Locust Control Research Articles

Optimum Flight Height for the Control of Desert Locusts Using Unmanned Aerial Vehicles (UAV)

Desert locust is one of the most destructive migratory pest in the world. Current methods of control rely on conventional chemical insecticides during invasion. Some environmentally friendly biopesticides based on Metarhizium acridum and insect growth regulators have also been deployed in preventive control operations. They have been tested in sprayers mounted on commonly used platforms such as vehicles, aircraft, and human. However, despite being used successfully, these tools present many challenges, hence the need to supplement them with suitable alternatives. The successful use of drones to control pests such as fall armyworm, planthoppers, aphids, among others, makes it an attractive technology that has the potential to improve locust management, especially in inaccessible areas. However, key parameters for the safe and optimal use of drones in desert locust control are not documented. This study established the key parameters for spraying desert locusts with a drone. To test the optimum height for spraying Metarhizium acridum on the locusts, the drone was flown at five different heights: 2.5, 5, 7.5, 10, and 12.5 m. At each height, the drone sprayed the ink mixture on spray cards pinned to the ground to approximate the droplet density and compare it to the standard droplet density recommended for desert locust control. To assess the efficacy of M. acridum and the effectiveness of drones in its application, 50 g of spores were mixed in 1 L of diesel and sprayed on caged live locusts of different stages (3rd and 4th instars, as well as the adults); they were monitored for twenty-one days in a controlled room, and their mortality was determined. Variation in droplet density between the tested heights was significant. A height of 10 m agrees with the recommended standard droplet density within the 45 droplets/cm2 range. Mortality varied among the locusts’ developmental stages within and between heights. Survival probability varied between heights for 3rd instar, 4th instar, and adults. All the developmental stages of the desert locust were susceptible to Novacrid and the recommended target stage is the 3rd instar. Management of desert locusts by the use of drone technology appears promising when the pesticides are applied at an optimum height and standard operating procedures are followed. Further research could explore the gap in the effects of environmental parameters on flight application efficiency.

Study on the Identification of Habitat Suitability Areas for the Dominant Locust Species Dasyhippus Barbipes in Inner Mongolia

Grassland locusts harm a large amount of grassland every year. Grassland locusts have caused devastating disasters across grassland resources and have greatly impacted the lives of herdsmen. Due to the impacts of climate change and human activity, the distribution of grassland locust habitats changes constantly. The monitoring and identification of locust habitats is of great significance for the production and utilization of grassland resources. In order to further understand the behavior of these grassland pests and carry out precise prevention and control strategies, researchers have often used survey points to reveal the distribution of habitat-suitability areas or establish the high density of locusts (more than 15 locusts/m2) to identify the different risk levels of habitat-suitability areas for grassland locusts. However, the results of these two methods have often been too large, which is not conducive to the precise control of grassland locusts in large areas. Starting from the sample points of our locust investigation, we conducted a hierarchical prediction of the density of locusts and used the probability value of locust occurrence, as predicted by a maximum entropy model, to categorize the habitat-suitability areas according to the probability thresholds of suitable species growth. The results were in good agreement with the actual situation and there was little difference between the prediction results for locust densities greater than 15 locusts/m2 in the middle- and high-density habitat-suitability areas and those for all survey points, while there was a big difference between the prediction results for densities in the middle- and low-density habitat-suitability areas and those for all survey points. These results could provide a basis for the efficient and accurate control of grassland locusts and could have practical significance for future guidance.

Sweet chestnut forests under black locust invasion threat and different management: An assessment of stand structure and biodiversity

Sweet chestnut forests in Europe are impacted by management abandonment, non-native species invasions and diseases, among other factors. Understanding the effects of these factors is crucial for forecasting future biodiversity changes, as well as proposing appropriate planning and management strategies. We studied sweet chestnut (Castanea sativa Mill.) and black locust (Robinia pseudoacacia L.) dominated forests within three hilly landscapes (Euganean hills, Montello, and Berici hills) of north-eastern Italy. We surveyed 25 paired sweet chestnut and black locust dominated plots of 100 m2 representing coppice or over-aged stands. We collected and analysed data related to vascular plant composition and richness, soil physical features (moisture content, shear strength and penetration resistance), ammonia-oxidising archaea in the soil, and stand structure features. Composition of vascular plants differed significantly between the two forest types, without the influence of management regime. Soil characteristics did not change comparing forest types, management regimes and their interaction, except for soil moisture that was higher in coppice forests. Ammonia-oxidising archaea abundance was lower in sweet chestnut stands. Sweet chestnut and black locust forests have a similar stand structure. The management regime played a role in determining mean diameter, number of stems and deadwood volume. We suggest adopting a heterogeneous array of silviculture practices to achieve the highest variety of forest structures and plant composition in Mediterranean hilly landscapes, coupled with management practices aimed at black locust control.

