Arthropod-Plant Interactions最新文献

Mosquitoes are major disease vectors, causing millions of deaths annually. Resistance to chemical insecticides has reduced their effectiveness, prompting the need for safer alternatives, such as plant-derived phytochemicals. This research assessed the effectiveness of solvent extracts derived from mature Phyllanthus acidus leaves on different developmental stages of Culex quinquefasciatus, Culex vishnui, and Aedes albopictus. Six solvent extracts, namely petroleum ether, n-hexane, ethyl acetate, chloroform: methanol (1:1 v/v), acetone, and ethanol, were prepared using leaves. Among them, ethanol leaf extract showed the highest larvicidal, pupicidal, adulticidal, and repellent activities. The ethanol extracts demonstrated significant mosquito mortality, with LC₅₀ values of 21.32, 18.87, and 51.62 ppm for third instar larvae of Cx. quinquefasciatus, Cx. vishnui, and Ae. albopictus, respectively. The pupicidal activity was notably higher in ethanol-based leaf extracts, with an LC₅₀ value of 98.44 ppm with Cx. vishnui being the most susceptible species. In adulticidal and smoke toxicity tests, ethanol leaf extracts showed strong effects, causing 86.74–96.18% knockdown. Effective extracts were further purified using column and thin-layer chromatography. FTIR analysis identified several bioactive functional groups, such as hydroxyl, nitro, alkoxy, amino, and halogen groups. LC–MS analysis confirmed the presence of jatrorrhizine (C₂₀H₂₀NO₄), a potent alkaloid with known biological activity that interferes with mosquito physiology by disrupting neurotransmission, altering enzyme functions, impairing respiration, and compromising the integrity of the midgut. Importantly, bioassays showed no toxicity toward non-target organisms. The data suggest that the ethanol extract of the leaves of P. acidus shows promise as an eco-friendly agent for controlling medically significant vectors.

Drought-induced stress and nutrient deficiency are the most studied abiotic stresses due to their complex effects on plants. As the consequences of climate change become more apparent, few studies have considered the effects of these abiotic stresses on plant–insect interactions. The aster leafhopper (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) is the main vector of Aster Yellows phytoplasma (AYp), a plant pathogen that can infect several plant species in the Western Canadian Prairies and the United States Upper Midwest, including cereals and canola. The mechanisms of insect nutrition and AYp transmission have an intimate association with the probing behavior of aster leafhoppers, namely with phloem-associated behaviors such as phloem ingestion and phloem salivation. The aim of this study is to examine the probing behavior of aster leafhoppers on canola grown under water stress, nutrient stress, and controlled conditions using the electropenetrography technique. Aster leafhoppers on stressed plants spent 62–63% of their time probing, while insects on control plants spent 45% of their time doing so. Aster leafhoppers on water-stressed plants were more likely to ingest from xylem tissues compared to insects in the other treatments. While aster leafhoppers from the different treatments spent 14–19% of their time ingesting from phloem, differences were observed in their ability to salivate into these tissues. Insects on nutrient-stressed plants spent more time salivating in the phloem compared to those on control plants, while aster leafhoppers on water-stressed plants rarely displayed this behavior.

Insect herbivores cause substantial economic loss to agricultural crops and insecticides are the foremost strategy in their management. Increasing crop diversity is expected to improve biological control services and primary productivity. However, the benefits of mixing more than two annual crop species remain poorly understood. Using okra (Abelmoschus esculentus), calabash (Lagenaria siceraria), and sponge gourd (Luffa acutangular), we compared the effect of double and triple cropping to monocropping on insect herbivore and predator abundance and diversity and the number of marketable fruits as yield in nine fields over 2022 and 2023 in Pakistan. We found 21 insect species, including 9 species of herbivores and 12 species of predators. Herbivore abundance of almost all species was significantly lower while predator abundance of all species was significantly higher in triple cropping. Herbivore richness was significantly and positively correlated with increasing vegetable diversity while a non-significant relation was noted for herbivore diversity and dominance. Predator diversity, richness and dominance were significantly and positively correlated with increasing crop diversity. Increasing landscape diversity (Shannon diversity) significantly reduced pest abundance and increased the diversity of pests and predators as well as predator abundance. Predator abundance and diversity matrices played a significant role in herbivore suppression suggesting a strong top-down effect. Number of fruits was higher in triple cropping. Path analyses proved that herbivore abundance affected the yield indirectly through predator diversity. Our results suggest that local and landscape diversity and complementarity among crop species and predator species are simultaneously regulating biological control and primary productivity in vegetable diversity gradient.

