenberg et Strand (Araneae: Lycosidae). The 0.5 μg/μL linalool concentration was attractive, and also shortened the predation latency in male P. subpiraticus and female P. pseudoannulata. The 0.5 μg/μL linalool concentration increased the daily predation capacity of female P. pseudoannulata. Male P. pseudoannulata were attracted to 1.0 g/L methyl salicylate, which also shortened their predation latency. In field experiments, methyl salicylate and linalool were effective for trapping spiders. Herbivore-induced rice volatiles attract rice field spiders and affect their predatory ability. These results suggest that herbivore-induced rice volatiles can be used to attract spiders and provide improved control of rice pests. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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14 pages, 8860 KiB  
Article
Combined Effect of Different Flower Stem Features on the Visiting Frequency of the Generalist Ant Lasius niger: An Experimental Study
by Elena V. Gorb and Stanislav N. Gorb
Insects 2021, 12(11), 1026; https://doi.org/10.3390/insects12111026 - 14 Nov 2021
Cited by 3 | Viewed by 1815
Abstract
In order to understand the effects of the morphology and surface texture of flower stems in Smyrnium rotundifolium on the visiting frequency of generalist ants, we conducted experiments with Lasius niger ants running on dry wooden sticks mimicking different types of stems: (1) [...] Read more.
In order to understand the effects of the morphology and surface texture of flower stems in Smyrnium rotundifolium on the visiting frequency of generalist ants, we conducted experiments with Lasius niger ants running on dry wooden sticks mimicking different types of stems: (1) intact (grooved) sticks; (2) sticks painted with slaked (hydrated) lime (calcium carbonate coverage) imitating plant epicuticular wax coverage; (3) intact sticks with smooth polyester plate-shaped cuffs imitating upper leaves; and (4) intact sticks bearing cuffs painted with slaked lime. Ants were attracted by the sweet sugar syrup droplets placed on a stick tip, and the number of ants visiting the drops was counted. Our data showed significant differences in the visiting frequencies between the different types of stem-mimicking samples. The number of recorded ants progressively decreased in the following order of samples: intact sticks—painted sticks—sticks with intact cuffs—sticks with painted cuffs. These results clearly demonstrated that micro/nanoscopic surface coverages and macroscopic physical barriers, especially if combined, have a negative impact on the attractiveness of stems to ants. This study provides further evidence for the hypothesis that having a diversity of plant stems in the field, generalist ants prefer substrates where their locomotion is less hindered by obstacles and/or surface slipperiness. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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13 pages, 801 KiB  
Article
Defensive Traits during White Spruce (Picea glauca) Leaf Ontogeny
by Antoine-Olivier Lirette and Emma Despland
Insects 2021, 12(7), 644; https://doi.org/10.3390/insects12070644 - 15 Jul 2021
Cited by 2 | Viewed by 2476
Abstract
Changes during leaf ontogeny affect palatability to herbivores, such that many insects, including the eastern spruce budworm (Choristoneura fumiferana (Clem.)), are specialist feeders on growing conifer leaves and buds. Developmental constraints imply lower toughness in developing foliage, and optimal defense theory predicts [...] Read more.
Changes during leaf ontogeny affect palatability to herbivores, such that many insects, including the eastern spruce budworm (Choristoneura fumiferana (Clem.)), are specialist feeders on growing conifer leaves and buds. Developmental constraints imply lower toughness in developing foliage, and optimal defense theory predicts higher investment in chemical defense in these vulnerable yet valuable developing leaves. We summarize the literature on the time course of defensive compounds in developing white spruce (Picea glauca (Moench) Voss) needles and report original research findings on the ontogeny of white spruce needle toughness. Our results show the predicted pattern of buds decreasing in toughness followed by leaves increasing in toughness during expansion, accompanied by opposite trends in water content. Toughness of mature foliage decreased slightly during the growing season, with no significant relationship with water content. Toughness of sun-grown leaves was slightly higher than that of shade-grown leaves. However, the literature review did not support the expected pattern of higher defensive compounds in expanding leaves than in mature leaves, suggesting that white spruce might instead exhibit a fast-growth low-defense strategy. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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17 pages, 2893 KiB  
Article
Role of Fruit Epicuticular Waxes in Preventing Bactrocera oleae (Diptera: Tephritidae) Attachment in Different Cultivars of Olea europaea
by Manuela Rebora, Gianandrea Salerno, Silvana Piersanti, Elena Gorb and Stanislav Gorb
Insects 2020, 11(3), 189; https://doi.org/10.3390/insects11030189 - 17 Mar 2020
Cited by 19 | Viewed by 3061
Abstract
The olive fruit fly Bactrocera oleae (Diptera: Tephritidae) is the major pest of cultivated olives (Olea europaea L.), and a serious threat in all of the Mediterranean Region. In the present investigation, we demonstrated with traction force experiments that B. oleae female [...] Read more.
The olive fruit fly Bactrocera oleae (Diptera: Tephritidae) is the major pest of cultivated olives (Olea europaea L.), and a serious threat in all of the Mediterranean Region. In the present investigation, we demonstrated with traction force experiments that B. oleae female adhesion is reduced by epicuticular waxes (EWs) fruit surface, and that the olive fruit fly shows a different ability to attach to the ripe olive surface of different cultivars of O. europaea (Arbequina, Carolea, Dolce Agogia, Frantoio, Kalamata, Leccino, Manzanilla, Picholine, Nostrale di Rigali, Pendolino and San Felice) in terms of friction force and adhesion, in relation with different mean values of olive surface wettability. Cryo-scanning morphological investigation revealed that the EW present on the olive surface of the different analyzed cultivars are represented by irregular platelets varying in the orientation, thus contributing to affect the surface microroughness and wettability in the different cultivars, and consequently the olive fruit fly attachment. Further investigations to elucidate the role of EW in olive varietal resistance to the olive fruit fly in relation to the olive developmental stage and environmental conditions could be relevant to develop control methods alternative to the use of harmful pesticides. Full article
(This article belongs to the Special Issue Physical and Chemical Interactions between Insects and Plants)
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