Arthropod-Plant Interactions最新文献

The Plant Vigor Hypothesis (PVH) predicts that herbivorous insects will preferentially feed on large plants with more vigorous growth, or on more vigorous parts of the plant. However, we still need to understand how these predictions work throughout the ontogenic stages of plants and with other groups of natural plant enemies. We tested the PVH using gall-inducing insects, free-living herbivorous insects, and pathogenic fungi associated with Hymenaea courbaril seedlings of the same age cohort (six months) from seeds germinated in greenhouses. We classified the plants into three different sizes: small, medium, and large seedlings, and then measured above and belowground biomass, plant height, leaf area, and leaf area consumed by free-living herbivores. We also measured nutrient partitioning among roots, stems, and leaves and estimated hypersensitive responses. We found no differences in leaf area consumed by free-living herbivorous insects between plant size groups. However, we observed that larger seedlings were more vigorous and had greater nutritional value and, thus, represented adequate niches for colonization by pathogens and gall-inducing insects, confirming the PVH for both groups. The hypersensitive response was greater in medium and large seedlings, proving to be an effective defense mechanism against gall-inducing insects. Therefore, we highlight that nutritional quality, plant vigor and hypersensitivity response are factors that influence the incidence of pathogens and galling insects on H. courbaril seedlings.

The fruit flies in Tephritidae include many severe fruits and vegetables pests. To date, the genomes and transcriptomes of tephritid flies are distributed in different major databases. However, the tephritid flies community lacks an integrated database. Here, we introduce the first release of TephritidBase, available online at https://tephritid.biodb.org. The database encompasses 12 tephritid genomes, 677 tephritid transcriptomes and nearly 7 million docking results. Transcripts Per Kilobase of exon model per Million mapped reads (TPM), Fragments Per Kilobase of exon model per Million mapped fragments (FPKM) or Reads Per Kilobase of exon model per Million mapped reads (RPKM) were evaluated, and transcriptome samples were grouped in detail so that users could analyze transcriptome results at various developmental stages, tissues, treatments and so on. In total, there were 2,694 predicted chemoreception genes with accessible three-dimensional (3D) protein structures simulated by AlphaFold2. Furthermore, TephritidBase provided molecular docking data for 2,074 insect pheromones and 794 natural ingredients of host plants with these proteins. In addition, TephritidBase provides evolutionary data for the genome, principal component analysis and co-expression network data for the transcriptome. TephritidBase provides useful information and guidance for screening of bioactive compounds against tephritid flies targeting the chemoreception proteins.

Honeydew is a nutrient rich excretion of aphids. This substance also emits kairomones, serving as a signal that attracts aphid predators and thereby influences the interaction among plants, aphids, and other predators. The overall aim of this study was to investigate the role of honeydew from two aphids species, Aphis fabae Scopoli, 1763 and Acyrthosiphon pisum (Harris 1776) in the predatory behavior of Adalia bipunctata (Linnaeus 1758) and Episyrphus balteatus (De Geer 1776). Specifically, we aimed to (1) evaluate the impact of honeydew on A. bipunctata and (2) E. balteatus and on intraguild interactions (IGI) among them. Our results showed that the presence of honeydew enhanced the mobility of predators by stimulating foraging behavior. In addition, the number of aphids consumed was significantly higher in the presence of honeydew. Interestingly, the predators were more attracted to A. fabae in the presence of A. pisum honeydew. These findings highlight the key role of honeydew in intraguild relationships, altering the prey’s perception from being less preferred to becoming more appealing to predators, akin to their favored prey. These results provide interesting perspectives to improve aphid biological control.

Insufficient investigation of nocturnal floral visitors may bias our understanding of floral diversification in many plant lineages. Here we re-examined the pollination ecology of Rhododendron excellens, which lacks a narrow floral tube characteristic of many hawkmoth flowers and has been considered a bee specialist with daytime observations alone. We used five temporally sequential proxies (i.e. visitation rate, pollen deposition, fruit production, seed production, and seed viability) covering the entire process of reproduction to track the relative importance of the two floral visitor groups that were active by day and by night respectively. We then quantified the floral syndrome and tested the mating system with hand pollination treatments. Both bumblebees and hawkmoths regularly visited R. excellens in two flowering seasons. Hawkmoths’ relative importance increased step-by-step from being inferior to bumblebees (floral visitation and pollen deposition) to making over three times the contribution by bumblebees (seed viability). This is probably because they differ in the ability to deliver outcross pollen for this partially self-compatible species. Correspondingly, R. excellens exhibits a floral syndrome associated with a particular subdivision of sphingophily. We revealed a distinctive pollination mode that mainly involves nocturnal pollinators and is likely to have repeatedly evolved in Rhododendron. Our findings also highlight the need to consider the ‘quality’ of pollen deposited onto stigmas, whose effect on plant fecundity may significantly expand over the course of sexual reproduction.

