Approximate Zero Polynomials of Polynomial Matrices and Linear Systems

The aim of this paper is to extend recent results on the approximate GCD of polynomials [1] and approximate zeros to the case of a polynomial matrices within the framework of exterior algebra [2]. The results provide the means to introduce a new characterization of approximate decoupling zeros and measures for approximate controllability and observability for the case of linear systems

Prospects of herbivore egg-killing plant defenses for sustainable crop protection

Due to a growing demand of food production worldwide, new strategies are suggested to allow for sustainable production of food with minimal effects on natural resources. A promising alternative to the application of chemical pesticides is the implementation of crops resistant to insect pests. Plants produce compounds that are harmful to a wide range of attackers, including insect pests; thus, exploitation of their natural defense system can be the key for the development of pest-resistant crops. Interestingly, some plants possess a unique first line of defense that eliminates the enemy before it becomes destructive: egg-killing. Insect eggs can trigger (1) direct defenses, mostly including plant cell tissue growth or cell death that lead to eggs desiccating, being crushed or falling off the plant or (2) indirect defenses, plant chemical cues recruiting natural enemies that kill the egg or hatching larvae (parasitoids). The consequences of plant responses to eggs are that insect larvae do not hatch or that they are impeded in development, and damage to the plant is reduced. Here, we provide an overview on the ubiquity and evolutionary history of egg-killing traits within the plant kingdom including crops. Up to now, little is known on the mechanisms and on the genetic basis of egg-killing traits. Making use of egg-killing defense traits in crops is a promising new way to sustainably reduce losses of crop yield. We provide suggestions for new breeding strategies to grow egg-killing crops and improve biological control

Attraction of Trichogramma Wasps to Butterfly Oviposition-Induced Plant Volatiles Depends on Brassica Species, Wasp Strain and Leaf Necrosis

Within the Brassicaceae, wild as well as crop species are challenged by specialist herbivores including cabbage white butterflies (Pieris spp.). The wild crucifer Brassica nigra responds to oviposition by Pieris butterflies by the synergistic expression of two egg-killing traits. Genotypes that express a hypersensitive response (HR)-like necrosis (direct egg-killing) also emit oviposition-induced plant volatiles (OIPVs) attracting Trichogramma egg parasitoids (indirect egg-killing). This so-called double defense line can result in high butterfly egg mortalities. It remains unknown whether this strategy is unique to B. nigra or more common in Brassica species. To test this, we examined the response of different Trichogramma evanescens lines to OIPVs emitted by B. nigra and three close relatives (Brassica napus, Brassica rapa, and Brassica oleracea). Furthermore, we evaluated whether HR-like necrosis played a role in the attraction toward plant volatiles. Our results show a specificity in wasp attraction to different plant species. Three out of four plant species attracted a specific T. evanescens strain, including the crops B. rapa and B. napus. Parasitoid attraction was positively affected by presence of HR-like necrosis in one plant species. Our findings imply that, despite being a true generalist in terms of host range, T. evanescens shows intraspecific variation during host searching, which should be taken into account when selecting parasitoid lines for biocontrol of certain crops. Finally, we conclude that also crop plants within the Brassicaceae family possess egg-killing traits and can exert the double-defense line which may enable effective selection of egg-killing defense traits by cabbage breeders

Finding an egg in a haystack: variation in chemical cue use by egg parasitoids of herbivorous insects

Egg parasitoids of herbivorous insects use an interplay of short -and long-range chemical cues emitted by hosts and host plants to find eggs to parasitize. Volatile compounds that attract egg parasitoids can be identified via behavioral assays and used to manipulate parasitoid behavior in the field for biological control of herbivorous pests. However, how and when a particular cue will be used varies over the life of an individual, as well as at and below species level. Future research should expand taxonomic coverage to explore variation in chemical cue use in more natural, dynamic settings. More nuanced understanding of the variability of egg parasitoid host-finding strategies will aid in disentangling the underlying genetics and further enhancing biological control

The Neotropical mirid predator Macrolophus basicornis uses volatile cues to avoid contacting old, Trichogramma pretiosum parasitized eggs of Tuta absoluta

Polyphagous mirid predators are increasingly used in commercial, augmentative biological control. Information about their foraging behaviour is essential, especially if one intends to use several natural enemies to control one or more pests in a crop, to detect if negative intraguild effects occur. We studied a case of intraguild predation (IGP) involving the predator Macrolophus basicornis (Stal) (Hemiptera Miridae) of the worldwide invasive South American tomato leaf miner Tuta absoluta (Meyrick) (Lepidoptera Gelechiidae) and explored how this predator deals with prey parasitized by Trichogramma pretiosum (Riley) (Hymenoptera Trichogrammatidae). Behavioural observations show that M. basicornis predators contacted significantly fewer old, parasitized eggs of T. absoluta than recently parasitized eggs. Olfactometer tests revealed that predators could smell differences between vola-tiles of tomato leaves infested with eggs of different qualities to locate suitable prey. They preferred volatiles from leaflets with unparasitized eggs above control leaflets and, moreover, preferred volatiles from leaflets with recently parasitized eggs over volatiles of leaflets with 5-day-old parasitized eggs. When predators and parasitoids are used together to control T. absoluta, parasitoids should be introduced one week before predators are released to prevent high levels of IGP

Intensity of intraguild predation of parasitized eggs by mirid predators depends on time since parasitization: a case study with the parasitoid Trichogramma pretiosum and the predator Macrolophus basicornis attacking Tuta absoluta eggs

