Arthropod-Plant Interactions最新文献

The role of nocturnal pollinators has been globally understudied, particularly in agriculture, but growing evidence suggests that crops often assumed to be pollinated during the day also receive additional pollination by night-active animals. In our study, we assessed six different types of evidence to determine whether blueberry flowers, which are typically associated with diurnal pollinators, could also be pollinated at night. We used observational and experimental approaches commonly used and validated for assessing nocturnal pollination, including variation in stigma receptivity and pollen viability at day and night, nectar standing crop dynamics, temporal effects of pollen germination, pollinator exclusion experiments and the presence of pollen on the bodies of potential nocturnal pollinators (moths). Stigma receptivity and pollen viability were similar between our day and night sample points. We found no negative effects of time of pollination on pollen germination. Nectar availability was strongly associated with time of day, and although nectar was available both day and night, nectar volume was highest at night. Fruit set was highest in flowers with unrestricted access to pollinators, but we are unable to determine the relative importance of nocturnal versus diurnal pollination as these treatments gave the same result as our control. Moths caught in blueberry orchards carried pollen from 25 plant species, with blueberry pollen being the fifth most abundant. Our results show that blueberry flowers have floral traits that allow pollination at night as well as during the day, and that moths, along with other nocturnal insects, may be contributing to this. However, the importance of nocturnal pollination relative to diurnal pollination remains unknown.

The remarkable species richness of the Neotropical aroid genus Philodendron (Araceae) is closely linked to its specialized nocturnal pollination system, where chemically distinct floral scents selectively attract night-active cyclocephaline beetles (Melolonthidae, Cyclocephalini). This study explores the floral biology and chemical ecology of Philodendron cipoense, an endangered, rupicolous species endemic to Brazil’s Espinhaço mountain range in the Campo Rupestre. Through qualitative and quantitative analyses of floral scent chemistry and field experiments, we assessed the role of key volatile organic compounds (VOCs) in pollinator attraction. P. cipoense relies heavily on pollinators and attracted a diverse assemblage of specialized beetles, including Cyclocephala atricapilla, C. variolosa, Chalepides dilatatus, and Erioscelis sp. Its floral scent is dominated by (Z)-jasmone, 4-vinylanisole, and isojasmol, collectively accounting for 97% of total emissions. Field experiments confirmed the attractiveness of (Z)-jasmone, successfully luring a male of C. atricapilla (pollinator) and C. celata (non-pollinator) individuals of both sexes. These findings underscore the pivotal role of floral scent as an olfactory cue in pollinator attraction, revealing asymmetrical mutualisms and interdependence between P. cipoense and its pollinators. Our results provide valuable insights for conservation strategies and targeted action plans to protect this threatened species.

Florivores modify the attributes of flowers while feeding, that affects the behavior and frequency of pollinators that visit flowers and setting of fruits and seed as a result of low pollen deposition. We determined the effect of experimental florivory on pollinators visitations, fruit-set, and seed-set of Opuntia cantabrigiensis. Four treatments were applied on intact flowers during reproductive season: 1) removal of 50% of the perianth, 2) emasculated flower, 3) flower without stigma, perianth and stamens (stigma-perianth) and 4) intact flower-control; selected treatments mimic the types of florivory observed in the population. The frequency of visitation, activity and taxonomic identity of the pollinator were recorded. We found that frequency of pollinators decreased with damage to the flower, with the stigma-perianth treatment receiving the fewest visits. The most frequent pollinators were the solitary bees Macrotera sinaloana, Diadasia rinconis, and Lithurgopsis apicalis (Hymenoptera) that collect rewards and perch on the stigma of flowers. Pollinators responded differently to florivory; Ashmeadiella opuntiae avoided flowers with perianth damage, possibly associating it with a lack of rewards, while D. rinconis prefered such flowers, the removal of this structure facilitated access to floral rewards. Flowers in the stigma-perianth treatment produced seedless fruit. Intact flowers had higher seed production than those with perianth damage or emasculation due to low pollinator visitation and pollen deposition. Opuntia cantabrigiensis is a xenogamous species with dependence on biotic vectors, therefore the damage caused by florivores reduces the visit of their pollinators and its reproductive success, which could negatively affect the population persistence.

Pollination is a key component for plant reproduction and maintenance and can be directly altered by anthropogenic disturbances, such as traditional plant management. Plant management causes changes in several floral and reproductive traits, including floral morphology, number of reproductive structures, and reproductive success. We investigated floral morphology, pollination biology and ecology, and quantified measures of investment in male function (i.e., amount of pollen/anther, pollen/flower, and pollen viability); female function and reproductive success (i.e., number of ovules/ovary, fruit set, and seed set) of managed and unmanaged Cereus jamacaru DC. (Cactaceae) individuals in the Caatinga. For this purpose, we conducted observations, pollination experiments and analysed flower buds, flowers and fruits. We observed that managed individuals exhibited flowers with greater a) corolla area (64%), b) corolla diameter (30%) and c) floral tube length (16%), d) herkogamy (i.e., stigma-anther distance; 600%), e) number of ovules (16%) f) pollen/flower (7.1%), fruit set (133%) and seed set (49%) in relation to the unmanaged population. The flowers of the managed population were visited exclusively by Manduca rustica and those of the unmanaged population by M. paphus. Our findings reveal that traditional management favours C. jamacaru individuals in the Caatinga dry forest. Furthermore, pollination by species of Sphingids exclusive to each population, together with herkogamy, can act as a barrier to pollen/gene flow between managed and unmanaged individuals. Thus, traditional management may not be able to maintain C. jamacaru populations in the Caatinga, as well as its associated fauna, i.e., pollinating and dispersing animals.