Observations on the display flights of male Brown Songlarks (Cincloramphus cruralis Vigors and Horsfield 1827) before and after the application of fenitrothion, an organophosphorous pesticide for locust control, in a semi-arid grassland in south-western New South Wales and suggestions for further research

ABSTRACT Exposure of songbirds to organophosphorous pesticides has been shown to affect a range of behavioural characteristics including singing, displaying and flying that consequently can have significant impacts on the viability of free-living individuals and populations. In the current study, display flights of male Brown Songlarks (Cincloramphus cruralis Vigors and Horsfield 1827) before and after the application of fenitrothion (O,O-dimethyl-O-[3-methyl-4-nitrophenyl]-phosphorothioate) during locust spray operations around Conargo, south western New South Wales, were monitored incidentally for number, duration and the presence of song during flight. The duration of display flights undertaken by male C. cruralis showed a statistically significant increase after exposure to fenitrothion (t0.05, 398 = 1.97; p = 0.0085, analysed using log10 transformed flight duration data), despite the mean number of flights undertaken decreasing from 5.7 pre-spray to 4.7 post-spray during 10 min survey periods. The proportion of display flights in which the male was calling, however, did not differ between pesticide-exposed and unexposed male C. cruralis (χ2(0.05, 1) = 0.323; p = 0.570). To better understand the impacts of pesticide exposure on C. cruralis behaviour and ecology, the observations presented here require further study and validation with the addition of other variables such as territory mapping, assessment of reproductive success and the quantification of enzymatic biomarkers indicative of exposure to organophosphorous insecticides, undertaken concomitantly.

The Application of Drone Technology for Sustainable Agriculture in India

Agriculture in India faces challenges from multiple fronts: decline in productivity, climate change and sustainability. Using drones in farming contributes to sustainable agriculture in terms of social, economic and environmental dimensions. This article discusses the advantages of adopting drone technology in India. The drones are useful in multiple ways, such as, soil analysis for field planning, plant establishment, precision application of agrochemicals, crop monitoring, irrigation management, crop health assessment, livestock monitoring, and disaster management, geo-fencing, crop biomass and damage estimation, locust control, and transporting goods in agriculture. The paper also describes the initiatives of Government of India towards promoting drone technology. Challenges in use of the drone technology have been discussed. The study found that the application of drone technology saves time, labour, water, and cuts spending on chemicals. It also reduces use of chemicals and eliminates the chemical exposure to human. The paper concludes that the government should effectively adopt and leverage the potential of drone technology for transforming the agriculture sector and life of millions of farmers in India.

Avian assemblages are maintained after aerial applications of ULV fenitrothion for control of the Australian plague locust (Chortoicetes terminifera (Walker)) in arid and semiarid agroecosystems

Context Risk assessments currently undertaken to approve pesticides for use against locusts in Australia are predominated by laboratory-generated data, often collected from non-endemic species. Very little information exists concerning the potential ecological effects of insecticides used for locust control. Aim To determine the effect of aerial ultra-low volume (ULV) applications of the organophosphorous insecticide, fenitrothion (used for locust control), on avian assemblages in arid and semiarid agro-ecosystems. Methods Avian abundance was surveyed in pesticide-exposed and unexposed locations during standard locust control operations, using fenitrothion, in western New South Wales and Queensland in the spring and summer of 1996, 1997 and 2000, using a transect-point method. Temporal changes in assemblages were analysed using multi-dimensional ordination (MDS) and permutational analysis of variance (PERMANOVA) with PRIMER (V7). Key results Avian assemblages varied over time, independent of pesticide application, reflecting significant redistribution and mobility of birds across a highly disturbed agricultural landscape, irrespective of pesticide exposure. Additionally, pesticide exposure did not affect species abundance or diversity. Conclusions There was no evidence that ultra-low volume (ULV) applications of fenitrothion, currently used in locust control, are impacting avian assemblages, despite previous research indicating that individual birds co-occurring with spray operations suffer suppressions in the enzymatic biomarker for OP exposure, plasma acetylcholinesterase (AChE). Implications Although the risk to avian assemblages associated with the aerial application of locusticides is reduced by the small proportion of the landscape where locust control activities are focused, any change in spray application parameters would necessitate a re-evaluation of the risks associated with insecticide exposure.