Concurrent releases of several species of natural enemies for pest control have been studied in various crops with either positive, neutral, or negative results. To control the pest Tuta absoluta (Meyrick) (Lepidoptera Gelechiidae), only the egg parasitoid Trichogramma pretiosum Riley (Hymenoptera Trichogrammatidae) is applied on many hectares with tomatoes in South America. Use of the mirid predator Macrolophus basicornis Stal (Hemiptera Miridae) is considered either alone or in combination with the parasitoid T. pretiosum. To determine if intraguild relationships between the two natural enemies negatively affect concurrent releases, unparasitized eggs and eggs parasitized by T. pretiosum were exposed to the predator. Knowing which stages of parasitized eggs are consumed or rejected by the predator is important for development of a release strategy resulting in highest pest mortality. M. basicornis consumed 1-2 day old parasitized eggs as well as unparasitized eggs, and, consequently, expressed strong intraguild predation (IGP). Five and 9-day old parasitized eggs were often not consumed, and, therefore, exerted the phenomenon of competitive exclusion (CE). Predation rates of old parasitized eggs were very low and similar in no-choice and choice tests, and in experiments with a large (100), medium (50) and very limited (10) number of preys offered, demonstrating a strong CE effect. Interestingly, in choice experiments with unparasitized and old parasitized eggs, predators started to consume unparasitized eggs significantly later than when only unparasitized or young parasitized eggs were offered. This suggests that old, parasitized eggs in some way reduce the foraging activity of M. basicornis. We expect that stronger pest reduction by concurrent releases of both natural enemies will only occur at the start of the tomato production season and when the egg parasitoid is introduced seven days before the mirid predator in order to reduce intraguild predation of parasitized eggs by the predator

Numerical and Symbolical Methods for the GCD of Several Polynomials

The computation of the Greatest Common Divisor (GCD) of a set of polynomials is an important issue in computational mathematics and it is linked to Control Theory very strong. In this paper we present different matrix-based methods, which are developed for the efficient computation of the GCD of several polynomials. Some of these methods are naturally developed for dealing with numerical inaccuracies in the input data and produce meaningful approximate results. Therefore, we describe and compare numerically and symbolically methods such as the ERES, the Matrix Pencil and other resultant type methods, with respect to their complexity and effectiveness. The combination of numerical and symbolic operations suggests a new approach in software mathematical computations denoted as hybrid computations. This combination offers great advantages, especially when we are interested in finding approximate solutions. Finally the notion of approximate GCD is discussed and a useful criterion estimating the strength of a given approximate GCD is also developed

Development of an Unified Food Composition Database for the European Project “Stance4Health”

The European Commission funded project Stance4Health (S4H) aims to develop a complete personalised nutrition service. In order to succeed, sources of information on nutritional composition and other characteristics of foods need to be as comprehensive as possible. Food composition tables or databases (FCT/FCDB) are the most commonly used tools for this purpose. The aim of this study is to describe the harmonisation efforts carried out to obtain the Stance4Health FCDB. A total of 10 FCT/FCDB were selected from different countries and organizations. Data were classified using FoodEx2 and INFOODS tagnames to harmonise the information. Hazard analysis and critical control points analysis was applied as the quality control method. Data were processed by spreadsheets and MySQL. S4H’s FCDB is composed of 880 elements, including nutrients and bioactive compounds. A total of 2648 unified foods were used to complete the missing values of the national FCDB used. Recipes and dishes were estimated following EuroFIR standards via linked tables. S4H’s FCDB will be part of the smartphone app developed in the framework of the Stance4Health European project, which will be used in different personalized nutrition intervention studies. S4H FCDB has great perspectives, being one of the most complete in terms of number of harmonized foods, nutrients and bioactive compounds included.European Research Commission (Research Executive Agency) under the research project Stance4Health (Grant Contract No. 816303)“Plan propio de Investigación y Transferencia” of the University of Granada under the programs “Intensificación de la Investigación, modalidad B

The effects of low and high glycemic index foods on exercise performance and beta-endorphin responses

Τhe aim of this study was to examine the effects of the consumption of foods of various glycemic index values on performance, β-endorphin levels and substrate (fat and carbohydrate) utilization during prolonged exercise. Eight untrained healthy males underwent, in a randomized counterbalanced design, three experimental conditions under which they received carbohydrates (1.5 gr. kg-1 of body weight) of low glycemic index (LGI), high glycemic index (HGI) or placebo. Food was administered 30 min prior to exercise. Subjects cycled for 60 min at an intensity corresponding to 65% of VO2max, which was increased to 90% of VO2max, then they cycled until exhaustion and the time to exhaustion was recorded. Blood was collected prior to food consumption, 15 min prior to exercise, 0, 20, 40, and 60 min into exercise as well as at exhaustion. Blood was analyzed for β-endorphin, glucose, insulin, and lactate. The mean time to exhaustion did not differ between the three conditions (LGI = 3.2 ± 0.9 min; HGI = 2.9 ± 0.9 min; placebo = 2.7 ± 0.7 min). There was a significant interaction in glucose and insulin response (P < 0.05) with HGI exhibiting higher values before exercise. β-endorphin increased significantly (P < 0.05) at the end of exercise without, however, a significant interaction between the three conditions. Rate of perceived exertion, heart rate, ventilation, lactate, respiratory quotient and substrate oxidation rate did not differ between the three conditions. The present study indicates that ingestion of foods of different glycemic index 30 min prior to one hour cycling exercise does not result in significant changes in exercise performance, β-endorphin levels as well as carbohydrate and fat oxidation during exercise