Plants respond to complex blends of above- and below-ground volatile organic compounds (VOCs) emitted by neighboring plants. These responses often involve priming (i.e., preparation) or induction (i.e., increase) of defenses by “receiver” plants upon exposure to VOCs released by herbivore-damaged neighboring “emitters.” However, recent work has shown that induction of VOC emissions by herbivory is modulated by abiotic factors, potentially affecting plant–plant signaling. We tested the effect of soil salinization on the induction of VOC emissions in wild cotton (Gossypium hirsutum) due to leaf damage and its consequences for the induction of defenses in neighboring plants. To this end, we performed a greenhouse factorial experiment where emitter plants were subjected to augmented soil salinity (vs. ambient salinity) and within each group emitter plants were subsequently exposed to simulated caterpillar damage (mechanical leaf damage treated with Spodoptera frugiperda oral secretion) or no damage (control). After 48 h of exposure, we collected VOCs released by emitter plants and then damaged the receivers and collected their leaves to measure levels of chemical defenses (terpenoid aldehydes of known insecticidal effects). We found an interaction between leaf damage and salinization for two groups of VOCs released by emitters (sesquiterpenes and other aromatic compounds), whereby damaged receivers had higher emissions than control plants under ambient but not salinized soil conditions. We also found that, upon being damaged, receiver plants exposed to damaged emitters exhibited a significantly higher concentration of heliocides (but not gossypol) than control plants. However, salinization did not alter this VOC exposure effect on receiver induced responses to damage. Overall, we show that exposure to induced VOC emissions from damaged plants magnifies the induction of chemical defenses due to leaf damage in neighboring individuals and that this is not contingent on the level of soil salinity despite the latter's effect on VOC induction.

The flowering plant family Asteraceae is diverse and its constituent species are common in many habitats worldwide. However, its pollen, although widely available, is rarely collected by generalist bee species, suggesting it possesses properties that deter these bees from over-exploiting it. Previous studies have proposed that the conspicuous spines on Asteraceae pollen grains might serve as a deterrent against exploitation, but these studies have not separated the effects of pollen morphology from those of pollen chemical composition. Here, we assessed whether Asteraceae pollen spines are detrimental to generalist bees independently of any effects of pollen chemistry. To do so, we administered three pollen diet treatments to queenless bumble bee microcolonies: one treatment incorporated sporopollenin exine “shells” extracted from spinous (echinate) sunflower pollen; a second incorporated chemically identical shells from non-spinous mixed pollen; and the third was a control diet with no added exine. We found that the presence of pollen spines in the diet significantly reduced larval growth, beyond the reduction caused by adding exine to the diet. However, we observed no effect of pollen spines on the survival of adult workers or larvae, nor did we find substantially increased intestinal damage in adults. Our results show that Asteraceae pollen spines impair larval development of generalist bumble bees, but further investigation is required to elucidate the mechanism behind this phenomenon.

Scopolia carniolica Jacq. is a perennial plant from the family Solanaceae. The study objective was to examine floral traits that may be important for interactions with floral visitors (i.e., blooming phenology, floral micromorphology, nectary characteristics, nectar quantity, nectar sugar composition, and pollen production). In S. carniolica, papillae, numerous non-glandular trichomes, and a few glandular trichomes were present on the inner corolla epidermal surface. Lipids, acidic lipids, tannins, and alkaloids were present in the non-glandular trichomes and in the corolla cells. The discoid-type nectary was located at the base of the ovary. Floral nectar was released through nectarostomata. The process of nectar release started in the bud stage (ca. 5–8 h before corolla opening) and continued to the 4th day of anthesis. The amount of secreted nectar peaked in 2-day-old flowers. The amount of produced nectar, nectar sugar concentration, and sugar mass varied significantly across years. On average, the total mass of sugars in the nectar was 0.54 mg/flower. S. carniolica produced sucrose-dominant nectar with no glucose. The sugar proportions did not differ during the flowering season. On average, 1.95 mg of pollen per flower was produced. Among floral visitors, bumblebees were most frequently noted, accounting for 79.7% of the total number of floral visitors to S. carniolica flowers. The species can be used in early spring ornamental arrangements to support the food supply for insects, mainly bumblebees.