Effect of temperature and some factors on gut α-amylase of the desert locust; Schistocerca gregaria Forsk. (Orthoptera:Acrididae)

Gut of 4th nymphal instar of the desert locust; Schistocerca gregaria Forsk. was analyzed to study the effect of ambient temperature and some factors controlling α-amylase activity ( in vitro ) as a key carbohydrase enzyme for carbohydrate digestion. The study might provide a basis for locust control in different environments conditions. Crude gut enzymes as α-amylase, cellulase, invertase and trehalase were extracted by gut homogenization and differential centrifugation up to 100,000 Xg. Invertase had the highest activity in the gut followed by amylase and trehalase, while cellulase had the lowest one. Increasing ambient temperature from 10 to 37 °C enhanced, in vivo , α-amylase activity which declined when environmental temperature increased more than 37 °C. In vitro experiments revealed that α-amylase. crude protein extract showed optimal activity at pH 6, 45 °C and 17.9mg/ml soluble starch (substrate) concentration. Amylase was thermostable up to 50 °C, while it did not able to keep its major activity at 70 °C. The enzyme was more stable when exposed to acidic than to alkaline media.V max of α-amylase was 3.73 μmol glucose min −1 mg protein −1 . The results revealed that gut α-amylase had a relatively low affinity to soluble starch (high K m value), and low activation energy (0.451 KJ mol −1 ). Relatively high ambient temperature reduced α-amylase that might affect carbohydrates digestion and reduce locust nutrition.

Observations on populations of a small insectivorous bird,

The use of chemical pesticides to manage locust populations in natural ecosystems is likely to impact non-target arthropods and their predators. However, the relative effects of different locust control applications on Australian birds are unknown. Aerial applications of fipronil and fenitrothion are examples of two pesticides used in locust control in semiarid Australia. To test the relative impacts of pesticides on non-target fauna, pesticides were applied to replicate sites using aerial ultra-low-volume application methods. The body condition and biomarkers of pesticide exposure in resident white-winged fairy wrens (Malurus leucopterus leuconotus) at treatment and control sites were measured for two weeks before and after treatments. No measures suggested negative impacts of pesticide applications. However, birds monitored at treatment sites gained mass, possibly due to indirect impacts of pesticides on bird feeding patterns or the availability or behaviour of insect prey. Bird mass measures remained high at fipronil sites, whereas the mass of birds at fenitrothion sites returned to baseline levels within one week. As this study was conducted during dry conditions, when locust plagues are less likely, future insecticide research should also consider the availability of insect prey, its effect on insectivore feeding behaviour and the interaction of rainfall events.

Governing nature, modernizing colonialism: Hans J. Brédo, locust control research and inter-imperial cooperation in Africa (1930s–1950s)

Governing nature, modernizing colonialism: Hans J. Brédo, locust control research and inter-imperial cooperation in Africa (1930s–1950s)

Disaster management takes to the skies: How new technologies are reconfiguring spatialities of power in desert locust management

This article explores how new technologies – such as drones and satellites – are incorporated into disaster management and questions the implications for power relations between disaster authorities and subjects. This is a critical area of research, as the proliferation of aerial and networked technologies has made their use in disaster management and response more common. Although concerns have been raised about the potential use of aerial and networked technologies in the surveillance and spatial discipline of populations by commercial and government actors, few have considered the implications for disaster management. In response, this article turns to geographical literature on necropower, verticality, and planetary spatialities to analyse technological innovations in responses to desert locust upsurges in Kenya. Drawing from qualitative research carried out between February 2020 and January 2021, we explain how desert locust control operations have shifted from horizontal to vertical to networked and planetary in nature through experimentation with new technologies over the past century. We argue that aerial and networked technologies have led to a volumetric shift in desert locust management and response, giving remote and increasingly automated actors who operate ‘above’ greater power over the life and death of populations ‘below’. In making this argument, we adopt a more-than-human perspective to account for how nonhuman entities and lifeforms shape and are subjected to necropolitical disaster management and responses. We conclude by reflecting on what this analytical approach has to offer the study of vertical and volumetric geographies.

