Arthropod-Plant Interactions最新文献

The specific interaction of fig (Ficus) and its fig wasp pollinator (Agaonidae) is sustained by the olfactory signal in combination with morphological co-adaptations. Ficus deltoidea complex is a dioecious fig tree that is regularly pollinated by the fig wasp Blastophaga spp. This complex includes 13 varieties, seven of which are native to Peninsular Malaysia. The classification relies exclusively on leaf characterisation, without considering gene flow across sympatric taxa. Additionally, it remains unexplored whether different varieties support distinct fig wasp pollinators, or to what extent the floral scents emitted by receptive phase figs of these varieties differ. An experiment was conducted to determine the host specificity of Blastophaga sp. from var. trengganuensis in the germplasm of UniSZA by placing a donor male tree from var. trengganuensis surrounded by other varieties. To see the correlation between the varieties entered by the fig wasps and the volatile odour compound (VOC) releases from the receptive figs, a headspace solid-phase microextraction and gas chromatography–mass spectrometry analysis were used. The breakdown of one-to-one specificity in fig and fig wasp mutualism occurs when Blastophaga sp. from var. trengganuensis enters another variety (var. kunstleri) apart from its own variety. Monoterpenes, sesquiterpenes, and aliphatic compounds were detected in the odours of five sympatric fig varieties of F. deltoidea with varying compositions. Multivariate data analysis using PLS revealed the existence of three distinct groups based on differences in VOC content. Females of both var. kunstleri and var. trengganuensis were clustered together, with 12 compounds identified as potentially correlated with the number of fig wasps that entered. Our findings imply that pollinator specificity in figs was potentially mediated by chemical signals in the fig odour where the overlapping of compounds between two varieties caused the pollinators from one variety to reach their non-host plants. Pollinator sharing between two varieties revealed the breakdown of pollinator specificity in var. trengganuensis, showing gene flow is happening in the closely related trees that differ in appearance.

Flower mites are often assumed to negatively impact plant reproductive fitness by depleting floral resources for pollinators. However, there is a lack of studies directly investigating the effects of mites on pollination. This study explores the potential role of Hattena rhizophorae mites in the pollination of the anemophilous species Rhizophora mangle. We hypothesized that H. rhizophorae mites might contribute to the pollination of R. mangle if they (1) are prevalent on flowers, (2) can easily disperse through means other than phoresy, and (3) contribute to pollen transport and deposition.

We examined the spatiotemporal variability of H. rhizophorae mites on R. mangle flowers in relation to the season, the R. mangle patch size, and the abundance of insect visitors that may act as their dispersal vectors We also investigated whether mites could alternatively disperse among flowers via air currents and running water, quantified the pollen grains on the mites’ bodies, and observed whether they made contact with the flower stigmas. We found that mites might serve as pollinators of R. mangle as they were relatively common on flowers, with an average infestation frequency of 40% ± 7% of flowers and an abundance of 68.4 ± 15.5 mites per flower. Their numbers increased with patch size, insect visitor abundance, and during the rainy season. Mites were transported by wind, though there was no evidence of transportation by running water. They appeared to contribute to pollen transport and deposition, as we observed pollen grains attached to their bodies and mites walking on flower stigmas.

Insect damage to a plant activates induced defenses, which include releases of herbivore induced plant volatiles (HIPVs) that attract natural enemies and usually repel generalist herbivores. Oppositely, most herbivore specialists have evolved responses against these defenses, and in many cases are attracted to host HIPVs. However, it is not clear if a specialist is able to discriminate HIPVs released by conspecifics, other specialists, or generalist damage. Dioscorea bulbifera is an invasive vine native to Asia and Africa with infestations in the southeastern United States, Hawai’i, and Puerto Rico. A host specific biological control agent, Lilioceris cheni (Coleoptera: Chrysomelidae) was introduced in 2011 to control D. bulbifera. Recently, a new host specific biological control agent, Lilioceris egena, has been released to improve the biological control program for D. bulbifera. In this study, attraction of L. cheni to HIPVs from generalist, Spodoptera frugiperda (Lepidoptera: Noctuidae); specialist, L. egena; and conspecific damage were investigated. Behavioral assays indicated L. cheni had preference for any type of herbivore damaged plants compared to undamaged plants and discriminated between conspecific damaged plants in the presence of generalist damaged plants, favoring conspecific damaged plants. Differently damaged D. bulbifera plants were then evaluated using gas chromatography coupled with mass spectroscopy which revealed significant quantitative differences between both the specialists’ herbivore damage compared to the generalist volatile profiles with induction of 11 volatiles and suppression of four. This study highlights the importance of understanding an invasive plant’s response to specialist and generalist damage for better management of the invasive species.

