Drones: Innovative Technology for Use in Precision Pest Management.

Arthropod pest outbreaks are unpredictable and not uniformly distributed within fields. Early outbreak detection and treatment application are inherent to effective pest management, allowing management decisions to be implemented before pests are well-established and crop losses accrue. Pest monitoring is time-consuming and may be hampered by lack of reliable or cost-effective sampling techniques. Thus, we argue that an important research challenge associated with enhanced sustainability of pest management in modern agriculture is developing and promoting improved crop monitoring procedures. Biotic stress, such as herbivory by arthropod pests, elicits physiological defense responses in plants, leading to changes in leaf reflectance. Advanced imaging technologies can detect such changes, and can, therefore, be used as noninvasive crop monitoring methods. Furthermore, novel methods of treatment precision application are required. Both sensing and actuation technologies can be mounted on equipment moving through fields (e.g., irrigation equipment), on (un)manned driving vehicles, and on small drones. In this review, we focus specifically on use of small unmanned aerial robots, or small drones, in agricultural systems. Acquired and processed canopy reflectance data obtained with sensing drones could potentially be transmitted as a digital map to guide a second type of drone, actuation drones, to deliver solutions to the identified pest hotspots, such as precision releases of natural enemies and/or precision-sprays of pesticides. We emphasize how sustainable pest management in 21st-century agriculture will depend heavily on novel technologies, and how this trend will lead to a growing need for multi-disciplinary research collaborations between agronomists, ecologists, software programmers, and engineers

Concurrent herbivory and metal accumulation: The outcome for plants and herbivores

The effects of metals on plants and herbivores, as well as the interaction among the latter, are well documented. However, the effects of simultaneous herbivory and metal accumulation remain poorly studied. Here, we shed light on this topic by infesting cadmium-accumulating tomato plants (Solanum lycopersicum), either exposed to cadmium or not, with herbivorous spider mites, Tetranychus urticae or T. evansi during 14 days. Whereas on plants without cadmium T. evansi had higher growth rate than T. urticae, on plants with cadmium both mite species had similar growth rates, which were lower than on plants without metal. Plants were affected by both cadmium toxicity and by herbivory, as shown by leaf reflectance, but not on the same wavelengths. Moreover, changes in leaf reflectance on the wavelength affected by herbivores were similar on plants with and without cadmium, and vice versa. Long-term effects of cadmium and herbivory did not affect H2O2 concentrations in the plant. Finally, plants infested with spider mites did not accumulate more cadmium, suggesting that metal accumulation is not induced by herbivory. We thus conclude that cadmium accumulation affects two congeneric herbivore species differently and that the effects of herbivory and cadmium toxicity on plants may be disentangled, via leaf reflectance, even during simultaneous exposure.info:eu-repo/semantics/publishedVersio

Evaluation of The Magnitude of Citus Yield Losses Due to African Citrus Triozid, False Codling Moth, the Greening Disease and Other Pests of Economic Importance in Kenya

Pests and diseases have continued to hamper productivity of the horticultural inductry round the globe. The Kenyan citrus industry is no exemption with a huge decline on its perfomance over the last decade. Although faced with numerous challenges including low productivity, inadequate capacity to buy farm inputs, lack of improved crop varieties, insect pests and diseases are cited to be the most appalling attribute to the decline in citrus productivity. Key among them are the African Citrus Triozid (ACT) and False Codling Moth (FCM) pests and the Greening disease. The objective of this paper was to evaluate the magnitude of citrus yield losses due to these three major pests and disease. Primary data was utilized and obtained from farmers and key informants from two major citrus producing counties in Kenya. Results on magnitude of citrus yield losses show that ACT, HLB and FCM leads to proportional losses of 8.6%, 10.6% and 15.86% respectively. This translates to economic losses of USD 933.88, 1528.27 and 2396 per hectare due to ACT, HLB and FCM respectively. The losses impact significantly on the livelihoods of the citrus farmers, and thus may render the citrus industry unsustainable if no intervention measures are put in place. Keywords: False Codling Moth, African Citrus Trioza, Greening disease, citrus, Yield loss DOI: 10.7176/JESD/10-20-11 Publication date:October 31st 201

Differential responses of trees to temperature variation during the chilling and forcing phases

