Plant feeding by Nesidiocoris tenuis: Quantifying its behavioral and mechanical components

Zoophytophagous predators play an important, though sometimes controversial, role in pest management programs in different crops. In tomato crops, damage caused by phytophagy of the mirid Nesidiocoris tenuis has mainly been reported at high predator population levels or when prey is scarce. Previous research has focused on predator/prey ratios, stylet morphology and saliva composition to explain plant damage by N. tenuis. In this study, we investigated the behavioral and mechanical components of the damage. For this, we compared the feeding behaviors of males, females and fifth-instar nymphs of N. tenuis. Additionally, we investigated the type of stylet activities performed by each stage while probing in plant tissue, using the electrical penetration graph technique (EPG). Furthermore, stylectomy was performed and plant histology studied with the aim to correlate the feeding activities observed in the EPG recordings with stylet tip positions in specific tissues of the leaf petioles. Behavioral observations during a 30-min period showed that nymphs probed more frequently (38.6 ± 1.5 probes) than males and females (25.3 ± 1.1 and 24.3 ± 1.1 probes, respectively). Similarly, nymphs spent a higher proportion of time (656.0 ± 67.6 s) feeding on tomato apical sections compared to males and females (403.0 ± 48.8 s and 356.0 ± 43.7 s, respectively). The EPG recordings during 5 h indicated that cell-rupturing was the main stylet activity for all insect stages, and that fifth-instar nymphs spent a higher proportion of time on cell-rupturing events compared to adults. The histological studies revealed a trend of N. tenuis for the tissues within the vascular semi-ring. The stylet tips were found both in the vascular bundles and in the parenchyma of the interfascicular region. The findings of this study confirm an important role of fifth-instar nymphs feeding behavior in the damage potential of N. tenuis. Moreover, the increased time spent on cell rupturing behaviour suggests that stylet laceration and enzymatic maceration of the saliva occurring during this event might greatly contribute to the inflicted damage. A comprehensive understanding of the interactions of N. tenuis with the plant, at both the behavioral and mechanical levels, might shed light on new approaches to minimize its damage potential to tomato while maintaining its benefits as biocontrol agent

Exploring the potential for the selective breeding of Nesidiocoris Tenuis: A study of its genetics and feeding behavior

Nesidiocoris tenuis is a zoophytopbagous insect used in tomato crops to control key pests. Its ability to foed on plant tissues gives it the advantages to be able to establish in the crops before the arrival afthe pest, remain in the crop when pest levels are low as well as the activation afthe plant defenses against other herbivores. However, duo to!bis pbytopbagous bebavior it is reported as a pest in sorne countries. In the present thesis, the possibilities for the genetic improvement of N. tenuis were studied through the investigation of its population genetics, the genetic variability of its feeding behavior and the mechanical and behavioral components of its phytophagy.Nesidiocoris tenuis es un insecto zoofitófago empIeado en cultivos de tomate para control de plagas clave. Su capacidad de alimentarse de tejidos vegetales le confiere ventajas para poder establecerse en los cultivos antes de la llegada de la plaga, permanecer en el cultivo cuando los niveles de plaga son bajos así como la activación de las defensas de la planta contra otros herbívoros. Sin embargo, debido a este comportamiento fitófago es reportado como plaga en algunos paises. En la presente tesis se estudiaron las posibilidades para la mejora genética de N. tenuis a través de la investigación de su genética de poblaciones, la variabilidad genética de su comportamiento alimenticio y los componentes mecánicos y de comportamiento de su fitofagia.Programa de Doctorat en Cièncie

Exploring the potential for the selective breeding of Nesidiocoris tenuis: a study of its genetics and feeding behavior

Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is a cosmopolitan zoophytophagous predator, which zoophagy and phytophagy have given it both the status as biocontrol agent and pest, respectively. Thus, it fits into the category of biocontrol agents with traits that hinder its performance. In regions where it is valued as a biocontrol agent, it is mainly released in tomato crops to suppress key pests such as Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) and Tuta absoluta Meyrick (Lepidoptera: Gelechiidae). Its role in the activation of plant defenses has also been confirmed more recently. However, its phytophagous behavior can inflict damage on tomato crops under circumstances of prey scarcity. This can produce esthetical or yield losses, or lead to the application of pesticides to reduce its population, thus disrupting the biocontrol programs. Selective breeding in N. tenuis have been suggested as an alternative to minimize the detrimental effects of its phytophagy, however, no genetic or genomic information on the species was reported to date

Genetic variation in the feeding behavior of isofemale lines of nesidiocoris tenuis

Zoophytophagous predators provide biocontrol services in various major crops of modern horticulture due to the combination of its predatory capacity and the induction of plant defenses derived from its phytophagy. However, under certain conditions of prey scarcity, these natural enemies can inflict plant damage. Exploitation of genetic variation and subsequent selective breeding on foraging traits is a potential alternative to overcome this inconvenience. In this study, we quantified the genetic variation of phytophagy and zoophagy of Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), a zoophytophagous predator widely used in tomato crops to suppress key pests. We compared nine isofemale lines on their capacity to produce necrotic rings and wilting on tomato plants as a proxy for phytophagy, as well as their efficacy to prey on Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs, as a proxy for zoophagy. Differences between isofemale lines in phytophagy and zoophagy indicated a genetic basis. Variation found in the zoophagy levels was larger than that in phytophagy levels. Our results showed that there is a genetic basis for the variation observed in the feeding behavior of isofemale lines of N. tenuis, highlighting the potential importance of selective breeding for such traits of biocontrol interest.</p

