Leaf Damage Research Articles

Divergent reproductive responses of Caatinga dry forest plants to leaf-cutting ant herbivory

Herbivory is one of the key processes shaping life history traits linked to plant fitness and the leaf-cutting ants are amongst the most voracious and polyphagous herbivores of the Neotropics. They extensively harvest aboveground plant parts to grow their symbiotic fungus, including vegetative and reproductive tissues. Although leaf-cutting ant herbivory is expected to reduce plant reproductive success, the potentially different outputs of damage to vegetative and reproductive parts are still poorly known. This study investigates the influence of Atta opaciceps herbivory on the reproductive success of three plant species native to the Caatinga dry forest: Croton argyrophylloides (Euphorbiaceae), Cenostigma pyramidale, and Indigofera suffruticosa (Leguminosae). We selected 10 adult and active nests of A. opaciceps based on the presence of individuals of the three focal plant species in their vicinity. For each colony, we marked four individuals of each plant species (totaling 12 individuals per colony), which were then subjected to one of four herbivory treatments: (1) ant herbivory on both reproductive and vegetative parts, (2) manually simulated herbivory on the reproductive parts alone, (3) ant herbivory exclusively on vegetative parts, and (4) no herbivory. From January to April 2020, we monitored all 120 individuals, recording the number of inflorescences, flower buds, flowers, fruits, and the proportion of flowers maturing into fruits (fruit set, as a proxy of reproductive success). Results revealed variations in reproductive structure production and divergent responses to leaf-cutting ant herbivory among our focal species. In terms of inflorescence, flower bud production, and fruit set C. argyrophylloides showed reduced numbers when subjected to higher levels of total herbivory (reproductive and vegetative parts), but increased inflorescence and flower bud production when plants suffered only leaf damage. Cenostigma pyramidale individuals under partial herbivory displayed lower flower bud numbers than protected ones. In contrast, I. suffruticosa displayed conflicting results, with fully exposed plants producing more inflorescences than partially exposed counterparts and more flowers than leaf-damaged and protected individuals. Despite the varied effects on different plant parts across all three study species, the overall reproductive success (i.e. fruit set) of only one species (C. argyrophylloides) was significantly reduced by leaf-cutting ant herbivory. The resilience of the two other plant species to leaf-cutting ant pressure may be attributed to compensatory mechanisms, shedding light on the intricate interplay between herbivores and plants in the Caatinga dry forest. As leaf-cutting ants proliferate in response to anthropogenic disturbances, the patterns described in this study may become more pronounced, potentially affecting the organization of plant communities in the Caatinga dry forest.

Development of Menthyl Esters of Valine for Pest Control in Tomato and Lettuce Crops.

Menthyl ester of valine (MV) has been developed as a plant defense potentiator to induce pest resistance in crops. In this study, we attempted to establish MV hydrochloride (MV-HCl) in lettuce and tomato crops. When MV-HCl solutions were used to treat soil or leaves of potted tomato and lettuce plants, 1 µM MV-HCl solution applied to potted plant soil was most effective in increasing the transcript level of defense genes such as pathogenesis-related 1 (PR1). As a result, leaf damage caused by Spodoptera litura and oviposition by Tetranychus urticae were significantly reduced. In addition, MV-HCl-treated plants showed an increased ability to attract Phytoseiulus persimilis, a predatory mite of T. urticae, when they were attacked by T. urticae. Overall, our findings showed that MV-HCl is likely to be effective in promoting not only direct defense by activating defense genes, but also indirect defense mediated by herbivore-induced plant volatiles. Moreover, based on the results of the sustainability of PR1 expression in tomato plants treated with MV-HCl every 3 days, field trials were conducted and showed a 70% reduction in natural leaf damage. Our results suggest a practical approach to promoting organic tomato and lettuce production using this new plant defense potentiator.

Dose-Dependent Effect on Plant Growth of Exposure to Metal-Organic Framework MIL-101(Cr).