AbstractTemperate-zone trees must fulfill cultivar-specific chilling and heat requirements during the dormant period, in order to produce leaves and flowers in the following growing season. Timing and accumulation rate of chill and heat are understood to determine the timing of spring events, but both processes are difficult to observe in dormant tree buds. Where long-term phenological observations are available, Partial Least Squares (PLS) regression offers a statistical opportunity to delineate phases of chill and heat accumulation and determine the climatic requirements of trees. This study uses PLS regression to explore how the timing of spring events of chestnut in China, cherry in Germany and walnut in California is related to variation in the daily rates of chill and heat accumulation, as calculated with horticultural models. Dependent variables were 39 years of flowering dates for chestnuts in Beijing (China), 25 years of cherry bloom in Klein-Altendorf (Germany) and 54 years of walnut leaf emergence in Davis (California, USA). These were related to daily accumulation rates of chill, calculated with the Dynamic Model, and heat, calculated with the Growing Degree Hours Model. Compared to an earlier version of the procedure, in which phenological dates were related to unprocessed temperature data, delineation of chilling and forcing phases was much clearer when using horticultural metrics to quantify chill and heat. Chestnut bloom in the cold-winter climate of Beijing was found to depend primarily on the rate of heat accumulation, while cherry bloom in the temperate climate of Germany showed dependence on both chill and heat accumulation rates. The timing of walnut leaf emergence in the mild-winter climate of California depended much more strongly on chill accumulation rates. Chilling (in Chill Portions=CP) and heat (in Growing Degree Hours=GDH) requirements determined based on PLS regression were 79.8±5.3 CP and 13,466±1918 GDH for chestnut bloom in Beijing, 104.2±8.9 CP and 2698±1183 GDH for cherry bloom in Germany, and 37.5±5.0 CP and 11,245±1697 GDH for walnut leaf emergence in California. Spring phases of cherry in Klein-Altendorf and especially chestnut in Beijing will likely continue to advance in response to global warming, while for walnut in California, inadequate chilling may cause delays in flowering and leaf emergence. Such delays could serve as an early-warning indicator that future productivity may be threatened by climate change. The R package ‘chillR’ makes the method used in this study available for wider use

Utah Science Vol. 52 No. 3, Fall 1991

88The Dean Retires After 21 Year at the Helm Sustainable Agriculture Takes Root in Utah 90 Computer Program Help Agriculture Prepare for Environrnental Regulations 92 Sustainable Agriculture: Easy to Support, Difficult to Implement 97 The Fieldwork of Innovation Better Methods of Pest Control 99 Several Insects Promise to Control Weeds 102 New Farming Tactics May Not Reduce Need for Herbicides 104 Studies Examine Biocontrol of Russian Wheat Aphid 105 Research in Brief Conserving and Protecting Water 109 Conserving Water by a Reduction in Leaching 110 Is There Enough Water for Both Farms and Cities along the Wasatch Front? Range Management 113 Helping Ranchers Make the Right Choices 114 Training Livestock Could Cut Oil, Pesticide Use 115 A Ban on Grazing Unlikely to Improve Some Rangeland 118 Saving Endangered Plant while Stopping Grasshoppers Orchard Management 121 Integrated Pest Management Gain a Foothold in Fruit Orchards 125 Study Weigh Advantage, Disadvantage

Pathogen Population Biology Research can Reduce International Threats to Tree Health Posed by Invasive Fungi