Lentil (Lens culinaris) is a leguminous crop of significant agricultural importance due to its phenotypic adaptations to drought conditions and various soil types. Furthermore, lentils stand out nutritionally among other legumes, due to their high protein content and a high proportion of carbohydrates with low digestibility, which contribute to the protection of the gut microbiota and the reduction of chronic diseases. In Mexico, lentil cultivation is primarily concentrated in the state of Michoacán, accounting for 96% of the national production. However, its cultivation is affected by several challenges that lead to low crop yields. Preliminary observations in our research group revealed that, in household vermicompost, Astigmatid mites promoted root elongation and lateral root development in L. culinaris without consuming the seeds. Therefore, in the present study, we evaluated the interaction between mites of the Astigmatina cohort (genus Cosmoglyphus) and L. culinaris as a potential strategy for sustainable agriculture, given that these soil mites are saprophagous to plants and may play a role in nutrient recycling. Initially, a gradient of 0, 10, 20, 30, and 40 mites per plant was established in interaction with lentils grown in substrates supplemented with compost. The most pronounced growth-promoting effects were observed at a density of 20 mites per plant. These beneficial effects persisted when lentils were grown in agricultural soil. Finally, a mite count was conducted on the agricultural soil, both supplemented and non-supplemented with compost. A higher mite population was found in the compost-supplemented soil, which correlated with the observed growth promotion.

Background

Plant-derived natural compounds have recently emerged as safer, eco-friendly alternatives to control sand flies. This study investigates the adulticidal effects of Delphinium speciosum extract and Trachyspermum ammi essential oil on the primary vectors of cutaneous leishmaniasis.

Methods

D. speciosum aerial parts were Soxhlet-extracted, and T. ammi essential oil was hydro-distilled, with both processed into various concentrations for bioassay. Sand flies were reared in the Phlebotomine insectary. We used modified WHO Standard Holding Tubes for mosquito susceptibility tests. Concentrations of 50, 100, 200, and 400 mg/mL of D. speciosum extract in ethanol and 2.5, 5, 10, and 20 mg/mL of T. ammi essential oil in methanol were tested.

Results

Both species showed dose-dependent mortality, with LD₅₀ and LD₉₀ values indicating higher efficacy of the essential oil compared to the plant extract. Linear regression analysis also showed that there was a good correlation between the dose and response, where increased concentration of the treatment led to increased mortality. Additionally, KT₅₀ and KT₉₀ analyses highlighted the rapid action of essential oils, which acted faster on Ph. papatasi than on Ph. sergenti.

Conclusion

T. ammi essential oils were effective against Ph. papatasi and Ph. sergenti with a high mortality rate and dose dependent manner. These findings support the use of these natural compounds for sand fly control in leishmaniasis management.

Graphical abstract

Gall-inducing insects manipulate host plant physiology and morphology, offering a unique system to explore insect–plant interactions. In this study, we investigated the effects of Bruggmanniella litseae (Diptera: Cecidomyiidae) galls on the performance of its host plant, Litsea acuminata, by examining variation in leaf size and five phytochemical traits across different gall abundances. Our results show that galled leaves are significantly larger than ungalled ones, with leaf size increasing with gall abundance—up to a threshold of approximately 4000 mm²—suggesting possible host manipulation to meet the nutritional requirement of the gall inducer. Among the phytochemicals examined, polyphenol content increased with gall abundance. This may support larger leaf size via polyphenol-enhanced auxin (IAA) synthesis, promoting cell differentiation and growth. Contrary to expectations, no significant different was found between gall abundance and folivory, despite elevated polyphenol levels, which are typically associated with herbivore defense. Overall, higher gall densities of B. litseae are associated with increased leaf size and polyphenol levels, which may represent a strategy to optimize host photosynthesis and maintain nutritional homeostasis for gall development.

Patterns of egg distribution in eruptive phytophagous insects represent an important, yet understudied, component of their population dynamics. This study investigates oviposition strategies in an eruptive lepidopteran species, the black-veined white (Aporia crataegi), during the peak phase of an outbreak cycle. We analysed the number and size of egg clutches in relation to the characteristics of host plants. Additionally, we examined the colonisation dynamics of these host plants during the outbreak. Our findings demonstrate that A. crataegi exhibits selective oviposition. Females most frequently lay eggs on P. padus, with M. baccata and S. aucuparia being selected less frequently. Less preferred host plants are colonised with a greater selectivity; thus, most trees remain uncolonised, while individual trees exhibit a high density of egg clutches. Females preferentially oviposit on taller plants and do not avoid those defoliated within the current growing season, although depositing smaller clutches on such hosts. During the outbreak, colonisation rates increase on less preferred host plant species—M. baccata and S. aucuparia. We found no evidence of conspecific clutch avoidance, since clutch distribution across all host plants was aggregated. The highest degree of aggregation was observed on the least preferred host plant—S. aucuparia. The implications of clutch aggregation for offspring fitness and population dynamics are discussed.