With the increasing use of metal-organic frameworks (MOFs), they will inevitably enter the environment intentionally or unintentionally. However, the effects of MOFs on plant growth are poorly understood. Here, we investigated the effects of exposure of the rhizosphere to MOFs on plant growth. MIL-101(Cr) was selected as a research model due to its commercial availability and wide use. Soybean plants at the two-leaf stage were subjected to various durations (1-7 days) and concentrations (0-1000 mg/L) of exposure in hydroculture with a control group treated with ultrapure water. We found that MIL-101(Cr) had a positive effect on soybean growth at a lower dose (i.e., 200 mg/L); however, at higher doses (i.e., 500 and 1000 mg/L), it exhibited significant toxicity to plant growth, which is evidenced by leaf damage. To investigate the mechanism of this effect, we used Cr as an indicator to quantify, track, and image MIL-101(Cr) in the plant with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Results indicated that MIL-101(Cr) primarily accumulated in the cortex of roots (up to 40 times higher than that in stems), with limited translocation to stems and negligible presence in leaves and cotyledons. In addition, metabolomic analysis of soybeans indicated that low-dose MIL-101(Cr) could increase the sucrose content of soybean roots to promote plant growth, while a high dose could induce lipid oxidation in roots. This study provides valuable insights into the ecological toxicology of MOFs and underscores the importance of assessing their environmental impact for sustainable agricultural practices.

Plant-ant interactions mediate herbivore-induced conspecific negative density dependence in a subtropical forest

The early growth stage of plants is vital to community diversity and community regeneration. The Janzen-Connell hypothesis predicts that conspecific density dependence lowers the survival of conspecific seedlings by attracting specialist natural enemies, promoting the recruitment and performance of heterospecific neighbors. Recent work has underscored how this conspecific negative density dependence may be mediated by mutualists – such as how mycorrhizal fungi may mediate the accrual of host-specific pathogens beneath the crown of conspecific adult trees. Aboveground mutualist and enemy interactions exist as well, however, and may provide useful insight into density dependence that are as of yet unexplored. Using a long-term seedling demographic dataset in a subtropical forest plot in central China, we confirmed that conspecific neighborhoods had a significant negative effect on seedling survival in this subtropical forest. Furthermore, although we detected more leaf damage in species that were closely related to ants, we found that the presence of ants had significant positive effects on seedling survival. Beside this, we also found a negative effect of ant appearance on seedling growth which may reflect a trade-off between survival and growth. Overall, our findings suggested that ants and conspecific neighborhoods played important but inverse roles on seedling survival and growth. Our results suggest ants may mediate the influence of conspecific negative density dependence on seedling survival at community level.

Effect of air pollution on plant life in the city of Chittagong, Bangladesh

Bangladesh faces a serious problem with air pollution, which has a negative impact on human health and tree health. Leaf damage, slow development, and decreased photosynthetic activity are just a few of the harmful effects on trees that have been linked to high concentrations of pollutants such as particulate matter, sulfur dioxide, and nitrogen oxides. These consequences affect the aesthetic value of green spaces in addition to interfering with the functions of the ecosystem that trees offer, such as air filtration and carbon sequestration. Given the seriousness of the problem, the present study plan was implemented to evaluate the amount of pollutants such as SOx, NOx, O3, hydrocarbons, particulate matter 2.5, particulate matter 10 and suspended particulate matter in the air in several urban areas of Chittagong and to evaluate the amount of chlorophyll from the leaves of affected and without affected leaves so that it may understand how the photosynthesis process of plants is interrupted by air pollution. 2 Number Gate Circle, Akbarsha Lane Circle, Alongkar Mor Bus Stop, Barik Building Circle, BDR Field Circle, Halishahar Access Road, Artillery Center-North Halishahar, Bangladesh Forest Research Institute and CRB Circle were selected as sampling location based on their heavy traffic and crowdedness. For the analysis of chlorophyll, each plant leaves were collected in three sections such as unaffected, slightly affected, and affected for comparison. The data studied showed that the most polluted zone with particulate matter had a lower chlorophyll concentration in the surrounding tree leaves. This can indicate that particulate matter can hinder photosynthesis reactions.