Locust Attack: Managing and Control Strategies by the Government of Pakistan

During outbreaks of Schistocerca gregaria, the desert locust swarms, and plagues known to infest numerous regions across wide areas of Asia and Africa. The locust devours large amounts of crops and rangeland flora. Recently the locust outbreak began in June 2018 in Saudi Arabia’s distant areas and entered in Pakistan March 2019, destroying main crops such as cotton, wheat, rice and maize in many districts across Baluchistan, Punjab, Sindh and Khyber Pakhtunkhwa provinces. On February 1, 2020, a national emergency was proclaimed, and the Plant Protection department countered by launching monitoring and prevention activities with the help of other institutions in Pakistan, as well as global and bilateral organizations. Surveillance and control activities were carried out with the majority of the insecticide formulations being oil-based ultra-low volume, nonconventional and green technology approaches. In addition, the Pakistani government devised a comprehensive phase wised management strategy as well as a National Locust Control Center with fast retort troops deployed in critical areas. Additional surveillance and control measures are needed to stop or alleviate desert locust-related agriculture damages. The unusual characteristics of the desert locust, as well as the size and frequency of swarming events, make developing and implementing IPM measures difficult. The state of prospective integrated measures to control locusts is discussed, as well as proactive and preventive intervention options.

Novel Fungal and Bacterial Species exploited for the control of Locust

Insects like locusts and grasshoppers are one of the most dangerous bio-pests of cash crop. The locust control requires constant attentiveness. They could cause around 20 million people to be left without products of agriculture and that is only in Asia. Locusts attacked Khyber Pakhtunkhwa and Baluchistan provinces of Pakistan first in June 2019 moving towards Sindh and Southern Punjab. According to the Food and Agriculture Organization (FAO) 2020 the financial damages are range from 353 billion to 464 billion Pakistani rupees. The current environmental issues and high price of insecticides are increasing the demand of biological control. In this paper we have reviewed the microbes that can be effectively used to control locust attack in Pakistan

Study on the Forming Mechanism of the High-Density Spot of Locust Coupled with Habitat Dynamic Changes and Meteorological Conditions Based on Time-Series Remote Sensing Images

The outbreak of the Asian migratory locust (Locusta migratoria migratoria) (AML) can deal a great blow to agriculture and grassland farming. The emergence of high-density locusts facilitates the outbreak of locusts. Understanding the forming mechanism of the high-density spot of locust (HDSL) is very important for locust monitoring and control. To achieve this goal, this paper took Nong’an County, which used to form an HDSL in 2017, as the study area. Firstly, based on the habitat classification system, support vector machine (SVM), random forest (RF), and maximum likelihood (ML) methods were employed to explore the best classification method for locust habitats. Then, the optimal method was applied to monitor habitat dynamic changes from 2014 to 2017 in the HDSL in Nong’an. Finally, the HDSL forming mechanism was clarified coupled with habitat dynamic changes and meteorological data. The results showed that the SVM method was the optimal method, with an accuracy of 95.28%, which is higher than the RF and ML methods by 0.25% and 8.52%, respectively. The annual increased barren land and sufficient reeds provided adequate suitable habitats for the breeding of AML. From 2014 to 2016, the temperatures during the overwintering and hatching periods were higher than the 2010–2018 average, and the precipitation during the spawning period was lower than the 2010–2018 average. The precipitation during the growing period in 2017 was 30.8 mm less than the average from 2010 to 2018. All these characteristics were conducive to the reproduction of locusts. We concluded that the suitable habitat and meteorological conditions increased the locust quantity yearly, resulting in the formation of HDSL. These results are instrumental for monitoring potential high-risk outbreak areas, which is important to improve locust control and ensure food security.

