Plant Defence

Main conclusion

Coleoptera, the largest and the most diverse Insecta order, is characterized by multiple adaptations to plant feeding. Insect-associated microorganisms can be important mediators and modulators of interactions between insects and plants.

Interactions between plants and insects are highly complex and involve multiple factors. There are various defense mechanisms initiated by plants upon attack by herbivorous insects, including the development of morphological structures and the synthesis of toxic secondary metabolites and volatiles. In turn, herbivores have adapted to feeding on plants and further sophisticated adaptations to overcome plant responses may continue to evolve. Herbivorous insects may detoxify toxic phytocompounds, sequester poisonous plant factors, and alter their own overall gene expression pattern. Moreover, insects are associated with microbes, which not only considerably affect insects, but can also modify plant defense responses to the benefit of their host. Plants are also frequently associated with endophytes, which may act as bioinsecticides. Therefore, it is very important to consider the factors influencing the interaction between plants and insects. Herbivorous insects cause considerable damage to global crop production. Coleoptera is the largest and the most diverse order in the class Insecta. In this review, various aspects of the interactions among insects, microbes, and plants are described with a focus on coleopteran species, their bacterial symbionts, and their plant hosts to demonstrate that many factors contribute to the success of coleopteran herbivory.

SUMMARY Control of grapevine virus and phytoplasma diseases is currently based on prophylactic measures and cultur- al practices. Certification programs aim to avoid the in- troduction of diseased grapevines into healthy vine- yards, and cultural practices aim to reduce the popula- tions of virus vectors to limit virus spread. These ap- proaches however are of limited effectiveness. Addition- ally, there

SUMMARY The objective of this paper is to describe the various measures investigated to secure the behaviour of Oman-UAE interconnected power system when facing large disturbances. When occurring, the activation of the defence plan maintains or restores the stability of the interconnected system but also to limit the spreading of the disturbance or the instability phenomena to large portions of the power system. The main defence plan and emergency actions of concern are: • Defence actions against frequency instabilities which lead (most of the time) to the activation of the Under Frequency Load Shedding (UFLS). The paper assesses the need to harmonize the two existing UFLS plans to avoid unnecessary power transfer during transients involving the activation of UFLS plans. • Defence actions against loss of synchronism which could take place following various circumstances such as the occurrence of faults with delayed clearing or uncontrolled development of undamped power swings between various parts of the interconnected system. The most common loss of synchronism defence action is the detection and splitting of the portion of the system that lost synchronism. In the frame of the Oman-UAE interconnection, it would consist of the disconnection of the interconnector or the portions of the system that would have lost synchronism. A large number of severe contingencies have been simulated to locate the coherent group of generators following a loss of synchronism. These have been achieved by the simulation of 3-phase faults cleared in backup time close to 220 kV substations leading to the loss of two circuits or one 220 kV circuit and one transformer. The cases leading to the loss of synchronism of a set of generators have been detected. These cases should be addressed with adequately located and tuned out of step protections. In some situations the system splits into two or more coherent groups of generators. Simulations of faults cleared in backup time have shown that in very unlikely Oman exporting situations, the transmission system or part of it may lose synchronism with respect to the UAE system.

Globally, cassava is the second most important root crop after potatoes and the fifth most important crop overall in terms of human caloric intake. In addition to its growing global importance for feed, fuel, and starch, cassava has long been vital to food security in Sub-Saharan Africa. Climate change is expected to have its most severe impact on crops in food insecure regions, yet little is known about how cassava productivity will respond to climate change. The most important driver of climate change is globally increasing atmospheric CO2 concentration ([CO2]). However, the potential for cassava to enhance food security in an elevated [CO2] world is uncertain as greenhouse and open top chamber (OTC) study reports are ambiguous. Studies have yielded misleading results in the past regarding the effect of elevated [CO2] on crop productivity, particularly in cases where pots restricted sink growth. To resolve these conflicting results, we compare the response of cassava to growth at ambient (ca. 385 ppm) and elevated [CO2] (585 ppm) under field conditions and fully open air [CO2] elevation. After three and half months of growth at elevated [CO2], above ground biomass was 30% greater and cassava root tuber dry mass increased over 100% (fresh weight increased 89%). High photosynthetic rates and photosynthetic stimulation by elevated [CO2], larger canopies, and a large sink capacity all contributed to cassava’s growth and yield stimulation. Cassava exhibited photosynthetic acclimation via decreased Rubisco capacity early in the season prior to root tuber initiation when sink capacity was smaller. Importantly, and in contrast to a greenhouse study, we found no evidence of increased leaf N or total cyanide concentration in elevated [CO2]. All of our results are consistent with theoretical expectations; however, the magnitude of the yield increase reported here surpasses all other C3 crops and thus exceeds expectations.