The ability to detect, monitor, and forecast the movement of airborne plant pathogens in agricultural ecosystems is essential for developing rational approaches to managing these habitats. We developed an autonomous (self-controlling) unmanned aerial vehicle (UAV) platform for aerobiological sampling tens to hundreds of meters above agricultural fields. Autonomous UAVs have the potential to extend the range of aerobiological sampling, improve positional accuracy of sampling paths, and enable coordinated flight with multiple aircraft at different altitudes. We equipped a Senior Telemaster model airplane with two spore-sampling devices and a MicroPilot autonomous system, and we conducted over 60 autonomous microbe-sampling flights at Virginia Tech's Kentland Farm. To determine the most appropriate sampling path for aerobiological sampling, we explored a variety of different sampling patterns for our autonomous UAVs including multiple GPS waypoints plotted over a variety of spatial scales. We conducted a total of 25 autonomous aerobiological sampling flights for five different aerobiological sampling patterns. The pattern of a single waypoint exhibited the best flight characteristics with good positional accuracy and standard deviations in altitude from 1.6 to 2.8 meters. The four point pattern configured as a rectangle also demonstrated good flight characteristics and altitude standard deviations from 1.6 to 4.7 meters. / Master of Science

O Huanglongbing (HLB) é a doença mais limitante para a produção de citros no mundo na atualidade. A alta capacidade de disseminação das bactérias associadas ao HLB pode estar associada com a movimentação do psilídeo vetor, Diaphorina citri, não apenas entre pomares vizinhos, mas também a longas distâncias. A análise de comportamento de dispersão em populações de D. citri e outras espécies de Psylloidea foi abordada mediante o monitoramento espaço-temporal de populações de psilídeos em diferentes alturas e em planta. O monitoramento foi realizado em dois contextos da disseminação primária do HLB, sendo áreas circunvizinhas de pomares comerciais de citros com manejo convencional no Estado de São Paulo. O monitoramento em alturas foi realizado por meio de armadilhas adesivas amarelas alocadas em duas alturas (2,5 e 7,5 m) e armadilha de sucção estacionária. Nos pontos monitorados foram selecionadas plantas hospedeiras de D. citri, amostradas quinzenalmente por meio de rede de varredura e armadilha de sucção portátil. Nos dois contextos foi encontrada correlação positiva entre abundância das espécies de psilídeos em relação às alturas e as épocas de monitoramento. No contexto de \"plantas de fundo de quintal\" coletaram-se 48.8% de psilídeos a 2,5 m e 51.2% a 7,5 m. No contexto de \"pomares com manejo deficiente\" foi encontrado 48.4% dos indivíduos a 2,5 m e 51.6% a 7,5 m. Foram coletados 148.802 espécimes de psilídeos por meio de armadilhas adesivas amarelas, pertencentes a 6 famílias e 24 gêneros, sendo que as espécies mais frequentes e constantes foram Heteropsylla sp., Isogonoceraia divergipennis, Mitrapsylla spp., Glycaspis brimblecombei e Trioza sp. No contexto de \"plantas de fundo de quintal\" a frequência de D. citri em alturas foi 1.5% e em planta foi 70.3%. No contexto de pomares com manejo deficiente, a frequência de D. citri em alturas foi 0.11% e em planta foi 81.8%. A maior densidade de psilídeos (incluindo D. citri) ocorreu do final do inverno até o começo do verão, sendo particularmente concentrada na primavera em ambos os contextos tanto nas áreas circunvizinhas como na borda dos pomares comerciais de citros. CLas foi detectada em 40% dos indivíduos de D. citri encontrados a 7,5 m e em 63.3% dos indivíduos coletados em plantas cítricas. A detecção de CLas foi negativa para as outras espécies de Psylloidea coletadas em altura e em plantas hospedeiras de D. citri. A correlação positiva entre psilídeos coletados a 2,5 m e 7,5 m evidencia possíveis movimentos de ascensão vertical nas camadas atmosféricas. A coleta de psilídeos a alturas superiores à da copa de plantas cítricas (como 7,5 m) evidencia possíveis movimentos de longa distância, sugerindo que os insetos estejam sendo transportados pelo vento. A análise da ocorrência espaço-temporal de Psylloidea em armadilhas