Peter Burt

Windborne displacements of Desert Locusts from Africa to the Caribbean and South America

The Desert Locust is a major pest of agriculture in Africa, the Middle East and South-West Asia and swarms are known to make downwind flights over hundreds and thousands of kilometres between seasonal breeding areas. At the end of summer in 1988, swarms of locusts were moving north and south along the western margins of North Africa and in October and November, swarms crossed the Atlantic Ocean and invaded the Caribbean and neighbouring parts of South America for the first recorded time. Because of the extent of the migration and the evolutionary significance of linkages between Old and New World species of locusts, the weather associated with the migrations was studied and trajectory analysis was used to identify the source areas and estimate the flight times. Locusts were moving offshore from western North Africa throughout the autumn and on three occasions migrated west of 40° W with easterly Trade winds. Two trans-Atlantic crossings coincided with the passage of easterly waves. Over 100 trajectories were constructed at 950 and 850 hPa and within the time limit used (≤ 144-h), 28% successfully linked source and receptor areas. Minimum trajectory duration was 93-h, which is one-and-a-half times longer than the previously longest flight duration, derived for a similar migration to the British Isles in 1954. Upwind trajectories from the arrival areas, identified sources between 27 and 6° N in Africa, with most end-points located in Mauritania, Senegal, Gambia and Guinea-Bissau. Interspersed with the Atlantic crossings were a northward movement of locusts and an incursion of Saharan dust into Europe within the circulations of frontal depressions. While offshore migrations from northern Africa are common in autumn, the immigrants in the Caribbean and South America were probably at the extreme limits of flight endurance for the species. The results tend to confirm earlier hypotheses that New World species of locusts may have evolved from ancestral migrants from Africa.

Airborne spore loads and mesoscale dispersal of the fungal pathogens causing Sigatoka diseases in banana and plantain

The mesoscale dispersal of ascospores and conidia of the fungal pathogenMycosphaerella fijiensis, causing Black Sigatoka disease in banana and plantain, was investigated under field conditions in Costa Rica. Spores were sampled daily during the period April–August 1995, using three volumetric spore traps positioned in a 5 km straight line across the floor and up one side of a valley, to an elevation of 1000 m. The number of spores in each trap suggested that spores were not being released from nearby sources, but that they may have been transported from inoculum sources up to 40 km away. The implications of this when assessing the longer-distance transport of viable spores to new infection sites are discussed.

Effects of aeroallergens on the lung function of primary school children at two contrasting sites in South-East England

It is well known that airborne pollen canaffect lung function and general well-being. This is particularly true for individualspredisposed to respiratory complications (forexample sufferers from hay fever and asthma). Globally, there is evidence that asthmaincidence is increasing in children over 2years of age, and, within the UK, thesouth-east of England has the highest incidencefor all ages in the population.Variations in lung function of school children(measured as peak expiratory volume) withassociated changes in airborne pollen andpollution loads at two contrasting sites (oneurban, the other rural) within the Medway Townsin south-east England were measured during thepollen season in 1998. Children of similar agesand social backgrounds participated in thestudies, and account was taken of children withknown respiratory problems. Pollen, pollutionand weather data were collected at each site.A picture has been obtained of how changes inlocal and regional aeroallergen levels, as wellas other environmental factors, effect publichealth in this region of England. Children atthe urban site produced consistently betteraverage lung function results, although morepollen was caught there. At the rural sitethere was generally no relationship betweenpollen counts and lung function. As expected,lung function was lower on anticyclonic dayswhen there was less mixing in the air. Thereis strong evidence that episodes of airpollution were more important in promotingreduced peak expiratory flows than specificaeroallergen levels alone. Whilst thisrequires further investigation, it confirmsthat attributing changes in lung functionsolely to pollen levels may sometimes bemisleading.

Movement ofMycosphaerella fijiensis spores and sigatoka disease development on plantain close to an inoculum source

Investigations into the short-distance dispersal of ascospores and conidia ofMycosphaerella fijiensis and subsequent disease development, from point sources of inoculum, were carried out in a small plot of 100 initially uninfected plantain plants in Costa Rica during 1995. Plants were examined every 4 days from the time of planting in early May for the first appearance of disease symptoms. After 3 months, all plants were infected. Levels of inoculum within the plot were monitored with spore traps and weather data were collected. Results suggested that Black Sigatoka disease was spread on the wind, with conidia ofM. fijiensis probably responsible for short-distance dispersal and ascospores for spread of the disease over longer distances. No evidence was found to support splash dispersal of these spores.