Humankind owes much to trees, given their major role in sequestering carbon and providing oxygen, sugars and much of the energy on which ourselves and terrestrial ecosystems depend. Trees and forests are important culturally, economically, environmentally and socially. And yet, despite this, trees throughout the world are currently facing an increasing number of serious challenges. On a global scale, Curtis et al. (2018) report most forest loss is due to commodity driven deforestation through permanent conversion to nonforest land uses including agriculture (e.g. palm oil production), energy production and mining. The other main drivers of global forest loss, that might instead be considered less permanent and associated with subsequent regrowth, include forestry, shifting agriculture and wildfire. Additional threats to forests include those posed by climate change, and invasive biotic agents such as insect pests and pathogens. Most new tree disease outbreaks are due to introduction events, with a potential pathogen introduced from their endemic centres of origin (where they generally cause little or no disease on their plant host due to long-term coevolution) into a new geographic location, in which a naive host has not previously been exposed and can thus be highly susceptible. The incidence of such 'new encounter' diseases is increasing at an unprecedented rate due to globalisation with increased international trade in plants and travel, a scenario potentially exacerbated by a changing climate better suited to establishment of a pathogen once introduced. Identification of the centres of origin of fungal pathogens can be important for several reasons. First, given that the original host-fungus interaction will have typically stabilised over long periods of time, such geographic regions could be useful sources of host genetic resistance. Moreover, the longer time periods involved will have likely resulted in greater genetic diversity accruing in such endemic populations. More diverse pathogen populations have greater evolutionary potential, with increased genetic variation available for response to environmental change. This could enable host tolerance to be overcome, unexpected 'jumps' onto new hosts, increased risk of fungicide resistance, and better adaptability to changing environmental conditions (e.g. temperature). Thus, strategies to reduce introduction of additional genetic variation from source to sink regions can reduce tree health threats. In this article, such introduction events are considered in the context of three devastating tree diseases, namely ash dieback, Dutch Elm Disease (DED) and Dothistroma Needle Blight (DNB, mainly on pine). On all these tree hosts, multiple closely-related fungal species have now been associated with each of these different diseases. Such related species are often morphologically very similar or even indistinguishable by eye, and consequently this can result in taxonomic confusion and species misidentification, leading to delayed diagnosis of the true causal agent of a given disease outbreak. Research into such related species is important as they might pose very different plant health threats that require distinct disease management strategies. These differences might relate to pathogenicity, geographic distribution, host range, effectiveness of host resistance, sensitivity to fungicides, temperature optima, reproductive strategy and so on. Furthermore, when related fungal species come into physical contact with each other after a long period of separation, for instance via an introduction event, various outcomes are possible including: (1) replacement (and possible extinction) of one species by the other; (2) coexistence of the species; or (3) cross-species hybridisation. The remainder of this article focuses, using three major tree disease case histories, on how fundamental research on pathogen biology can provide new insights into the genetic structure of related pathogen populations that can be usefully applied to reduce the threat to tree health posed by invasive fungal species

Fruit Tree Responses to Water Stress: Automated Physiological Measurements and Rootstock Responses

New orchard plantings utilize trees grafted to dwarfing rootstocks planted close together to facilitate larger harvests. These dwarfing rootstocks have not been comprehensively studied for their ability to withstand drought. This is of special importance in the Intermountain West which has limited rainfall. Additionally, orchard growers face competition for water from a growing population and increased uncertainty in rainfall from climate change. My research examined the use of dendrometers, which measure changes in trunk diameter, and sap flow sensors, which measure how quickly sap moves, as methods to inform growers about tree water status. I also used a weighing lysimeter system to measure tree water use in four different rootstocks as they were subjected to drought. In a field study, I placed dendrometers and sap flow sensors in a high-density apple orchard. As the trees progressed through the season and put on fruit the responses from the sensors changed. By separating data from the sap flow sensors and dendrometers into seasons, their ability to predict tree water status improved. I found that overall dendrometers would be the best way to automate measurements of tree water status. In my first rootstock trial I examined responses of peach trees grown from seeds from an orchard maintained by Navajo farmers in South Western Utah, and a commercially available rootstock. I found that the Navajo peach trees put on more growth than the commercial trees despite drought, which suggests that they may be useful for rootstock development. In my second rootstock trial I examine the commercially available Krymsk® 5 and 6 series dwarfing cherry rootstocks for responses to drought. I found that the Krymsk® 6 rootstocks had higher rates of transpiration and used water faster than the Krymsk® 5 allowing them to put on growth quickly even during drought. Krymsk® 5 rootstocks have a lower percentage of their biomass in their roots which may have helped to conserve water

Proceedings of the 5th International Symposium on Biological Control of Arthropods

This proceedings contains papers dealing with issues affecting biological control, particularly pertaining to the use of parasitoids and predators as biological control agents. This includes all approaches to biological control: conservation, augmentation, and importation of natural enemy species for the control of arthropod targets, as well as other transversal issues related to its implementation. It has 14 sessions addressing the most relevant and current topics in the field of biological control of arthropods: (i) Accidental introductions of biocontrol agens: positive and negative aspects; (ii) The importance of pre and post release genetics in biological control; (iii) How well do we understand non-target impacts in arthropod biological control; (iv) Regulation and access and benefit sharing policies relevant for classical biological control approaches; (v) The role of native and alien natural enemy diversity in biological control; (vi) Frontiers in forest insect control; (vii) Biocontrol marketplace I; (viii) Weed and arthropod biological control: mutual benefits and challenges; (ix) Maximizing opportunities for biological control in Asia's rapidly changing agro-environments; (x) Biological control based integrated pest management: does it work?; (xi) Exploring the compatibility of arthropod biological control and pesticides: models and data; (xii) Successes and uptake of arthropod biological control in developing countries; (xiii) Socio-economic impacts of biological control; (xiv) Biocontrol marketplace II