This work aims to enhance our understanding of plant-defense mechanisms, which is crucial for developing resistant crops following pest attacks. Focusing on the susceptibility of Tunisian barley to the gall midge Mayetiola hordei, the current study explores how gall formation affects the structure of attacked organs, and how sensitive and resistant barley cultivars respond to infestations. Two barley cultivars, Kounouz and Rihane, were selected for this experiment in two semi-arid regions of North Tunisia, Zaghouan and Kef. Sampling was carried out at four stages of barley development (tillering, elongation, heading, and ripening). Kef region was identified as the most affected area, recording significant economic and severe infestations for Kounouz variety, particularly at the ripening stage (53% and 24%, respectively). While Rihane variety demonstrated the least susceptibility, with only 4% of tillers severely infested during the heading stage in Kef and 7% in Zaghouan. This study detected structural changes in the stem induced by gall formation, revealing cellular hypertrophy, tissue hyperplasia, and lignin accumulation. Furthermore, the findings demonstrated a significant increase in total polyphenol compounds and total peroxidase activity upon gall midge attack. Polyphenol, flavonoid, condensed tannins, and peroxidase activity concentrations after infestation reached 1.312 ± 0.056 mgGAE/gWF; 1.457 ± 0.079 mgRE/gWF; 0.237 ± 0.036 mgCE/gWF; and 4.160 U/g FW, respectively, for Rihane variety during the heading stage of barley in Kef. The study also highlighted a linear relationship between peroxidase activity and total phenolic content post-infestation, underscoring the role of phenolic compounds and peroxidase activity in plant resistance and defense in response to M. hordei-induced stress.

Although diverse wild pollinators contribute to crop pollination, nocturnal pollinators have been largely overlooked. In this study, we focused on buckwheat, which relies on various insect species for pollination. Since buckwheat flowers are believed to close in the evening, earlier studies have exclusively examined the role of diurnal pollinators. However, some buckwheat flowers have been observed opening at night; thus, we can assume that nocturnal insects play a role in buckwheat pollination. Our field observations showed that 80% of buckwheat flowers that opened in the morning remained open at night. The insects visiting buckwheat flowers at night belonged to the moth families of Noctuidae, Crambidae, and Pyralidae. These moths were all found to have buckwheat pollen on their bodies. To quantify the contribution of nocturnal pollinators to seed set, we conducted a pollinator exclusion experiment using the following bagging treatments: no pollinators (bagging for 24 h), only diurnal pollinators (bagging from 18:00 to 06:00), only nocturnal pollinators (bagging from 06:00 to 18:00), and natural pollination (no bagging). The results showed that the seed set decreased in the following order: natural pollination, diurnal pollinators only, nocturnal pollinators only, and no pollinators, with one-fourth of the buckwheat seed sets resulting from nocturnal pollinators. However, the proportion of flowers open at night decreased as the flowering period progress, and the role of nocturnal pollinators appeared to decline over time. Our findings suggests that nocturnal pollinators may complementarily increase buckwheat seed sets, emphasizing the need to investigate overlooked nocturnal pollinators in crop pollination services.

Inducible defense is an important anti-insect strategy in plants. This study investigated whether larval feeding by Hyphantria cunea at low-density and high-density levels can initiate inducible defense responses in the low-fitness host plant Tilia amurensis on the 7th- and 21th-day post-feeding. The results revealed significant alterations in the nutrient composition (e.g., amino acids, soluble sugars, and total proteins) within T. amurensis, with notable decreases observed on the 7th-day post-feeding, followed by increases on the 21st day, respectively. Specifically, the low-density feeding group prompted significant increases in tannin, total phenols, and total flavonoids on the 7th day, whereas the high-density feeding group induced significant decreases in these compounds. Conversely, total alkaloid levels exhibited an inverse pattern, with lignin contents notably decreasing. By the 21st-day post-feeding, all secondary metabolites demonstrated significant increases. Expression analysis of flavonoid biosynthetic genes mirrors the changes observed in the total flavonoid content. Furthermore, larval feeding activates the α-linoleic acid metabolism pathway consistently across all time points. Subsequent generations of H. cunea larvae in low-density feeding and high-density feeding groups demonstrated decreased growth, along with downregulation of growth regulatory genes and key genes involved in energy metabolism, digestion, and detoxification. Notably, the expression of digestive gene LIP10 and detoxification genes GST18 and CARE14 exhibits adaptive regulation in response to T. amurensis’ inducible defense. Overall, larval feeding by H. cunea elicits a robust and enduring inducible defense response in T. amurensis, ultimately decreasing the fitness of the subsequent generations of H. cunea larvae on T. amabilis.