Natural selection by pollinators on floral attractive and defensive traits did not translate into selection via fruits in common milkweed

Considering both pollinator and herbivore pressures on plant reproductive and defensive traits is key to understanding patterns of selection for plants. However, phenotypic selection studies connecting floral traits and plant defenses with pollinator activity and herbivore damage remain rare. We used the common milkweed, Asclepias syriaca (Apocynaceae), to study phenotypic selection on attractive and defensive traits, and nectar rewards. We measured herbivore (leaf damage) and pollinator activity (pollinia movement) and quantified selection via female (pollinia insertions and fruit number) and male fitness (pollinia removals). We found selection to increase plant and inflorescence size and to decrease floral size (i.e. petal width) via female fitness. We also detected selection to increase floral but not leaf latex. The lack of selection on leaf latex was congruent with the low herbivory observed, however we also did not observe florivory in the population that would explain the advantage of more floral latex. Interestingly, we found selection on attractive traits differed via pollinia insertions and fruits initiated, suggesting that something other than pollinators was driving selection via fruit production. In contrast to female fitness, we did not find selection on any trait through male fitness, suggesting no sexual conflicting selection, at least through these proxies. Our findings reinforce the importance of the direct assessment of pollinator pressures in phenotypic selection studies before assuming pollinators as drivers of floral evolution by natural selection. Further work in southern populations closer to the centre of the species range, where herbivory and plant defense investment are higher, may help elucidate selection on attractive and defensive traits.

Entomopathogenic nematodes as an effective and sustainable alternative to control the fall armyworm in Africa.

The recent invasion of the fall armyworm (FAW), a voracious pest, into Africa and Asia has resulted in unprecedented increases in insecticide applications, especially in maize cultivation. The health and environmental hazards posed by these chemicals have prompted a call for alternative control practices. Entomopathogenic nematodes are highly lethal to the FAWs, but their application aboveground has been challenging. In this study, we report on season-long field trials with an innocuous biodegradable gel made from carboxymethyl cellulose containing local nematodes that we specifically developed to target the FAW. In several Rwandan maize fields with distinct climatic conditions and natural infestation rates, we compared armyworm presence and damage in control plots and plots that were treated with either our nematode gel formulation, a commercial liquid nematode formulation, or the commonly used contact insecticide cypermethrin. The treatments were applied to the whorl of each plant, which was repeated three to four times, at 2-week intervals, starting when the plants were still seedlings. Although all three treatments reduced leaf damage, only the gel formulation decreased caterpillar infestation by about 50% and yielded an additional ton of maize per hectare compared with untreated plots. Importantly, we believe that the use of nematodes can be cost-effective, since we used nematode doses across the whole season that were at least 3-fold lower than their normal application against belowground pests. The overall results imply that precisely formulated and easy-to-apply nematodes can be a highly effective, affordable, and sustainable alternative to insecticides for FAW control.

Morpho-bioecological Accounts of the Phytophagous Coccinellid Beetle, Henosepilachna vigintioctopunctata (Fabricius, 1775) along with Botanical Pest Management from Eastern India

Field and laboratory investigations were carried out during 2022-23 to study the bioecology and efficacy of plant extracts for the phytophagous coccinellid, Henosepilachna vigintioctopunctata (F.) for understanding them properly to devise ecology based management techniques. Besides damaging the brinjal a significant population of H. vigintioctopunctata beetle was recorded from the solanaceous weeds like Solanum nigrum and Physalis spp. Biology of H. vigintioctopunctata on S. nigrum under laboratory conditions was conducted and the results revealed that the beetle completed its life cycle in 23.1±3.5 days and the mean fecundity was 220 ± 33.0 revealing that the beetle can very successfully breed on this host plant. Morphological and taxonomical descriptions of the immature as well as adult stages of these beetles were studied and for proper identification the male genitalia was dissected. The population fluctuation of H. vigintioctopunctata in relation to weather parameters was also monitored under field conditions and was observed to have significant influence altogether on the pest population in brinjal but not in alternate hosts. The methanolic extracts of Polygonum hydropiper and tobacco decoction were found moderately effective in lowering the leaf damage by the beetle.