Selección genética de caracteres de interés en Nesidiocoris tenuis Reuter (Hemiptera: Miridae)

Nesidiocoris tenuis Reuter (Hemiptera: Miridae) es un depredador zoofitófago ampliamente utilizado en programas de control biológico en el cultivo de tomate en el sureste español. Debido a su amplia polifagia, este mírido permite un control eficaz de plagas clave, como Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) o Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). Sin embargo, debido a su comportamiento fitófago, N. tenuis puede dañar gravemente las plantas de tomate cuando el nivel de presas es escaso

Effective applications of genome projects: a tale of three biocontrol species

This is a presentation given the the 5th International Entomophagous Insect Conference in Kyoto, Japan, on October 18th, 2017. <div><br></div><div>Abstract:</div><div><br></div><div><p>Innovations within the realm of genetic sequencing have led to increased accessibility for biologists, both in terms of costs as well as the educational resources available, regardless of background. Our project is a prime example, comprising three different biocontrol species (parasitoid wasp <i>Trichogramma brassicae</i>, mirid bug <i>Nesidiocoris tenuis</i>, and predatory mite <i>Amblyseius swirskii</i>). The goal is to sequence, assemble, and annotate a whole genome for each species to better inform ongoing projects. With <i>T. brassicae</i>, strain-specific molecular markers would help determine if there are intraguild effects of mass releases. In the case of both <i>A. swirskii</i> and <i>N. tenuis</i>, the genome will aid trait identification for selective breeding as well as assist in phylogenetic studies by identifying molecular markers. </p><div><br></div> The applications of this project extend beyond biocontrol, and additional questions can be addressed. Did commercialization lead to genetic drift or laboratory adaptation of commercial populations? Is there an indication of less genetic variation in commercial populations compared to their native or wild counterparts? The best way to address these questions is via population genomics – comparison between populations on a genomic level. Here, we present the status of each genome and their applications, as well as the implications for future research.<br></div

Next Generation Biological Control: The Need for Integrating Genetics and Evolution

Biological control is widely successful for controlling pests, but effective biocontrol agents are now more difficult to obtain due to more restrictive international trade laws. Coupled with increasing demand, the efficacy of existing and new biocontrol agents needs to be improved with genetic and genomic approaches. Although they have been underutilised in the past, applying genetic and genomic techniques is becoming more feasible from both technological and economic perspectives. We review current methods and provide a framework for using them, incorporating evolutionary and ecological principles. First, it is necessary to identify which biocontrol trait to select and in what direction. Next, the genes or markers linked to these traits need be determined to better target their selection, followed by how to implement this information into a breeding program. Choosing a trait can be assisted by modelling to account for the proper agro-ecological context, and by knowing which traits have sufficiently high heritability values. We provide guidelines for designing genomic strategies in biocontrol programs, which depends on the organism, budget, and desired objective. Genomic approaches start with genome sequencing and assembly. We provide a guide for deciding the most successful sequencing strategy for biocontrol agents. Gene discovery involves quantitative trait loci (QTL) analyses, transcriptomic and proteomic studies, and gene editing. Improving biocontrol practices include marker-assisted selection, genomic selection and microbiome manipulation of biocontrol agents, and monitoring for genetic variation during rearing and post-release. We conclude by identifying the most promising applications of genetic and genomic methods to improve biological control efficacy

Next-generation biological control: the need for integrating genetics and genomics

Biological control is widely successful at controlling pests, but effective biocontrol agents are now more difficult to import from countries of origin due to more restrictive international trade laws (the Nagoya Protocol). Coupled with increasing demand, the efficacy of existing and new biocontrol agents needs to be improved with genetic and genomic approaches. Although they have been underutilised in the past, application of genetic and genomic techniques is becoming more feasible from both technological and economic perspectives. We review current methods and provide a framework for using them. First, it is necessary to identify which biocontrol trait to select and in what direction. Next, the genes or markers linked to these traits need be determined, including how to implement this information into a selective breeding program. Choosing a trait can be assisted by modelling to account for the proper agro‐ecological context, and by knowing which traits have sufficiently high heritability values. We provide guidelines for designing genomic strategies in biocontrol programs, which depend on the organism, budget, and desired objective. Genomic approaches start with genome sequencing and assembly. We provide a guide for deciding the most successful sequencing strategy for biocontrol agents. Gene discovery involves quantitative trait loci analyses, transcriptomic and proteomic studies, and gene editing. Improving biocontrol practices includes marker‐assisted selection, genomic selection and microbiome manipulation of biocontrol agents, and monitoring for genetic variation during rearing and post‐release. We conclude by identifying the most promising applications of genetic and genomic methods to improve biological control efficacy