Interpolation of Rainfall Through Polynomial Regression in the Marche Region (Central Italy)

Notwithstanding its small size (less than 10,000 km2), because of its varied topography, ranging from the Apennines Range (up to more than 2000 m amsl) to coastal environments, the Marche Region (the Adriatic side of Central Italy), is characterized by many different types of climate. In this region there are no fully satisfactory models to interpolate and generalize rainfall data from the 111 available meteorological recording stations; however, in this study an innovative way to interpret data linking precipitation to many topographic parameters is introduced. Based on those considerations, statistical analyses were carried out on rainfall historical series in order to assess significantly variations during the last 60 years and to create a model capable of explaining rainfall distribution based on geographical and topographic parameters. The model highlighted a significant decrease of rainfall from 1961–1990 to 1991–2016, over the whole period, in the hilly and mountainous sectors (100–200 mm), while closer to the coast the difference is slight (about 0–100 mm). The new model also highlights the presence of some outliers in the rainfall values, which may lead to a better comprehension of climatic dynamics in this area.

Suction trap catches of airborne insects in relation to convection in the lower atmosphere

Over the last 25 years, since the classic work of Johnson CG. (London: Methuen, 1969) there have been a number of reviews on weather and the movement of insects in the air. These reflect increased field research by entomologists and meteorologists, particularly with the advent of remote-sensing techniques. There is, however, a gap in the literature relating to the influence of convective structures in the atmosphere on insect movement on the small scale (within and between fields). Such papers that have been published on insects and convection tend to report associations with large-scale convective structures (often several hundred kilometres in extent) and generally treat the insects as inert ‘particles’. Conversely, the relatively well-researched subject of insect movement on the small scale tends not to discuss possible convective influences, even though these might have been present. This paper presents the results of a field investigation of the spatial and temporal distributions of insects arriving in a suction trap sampling at a height of 12.2 m over arable land in southern England. It was found that the majority of insects caught were non-randomly distributed in time. The association of such clumps with the passage of convective structures through the atmosphere is discussed.

Using temperature to predict the end of flowering in the common grape (Vitis vinifera) in the Macerata wine region, Italy

The growth of the grapevine is determined largely by temperature, thus it is essential to investigate the role of temperature in crop phenology. This study takes into account three diverse cultivars of grapevine never studied phenologically in this area, on three farms in the province of Macerata (Central Italy, east side).The end of flowering date was chosen for the significance of the growth transition from the plant to the berries. Preventive climate analysis was implemented by GIS software through the cokriging geostatistical method to spatialize temperature, using altitude as the independent variable. The phenological dates of the cultivars of grapevine were related to temperatures iteratively, creating a new method for calculating growing degree days, on the basis of 4 key (cardinal) temperatures which influence plant growth. This study represents the first step towards creating an identity card for the three studied grapevines, as a tool to improve quality and quantity of yield.

Environmental and health impacts of poultry manure disposal methods: a case study of Lagelu and Egbeda local government areas in Oyo State, Nigeria

Indiscriminate disposal of poultry manure has been identified as a major source of environmental degradation in production areas through air and water pollution associated with nitrogen and phosphorus emissions and losses from manure. Methods of disposing of poultry manure which might have negative consequences on the environment and the farmers were investigated in two Local Government Areas of Oyo State, Nigeria. Data collected using structured questionnaires as well as direct field observations from a random sample of 100 farming households showed that the commonly used methods of manure disposal are burning (87 households) and application on crops (9 households). Almost all of the farmers (99) had no proper manure management facilities. Ammonia is the major air pollutant perceived by 71 farmers in the study area. Farmers suffered from discomforts ranging from various combinations of sneezing (65%), eye irritation (38%), coughing (34%), headache (20%), stomach ache (13%) and diarrhoea (6%). The awareness of farmers and authorities needs to be raised regarding the management of poultry manure and the need for protective equipment during its disposal: 99 farmers had no formal training in safe handling and disposal of poultry manure. There should be stricter enforcement of existing environmental regulations and enactment of new legislation to minimize the threats that the farmers’ current practices pose to their health and to the environment.