A General Review of Desert Locust – Schistoceragregaria

Locusts (Orthoptera Acridoidea) are the most dangerous agricultural pests. Their control is critical to food security worldwide and often requires governmental or international involvement. Although locust outbreak is now better controlled and often shorter in duration and reduced in extent, large outbreaks, often promoted by climate change continue to occur in many parts of the world. While some Locust control system are still curative, the recognition of the damage these pests can cause and the socio-economic consequences of Locust outbreaks have led to an increased paradigm shift from crop protection to preventive management.

Construction of Homozygous Mutants of Migratory Locust using CRISPR/Cas9 Technology

The migratory locust, Locusta migratoria, is not only one of the worldwide plague locusts that caused huge economic losses to human beings but also an important research model for insect metamorphosis. The CRISPR/Cas9 system can accurately locate at a specific DNA locus and cleave within the target site, efficiently introducing double-strand breaks to induce target gene knockout or integrate new gene fragments into the specific locus. CRISPR/Cas9-mediated genome editing is a powerful tool for addressing questions encountered in locust research as well as a promising technology for locust control. This study provides a systematic protocol for CRISPR/Cas9-mediated gene knockout with the complex of Cas9 protein and single guide RNAs (sgRNAs) in migratory locusts. The selection of target sites and design of sgRNA are described in detail, followed by in vitro synthesis and verification of the sgRNAs. Subsequent procedures include egg raft collection and tanned-egg separation to achieve successful microinjection with low mortality rate, egg culture, preliminary estimation of the mutation rate, locust breeding as well as detection, preservation, and passage of the mutants to ensure population stability of the edited locusts. This method can be used as a reference for CRISPR/Cas9 based gene editing applications in migratory locusts as well as in other insects.

Construction of Homozygous Mutants of Migratory Locust using CRISPR/Cas9 Technology.

The migratory locust, Locusta migratoria, is not only one of the worldwide plague locusts that caused huge economic losses to human beings but also an important research model for insect metamorphosis. The CRISPR/Cas9 system can accurately locate at a specific DNA locus and cleave within the target site, efficiently introducing double-strand breaks to induce target gene knockout or integrate new gene fragments into the specific locus. CRISPR/Cas9-mediated genome editing is a powerful tool for addressing questions encountered in locust research as well as a promising technology for locust control. This study provides a systematic protocol for CRISPR/Cas9-mediated gene knockout with the complex of Cas9 protein and single guide RNAs (sgRNAs) in migratory locusts. The selection of target sites and design of sgRNA are described in detail, followed by in vitro synthesis and verification of the sgRNAs. Subsequent procedures include egg raft collection and tanned-egg separation to achieve successful microinjection with low mortality rate, egg culture,preliminary estimation of the mutation rate, locust breeding as well as detection, preservation, and passage of the mutants to ensure population stability of the edited locusts. This method can be used as a reference for CRISPR/Cas9 based gene editing applications in migratory locusts as well as in other insects.

A Landscape-Based Habitat Suitability Model (LHS Model) for Oriental Migratory Locust Area Extraction at Large Scales: A Case Study along the Middle and Lower Reaches of the Yellow River

The Oriental migratory locust is a destructive agricultural pest in China. Large-scale locust area (the area possessing suitable breeding habitat for locusts and has locust infestation) extraction and its evolution analysis are essential for locust ecological control. Existing methods seldom consider the spatial differences in the locust development and habitat landscape structures in large areas. To analyze these effects, our study proposed a landscape-based habitat suitability model (LHS model) for large-scale locust area extraction based on remote sensing data, taking the middle and lower reaches of the Yellow River (MLYR) as an example. Firstly, the DD model was used to simulate locust development and obtain habitat factors of the corresponding dates; secondly, the patch distribution of different land cover classes and their adjacent landscape characteristics were analyzed to determine the landscape-based factors memberships; finally, the habitat suitability index was calculated by combining the factors memberships and weights to extract the locust area. Compared with the patch-based model using moving windows (patch based-analytic hierarchy process model, R2 = 0.77), the LHS model accuracy improved significantly (R2 = 0.83). Our results showed that the LHS model has a better application prospect in large-scale locust area extraction. By analyzing the locust areas evolution along the MLYR extracted using the LHS model, we found human activities were the main factors affecting the locust areas evolution from 2016 to 2020, including: (1) planting the plants that locusts do not like and urbanization caused the decrease of the locust area; (2) the wetland protection policies may cause the increase of the locust area. The model and research results help locust control and prevention to realize the sustainable development of agriculture.