Graphical abstract

Ants, a prominent insect group, play important roles in various terrestrial ecosystems, by engaging in diverse biotic interactions, such as those involving plants bearing extrafloral nectaries (EFNs). This study investigates the seasonal dynamics of this interaction throughout the dry and rainy seasons in a southern Sonoran Desert site. Results indicate that despite a relatively low coverage of EFN-bearing plants (4.97% ± 4.60), interactions between ants, and these plants are frequent, involving 31% of the perennial plant community (35 species) and 54% of the ant community (35 species). The cactus family exhibited the highest species richness (7 of 11 species) with EFNs in the study area. The location of EFNs varied among plant species and were associated with both vegetative and reproductive organs. Employing selective trapping for ants that forage on plants bearing EFNs, a higher ant species richness was recorded during the rainy season (19 vs 12 spp.). The network’s topology is associated with plant phenology, and slight seasonal differences in network structure parameters were observed. Seasonal variation in the interaction align with the phenology of EFN-bearing plants. Factors such as water availability could influence competition and, consequently, the inter-season variation in the number and dependencies of ant–plant interactions. Only two species were consistently recorded in both seasons within the core of generalists: the cactus Cylindropuntia fulgida and the ant Forelius pruinosus. Given the substantial involvement of ants with EFN-bearing plants, this association emerges as a fundamental component within the community of this desert site.

Annual loss of rice caused by insect pests accounts for about 30% of total production, and the use of traditional pesticides has brought about environmental pollution, food safety, and other problems. The use of secondary metabolites of rice to control pests has become a research hotspot, but little is known about the mechanism of rice self-resistance. Rice is a typical silicon accumulating crop. Previous study showed that silicon can significantly enhance the resistance of rice to Chilo suppressalis, but anti-insect active substances in silicon-treated rice were unknown. In current study, metabolomics analysis has been performed on two groups of rice (T1, treated with silicon and insect; T3, treated with only insect). A total of 151 significantly different metabolites were obtained, compared with T3 group, 23 metabolites in T1 were significantly up-regulated and 128 metabolites were significantly down-regulated. Different metabolites were mainly enriched to tryptophan metabolism, lipoic acid metabolism, linoleic acid metabolism, isoflavone biosynthesis, and indole alkaloid biosynthesis. The different metabolites (p < 0.1) enriched to lipoic acid metabolism and fatty acid biosynthesis were all significantly up-regulated. Ten significantly up-regulated different metabolites were selected from T1. These were 3-hydroxy-palmitic acid methyl ester (1), octanoic acid (2), 3-hydroxyoctadecanoic acid (3), 12-hydroxyoctadecanoic acid (4), 2-linoleoylglycerol (5), methyleugenol (6), alpha-asarone (7), 2,4,5-trimethoxybenzaldehyde (8), acitretin (9), and menatetrenone (10), and their anti-insect activity was evaluated. Compounds 1–5 and 7–10 could significantly inhibit the growth of Chilo suppressalis. Compounds 2 and 3 inhibited growth of the insect by 35.5 and 64.5%, respectively. Compound 2 belongs to lipoic acid metabolism and fatty acid biosynthesis. We speculate that silicon positively regulated the metabolic pathway of lipoic acid and fatty acid to enhance the resistance of rice to insects.

The endogenous protein complex myrosinase and glucosinolates form a defense system in cruciferous plants against insect pests. Transgenic ablation of myrosin cells produced MINELESS seeds of Brassica napus used to investigate plant–aphid interactions. In the present study, we conducted a non-choice experiment to test the performance and fecundity of the aphids Brevicoryne brassicae (specialist) and Lipaphis erysimi (generalist) on MINELESS transgenic seedlings and the wild-type cultivar Westar. Feeding preference showed that B. brassicae preferred wild-type seedlings and L. erysimi preferred MINELESS. Progeny of generalist and specialist aphids establish and affect wild-type and MINELESS seedlings differently. Glucosinolate hydrolysis products were higher under the influence of B. brassicae in both wild-type and MINELESS seedlings. In addition, allyl isothiocyanate decreased under the influence of L. erysimi, except 3,4 -epithiobutane nitrile. Infestation by L. erysimi induced the reduction of glucosinolates, whereas B. brassicae had an opposite effect. In conclusion, the present study showed that myrosin cells affected the preference of aphid species for Brassica napus plants.

Insect pests pose a global threat to ecosystem stability and food security, necessitating a move away from chemical pesticides and towards more environmentally friendly options. As a potential biocontrol tool, entomopathogenic fungi provides focused pest management with minimal negative impacts on humans and the environment. The processes underlying the action of entomopathogenic fungi, clarifying aspects affecting efficacy, contemporary formulations of mycoinsecticides and mycoacaricides that were available to combat various pests, emphasizing their crucial role in pest control initiatives and for a more sustainable and safe future were explored below. The formulations encompassing several entomopathogenic fungi, offer a wide range of environmentally beneficial alternatives for managing insect pests, signalling a paradigm change in plant protection methods towards remedies inspired by nature. In addition, a thorough assessment of the state of mycoinsecticide formulations, providing information on recent advancements and potential lines of inquiry were also presented. This review article lays the way for a harmonious cohabitation of agriculture and the environment by outlining an agenda for leveraging the potential of entomopathogenic fungi in sustainable insect pest management techniques.