The leafcutter bees, Megachile spp. (Megachilidae: Hymenoptera) serve as a significant pollinator in ecological systems. They collect leaf discs to enclose their brood cells. Nevertheless, our current understanding of using plants as nesting resources in various ecosystems in different seasons, essential for their conservation, needs to be improved. The seasonal and landscape-level alterations have significant impacts on leafcutter bees, influencing species richness, abundance, community composition and leaf foraging behaviour. This study underscores the critical role of different seasons and landscape characteristics in shaping the leaf-foraging behaviour of leafcutter bees. We noted that semi-urban areas (151 different plant species recorded with cut leaves), with their greater landscape heterogeneity and high-quality habitats, supported higher species richness and abundance of leafcutter bees. In contrast, fully urban (49 different plant species recorded with cut leaves) and intensively agricultural landscapes (85 different plant species recorded with cut leaves) posed challenges to the survival of these bees due to habitat loss and fragmentation. We also found that during early autumn, leafcutter bees emerged and constructed ephemeral nests, intensifying leaf-cutting behaviour, whereas the summer and monsoon seasons exhibited a heightened activity, with bees building seasonal nests and gathering leaf and other essential resources extensively. In winter, leafcutting ceased as these bees entered into dormant conditions, seeking shelter in their nests for insulation and protection. This study provides valuable insights into the foraging patterns and habitat preferences in different seasons of leafcutter bees, contributing to the broader understanding of pollinator ecology in changing landscapes and environments.

Tetranychus urticae is an economically important pest in many crops, such as cotton, soybean, beans, and tomato. The polyphagous behavior of this mite allows it to adapt to resistant hosts within a few generations. Here, we evaluated the resistance of tomato accessions to T. urticae through choice and no-choice trials, identified traits linked to resistance, and found candidate accessions for gene introgression in susceptible plants. In the choice trial, sixty-two accessions of S. lycopersicon from the Horticultural Germplasm Bank (HGB) were assessed together with ‘Santa Clara’ (susceptible control) and PI-134417 (resistant control) in a circular arena made of foam (50 cm diameter), followed by counting of mites on each accession. In the no-choice trial, four less preferred accessions from the choice trial plus the susceptible and resistant control were tested using 2-cm-diameter leaflets circles. Daily mortality was evaluated until the life cycle was completed. The content of zingiberene, 2-tridecanone, the number of idioblasts containing calcium oxalate crystals (COC), and the thickness of the lower and upper leaf epidermis, palisade parenchyma, lacunous parenchyma, and leaf blade were determined. The zingiberene, 2-tridecanone, number of idioblasts containing COC, lower and upper leaf epidermis thickness, palisade parenchyma, lacunous parenchyma, and leaf blade differed among treatments. In most situations, the accessions HGBs-2119 and 2123 had the highest thickness of the anatomical tissue components measured. The highest number of idioblasts containing COC was found in PI-134417 and HGB-2119. The zingeberene content was maximum in the HGB-2119 access and minimum in the resistant control PI-134417. Two-tridecanone was detected only in the resistant control PI-134417. The female survival rate and the number of eggs decreased significantly as the number of idioblasts containing COC increased. The overall analysis of the data shows that the accessions HGBs-2119, 813, 2123, and 327 have the greatest potential to serve as resistant sources for the introgression of resistant genes in tomato lines for processing industries.

Graphical abstract

Mosquitoes are crucial vectors globally, particularly prevalent in tropical regions. They are considered especially hazardous compared to other disease vectors due to the severe detrimental impacts they cause. The purpose of the present study was to evaluate the efficacy of essential oil from Stemodia viscosa against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus mosquitoes. Concentrations of 3.125–50 ppm were used to check the mosquitocidal activity. S. viscosa essential oil displayed 96–100% ovicidal mortality against the eggs of these three species at 50 ppm concentration within 24 h; it was comparable to that of temephos the positive control. Strong mosquitocidal activity was observed, with LC₅₀ and LC₉₀ values of 8. 8, 5.9, 5.1 ppm and 37.5, 33.7 and 25.7 ppm against larvae of Ae. aegypti, Cx. quinquefasciatus and An. stephensi mosquitoes, respectively, at 24 h. Essential oil showed the least activity against pupae of all three vector mosquitoes at 50 ppm concentration. Three major compounds—Caryophyllene (64.05%), Humulene (12.83%) and Androsta-1,4,6-triene-3,17-dione (10.31%)—were identified as the main compounds present in the essential oil which may account for these activities. Toxicity studies revealed that the essential oil from S. viscosa had no negative effects on tested natural predators. The essential oil was then formulated for field-level application and its toxicity was tested in laboratory setting. The results showed promising mosquitocidal activity without any toxicity toward the tested natural predators. These observations strongly indicate that the essential oil from S. viscosa can be used as mosquitocidal agent against three disease-transmitting mosquitoes without causing environmental damage, making it effective green mosquitocide.