The distribution and performance of two herbivorous spider-mites living in heterogeneous environments

A qualidade das plantas para os herbívoros depende de características da planta (e.g. nutrientes e defesas), de fatores abióticos (e.g. metais) e da presença de outros herbívoros e antagonistas na planta. O intuito desta tese foi caracterizar o efeito de diferentes qualidades da planta nas interações planta-herbívoro e herbívoro-herbívoro nos ácaros-aranha, Tetranychus urticae e T.evansi. Primeiro descrevemos a criação de populações com elevada consanguinidade e com elevada diversidade, ferramentas com importantes aplicações em estudos laboratoriais, que utilizámos durante a tese. Depois, estudámos o efeito da competição interespecífica na distribuição dos ácaros na planta. Em plantas sem heterospecíficos ambas as espécies tiveram maior desempenho reprodutivo em folhas jovens, preferindo colonizar estas. Em plantas com heterospecíficos esta preferência perdeu-se, substituída por diferentes comportamentos em resposta aos heterospecíficos. T. urticae evitando folhas com o competidor e T. evansi distribuindo-se uniformemente entre as folhas. T. urticae também aumentou a dispersão de hospedeiros com T. evansi. Não encontrámos, no entanto, uma correlação genética entre o dano causado à planta e dispersão para outro hospedeiro. O desempenho reprodutivo das duas espécies também mostrou ser afetado da mesma forma pela acumulação de cádmio em tomateiros, correspondendo a uma resposta hormética. Durante exposições mais longas T. evansi mostrou ser mais negativamente afetado pela acumulação de cádmio do que T. urticae. Não houve interações entre a indução/supressão de defesas do tomateiro (inibidores de proteínas) e acumulação de cádmio, sendo este último um mecanismo passivo, não induzido por herbivoria. Finalmente, mostrámos variação intraespecífica nos ácaros, na resposta hormética à acumulação de cádmio em tomateiros, sendo a hormesis potenciada diretamente pelo metal e não por alterações na planta. Esta tese demonstra a importância do sistema planta-metal-ácaro no estudo das consequências ecológicas da acumulação de metais e revelou novas perspetivas sobre as interações entre T. urticae e T. evansi em diferentes contextos.Plant quality for herbivores depends on plant characteristics (e.g. nutrients and defences), abiotic conditions (e.g. metal contamination) and the presence of competitors and antagonistic species. The aim of this thesis was to characterize how differences in plant quality affect plant-herbivore and herbivore-herbivore interactions in two spider-mite species, Tetranychus urticae and T. evansi. First, we describe the creation of outbred and inbred populations, important biological tools in laboratory studies, which we use throughout the thesis. Subsequently, we tested how interspecific competition affected within- and between-plant dispersal. We show that the performance of both spider mite species was higher on younger leaves. Accordingly, they chose this stratum on clean plants. However, on plants with heterospecifis, T. urticae avoided younger leaves, whereas the distribution of T. evansi was more even across strata. The dispersal of T. urticae away from host plants also increased in presence of T. evansi. However, we did not find evidence for a genetic correlation between the damage inflicted on plants and dispersal propensity. The performance of the two species was also similar on tomato plants exposed to different cadmium concentrations, revealing a hormetic response in both. However, T. evansi is more affected by cadmium accumulation than T. urticae. Also, induction/suppression of proteinase inhibitors did not interact with cadmium accumulation and the latter mechanism was not inducible by herbivory. Finally, we showed intraspecific variation for cadmium-induced hormesis in spider mites, being this metal the main driver of the patterns observed, rather than changes in the plant. This thesis establishes the powerful cadmium-tomato-mite system in the study of ecological consequences of metal accumulation and provides novel insight into the interaction between T. urticae and T. evansi under different scenarios