In a metabolomics analysis using GC–MS, we explored the metabolic responses of moderately resistant West Coast Tall (WCT) and susceptible Chowghat Orange Dwarf (COD) coconut varieties to infestation by the exotic whiteflies Aleurodicus rugioperculatus and Paraleyrodes bondari. WCT exhibited a low to medium Infestation Grade Index (IGI) for both whitefly species, while COD displayed a medium to high IGI. Additionally, the study examined the preferential feeding behavior of the whiteflies, highlighting their tendency to predominantly infest the bottom leaves rather than the top leaves. GC–MS analysis of healthy top leaves and whitefly-infested bottom leaves from the WCT and COD coconut varieties identified 56 metabolites, categorized into carbohydrates, fatty acids, organic acids, amino acids, and secondary metabolites. The WCT coconut variety exhibited moderate resistance to exotic whitefly infestation through the accumulation of boric acid. Furthermore, the activation of the biosynthetic pathway for unsaturated fatty acids, leading to increased levels of docosahexaenoic acid and arachidonic acid, played a significant role in its defense response. In WCT, the uninfested top leaves showed higher levels of shikimic acid, stearic acid, threonic acid, lactic acid, and palmitic acid, suggesting these compounds contribute to its defensive strategy. The abundance of sugars in the bottom leaves of COD likely facilitated the feeding and development of the whiteflies, making it a more favorable host for the pest. This study highlights distinct metabolic responses to whitefly resistance and lays the foundation for future research aimed at developing pest-resistant coconut cultivars.

Fire is a key ecological driver in the Brazilian Cerrado, shaping plant traits and influencing biotic interactions such as mutualisms. We assessed how the presence of extrafloral nectaries (EFNs) and associated ant mutualists affects post-fire recovery in three Malpighiaceae species with contrasting ant-plant associations: Peixotoa tomentosa and Banisteriopsis malifolia, which possess EFNs and have strong ant associations, and Byrsonima intermedia, which lacks EFNs and generally exhibits weaker associations with ants. Because ant activity was not measured directly, EFN presence was used as a proxy for mutualistic interactions. We hypothesized that fire would enhance vegetative growth and reproductive output in all species but that the effect would be stronger in species with EFNs. Our results showed that P. tomentosa experienced significant increases in total leaf production, plant height, leaf diameter, and reproductive output (floral buds, flowers, and fruits) in burned areas, along with a reduction in fungal leaf spots. B. malifolia also exhibited higher numbers of floral buds, flowers, and fruits in burned areas, indicating a positive reproductive response to fire. In contrast, B. intermedia showed no significant differences in leaf production or height between burned and unburned areas, and reproductive data were unavailable in this species due to delayed flowering after the fire. These contrasting responses suggest that EFN-bearing species may be better equipped to cope with post-fire conditions. While we did not directly measure ant activity, the observed patterns are consistent with the hypothesis that EFN-mediated mutualisms may contribute to plant resilience. Our findings contribute to the understanding of how species traits associated with ant-plant interactions might influence post-disturbance dynamics in tropical savannas.

Despite the long co-evolutionary history of ferns with insects (and other arthropods), the study of interactions between these two groups has been historically underrepresented compared to the study of interactions in angiosperms. Furthermore, recent reviews analyzing various types of fern-insect interactions worldwide have highlighted a significant lack of studies from regions in the Southern Hemisphere when compared to the abundant research conducted in the Northern Hemisphere. This disparity leads to structural biases in the available information, precluding a better understanding of the co-evolution and role of insects and ferns in the ecosystems, and their importance for biodiversity conservation in the Global South. In an effort to reduce this knowledge bias, we undertook a survey in the Paranaense rainforest (Misiones Province, Argentina), documenting for the first time fern-arthropod interactions within the country and laying the groundwork for future investigations. We assessed potential fern-arthropod interactions by thoroughly examining fern specimens along predetermined transects, recording all recognized activities related to shelter (galling, mining, cocoons), reproduction (oviposition), and invertebrate feeding. Fern-hosts and those arthropods observed in-situ were collected and taxonomically classified. Despite preliminary, our observations provided the first records of fern-arthropod interactions described for Argentina, revealing a diverse array of fern-arthropod interactions. This survey denoted that there is high potential for future qualitative and quantitative analyses and comparisons with other regions, further underscoring the critical need to gather information particularly from the Global South. We hope this work will help to incentivize additional research on this largely unexplored topic within the country.