The first step to better understand the relationship between natural enemy communities and pest control is to know which, when, and how frequently different natural enemies interact with their prey. In alfalfa fields of central Chile, aphids are the most common pests and are consumed by predators such as coccinellids, syrphids, and spiders. In this study, through video recording, we analyzed how natural enemy communities visiting aphid sentinel cards vary between scenarios of low and high abundance of aphids in alfalfa in spring. On 15 occasions, during the day, we monitored the natural enemies visiting cards with sentinel aphids (60 cards per field; total 900) located in fields with high (n = 6) and low (n = 9) aphid abundance. We also analyzed whether the abundance of coccinellid species visiting sentinel cards was related to their abundance in each field. In 750 h of video recording, we found 2749 natural enemies visiting the sentinel cards; 86.2% of them were coccinellids of five species. Total natural enemies and coccinellid visits were three times higher in low than in high aphid abundance scenarios. In contrast, the species richness and diversity of natural enemies and coccinellids visiting cards did not differ between aphid scenarios. The abundance of coccinellids in the field was positively associated with the abundance of coccinellids visiting cards, for the three most abundant species. Our study shows that video recording is useful for identifying changes in the communities of natural enemies of aphids in alfalfa, providing important new insights into trophic interactions in field situations.

Ectomyelois ceratoniae and Deudorix livia are the main pests of pomegranate Punica granatum L. in Tunisia. This study was carried out to investigate the susceptibility of five Tunisian pomegranate varieties (Tounsi, Guebsi, Gares, Zehri, and Baldi) from two oases (Gafsa and Degache) to infestation by E. ceratoniae and D. livia during fruit ripening. To this end, the physico-chemical properties of these pomegranate varieties were quantified during the ripening period and correlated with insect infestation. The results showed that all varieties were infested by E. ceratoniae and D. livia and that the severity of the infestation depended strongly on the pomegranate variety and the ripening stage of the fruit. It was observed that the infestation caused by E. ceratoniae was early as compared to D. livia on all the pomegranate varieties at two oases conditions. Moreover, results showed that biochemical and physico-chemical properties changed during fruit maturity. The total soluble solids (TSS), sugars, maturity index, fruit peel water content, and fruit weight are significantly increased but the titratable acidity and peel hardness are significantly decreased with ripening stage. The results pointed out that pomegranate infestation varied depending on the morphological changes of the fruit. In addition, a significant correlation was observed between E. ceratoniae and D. livia infestation and fruit juices TSS (r = 0.36 and r = 0.68), maturity index (r = 0.44 and r = 0.35), and total sugar (r = 0.36 and r = 0.67). Analyses also revealed a high negative correlation between fruit peel hardness and D. livia infestation (−0.63). The findings of this research will enhance comprehension regarding the behavior of D. livia and E. ceratoniae, which infest various pomegranate cultivars in Tunisian oases. Consequently, this will facilitate the refinement and implementation of management approaches aimed at addressing both species. For instance, early harvesting of fruits at the onset of ripening, prior to pest activity can significantly reduce levels of pomegranate infestation.

The prevalence of mosquito-borne diseases is increasing due to urbanization and climate change. Synthetic insecticides have resulted in resistance, and alternative control methods are needed. This study evaluated hexane, chloroform, and methanol extracts from Sphaeranthus indicus leaves for their efficacy against the larvae, pupae and eggs of Aedes aegypti and Culex quinquefasciatus mosquitoes. The plant materials were coarsely powdered and sequentially extracted in hexane, chloroform, and methanol using a Soxhlet apparatus, followed by filtration and concentration under reduced pressure with a rotary vacuum evaporator. In the case of Ae. aegypti, the hexane extract exhibited notable toxicity against all three examined stages. The LC₅₀ values for larval mortality, pupal lethality, and ovicidal activity were determined to be 81.83 ppm, 86.13 ppm, and 63.2 ppm, respectively. Similarly, for Cx. quinquefasciatus, the hexane extract showed efficacy with LC₅₀ values of 81.23 ppm for larval mortality, 93.24 ppm for pupal lethality, and 75.2 ppm for ovicidal activity. Following the hexane extract, the chloroform and methanol extracts demonstrated moderate larvicidal and pupicidal activity against both mosquito species, but they exhibited limited effectiveness against ovicidal activity. These findings suggest the potential use of natural extracts as supplementary control measures against mosquito vectors.