Development of Smart Agriculture to detect the Arabica Coffee Leaf Disease using IAFSA based MSAB with Channel and Spatial Attention Network

Plant diseases provide challenges for the agriculture sector, notably to produce Arabica coffee. Recognising issues on Arabica coffee leaves is a first step in avoiding and curing illnesses to prevent crop loss. With the extraordinary advancements achieved in convolutional neural networks (CNN) in recent years, Arabica coffee leaf damage can now be identified without the aid of a specialist. However, the local characteristics that convolutional layers in CNNs record are typically redundant and unable to make efficient use of global data to support the prediction process. The proposed Hybrid Attention UNet, also known as CMSAMB-UNet due to its feature extraction and global modelling capabilities, integrates both the Channel and Spatial Attention Module (CSAM) as well as the Multi-head Self-Attention Block (MSAB). In this study, CMSAMB-UNet is built on Resnet50 to extract multi-level features from plant picture data. Two shallow layers of feature maps are used with CSAM according to local attention. used throughout the feature extraction process to enrich the features and adaptively disregard unwanted features. In order to recreate the spatial feature connection of the input pictures using high-resolution feature maps, two global attention maps produced by MSAB are combined.

Biological Control and Habitat Management for the Control of Onion Thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), in Onion Production in Quebec, Canada.

Onion thrips (Thrips tabaci) can pose a significant threat to onion crops, causing leaf damage, reduced bulb size and quality, and yield loss during severe infestations. Conventional insecticide use has been the primary method for managing this pest species, but the efficacy of this approach is inconsistent. Furthermore, emerging pest resistance is a growing concern in some regions. This two-year field study aimed to assess the effectiveness of several pest management strategies in controlling onion thrips populations and limiting their impact on onion yields. The strategies tested consisted of habitat manipulations (including flower strips and straw mulch), biological control agents (Stratiolaelaps scimitus, Neoseiulus cucumeris, Amblyseius swirskii, and Beauveria bassiana), as well as physical barrier control methods (exclusion nets, kaolin, and mineral oil). Habitat manipulation techniques, particularly the use of flower strips, reduced thrips populations by up to 50% and increased onion yields by 25%. In contrast, exclusion nets had a detrimental effect on onion yields, and the other alternative control methods produced results comparable to those obtained for untreated controls. When used alone, biological control agents were not effective at maintaining thrips populations below economically damaging levels. This study offers valuable insights into effective and sustainable pest management practices for the onion industry.

Screening of Popular Maize Hybrids against fall Armyworm, Spodoptera frugiperda

Fall armyworm (Spodoptera frugiperda) was the member of noctuidae family which has got economic importance as polyphagous and extreme pest of many important crops, including maize in India and elsewhere. In this context, screening experiment was conducted by using 15 different maize cultivars viz., CP 818, NK 6240, GPMH 1110, GH 0727, 900 M Gold, NK 6801, SM- 2, S- 4717, GK 3207, KMH 225, KMH 8333, Sunny NMH 777, 30 B07, PMH 2244 and Kaveri minchu in MARS, Dharwad. The results revealed that PMH 2244 was recorded the least mean larval load (0.67 larvae per plant) compared to rest of the cultivars. Among fifteen different cultivars screened, Kaveri minchu recorded the highest mean leaf damage score (4.62) whereas, the hybrid PMH 224 recorded the least mean leaf damage score (0.73). The cultivars, PMH 2244, NK 6801 and 900 M Gold were recorded with the least egg mass (0.33 per plant) whereas, the hybrids SM- 2 and Kaveri minchu were recorded with the highest egg mass of 0.63 and 0.61 per plant, respectively. Biophysical parameters of plant such as plant height, leaf area, stem girth and trichome density have been implicated in maize resistance to the fall armyworm. All the plant characters except leaf area which are mentioned above showed significant negative correlation with fall armyworm infestation whereas, leaf area was found significantly positive correlation.

Effect of Date of Sowing on Incidence of Fall Armyworm, Spodoptera frugiperda in Maize

Fall armyworm (Spodoptera frugiperda) is a member of the Noctuidae family which has economic importance as a polyphagous and extreme pest of many important crops, including maize in India and elsewhere. In this context, an experiment regarding the influence of different dates of sowing on the incidence of fall armyworm was conducted in MARS, Dharwad. The results revealed that the least mean larval load of fall armyworm was recorded in crop sown during the July 2nd fortnight (0.75 larvae per plant) and the highest was recorded in crop sown during the August 2nd fortnight (1.53 larvae per plant). Whereas, the lowest mean leaf damage score of 2.95 was observed in crop sown during 2nd fortnight of July and the highest was recorded in the crop sown during 2nd fortnight of August (4.82).