To investigate how plant-pollinator ecological interactions are affected by habitat modification, and to provide information to support restoration efforts, we characterized trophic interaction networks between bees and plants in a natural regeneration area and forest edge environments in a post-bauxite mining area in the eastern Amazon. For this purpose, bees were collected on the flowers of Gouania cornifolia Reissek (Rhamnaceae), an ordinary native liana in the studied areas, which plays a crucial role in post-mining regeneration by enhancing ecosystem interaction networks between plants and pollinators, and attracting a diversity of floral visitors. The pollen deposited on the bees’ bodies was removed, and through palynology, the plant species that bees visited to collect food were identified. Subsequently, a presence-absence matrix was constructed, trophic interaction networks were created, and metrics analyses were performed. Forest edge areas showed greater native bee diversity, a higher richness of pollen types, and a more nested interaction network with the exclusion of the exotic species Apis mellifera compared to natural regeneration areas. Apis mellifera exploited a greater richness of floral sources due to its wide foraging range, which allowed for movement between different environments, including preserved forest, forest edge, and natural regeneration. This exotic bee alters the structure of interaction networks, being more evident in areas of natural regeneration. We found that bee-plant networks at forest edges demonstrated greater resilience compared to those in natural regeneration areas, emphasizing the importance of preserved forest environments in the recovery of ecological networks.

Plant volatiles play an important role as cues for herbivorous insects in search of resources, mates, and oviposition sites in complex environments. The use of plant volatiles as attractants or repellents can be utilized to monitor and control pest populations. Spodoptera exigua (Lepidoptera: Noctuidae, Hübner, 1808) is a highly destructive pest of cruciferous crops that has developed resistance to a variety of insecticides, making the management challenging. This study aimed to investigate the behavioral response of the pest to volatile organic compounds (VOCs) emitted by Rosmarinus officinalis (Lamiales: Lamiaceae, Linnaeus, 1753). We identified ten compounds from the rosemary using gas chromatography-electroantennographic detection (GC-EAD). We then subjected these compounds to ovipositional and olfactory bioassays. The results revealed that the moths were significantly attracted to seven compounds while being repelled by the others. In oviposition bioassays, linalool showed the greatest attractive effect at 69.97% (P < 0.001) at 15,000 μg·mL⁻¹, while eucalyptol exhibited the highest repellent rate at 47.11% (P < 0.01) at 1500 μg·mL⁻¹. In olfactory bioassays, β-pinene showed high attractiveness at a concentration of 150 μg·mL⁻¹, with the attractive rate of 66.67% (χ² = 8.64, df = 1, P = 0.001). Eucalyptol again displayed strong repellent activity at 42.86% (χ² = 5.14, df = 1, P = 0.023) at a concentration of 1500 μg·mL⁻¹. Furthermore, these compounds elicited a dose–response from the moth in these bioassays. This study demonstrates the theoretical feasibility of using rosemary as an attractive crop in agricultural fields for the environmentally friendly management of beet armyworms. However, when VOCs are applied in the field, they often experience significant dilution, resulting in behaviors much less than those observed in the lab. Therefore, these compounds require testing in field settings to ensure their viability as a management strategy for insects.

Baculoviruses are a group of entomopathogenic viruses that are important natural enemies of insects, particularly lepidopteran larvae. An important component of baculovirus transmission efficiency is the frequency with which hosts encounter patchily distributed virions on plants. Little is known about the ecology and bacterial composition of virus-killed cadavers. We used a baculovirus and host Trichoplusia ni caterpillars to study the effects of virus-killed cadavers on tomato plant defenses and T. ni behavior. We also compared bacterial communities associated with virus-killed and uninfected (freeze-killed) cadavers and found that there was no significant difference in community composition and membership between tomato-fed virus-killed or freeze-killed cadavers. Comparison of virus-killed cadavers from two separate experiments revealed significant differences in bacterial community composition, suggesting that host plant could play a more important role in shaping bacterial communities than virus infection status. Culture-dependent plating indicated that virus-killed cadavers had significantly higher bacterial titers compared with uninfected cadavers. We found that virus-killed cadavers suppressed polyphenol oxidase activity, an important plant defense protein, in mechanically damaged plants, but not in plants damaged by herbivory. Although cadavers did not influence plant defenses induced by feeding damage inflicted by healthy or infected T. ni, this study provides the first evidence that baculoviruses could influence plant defenses through host cadavers. When applied to intact plants, neither virus-killed or freeze-killed cadavers influenced T. ni oviposition, larval choice, or larval consumption, indicating these insects did not discriminate cadaver cues. Virus-killed cadavers could play important roles in mediating interactions between plants, herbivores, and other trophic levels, with potential implications for viral transmission dynamics.