adesivas pode auxiliar na previsão de movimentos a curta e longa distância de D. citri. / Huanglongbing (HLB) is the most limiting disease for the production of Citrus in the world today. The high dissemination capacity of the HLB-associated bacteria may be associated with the movement of the psyllid vector, Diaphorina citri, not only between neighboring groves, but also at long distances. The dispersion behavior analysis in populations of D. citri and other species of Psylloidea was approached through the spatio-temporal analysis of psyllid populations at different heights and plants. The monitoring was carried out in two contexts of the primary spread of HLB, in areas surrounding commercially managed groves in the State of São Paulo. Monitoring at heights was performed using yellow sticky traps allocated at two heights (2.5 and 7.5 m) and a stationery suction-trap. At the monitored points, host plants of D. citri were sampled biweekly by means of a sweep net and a portable suction device. In both contexts a positive correlation was found between the abundance of the species of psyllids in relation to the heights and the seasons of monitoring. In the context of backyard plants, 48.8% of the psyllids were collected at 2.5 m and 51.2% at 7.5m. In the context of poor management groves, 48.4% of the individuals were found at 2.5 m and 51.6% at 7.5 m. A total of 148,802 specimens of psyllids were collected using yellow sticky traps belonging to 6 families and 24 genera. The most frequent and constant species were Heteropsylla sp., Isogonoceraia divergipennis, Mitrapsylla spp., Glycaspis brimblecombei and Trioza sp. In the context of backyard plants the frequency of D. citri at the two sampling heights was 1.5% and on plants was 70.3%. In the context of poor management groves, the frequency of D. citri at the two heights was 0.11% and in plant was 81.8%. The highest density of psyllids occurred from late winter to early summer, but particularly concentrated in the spring in both contexts. Similarly, D. citri showed a population peak in the spring, both in the surrounding areas and on the edge of commercially managed Citrus groves. CLas was detected in 40% of the D. citri individuals found at 7.5 m and in 63.3% of the individuals collected on Citrus plants. The detection of CLas was negative for the other species of Psylloidea collected by yellow sticky traps and on host plants of D. citri. The positive correlation between psyllids collected at 2.5 m and 7.5 m shows possible vertical ascending movements in the atmospheric layers. The collection of psyllids at heights higher than the canopy of Citrus plants (e.g. 7.5 m) shows possible long distance movements, suggesting that the insects are being carried by the wind. The spatio-temporal analysis of Psylloidea in yellow sticky traps may aid in the prediction of short and long distance movements of D. citri.

A system was developed to perform real-time biological threat agent (BTA) detection with a small autonomous unmanned aerial vehicle (UAV). Biological sensors just recently reached a level of miniaturization and sensitivity that made UAV integration a feasible task. A Surface Plasmon Resonance (SPR) biosensor was integrated for the first time into a small UAV platform, allowing the UAV platform to collect and then quantify the concentration of an aerosolized biological agent in real-time. A sensor operator ran the SPR unit through a groundstation laptop and was able to wirelessly view detection results in real time. An aerial sampling mechanism was also developed for use with the SPR sensor. The collection system utilized a custom impinger setup to collect and concentrate aerosolized particles. The particles were then relocated and pressurized for use with the SPR sensor. The sampling system was tested by flying the UAV through a ground based plume of water soluble dye. During a second flight test utilizing the onboard SPR sensor, a sucrose solution was autonomously aerosolized, collected, and then detected by the combined sampling and SPR sensor subsystems, validating the system\'s functionality. The real-time BTA detection system has paved the way for future work quantifying biological agents in the atmosphere and performing source localization procedures. / Master of Science