Novel Potential of Rose Essential Oil as a Powerful Plant Defense Potentiator.

Terpenoids, natural compounds released by plants, function to enhance plant defense. The aim of this study was to investigate the effects of terpenoid-enriched essential oils (EOs) on tomato plants. From the application of a highly diluted solution of 11 different EOs to potted tomato soil, our study showed that rose essential oil (REO), rich in β-citronellol, played a crucial role in activating defense genes in tomato leaves. As a result, leaf damage caused by herbivores, such as Spodoptera litura and Tetranychus urticae, was significantly reduced. In addition, our results were validated in field trials, providing evidence that REO is an effective biostimulant for enhancing plant defense against pests. Notably, the REO solution also had the added benefit of attracting herbivore predators, such as Phytoseiulus persimilis. Our findings suggest a practical approach to promote organic tomato production that encourages environmentally friendly and sustainable practices.

Exploring host plant resistance in chilli (Capsicum spp) against Southeast Asian thrips (Thripsparvispinus Karny)

Southeast Asian thrips (Thrips parvispinus Karny), poses a significant threat to chilli crop production causing severe economic losses. They feed heavily on leaves, flowers and young fruits causing severe damage to the crop. Exploring host plant resistance is the best ecofriendly management strategy to combat this pest. Large-scale field screening of 481 germplasm accessions, followed by further screening of selected accessions under polyhouse conditions led to identification of fourteen accessions that showed resistance against Southeast Asian thrips. Among the screened accessions, IIHR-B-HP-79 showed the highest level of Southeast Asian thrips resistance with significantly low leaf and fruit damage scores of 0.28 and 0.13, respectively. Further, screening of selected fourteen field resistant accessions was performed through whole plant bio-assay where in four accessions i.e., IIHR-B-HP-79 (C. frutescens), IIHR 4550, IIHR 4501 & IIHR 4410 (C. chinense) showed good level of resistance. Multi-choice leaf disc assay, demonstrated that IIHR-B-HP-79 exhibited a high level of resistance with the lowest percent of scraping damage during both the vegetative (10.98) and flowering stages (15.31). The identified resistant accession IIHR-B-HP-79 (C. frutescens), has the potential to be a valuable genetic resource as donor in breeding for Southeast Asian thrips resistance.

Plant–plant communication in Camellia japonica and C. rusticana via volatiles

Plants emit volatile compounds when they are subjected to herbivorous, pathogenic, or artificial damages. Both the damaged plant and the neighboring intact plants induce resistance when they receive these volatiles, a phenomenon known as plant–plant communication. However, field observations of this phenomenon are limited. To understand the nature of plant–plant communication, we collected information about intra- and inter-plant signaling via volatiles in Camellia japonica and C. rusticana under natural conditions. We exposed intact branches of damaged plant (intra-plant) or neighboring plant (inter-plant) to artificially damaged plant volatiles (ADPVs). Leaf damage reduced in ADPVs-exposed branches in the neighboring plants compared to branches that were exposed to volatiles from intact leaves, thus, indicating that inter-plant signaling occur by the emission of volatiles from damaged leaves. We also conducted an air-transfer experiment wherein the headspace air of the damaged branch was transferred to the headspace of intact branches. Leaf damage reduced on the ADPVs-transferred branch compared to the control branch. The effect of volatiles on damage reduction lasted for three months. Our results indicate that ADPVs in Camellia species contain cues that induce resistance in neighboring plants. Our findings improve understanding of plant defense strategies that may be used in horticulture and agriculture.

The population dynamics of Spodoptera frugiperda after its invasion in Lampung Province, Indonesia

Spodoptera frugiperda is an invasive pest that attacks maize throughout Indonesia. As an invasive pest, the population of S. frugiperda continues to increase exponentially, leading to outbreaks. Both internal factors (biology) and external factors (weather, host, and natural enemies) can affect the growth rate of pest populations. This research was conducted to assess the population dynamics of S. frugiperda based on the extent of its infestation and damage to maize post-invasion in Lampung Province. Observations were made in maize fields in 15 districts of Lampung Province from 2019 to 2022. Damage intensity was calculated based on the leaf damage scale. Weather data from 2019 to 2022 was obtained from the Lampung Province Central Statistics Agency. The research results indicate that upon the initial introduction of S. frugiperda to Lampung Province, the population increased exponentially, as observed based on the level of infestation and damage to maize. There was an outbreak from late 2019 to early 2020, and after that, there was a population decline. The population increase coincided with the early rainy season, which is associated with the beginning of the maize planting season. Although the level of damage to the maize is considered slight, S. frugiperda can cause anywhere between 21.94% to 51.38% of damage.