Desert Locust Episode in Pakistan, 2018–2021, and the Current Status of Integrated Desert Locust Management

AbstractDesert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), swarms during outbreaks, and plagues can invade many countries across vast regions of Africa and Asia, consuming substantial quantities of crops and rangeland vegetation. In the most recent desert locust episode, which originated in Saudi Arabia’s remote interior in June 2018, and swarms entered Pakistan in March 2019, devastating important crops, such as cotton, Gossypium hirsutum L.; wheat, Triticum aestivum L.; and maize, Zea mays L., in >60 districts of Baluchistan, Punjab, Khyber Pakhtunkhwa, and Sindh provinces. A national emergency was declared on 1 February 2020. A national emergency was declared on 1 February 2020 and the Department of Plant Protection responded by conducting surveillance and control operations with the assistance of other Pakistani organizations, and multilateral and bilateral international aid agencies. Surveillance and control operations were performed by ground and by air, applying mostly oil-based ultra-low volume insecticide formulations combined with some nonconventional control tactics. The Pakistan government also established a detailed multi-phased locust control policy and a National Locust Control Center with rapid response units deployed to vulnerable districts. To prevent or mitigate desert locust-associated agricultural damage, additional improvements to surveillance and control approaches are needed. The desert locust’s unique behaviors, and the magnitude and intermittency of swarming episodes, pose challenges to the development and implementation of coherent integrated pest management strategies. The status of a possible integrated approach to desert locust management, including proactive and preventive intervention strategies, is discussed.

УЧАСТИЕ ТУРКЕСТАНСКОГО ОТДЕЛА РУССКОГО ГЕОГРАФИЧЕСКОГО ОБЩЕСТВА В ПРАВИТЕЛЬСТВЕННЫХ ПРОГРАММАХ ПО ВОПРОСАМ ВОДОПОЛЬЗОВАНИЯ И ЗЕМЛЕУСТРОЙСТВА В ТУРКЕСТАНСКОМ КРАЕ В XIX-XX ВВ.

The article studies the role of the Turkestan Branch of the Russian Geographical Society in organizing the research of the hydrology and geology of the Turkestan Territory in the context of the colonial policy of the Russian Empire in the Central Asian region at the turn of the 19th–20th centuries. The Turkestan Branch of the Russian Geographical Society considered the organization of permanent hydrometric observation of the Aral Sea and the Central Asian rivers – the Amu Darya and Syr Darya as the most important direction of its activity. Organized and systematic study of the water areas in the Turkestan Territory should have contributed to erecting the irrigation and road structures, construction of canals and aryks (ditches), development of agriculture and farming that served the economic interests of the Russian government in the Turkestan Territory. In addition to the study of water and land use in Turkestan Territory, the article also analyses the issue of the development of the Hungry Steppe. A separate direction of scientific activity of the Turkestan Branch of the Russian Geographical Society was a series of expeditions aimed at studying biological properties of soil, locust control and mono-cultivation of cotton crops in Turkestan Territory. The author concludes that the systematic study of water and land resources of the Turkestan Territory was of practical importance in the development of Central Asia. The Russian government implemented long-term projects on erecting irrigation systems and a canal in the Hungry Steppe, and partially solved the issues of land use in the Turkestan Territory.

Impact of insecticides used in controlling desert locust (Schistocerca gregaria Forskal) and on crawling arthropods in Shieb, Eritrea

The experiment conducted at Shelshela, sub-region Shieb – Eritrea during November 2015 to February 2016 showed that the use of fenitrothion 96 per cent ULV and chlorpyrifos 45 per cent ULV to control locust led to significant reduction in arthropod population after 48 hrs of post-spray than the control plot. The fenitrothion treated plots generally showed more reduction in population count than chlorpyrifos. Fenitrothion treated plots recorded maximum reduction (89%) of formicids population. Whereas, chlorpyriphos recorded the lowest of carabids (52%). Population count of Gryllidae and Tenebrionidae showed slight improvement after a month of spray than others. Generally, a population reduction of 86.2 per cent in fenitrothion and 81.1 per cent in chlorpyrifos was recorded in first post-spray count of D3 as compared to pre-spray counts of D1 and D2. From the study it is also observed that Formicidae and Gryllidae can be used as bio-indicators during insecticide control of desert locust in the study areas.