Seasonal Incidence and Infestation Pattern of Sunflower Head Borer (Helicoverpa armigera) and Leaf Eating Caterpillar (Spodoptera litura) under the Influence of Climatic Factors

Field experiments were conducted at Regional Research and Technology Transfer Station (RRTTS), Ranital, Bhadrak, OUAT during the summer seasons of 2019-20 and 2020-21 to study the seasonal incidence of sunflower head borer and leaf-eating caterpillar in sunflower in relation to the abiotic factor. The seasonal incidence of the target insects, Spodoptera litura and Helicoverpa armigera, was investigated using pheromone traps installed in the unprotected sunflower plots (10 m x 5 m) at the research block. The trap catches of male adults were expressed as a number of males trapped per trap per week. In the observation plots, the sunflower hybrid Aruna was cultivated with the approved agronomic package of techniques without any plant protection measures. Weekwise larval populations of Spodoptera litura and Helicoverpa armigera were counted from 10 randomly selected tagged plants starting from the initiation of damage and expressed as larval intensity i.e. average larval population per plant. Besides, weekwise incidence of the pest (leaf damage by tobacco caterpillar and head damage by head borer) were also recorded. The findings of the investigation indicated that tobacco caterpillars' adult activity commenced from the 5th to 6th standard weeks (1st and 2nd week of February) and peak activity in the 11th standard week (3rd week of March). Similarly, the larval population began to appear in the 6th to 7th standard weeks in 2020 and 2021, respectively with a peak population build-up stage during the 12th standard week and their activity steadily decreased as the cropping season progressed. The peak infestation stage coincided with the period of maximum larval activity and the pest caused sizable damage from the early vegetative stage to the peak flowering stage of the crop. The sunflower head borer (Helicoverpa armigera) infested sunflower crops throughout the reproductive stage of the plant with adult activity beginning in the 9th to 10th standard weeks (last week of February-first week of March) and attaining the peak in the 12th to 13th standard weeks (3rd-4th week of March). Similarly, the larval population began to appear in the 10th to 11th standard week and reached the peak in the 13th to 14th standard week (last week of March to first week of April). Various environmental parameters viz. temperature, relative humidity and rainfall were collected from the automated weather station of Gramin Krishi Mausam Sewa (GKMS) located at RRTTS, Ranital., These abiotic factors were correlated with trap catch, larval intensity, leaf damage head damage to study the influence of ecological parameters on pest incidence and infestation. The findings of the investigation indicated that among the abiotic factors temperature had a positive influence and relative humidity exhibited a negative effect on the population and damage of Spodoptera litura. All the temperature variables and bright sunshine hour (BSH) exhibited a significant positive correlation and relative humidity (afternoon) had a significant negative correlation with the head damage Helicoverpa armigera.

Insecticidal Effects of Transgenic Maize Bt-Cry1Ab, Bt-Vip3Aa, and Bt-Cry1Ab+Vip3Aa against the Oriental Armyworm, Mythimna separata (Walker) in Southwest China.

The oriental armyworm, Mythimna separata (Walker), an important migratory pest of maize and wheat, is posing a severe threat to maize production in Asian countries. As source areas of spring-summer emigratory populations, the control of M. separata in southwestern China is of great significance for East Asian maize production. To assess the toxicity of Bt maize against the pest, bioassays of Bt-(Cry1Ab+Vip3Aa) maize (event DBN3601T), Bt-Cry1Ab maize (event DBN9936), and Bt-Vip3Aa maize (event DBN9501) were conducted in Yunnan province of southwest China. There were significant differences in insecticidal activity between the three Bt maize events, and DBN3601T presented the highest insecticidal role. The results also indicated that the insecticidal effect of various Bt maize tissues took an order in leaf > kernel > silk, which is highly consistent with the expression amounts of Bt insecticidal protein in leaf (69.69 ± 1.18 μg/g), kernel (11.69 ± 0.75 μg/g), and silk (7.32 ± 0.31 μg/g). In field trials, all larval population densities, plant damage rates, and leaf damage levels of DBN3601T maize were significantly lower than the conventional maize. This research indicated that the DBN3601T event had a high control efficiency against M. separata and could be deployed in southwest China for the management of M. separata.

Photosynthesis of rice leaves with a parallel venation is highly tolerant to vein severing.

Vein severing in plants caused by leaf damage is common in fields where crops are cultivated. It is hypothesized that leaves with complex reticulate venation can withstand hydraulic disturbances caused by vein severing, thereby preserving leaf carbon assimilation. However, limited research focuses on vein damage of leaves with parallel venation. We studied how vein-severing affected the photosynthetic traits of rice (Oryza sativa) leaves in seconds, minutes and days, under varying water-demand conditions and differing extents of water supply disruption. Rice leaves completely lost their photosynthetic capacity within 2.5 minutes after excision. Severing the midrib resulted in reduced light-saturated photosynthetic rate (A), stomatal conductance (gsw ) and transpiration rate (E) by 2.6, 6.8 and 5.9%, respectively, already after thirty minutes. We further investigated the photosynthetic trait responses to various extents of leaf width severing, while keeping the midrib functional. Surprisingly, A, gsw and E in the downstream area of the severed leaves largely remained stable, showing minimal variation across different leaf width severing ratios. These traits declined only slightly even under increased ambient light intensity and leaf-to-air vapor pressure deficit. This sustained photosynthesis post-severing is attributed to the efficient lateral water transport. Long-term leaf damage slightly but not significantly, impacted the downstream photosynthetic traits within five days post-severing. However, a more pronounced reduction in gas exchange during leaf senescence was observed nine days after severing. These findings suggested that rice leaves can tolerate hydraulic disturbances from vein severing and maintain functionality under various conditions, which is crucial for crop yield stability. However, long-term consequences require further investigation.

Morphological and Molecular Analysis of Two Mycophagous Nematodes, Aphelenchoides bicaudatus and A. rutgersi (Nematoda: Aphelenchoididae) from Florida Strawberry.

From 2016 to 2021, nematode surveys in Florida strawberry fields revealed several species of foliar nematodes (Aphelenchoides spp.). Aphelenchoides besseyi sensu stricto was detected only in 2016 and 2017 on photosynthetic strawberry leaves/buds, but other not well characterized populations of Aphelenchoides sp. were found on declining/dessicated leaves. Morphological analyses showed that these samples of Aphelenchoides sp. consisted of A. bicaudatus, a species detected in Florida for the first time, and A. rutgersi, a species previously reported in Florida from the citrus rhizosphere. These two species differed from A. besseyi in the shape of their tail terminus: bifurcate in A. bicaudatus; mucronate with a ventral thin mucro in A. rutgersi; and stellate in A. besseyi. One population each of these species was used for morphological and molecular analyses after being reared on Monilinia fructicola. Body and tail length differences were observed among Florida A. bicaudatus and other populations from the Far East and South Africa. Phylogenetic analyses of the rRNA gene sequences showed that Florida A. bicaudatus grouped with those of species from South Korea, Taiwan, and the Netherlands and several other populations listed as Aphelenchoides sp. from Brazil, Costa Rica, and Japan, which were considered as representatives of A. bicaudatus in this study. Similarly, sequences of Florida A. rutgersi grouped with those from environmental samples in Japan and North Carolina, which were listed as Aphelenchoides sp. and were considered as representatives of A. rutgersi in this study. Photosynthetic strawberry leaf samples were free from both A. bicaudatus and A. rutgersi, indicating that these two species did not damage strawberry. They were associated with desiccated leaves and/or propagative stolons, usually infected by fungi, confirming that they are mycetophagous under field conditions in this study. Results of soybean leaf inoculation on moist filter paper containing A. bicaudatus specimens showed that this species could become phytophagous under artificial conditions. Nematodes penetrated the leaf epidermis and migrated into the mesophyll causing leaf tissue discoloration/necrosis, which remained localized within the infested area. Soybean leaf damage was almost negligible, and no nematode reproduction was observed in the inoculated soybean areas.